Patent Application
20210338955
The present invention relates generally to medical suction catheter systems, and specifically to endotracheal tube inflatable cuff manometers.
Suction catheters are commonly used to aspirate tracheobronchial fluids in patients ventilated with endotracheal tube (ETT) and tracheostomy tube devices.
UK Publication GB 2482618 A to Einav et al., which is assigned to the assignee of the present application and is incorporated herein by reference, describes a multi-lumen catheter for multiple fluids conduction, including balloon inflation with air via an inflation lumen, suction via a suction lumen, and cleaning fluids delivery via a cleaning fluid-delivery lumen.
U.S. Pat. No. 8,999,074 to Zachar et al., which is assigned to the assignee of the present application and is incorporated herein by reference, describes a cleaning catheter that includes fluid-delivery and suction lumens. A flow regulator defines suction and fluid ports. A mechanical user control element is configured to mechanically and non-electrically set activation states of the flow regulator, and transition between first and third configurations via a second configuration. When the control element is in the first configuration, the flow regulator blocks fluid communication (a) between the suction port and the suction lumen and (b) between the fluid port and the fluid-delivery lumen. When the control element is in the second configuration, the flow regulator effects fluid communication between the suction port and the suction lumen, and blocks fluid communication between the fluid port and the fluid-delivery lumen. When the control element is in the third configuration, the flow regulator effects fluid communication (a) between the suction port and the suction lumen and (b) between the fluid port and the fluid-delivery lumen.
Some ETTs comprise an inflatable cuff, which forms a seal against the tracheal wall. This seal prevents gases from leaking past the cuff and allows positive pressure ventilation. Desired safe inflatable cuff pressure is in the range of 23-27 cm H2O, with optimal pressure about 25 cm H2O. Pressure above 30 cm H2O can cause irritation to the surrounding tracheal tissue. Extended duration of such high cuff pressure can interfere with oxygen flow to the tissue, causing tissue necrosis and a substantial wound. Low cuff balloon pressure, typically below 20 cm H2O, compromises the cuff sealing performance, and allows leakage into the lungs of subglottic fluids descending from above the balloon.
The external surface of inflatable cuffs is in communication with the ventilation pressure of the lungs. The pressure of the inflatable cuff cycles with the ventilation cycle. When an artificially-ventilated patient is also anesthetized, the plastic of the inflatable cuff absorbs the nitrous oxide (N2O) gas used in anesthesia, which increases pressure in the cuff.
In current clinical settings of intensive care patients, changes of body positioning lead to significant changes in cuff pressure in the range of 10-50 cm H2O, i.e., out of the safe range of 20-30 cm H2O, and certainly out of the desired range of 23-27 cm H2O. See, for example, Lizy C et al., “Cuff pressure of endotracheal tubes after changes in body position in critically ill patients treated with mechanical ventilation,” Am J Crit Care. 2014 January; 23(1):e1-8.
Therefore, there is a need to safely maintain the inflatable cuff pressure is in the range of 23-27 cm H2O, optimally about 25 cm H2O, and to avoid extended periods of pressure above 30 cm H2O. In particular, there is a need to suppress the fluctuations of pressure in clinical settings caused by patient change of body positions.
Currently, the most common practiced approach for ETT cuff pressure management is manual monitoring (using a manometer) and adjustment of cuff pressure, which contributes to ICU staff workload. It has been shown that up to eight manual adjustments of cuff pressure are required daily to maintain recommended cuff pressure ranges. Even so, the cuff pressure is uncontrolled during the long time periods between manual cuff adjustments. In addition, the manometer must be connected to and disconnected from the ETT cuff for each pressure measurement, which allows a small amount of air to escape from the ETT cuff. Still further, many conventional ETT manometers lose calibration relatively quickly.
Prior art cuff pressure regulators can be divided into two groups: (a) large bedside non-disposable expensive electric pump and electronic pressure monitors; and (b) small and light disposable non-electric limited-pressure reservoir compartments that must be filled manually. Use of disposable devices both prevents cross-contamination between patients and obviates the need for costly sterilization processes between patients. Moreover, the compactness of the disposable devices allows them to be attached on the ETT circuit and not occupy bedside space and an electric power cable connection.
Some applications of the present invention provide a cuff pressure stabilizer for use with a gas and a catheter, such as a tracheal ventilation tube that comprises inflatable cuff, an inflation lumen, and an inflation lumen proximal port. The cuff pressure stabilizer is configured to provide automatic pressure regulation of the inflatable cuff, while simultaneously continuously displaying the pressure in the inflatable cuff.
In some applications of the present invention, the cuff pressure stabilizer comprises (a) an inflation lumen proximal port connector, which is shaped to form an air-tight seal with the inflation lumen proximal port of tracheal ventilation tube, (b) a fluid reservoir, (c) a liquid column container, which is (i) open to the atmosphere at at least one site along the liquid column container, (ii) in fluid communication with the fluid reservoir, and (iii) in communication with the inflation lumen proximal port connector via the fluid reservoir and (d) a liquid, which is contained in the fluid reservoir and/or in liquid column container. Typically, the liquid has a density of between 1.5 and 5 g/cm3 at 4 degrees Celsius at 1 atm, and/or a density of between 1.5 and 5 g/cm3 at 20 degrees Celsius at 1 atm.
When the system is in equilibrium, the pressure of the gas in the fluid reservoir equals the pressure of the gas in the inflatable cuff. The cuff pressure stabilizer typically provides uninterrupted fluid communication between the inflatable cuff and the fluid reservoir, including during pressure measurement. The cuff pressure stabilizer has a plurality of pressure indicia markings distributed along the liquid column container for measuring a height of the liquid in the liquid column container. The liquid column container is typically used in an aligned orientation in which the pressure indicia markings reflect, to within 1 cm H2O (i.e., with no error or an error of no more than 1 cm H2O), pressure of the gas in the fluid reservoir at least in a relevant pressure range of 23-27 cm H2O, such as a range of 22-28 cm H2O, e.g., a range of 20-30 cm H2O. The pressure is read by comparing a level of fluid in the liquid column container with the pressure indicia markings, as is known in the manometer art.
For some applications, when the liquid column container is oriented in the aligned orientation, the liquid column container has an inner cross-sectional area, measured in a horizontal plane, of at least 0.16 cm2 (e.g., at least 0.25 cm2, 0.5 cm2, or 1 cm2) at a plurality of (such as at most or all) axial locations along the liquid column container corresponding to the pressure of the gas in the fluid reservoir at a respective plurality of pressures in the relevant pressure range. As a result of this relatively large cross-sectional area, the cuff pressure stabilizer regulates (i.e., reduces fluctuations) the pressure of the gas in the fluid reservoir at least for changes of gas volume in the range of 0-2 cc, and thus at a gas inlet and in the inflatable cuff, in addition to measuring the pressure. In contrast, conventional manometers only measure the pressure, without substantially affecting the pressure, as it is ideally and commonly the goal of measurement devices to not affect the measured target. For a given cuff of initial gas volume V, as the squeezing of the inflatable cuff by the trachea increases such that the available gas volume decreases, the volume of the gas in the inflatable cuff decreases by some fraction equal to the change in V divided by V because the cuff is nearly non-compliant. For endotracheal tubes without external regulation, this decrease in volume of the inflatable cuff results in an increase in pressure of the gas within the system, including within the inflatable cuff, since the gas contained in the cuff has no significant external volume to move into, in accordance with the ideal gas law; the opposite occurs when the level of squeezing on the cuff by the trachea decreases.
In experiments conducted by the inventors, the inventors found that, for real endotracheal tube cuff balloons of volumes around 10 cc, each 0.1 cc decrease in volume in the inflatable cuff resulted in about a 1 cm H2O increase in pressure in the system and the cuff, and each 0.1 cc increase in volume in the inflatable cuff resulted in about a 1 cm H2O decrease in pressure in the system and the cuff. This is a surprising significant departure from the ideal non-compliant gas law calculation which would predict a 0.01 cc volume change per 1 cm H2O pressure change. The inventors thus concluded that real endotracheal tube cuff balloons are in fact semi-compliant. Therefore, the mitigation volumes should be calculated based on the experimental finding. In clinical practice, the pressure in ETT inflatable cuffs generally varies +/−10 cm H2O from the typically target pressure of 25 cm H2O, i.e., varies between 15 and 35 cm H2O. Based on the above-mentioned experimental data, the inventors appreciated that the volume in ETT inflatable cuffs generally varies by +/−1 cc (+/−10 cm H2O times 0.1 cc/cm H2O), i.e., a total range of 2 cc, and, among a broader spectrum of patients, the volume of ETT inflatable cuffs generally varies by +/−20 cm H2O from the typically target pressure of 25 cm H2O, i.e., a total range of at least 4 cc.
The inventors appreciated that to the extent that the cuff pressure stabilizer is able to offset the changes in volume in the inflatable cuff, the pressure changes are also offset, thereby stabilizing the pressure in the inflatable cuff. The cuff pressure stabilizer is able to offset the changes in volume in the inflatable cuff because of the relatively large cross-sectional area of the liquid column container at the relevant pressure range, e.g., 23-27 cm H2O.
For example, assume that (a) the liquid comprises water, (b) the cross-sectional area of the liquid column container at the relevant pressure range is 1 cm2, (c) the pressure indicia markings are spaced at 1-cm intervals, and (d) the initial pressure in the inflatable cuff is 25 cm H2O. A decrease in volume of the inflatable cuff of 1 cc (caused by increased squeezing by the trachea) would displace from the inflatable cuff the excess 1 cc of gas into the fluid reservoir, and a corresponding additional 1 cc of water out of the fluid reservoir into the liquid column container. This additional 1 cc of water would fill an additional 1 cc of the fluid reservoir, raising the level of fluid by 1 cm, and thus the pressure in the inflatable cuff (as indicated by the pressure indicia markings) by 1 cm H2O, from 25 cm H2O to 26 cm H2O.
For a real inflatable cuff having a volume of 10 cc without attachment of the regulation system, a decrease in volume of the inflatable cuff of 1 cc would have resulted in an increase of the cuff pressure gas by about 10 cm H2O, based on the inventors' experimental data, i.e., the integration of the pressure regulator with the tracheal ventilation tube results in a factor of 10 suppression of the pressure change, resulting in the pressure regulation described herein.
Typically, the liquid column container is wider (i.e., has a greater cross-sectional area) in (a) a relevant-range fluid compartment that includes the relevant pressure range than in (b) a lower-range fluid compartment that reflects pressures of the gas in the fluid reservoir of less than 20 cm H2O. The narrower liquid column container in the lower-range fluid compartment reduces the total required amount of the liquid, which is useful in configurations in which the liquid comprises an expensive heavy liquid.
For some applications, the liquid column container is wider (i.e., has a greater cross-sectional area) in (a) a buffer fluid compartment that reflects pressures of the gas in the fluid reservoir of greater than 28 cm H2O, e.g., greater than 30 cm H2O that includes the relevant pressure range than in (b) the relevant-range fluid compartment that includes the relevant pressure range. The wider liquid column container in the buffer fluid compartment substantially reduces increases in pressure if the pressure should exceed the lower end of the pressure range of the buffer fluid compartment, because the buffer fluid compartment can hold a greater volume of liquid per unit of height than can the relevant-range fluid compartment.
For some applications, the liquid has a density of between 0.8 and 12 g/cm3 at 4 degrees Celsius at 1 atm, and/or a density of between 0.8 and 12 g/cm3 at 20 degrees Celsius at 1 atm. Typically, the density (whether at 4 degrees or at 20 degrees) is between 1.5 and 5 g/cm3, such as between 2 and 4 g/cm3, e.g., between 2.5 and 3.5 g/cm3 (all of these values are more dense than water and less dense than mercury). For some applications, the liquid is selected from the group consisting of: sodium polytungstate, sodium metatungstate, lithium polytungstate, and lithium metatungstate.
To the extent that the density of the liquid is greater than that of water, i.e., greater than 1 g/cm3 at 4 degrees Celsius at 1 atm, a shorter the liquid column container can be used to measure and regulate pressures, and the pressure indicia markings are closer together. Assuming a container of uniform cross section and a liquid column of uniform cross section, it follows that, if using a liquid of the density compared with using water, the distance between the pressure indicia markings for indicating a 1 cm H2O change in pressure equals the quotient of (a) 1 cm divided by (b) the density of the liquid at 4 degrees Celsius at 1 atm.
Typically, the liquid column container is open to the atmosphere at at least one site along the liquid column container. The liquid column container has first and second ends at opposite ends of the liquid column container. For some applications, the liquid column container is in fluid communication with the fluid reservoir via the first end, the at least one site is at the second end, and the liquid column container is open to the atmosphere at the second end. For some applications, the liquid column container defines an opening having an area of between 0.09 and 1 mm2, and the liquid column container is open to the atmosphere via the opening.
Typically, the volume of the liquid is less than the volume of the wider portion of the liquid column container in the relevant pressure range. Under normal working conditions, there is a fixed amount of gas enclosed between the cuff balloon and the liquid. As the pressure within the cuff changes, only the fraction of the gas is in the cuff and the fraction of the gas outside the cuff change. However, since the liquid total volume is less than the total volume of the gas in the cuff, there is an upper limit to the magnitude of volume variation in the cuff that can be offset by only movement of the liquid surface. Consequently, if the inflatable cuff is squeezed to a high threshold pressure at which all available liquid has moved into the wider portion of the liquid column container, further squeezing of the inflatable cuff releases gas bubbles through the liquid in the liquid column container and into fluid communication with the atmosphere, and thus prevents the pressure from further increasing within the inflatable cuff. If the volume of the liquid were instead greater than the volume of the wider portion of the liquid column container, some liquid would spill out of the liquid column container and prevent continued accurate function of the cuff pressure stabilizer. (A small amount of the liquid generally remains in the reservoir regardless of the pressure in the cuff because of the geometry of the interface between the reservoir and the liquid column container.) This arrangement effectively serves the same function as a maximum pressure release valve.
For some applications, the cuff pressure stabilizer further comprises (a) an inflation inlet port, which is coupleable with an external inflation source, such as a syringe, (b) a first connector tube, which couples the inflation lumen proximal port connector in fluid communication with the inflation inlet port, and (c) a second connector tube, which couples the gas inlet in fluid communication with the inflation inlet port, such that the inflation lumen proximal port connector is in fluid communication with the gas inlet via the first connector tube and the second connector tube. For some applications, the cuff pressure stabilizer further comprises an inlet junction, which comprises the inflation inlet port, and which couples in fluid communication the inflation inlet port, the first connector tube, and the second connector tube.
For some applications, when (a) the inflation lumen proximal port connector forms the air-tight seal with the inflation lumen proximal port of the tracheal ventilation tube and (b) a pressure of the gas of the gas in the fluid reservoir is 10 cm H2O, (i) a first combined air-flow resistance between the inflation inlet port and an interior of the inflatable cuff equals between 80% and 120% of (ii) a second combined air-flow resistance between inflation inlet port and the fluid reservoir, such as between 90% and 110%, e.g., between 95% and 105%. Typically, in order to achieve these relative air-flow resistances, the relative lengths of the first and second connector tubes are set such that the resistance of the second connector tube equals the sum of the resistance of the first connector tube and a fixed constant resistance of all elements of the tracheal ventilation tube in the flow path. This approximately equal air-flow resistance prevents transient false pressure readings immediately following inflation or reinflation of the inflatable cuff via the inflation inlet port, without being dependent on the technique of the healthcare worker. For example, if the resistance from the inflation inlet port were lower in the second connector tube (to the cuff pressure stabilizer) than in the first connector tube (to the inflatable cuff), during inflation initially a majority of the air would flow toward the cuff pressure stabilizer. As a result, the level of fluid in the liquid column container would indicate a higher pressure than the true pressure of the inflatable cuff. If the external inflation source were to be disconnected at this point in time, the pressure shown by the liquid column container would gradually decrease as pressure equilibrium between the inflatable cuff and the fluid reservoir is gradually reached.
For some applications, the cuff pressure stabilizer further comprises one or more connector tubes, which couple the inflation lumen proximal port connector in fluid communication with the gas inlet. When the inflation lumen proximal port connector forms the air-tight seal with the inflation lumen proximal port of the tracheal ventilation tube, a combined air-flow resistance between an interior of the inflatable cuff and the fluid reservoir is such that a transient pressure difference of 5 cm H2O between the interior of the inflatable cuff and the fluid reservoir results in less than a 0.05, a 0.02, or a 0.01 cc per second, fluid flow from the inflatable cuff into the fluid reservoir. The slow rate of flow delays the automatic pressure-regulation response from the cuff pressure stabilizer. A too rapid pressure-regulation response might underinflate the inflatable cuff during transient, short-term increases in pressure in the inflatable cuff, such as during the positive pressure phase of the ventilation cycle when high-pressure ventilation (generally greater than 25 cm H2O) is applied to the patient, generally for only a few seconds, typically less than 3 seconds.
For some applications, the liquid column container is arranged such that, when (a) the liquid column container is oriented in the aligned orientation and (b) the pressure of the gas in the fluid reservoir is 25 cm H2O: an increase in a volume of the gas in the fluid reservoir of up to 2 cc results in less than a 10 cm H2O increase in the pressure of the gas in the fluid reservoir, such as less than a 6 cm H2O increase in the pressure of the gas in the fluid reservoir, e.g., less than a 5 cm H2O or less than a 4 cm H2O increase.
Typically, the cuff pressure stabilizer does not comprise any membranes in contact with the liquid, and does not comprise any membranes in a fluid path between the liquid and the atmosphere.
In some applications of the present invention, the liquid column container is shaped so as to define a wider portion and a narrower portion axially between the wider portion and the fluid reservoir, and the cuff pressure stabilizer is arranged to provide an adjustable distance between a wider portion of the liquid column container and the fluid reservoir. Providing the adjustable difference allows a healthcare worker to optimize the cuff pressure stabilizer for a desired target pressure and target pressure range. For example, some patients that are ventilated at higher pressure need higher average cuff pressures, e.g., 28 cm H2O or 30 cm H2O, rather than the typical 25 cm H2O target. There is also a range of preferred target pressures even for patients ventilated at normal pressure, depending on the patient's particular circumstances and the medical opinion of the physician.
For some applications, the wider portion of the liquid column container has a target-pressure indicator marker, which is axially slidable with respect to the pressure indicia markings, which are typically provided on the casing. The healthcare worker may set the target-pressure indicator marker to indicate a desired target pressure in the inflatable cuff, and then inflate the inflatable cuff at least approximately to this target pressure. Such setting of the target-pressure indicator marker, by axially moving the target-pressure indicator marker with respect to the pressure indicia markings, has the effect of adjusting the adjustable distance between the wider portion of the liquid column container and the fluid reservoir. For some applications, at least an axial portion of the narrower portion of the liquid column container is flexible, so as to provide a variable axial length to the narrower portion.
For some applications, the narrower portion of the liquid column container is generally thin and flat, for example, shaped generally as a ribbon. For example, at each of all axial locations along the narrower portion of the liquid column container, the liquid column container may (a) have a largest inner dimension equal to a greatest distance between any two points within the liquid column container in (i) the above-mentioned horizontal plane, and/or (ii) a plane perpendicular to the longitudinal axis of the liquid column container, and (b) be able to encompass a largest circle in the horizontal plane. At most or all (e.g., all) of the axial locations along the narrower portion of the liquid column container, a ratio of (a) the largest inner dimension to (b) the diameter of the circle equals at least 2:1, such as at least 4:1, e.g., at least 8:1. For some applications, at most or all of the axial locations along the narrower portion of the liquid column container, the liquid column container has a non-circular cross-sectional shape, such as a rectangle, an oblong shape, an ellipse, or a crescent. Alternatively or additionally, for some applications, at each of the axial locations along the narrower portion of the liquid column container, at least 80% of the inner cross-sectional area is within 1 mm of an inner surface of the liquid column container, such as within 0.5 mm of the inner surface.
The relatively thin flat shape of the cross-sectional shape of the narrower portion of the liquid column container prevents gas bubbles from occluding the narrower portion. The surface tension of the bubble causes the bubble not to reach the edges of the liquid column container. By contrast, in configurations in which the narrower portion is circular in cross-section, gas bubbles may sometimes occlude the narrower portion, particularly if the diameter of the tube is very small. The generally thin flat shape of the cross-sectional shape generally prevents such occlusion.
There is therefore provided, in accordance with an inventive concept 1 of the present invention, apparatus for use in contact with the atmosphere of the Earth and for use with a gas and a catheter having an inflatable cuff, an inflation lumen, and an inflation lumen proximal port, the apparatus including a cuff pressure stabilizer, which includes:
an inflation lumen proximal port connector, which is shaped to form an air-tight seal with the inflation lumen proximal port of the catheter;
a fluid reservoir;
a liquid column container, which is (a) open to the atmosphere at at least one site along the liquid column container, (b) in fluid communication with the fluid reservoir, and (c) in communication with the inflation lumen proximal port connector via the fluid reservoir; and
a liquid, which is contained (a) in the fluid reservoir, (b) in the liquid column container, or (c) partially in the fluid reservoir and partially in the liquid column container, and which has a density of between 1.5 and 5 g/cm3 at 4 degrees Celsius at 1 atm,
wherein the cuff pressure stabilizer has a plurality of pressure indicia markings distributed along the liquid column container tube for measuring a height of the liquid in the liquid column container.
extends to the inflation lumen proximal port connector,
contains some of the gas,
is not in liquid communication with the fluid reservoir, and
includes at least one wall that includes a volume-compensation movable wall, which is in pressure communication with the atmosphere.
wherein the gas container includes a buffer chamber, which is shaped so as to define a chamber inlet port that is in fluid communication with the inflation lumen proximal port connector, and
wherein the pressure-communicating movable wall is disposed at least partially within the buffer chamber.
Inventive concept 27. The apparatus according to inventive concept 25, wherein a volume of the buffer chamber increases by at least 1 cc when a pressure of the gas in the buffer chamber increases from 25 cm H2O to 30 cm H2O.
wherein the fluid reservoir includes a buffer chamber, which is shaped so as to define a chamber inlet port that is in fluid communication with the inflation lumen proximal port connector, and
wherein the buffer chamber includes the at least one wall that includes the volume-compensation movable wall.
wherein the cuff pressure stabilizer includes a gas container, which (a) extends to the inflation lumen proximal port connector, (b) contains some of the gas, and (c) is not in liquid communication with the fluid reservoir,
wherein the gas container includes a buffer chamber, which is shaped so as to define a chamber inlet port that is in fluid communication with the inflation lumen proximal port connector, and
wherein when the liquid column container is oriented in an aligned orientation in which the pressure indicia markings reflect, to within 1 cm H2O, pressure of the gas in the buffer chamber at least in a relevant pressure range of 23-27 cm H2O:
wherein the fluid reservoir contains some of the gas, and
wherein when the liquid column container is oriented in an aligned orientation in which the pressure indicia markings reflect, to within 1 cm H2O, pressure of the gas in the fluid reservoir at least in a relevant pressure range of 23-27 cm H2O:
wherein the liquid column container has first and second ends at opposite ends of the liquid column container,
wherein the liquid column container is in fluid communication with the fluid reservoir via the first end, and
wherein the at least one site is at the second end, and the liquid column container is open to the atmosphere at the second end.
There is still further provided, in accordance with an inventive concept 53 of the present invention, apparatus for use in contact with the atmosphere of the Earth and for use with a gas and a catheter having an inflatable cuff, an inflation lumen, and an inflation lumen proximal port, the apparatus including a cuff pressure stabilizer, which includes:
an inflation lumen proximal port connector, which is shaped to form an air-tight seal with the inflation lumen proximal port of the catheter;
a gas inlet, which is in fluid communication with the inflation lumen proximal port connector;
a fluid reservoir, which has a volume of at least 2 cc, and which contains some of the gas;
a liquid column container, which is in fluid communication with the gas inlet via the fluid reservoir; and
a liquid, which is contained (a) in the fluid reservoir, (b) in the liquid column container, or (c) partially in the fluid reservoir and partially in the liquid column container,
wherein the cuff pressure stabilizer has a plurality of pressure indicia markings distributed along the liquid column container for measuring a height of the liquid in the liquid column container, and
wherein when the liquid column container is oriented in an aligned orientation in which the pressure indicia markings reflect, to within 1 cm H2O, pressure of the gas in the fluid reservoir at least in a relevant pressure range of 23-27 cm H2O:
wherein the liquid column container has first and second ends at opposite ends of the liquid column container,
wherein the liquid column container is in fluid communication with the fluid reservoir via the first end, and
wherein the at least one site is at the second end, and the liquid column container is open to the atmosphere at the second end.
an open state when an orientation of the cuff pressure stabilizer differs from the aligned orientation by no more than a constant number of degrees, the constant equal to between 5 and 45 degrees, and
a reduced-flow state when the orientation of the cuff pressure stabilizer differs from the aligned orientation by more than the constant number of degrees,
wherein the valve is configured to reduce fluid communication thereacross by at least 90% when in the reduced-flow state compared to when in the open state.
wherein the tracheal ventilation tube further includes an inflating tube, which couples the inflation lumen in fluid communication with the inflation lumen proximal port,
wherein the cuff pressure stabilizer further includes:
wherein when (a) the inflation lumen proximal port connector forms the air-tight seal with the inflation lumen proximal port of the tracheal ventilation tube and (b) the pressure of the gas in the fluid reservoir is 10 cm H2O, (i) a first combined air-flow resistance between the inflation inlet port and an interior of the inflatable cuff equals between 80% and 120% of (ii) a second combined air-flow resistance between inflation inlet port and the fluid reservoir.
wherein the tracheal ventilation tube further includes an inflating tube, which couples the inflation lumen in fluid communication with the inflation lumen proximal port,
wherein the cuff pressure stabilizer further includes one or more connector tubes, which couple the inflation lumen proximal port connector in fluid communication with the gas inlet, and
wherein when the inflation lumen proximal port connector forms the air-tight seal with the inflation lumen proximal port of the tracheal ventilation tube, a combined air-flow resistance between an interior of the inflatable cuff and the fluid reservoir is such that a transient pressure difference of 5 cm H2O between the interior of the inflatable cuff and the fluid reservoir results in less than 0.01 cc per second fluid flow from the inflatable cuff into the fluid reservoir.
a flow-limiting state, in which the combined air-flow resistance between the interior of the inflatable cuff and the fluid reservoir is such that the transient pressure difference of 5 cm H2O between the interior of the inflatable cuff and the fluid reservoir results in less than 0.01 cc per second fluid flow from the inflatable cuff into the fluid reservoir, and
a fast-flow state, in which the combined air-flow resistance between the interior of the inflatable cuff and the fluid reservoir is such that the transient pressure difference of 5 cm H2O between the interior of the inflatable cuff and the fluid reservoir results in more than 0.02 cc per second fluid flow from the inflatable cuff into the fluid reservoir.
a hook or a loop, which is configured to automatically orient the liquid column container in the aligned orientation when hung from a hook of the IV pole, and
a squeezing coupler that is coupleable to a vertical or horizontal portion of the IV pole.
There is additionally provided, in accordance with an inventive concept 97 of the present invention, apparatus for use on the Earth with a gas and a catheter having an inflatable cuff, an inflation lumen, and an inflation lumen proximal port, the apparatus including a cuff pressure stabilizer, which includes:
an inflation lumen proximal port connector, which is shaped to form an air-tight seal with the inflation lumen proximal port of the catheter;
a gas inlet, which is in fluid communication with the inflation lumen proximal port connector;
a fluid reservoir, which has a volume of at least 2 cc, and which contains some of the gas;
a liquid column container, which is in fluid communication with the gas inlet via the fluid reservoir; and
a liquid, which is contained (a) in the fluid reservoir, (b) in the liquid column container, or (c) partially in the fluid reservoir and partially in the liquid column container,
wherein the cuff pressure stabilizer has a plurality of pressure indicia markings distributed along the liquid column container for measuring a height of the liquid in the liquid column container, and
wherein when the liquid column container is oriented in an aligned orientation in which the pressure indicia markings reflect, to within 1 cm H2O, pressure of the gas in the fluid reservoir at least in a relevant pressure range of 23-27 cm H2O, an inner cross-sectional area of the liquid column container, measured in a horizontal plane, at a plurality of axial locations along the liquid column container corresponding to the pressure of the gas in the fluid reservoir at a respective plurality of pressures in the relevant pressure range is greater than the product of (a) a factor equal to 200% and (b) an average inner cross-sectional area of the liquid column container, measured in the horizontal plane, at all axial locations along the liquid column container corresponding to a pressure of the gas in the fluid reservoir of between 5 and 15 cm H2O.
wherein the liquid column container is shaped so as to define a wider portion and a narrower portion axially between the wider portion and the fluid reservoir,
wherein at each of the axial locations along the narrower portion of the liquid column container, the liquid column container (a) has a largest inner dimension equal to a greatest distance in the horizontal plane between any two points within the liquid column container, and (b) can encompass a largest circle in the horizontal plane, and
wherein at most or all of the axial locations along the narrower portion of the liquid column container, a ratio of (a) the largest inner dimension to (b) the diameter of the circle equals at least 2:1.
wherein the liquid column container is shaped so as to define a wider portion and a narrower portion axially between the wider portion and the fluid reservoir, and
wherein at each of the axial locations along the narrower portion of the liquid column container, at least 80% of the inner cross-sectional area is within 1 mm of an inner surface of the liquid column container.
wherein the liquid column container is shaped so as to define a wider portion and a narrower portion axially between the wider portion and the fluid reservoir, and
wherein the cuff pressure stabilizer is arranged to provide an adjustable distance between the wider portion of the liquid column container and the fluid reservoir.
There is yet additionally provided, in accordance with an inventive concept 146 of the present invention, apparatus for use on the Earth with a gas, an inflatable chamber, an inflation lumen, and an inflation lumen proximal port in fluid communication with the inflatable chamber via the inflation lumen, the apparatus including a chamber pressure stabilizer, which includes:
an inflation lumen proximal port connector, which is shaped to form an air-tight seal with the inflation lumen proximal port;
a gas inlet, which is in fluid communication with the inflation lumen proximal port connector;
a fluid reservoir, which has a volume of at least 2 cc, and which contains some of the gas;
a liquid column container, which is in fluid communication with the gas inlet via the fluid reservoir, and which is shaped so as to define a wider portion and a narrower portion axially between the wider portion and the fluid reservoir, wherein the chamber pressure stabilizer is arranged to provide an adjustable distance between the wider portion of the liquid column container and the fluid reservoir; and
a liquid, which is contained (a) in the fluid reservoir, (b) in the liquid column container, or (c) partially in the fluid reservoir and partially in the liquid column container.
wherein at each of all axial locations along the narrower portion of the liquid column container, the liquid column container (a) has a largest inner dimension equal to a greatest distance, in a plane perpendicular to a longitudinal axis of the liquid column container, between any two points within the liquid column container, and (b) the liquid column container can encompass a largest circle in the plane, and
wherein at most or all of the axial locations along the narrower portion of the liquid column container, a ratio of (a) the largest inner dimension to (b) the diameter of the circle equals at least 2:1.
wherein the liquid column container has first and second ends at opposite ends of the liquid column container,
wherein the liquid column container is in fluid communication with the fluid reservoir via the first end, and
wherein the at least one site is at the second end, and the liquid column container is open to the atmosphere at the second end.
There is also provided, in accordance with an inventive concept 196 of the present invention, apparatus for use on the Earth with a gas, an inflatable chamber, an inflation lumen, and an inflation lumen proximal port in fluid communication with the inflatable chamber via the inflation lumen, the apparatus including a chamber pressure stabilizer, which includes:
an inflation lumen proximal port connector, which is shaped to form an air-tight seal with the inflation lumen proximal port;
a gas inlet, which is in fluid communication with the inflation lumen proximal port connector;
a fluid reservoir, which has a volume of at least 2 cc, and which contains some of the gas;
a liquid column container, which is in fluid communication with the gas inlet via the fluid reservoir, and which is shaped so as to define a wider portion and a narrower portion axially between the wider portion and the fluid reservoir; and
a liquid, which is contained (a) in the fluid reservoir, (b) in the liquid column container, or (c) partially in the fluid reservoir and partially in the liquid column container,
wherein at each of all axial locations along the narrower portion of the liquid column container, the liquid column container (a) has a largest inner dimension equal to a greatest distance, in a plane perpendicular to a longitudinal axis of the liquid column container, between any two points within the liquid column container, and (b) can encompass a largest circle in the plane, and
wherein at most or all of the axial locations along the narrower portion of the liquid column container, a ratio of (a) the largest inner dimension to (b) the diameter of the circle equals at least 2:1.
wherein the liquid column container has first and second ends at opposite ends of the liquid column container,
wherein the liquid column container is in fluid communication with the fluid reservoir via the first end, and
wherein the at least one site is at the second end, and the liquid column container is open to the atmosphere at the second end.
There is further provided, in accordance with an inventive concept 240 of the present invention, apparatus for use in contact with the atmosphere of the Earth and for use with a gas and a catheter having an inflatable cuff, an inflation lumen, and an inflation lumen proximal port, the apparatus including a cuff pressure stabilizer, which includes: an inflation lumen proximal port connector, which is shaped to form an air-tight seal with the inflation lumen proximal port of the catheter;
a gas inlet, which is in fluid communication with the inflation lumen proximal port connector;
a fluid reservoir, which has a volume of at least 2 cc, and which contains some of the gas;
a liquid column container, which is open to the atmosphere at at least one site along the liquid column container, and which is in fluid communication with the gas inlet via the fluid reservoir; and
a liquid, which is contained (a) in the fluid reservoir, (b) in the liquid column container, or (c) partially in the fluid reservoir and partially in the liquid column container,
wherein the cuff pressure stabilizer has a plurality of pressure indicia markings distributed along the liquid column container tube for measuring a height of the liquid in the liquid column container.
wherein the liquid column container has first and second ends at opposite ends of the liquid column container,
wherein the liquid column container is in fluid communication with the fluid reservoir via the first end, and
wherein the at least one site is at the second end, and the liquid column container is open to the atmosphere at the second end.
There is still further provided, in accordance with an inventive concept 249 of the present invention, apparatus for use in contact with the atmosphere of the Earth and for use with a gas and a catheter having an inflatable cuff, an inflation lumen, and an inflation lumen proximal port, the apparatus including a cuff pressure stabilizer, which includes:
an inflation lumen proximal port connector, which is shaped to form an air-tight seal with the inflation lumen proximal port of the catheter;
a gas inlet, which is in fluid communication with the inflation lumen proximal port connector;
a fluid reservoir, which has a volume of at least 2 cc, and which contains some of the gas;
a liquid column container, which is in fluid communication with the gas inlet via the fluid reservoir;
a liquid, which is contained (a) in the fluid reservoir, (b) in the liquid column container, or (c) partially in the fluid reservoir and partially in the liquid column container,
wherein the cuff pressure stabilizer has a plurality of pressure indicia markings distributed along the fluid column container for measuring a height of the liquid in the liquid column container, and
wherein the liquid column container is arranged such that, when (a) the liquid column container is oriented in an aligned orientation in which the pressure indicia markings reflect, to within 1 cm H2O, pressure of the gas in the fluid reservoir at least in a relevant pressure range of 23-27 cm H2O, and (b) the pressure of the gas in the fluid reservoir is 25 cm H2O:
There is additionally provided, in accordance with an inventive concept 256 of the present invention, apparatus for use on the Earth with a gas, the apparatus including:
a catheter, which includes an inflatable cuff, an inflation lumen, an inflation lumen proximal port, and an inflating tube, which couples the inflation lumen in fluid communication with the inflation lumen proximal port; and
a cuff pressure stabilizer, which includes:
wherein the cuff pressure stabilizer has a plurality of pressure indicia markings distributed along the liquid column container for measuring a height of the liquid in the liquid column container, and
wherein, when (a) when the inflation lumen proximal port connector forms the air-tight seal with the inflation lumen proximal port of the catheter, and (b) a pressure of the gas in the fluid reservoir is 10 cm H2O:
There is yet additionally provided, in accordance with an inventive concept 257 of the present invention, a method for use in contact with the atmosphere of the Earth and for use with a gas and a catheter having an inflatable cuff, an inflation lumen, and an inflation lumen proximal port, the method including:
providing a cuff pressure stabilizer, which includes (a) an inflation lumen proximal port connector, which is shaped to form an air-tight seal with the inflation lumen proximal port of the catheter, (b) a fluid reservoir, (c) a liquid column container, which is (i) open to the atmosphere at at least one site along the liquid column container, (ii) in fluid communication with the fluid reservoir, and (iii) in communication with the inflation lumen proximal port connector via the fluid reservoir, and (d) a liquid, which is contained (i) in the fluid reservoir, (ii) in the liquid column container, or (iii) partially in the fluid reservoir and partially in the liquid column container, and which has a density of between 1.5 and 5 g/cm3 at 4 degrees Celsius at 1 atm, wherein the cuff pressure stabilizer has a plurality of pressure indicia markings distributed along the liquid column container for measuring a height of the liquid in the liquid column container; and
coupling the inflation lumen proximal port connector to the inflation lumen proximal port of the catheter.
There is further provided, in accordance with an inventive concept 258 of the present invention, a method for use in contact with the atmosphere of the Earth and for use with a gas and a catheter having an inflatable cuff, an inflation lumen, and an inflation lumen proximal port, the method including:
providing a cuff pressure stabilizer, which includes (a) an inflation lumen proximal port connector, which is shaped to form an air-tight seal with the inflation lumen proximal port of the catheter, (b) a gas inlet, which is in fluid communication with the inflation lumen proximal port connector, (c) a fluid reservoir, which has a volume of at least 2 cc, and which contains some of the gas, (d) a liquid column container, which is in fluid communication with the gas inlet via the fluid reservoir, and (e) a liquid, which is contained (i) in the fluid reservoir, (ii) in the liquid column container, or (iii) partially in the fluid reservoir and partially in the liquid column container, wherein the cuff pressure stabilizer has a plurality of pressure indicia markings distributed along the liquid column container for measuring a height of the liquid in the liquid column container;
coupling the inflation lumen proximal port connector to the inflation lumen proximal port of the catheter; and
orienting the liquid column container in an aligned orientation in which the pressure indicia markings reflect, to within 1 cm H2O, pressure of the gas in the fluid reservoir at least in a relevant pressure range of 23-27 cm H2O,
wherein when the liquid column container is oriented in the aligned orientation, the liquid column container has an inner cross-sectional area, measured in a horizontal plane, of at least 0.25 cm2 at a plurality of axial locations along the liquid column container corresponding to the pressure of the gas in the fluid reservoir at a respective plurality of pressures in the relevant pressure range.
There is still further provided, in accordance with an inventive concept 259 of the present invention, a method for use on the Earth with a gas and a catheter having an inflatable cuff, an inflation lumen, and an inflation lumen proximal port, the method including:
providing a cuff pressure stabilizer, which includes (a) an inflation lumen proximal port connector, which is shaped to form an air-tight seal with the inflation lumen proximal port of the catheter, (b) a gas inlet, which is in fluid communication with the inflation lumen proximal port connector, (c) a fluid reservoir, which has a volume of at least 2 cc, and which contains some of the gas, (d) a liquid column container, which is in fluid communication with the gas inlet via the fluid reservoir, and (e) a liquid, which is contained (i) in the fluid reservoir, (ii) in the liquid column container, or (iii) partially in the fluid reservoir and partially in the liquid column container, wherein the cuff pressure stabilizer has a plurality of pressure indicia markings distributed along the liquid column container for measuring a height of the liquid in the liquid column container;
coupling the inflation lumen proximal port connector to the inflation lumen proximal port of the catheter; and
orienting the liquid column container in an aligned orientation in which the pressure indicia markings reflect, to within 1 cm H2O, pressure of the gas in the fluid reservoir at least in a relevant pressure range of 23-27 cm H2O,
wherein when the liquid column container is oriented in the aligned orientation, an inner cross-sectional area of the liquid column container, measured in a horizontal plane, at a plurality of axial locations along the liquid column container corresponding to the pressure of the gas in the fluid reservoir at a respective plurality of pressures in the relevant pressure range is greater than the product of (a) a factor equal to 200% and (b) an average inner cross-sectional area of the liquid column container, measured in the horizontal plane, at all axial locations along the liquid column container corresponding to a pressure of the gas in the fluid reservoir of between 5 and 15 cm H2O.
There is additionally provided, in accordance with an inventive concept 260 of the present invention, a method for use in contact with the atmosphere of the Earth and for use with a gas, an inflatable chamber, an inflation lumen, and an inflation lumen proximal port in fluid communication with the inflatable chamber via the inflation lumen, the method including:
providing a chamber pressure stabilizer, which includes (a) an inflation lumen proximal port connector, which is shaped to form an air-tight seal with the inflation lumen proximal port, (b) a gas inlet, which is in fluid communication with the inflation lumen proximal port connector, (c) a fluid reservoir, which has a volume of at least 2 cc, and which contains some of the gas, (d) a liquid column container, which is in fluid communication with the gas inlet via the fluid reservoir, and which is shaped so as to define a wider portion and a narrower portion axially between the wider portion and the fluid reservoir, wherein the chamber pressure stabilizer is arranged to provide an adjustable distance between the wider portion of the liquid column container and the fluid reservoir, and (e) a liquid, which is contained (i) in the fluid reservoir, (ii) in the liquid column container, or (iii) partially in the fluid reservoir and partially in the liquid column container;
coupling the inflation lumen proximal port connector to the inflation lumen proximal port; and
adjusting the adjustable distance between the wider portion of the liquid column container and the fluid reservoir.
wherein the inflatable chamber is an inflatable cuff,
wherein the method is for use with a tracheal ventilation tube having the inflatable cuff, the inflation lumen, and the inflation lumen proximal port,
wherein the inflation lumen proximal port connector is shaped to form the air-tight seal with the inflation lumen proximal port of the tracheal ventilation tube, and
wherein coupling includes coupling the inflation lumen proximal port connector to the inflation lumen proximal port of the tracheal ventilation tube.
There is yet additionally provided, in accordance with an inventive concept 262 of the present invention, a method for use in contact with the atmosphere of the Earth and for use with a gas, an inflatable chamber, an inflation lumen, and an inflation lumen proximal port in fluid communication with the inflatable chamber via the inflation lumen, the method including:
providing a chamber pressure stabilizer, which includes (a) an inflation lumen proximal port connector, which is shaped to form an air-tight seal with the inflation lumen proximal port, (b) a gas inlet, which is in fluid communication with the inflation lumen proximal port connector, (c) a fluid reservoir, which has a volume of at least 2 cc, and which contains some of the gas, (d) a liquid column container, which is in fluid communication with the gas inlet via the fluid reservoir, and which is shaped so as to define a wider portion and a narrower portion axially between the wider portion and the fluid reservoir, (e) a liquid, which is contained (i) in the fluid reservoir, (ii) in the liquid column container, or (iii) partially in the fluid reservoir and partially in the liquid column container, wherein at each of all axial locations along the narrower portion of the liquid column container, the liquid column container (a) has a largest inner dimension equal to a greatest distance, in a plane perpendicular to a longitudinal axis of the liquid column container, between any two points within the liquid column container, and (b) can encompass a largest circle in the plane, and wherein at most or all of the axial locations along the narrower portion of the liquid column container, a ratio of (a) the largest inner dimension to (b) the diameter of the circle equals at least 2:1; and
coupling the inflation lumen proximal port connector to the inflation lumen proximal port.
wherein the inflatable chamber is an inflatable cuff,
wherein the method is for use with a tracheal ventilation tube having the inflatable cuff, the inflation lumen, and the inflation lumen proximal port,
wherein the inflation lumen proximal port connector is shaped to form the air-tight seal with the inflation lumen proximal port of the tracheal ventilation tube, and
wherein coupling includes coupling the inflation lumen proximal port connector to the inflation lumen proximal port of the tracheal ventilation tube.
There is also provided, in accordance with an inventive concept 264 of the present invention, a method for use in contact with the atmosphere of the Earth and for use with a gas and a catheter having an inflatable cuff, an inflation lumen, and an inflation lumen proximal port, the method including:
providing a cuff pressure stabilizer, which includes (a) an inflation lumen proximal port connector, which is shaped to form an air-tight seal with the inflation lumen proximal port of the catheter, (b) a gas inlet, which is in fluid communication with the inflation lumen proximal port connector, (c) a fluid reservoir, which has a volume of at least 2 cc, and which contains some of the gas, (d) a liquid column container, which is open to the atmosphere at at least one site along the liquid column container, and which is in fluid communication with the gas inlet via the fluid reservoir, and (e) a liquid, which is contained (i) in the fluid reservoir, (ii) in the liquid column container, or (iii) partially in the fluid reservoir and partially in the liquid column container, wherein the cuff pressure stabilizer has a plurality of pressure indicia markings distributed along the liquid column container tube for measuring a height of the liquid in the liquid column container; and
coupling the inflation lumen proximal port connector to the inflation lumen proximal port of the catheter.
There is further provided, in accordance with an inventive concept 265 of the present invention, a method for use in contact with the atmosphere of the Earth and for use with a gas and a catheter having an inflatable cuff, an inflation lumen, and an inflation lumen proximal port, the method including:
providing a cuff pressure stabilizer, which includes (a) an inflation lumen proximal port connector, which is shaped to form an air-tight seal with the inflation lumen proximal port of the catheter, (b) a gas inlet, which is in fluid communication with the inflation lumen proximal port connector, (c) a fluid reservoir, which has a volume of at least 2 cc, and which contains some of the gas, (d) a liquid column container, which is in fluid communication with the gas inlet via the fluid reservoir, and (e) a liquid, which is contained (i) in the fluid reservoir, (ii) in the liquid column container, or (iii) partially in the fluid reservoir and partially in the liquid column container, wherein the cuff pressure stabilizer has a plurality of pressure indicia markings distributed along the fluid column container for measuring a height of the liquid in the liquid column container;
coupling the inflation lumen proximal port connector to the inflation lumen proximal port of the catheter; and
orienting the liquid column container in an aligned orientation in which the pressure indicia markings reflect, to within 1 cm H2O, pressure of the gas in the fluid reservoir at least in a relevant pressure range of 23-27 cm H2O,
wherein the liquid column container is arranged such that, when (a) the liquid column container is oriented in the aligned orientation and (b) the pressure of the gas in the fluid reservoir is 25 cm H2O:
There is still further provided, in accordance with an inventive concept 266 of the present invention, a method for use on the Earth with a gas, the method including:
inserting, into a trachea of a patient, a catheter, which includes an inflatable cuff, an inflation lumen, an inflation lumen proximal port, and an inflating tube, which couples the inflation lumen in fluid communication with the inflation lumen proximal port; and
providing a cuff pressure stabilizer, which includes (a) an inflation lumen proximal port connector, which is shaped to form an air-tight seal with the inflation lumen proximal port of the catheter, (b) a gas inlet, which is in fluid communication with the inflation lumen proximal port connector, (c) a fluid reservoir, which has a volume of at least 2 cc, and which contains some of the gas, (d) a liquid column container, which is in fluid communication with the gas inlet via the fluid reservoir, (e) a liquid, which is contained (i) in the fluid reservoir, (ii) in the liquid column container, or (iii) partially in the fluid reservoir and partially in the liquid column container, (f) an inflation inlet port, (g) a first connector tube, which couples the inflation lumen proximal port connector in fluid communication with the inflation inlet port, and (h) a second connector tube, which couples the gas inlet in fluid communication with the inflation inlet port, such that the inflation lumen proximal port connector is in fluid communication with the gas inlet via the first connector tube and the second connector tube, wherein the cuff pressure stabilizer has a plurality of pressure indicia markings distributed along the liquid column container for measuring a height of the liquid in the liquid column container; and
coupling the inflation lumen proximal port connector to the inflation lumen proximal port of the catheter,
wherein when (a) the inflation lumen proximal port connector forms the air-tight seal with the inflation lumen proximal port of the catheter, and (b) a pressure of the gas in the fluid reservoir is 10 cm H2O:
The present invention will be more fully understood from the following detailed description of embodiments thereof, taken together with the drawings, in which:
Tracheal ventilation tube 10 comprises an inflatable cuff 11, an inflation lumen 13, and an inflation lumen proximal port 15. Inflatable cuff 11 may comprise, for example, a balloon, and is typically mounted on tracheal ventilation tube 10 near a distal end of the tracheal ventilation tube, e.g., within 3 cm, such as within 1 cm, of the distal end. Inflatable cuff 11 typically comprises a nearly non-compliant material. A “balloon,” as used in the present application, including the claims, is an inflatable flexible bag, having any level of elasticity, including nearly non-elastic. Typically, inflatable cuff 11 has a volume of around 10 cc. Tracheal ventilation tube 10 typically further comprises a cuff inflation lumen distal port 12, a tracheal ventilation tube ventilation port 16, a tracheal ventilation tube ventilation lumen 17, and a tracheal ventilation tube ventilator connection 19. For some applications, tracheal ventilation tube 10 further comprises an inflating tube 14, which couples inflation lumen 13 in fluid communication with inflation lumen proximal port 15. Tracheal ventilation tube 10 is schematically shown inserted into a trachea 18. Inflatable cuff 11 is inflatable into sealing contact with the inner surface of trachea 18. As used in the present application, including in the claims, a “tracheal ventilation tube” comprises an endotracheal tube (ETT) or a tracheostomy tube.
Cuff pressure stabilizer 100 comprises:
As can be seen, the gas partially fills fluid reservoir 120. When the system is in equilibrium, the pressure of the gas in fluid reservoir 120 equals the pressure of the gas in inflatable cuff 11. For some applications, inflation lumen proximal port connector 134 comprises a male conical fitting with a taper. For some applications, the taper is at least a 5% taper. For some applications, the taper is a 6% taper, and the male conical fitting with the 6% taper complies with International Standard ISO 594-1:1986, which is the standard for connections to conventional inflation lumen proximal ports of tracheal ventilation tubes. Typically, gas inlet 141 has a large cross-sectional area, such as at least 9 mm2, so that any droplets of liquid 121 that should happen to form will not clog the gas inlet.
Cuff pressure stabilizer 100 has a plurality of pressure indicia markings 126 distributed along liquid column container 118 for measuring a height of liquid 121 in liquid column container 118. Typically, casing 110 has pressure indicia markings 126, as shown in the figures, in which case pressure indicia markings 126 are distributed along liquid column container 118 by being distributed alongside liquid column container 118. Alternatively, for some applications, liquid column container 118 has pressure indicia markings 126 therealong. Liquid column container 118 is used in an aligned orientation (hereinbelow, the “aligned orientation”) in which pressure indicia markings 126 reflect, to within 1 cm H2O (i.e., with no error or an error of no more than 1 cm H2O), pressure of the gas in fluid reservoir 120 at least in a relevant pressure range 127 of 23-27 cm H2O, such as a range of 22-28 cm H2O, e.g., a range of 20-30 cm H2O, as marked numerically in the figures. The full marked scale 125 range typically extends both above and below the range of 20-30 cm H2O. The pressure is read by comparing a level 129 of fluid in liquid column container 118 with pressure indicia markings 126, as is known in the manometer art.
Typically, pressure indicia markings 126 reflect the height of liquid 121 in liquid column container 118 relative to the height of liquid 121 in fluid reservoir 120, as is known in the manometer art (as the liquid surface ascends in liquid column container 118, the liquid surface descends in fluid reservoir 120, though typically not by the same changes in heights). Therefore, the spacing of pressure indicia markings 126 depends in part on the shape and volume of fluid reservoir 120. For example, the spacing of pressure indicia markings 126 between 25 and 26 cm H2O may be different from the spacing of pressure indicia markings 126 between 26 and 27 cm H2O. In addition, for example, the wider the fluid reservoir, the greater the spacing of pressure indicia markings 126. For some applications, pressure indicia markings 126 are distributed evenly throughout at least relevant pressure range 127.
Typically, for applications in which liquid 121 comprises water, pressure indicia markings 126 are spaced at close to 1-cm intervals. For applications in which liquid 121 comprises a liquid with a higher or lower density than that of water, pressure indicia markings 126 are not spaced at 1-cm intervals, such as described hereinbelow. Optionally, liquid 121 comprises a dye to increase the visibility of the liquid for making the pressure measurements.
Typically, liquid column container 118 is configured to automatically assume the aligned orientation when cuff pressure stabilizer 100 is hung from or otherwise attached to a conventional IV pole, hospital wall, or other surface or object. For example, cuff pressure stabilizer 100 may comprise a coupling element that is configured to automatically orient liquid column container 118 in the aligned orientation. The coupling element may comprise a hook or a loop 128 that is hangable from a conventional hook of a conventional IV pole, similar to the standard hook of IV bags. Alternatively or additionally, the coupling element may comprise a squeezing coupler (e.g., a gripper or a clamp) that is coupleable to a vertical pole (e.g., a vertical IV pole) or a horizontal pole (e.g., a horizontal portion of one of the hooks of the IV pole), or another connector that is configured to be attached to a vertical surface, such as a hospital wall.
For some applications, when liquid column container 118 is oriented in the aligned orientation, liquid column container 118 has an inner cross-sectional area, measured in a horizontal plane 135, of at least 0.16 cm2 (e.g., at least 0.25 cm2, 0.5 cm2, or 1 cm2) at a plurality of (such as at most or all) axial locations along liquid column container 118 corresponding to the pressure of the gas in fluid reservoir 120 at a respective plurality of pressures in relevant pressure range 127. Typically, the inner cross-sectional area, measured in horizontal plane 135, is less than 2 cm2 at a plurality of (such as at most or all) axial locations along liquid column container 118 corresponding to the pressure of the gas in fluid reservoir 120 at a respective plurality of pressures in relevant pressure range 127, when liquid column container 118 is oriented in the aligned orientation.
As a result of this relatively large cross-sectional area, cuff pressure stabilizer 100 regulates (i.e., reduces fluctuations) the pressure of the gas in fluid reservoir 120 at least for changes of gas volume in the range of 0-2 cc, and thus at gas inlet 141 and in inflatable cuff 11, in addition to measuring the pressure. In contrast, conventional manometers only measure the pressure, without substantially affecting the pressure, as it is ideally and commonly the goal of measurement devices to not affect the measured target. For a given cuff of initial gas volume V, as the squeezing of inflatable cuff 11 by trachea 18 increases such that the available gas volume decreases, the volume of the gas in inflatable cuff 11 decreases by some fraction equal to the change in V divided by V because the cuff is nearly non-compliant. For endotracheal tubes without external regulation, this decrease in volume of the inflatable cuff results in an increase in pressure of the gas within the system, including within the inflatable cuff, since the gas contained in the cuff has no significant external volume to move into, in accordance with the ideal gas law; the opposite occurs when the level of squeezing on the cuff by the trachea decreases.
In experiments conducted by the inventors, the inventors found that, for real endotracheal tube cuff balloons of volumes around 10 cc, each 0.1 cc decrease in volume in the inflatable cuff resulted in about a 1 cm H2O increase in pressure in the system and the cuff, and each 0.1 cc increase in volume in the inflatable cuff resulted in about a 1 cm H2O decrease in pressure in the system and the cuff. This is a surprising significant departure from the ideal non-compliant gas law calculation which would predict a 0.01 cc volume change per 1 cm H2O pressure change. The inventors thus concluded that real endotracheal tube cuff balloons are in fact semi-compliant. Therefore, the mitigation volumes should be calculated based on the experimental finding. In clinical practice, the pressure in ETT inflatable cuffs generally varies +/−10 cm H2O from the typically target pressure of 25 cm H2O, i.e., varies between 15 and 35 cm H2O. Based on the above-mentioned experimental data, the inventors appreciated that the volume in ETT inflatable cuffs generally varies by +/−1 cc (+/−10 cm H2O times 0.1 cc/cm H2O), i.e., a total range of 2 cc, and, among a broader spectrum of patients, the volume of ETT inflatable cuffs generally varies by +/−20 cm H2O from the typical target pressure of 25 cm H2O, i.e., a total range of at least 4 cc.
The inventors appreciated that to the extent that cuff pressure stabilizer 100 is able to offset the changes in volume in inflatable cuff 11, the pressure changes are also offset, thereby stabilizing the pressure in inflatable cuff 11. Cuff pressure stabilizer 100 is able to offset the changes in volume in inflatable cuff 11 because of the relatively large cross-sectional area of liquid column container 118 at relevant pressure range 127, e.g., 23-27 cm H2O.
For example, assume that (a) liquid 121 comprises water, (b) the cross-sectional area of liquid column container 118 at relevant pressure range 127 is 1 cm2, (c) pressure indicia markings 126 are spaced at 1-cm intervals, and (d) the initial pressure in inflatable cuff 11 is 25 cm H2O. A decrease in volume of inflatable cuff 11 of 1 cc (caused by increased squeezing by the trachea) would displace from the inflatable cuff the excess 1 cc of gas into fluid reservoir 120, and a corresponding additional 1 cc of water out of fluid reservoir 120 into liquid column container 118. This additional 1 cc of water would fill an additional 1 cc of fluid reservoir 120, raising level 129 of fluid by 1 cm, and thus the pressure in inflatable cuff 11 (as indicated by pressure indicia markings 126) by 1 cm H2O, from 25 cm H2O to 26 cm H2O.
For a real inflatable cuff having a volume of 10 cc without attachment of the regulation system, a decrease in volume of inflatable cuff 11 of 1 cc would have resulted in an increase of the cuff pressure gas by about 10 cm H2O, based on the inventors' experimental data, i.e., the integration of the pressure regulator with tracheal ventilation tube 10 results in a factor of 10 suppression of the pressure change, resulting in the pressure regulation described herein.
More generally, the change in pressure in inflatable cuff 11 within relevant pressure range 127, resulting from a change in volume of inflatable cuff 11, when liquid 121 does not necessarily comprise water, is expressed by the following Equation 1:
ΔP=(ΔV/A)*d
in which:
As used in the present application, including in the claims, “horizontal” means horizontal with respect to the Earth, i.e., perpendicular to a vertical line 102 directed to the center of gravity of the Earth, e.g., as ascertained using a plumb-line.
For some applications, at the plurality of axial locations along liquid column container 118 corresponding to the pressure of the gas in fluid reservoir 120 at the respective plurality of pressures in relevant pressure range 127, the inner cross-sectional area is at least 0.16 cm2 (e.g., at least 0.25 cm2, 0.5 cm2, or 1 cm2), when liquid column container 118 is oriented in the aligned orientation.
Typically, liquid column container 118 is wider (i.e., has a greater cross-sectional area) in (a) a relevant-range fluid compartment 123 that includes relevant pressure range 127 than in (b) a lower-range fluid compartment 122 that reflects pressures of the gas in fluid reservoir 120 of less than 20 cm H2O. In other words, when liquid column container 118 is oriented in the aligned orientation, an average inner cross-sectional area, measured in horizontal plane 135, at all axial locations along liquid column container 118 corresponding to the pressure of the gas in fluid reservoir 120 at the respective plurality of pressures in relevant pressure range 127 is greater than the product of (a) a factor greater than one and (b) an average inner cross-sectional area of liquid column container 118, measured in horizontal plane 135, at all axial locations along liquid column container 118 corresponding to pressure of the gas in fluid reservoir 120 of less than 20 cm H2O. For some applications, the factor is 150%, such as 200%, 300%, 400%, or 500%. The narrower liquid column container 118 in lower-range fluid compartment 122 reduces the total required amount of liquid 121, which is useful in configurations in which liquid 121 comprises an expensive heavy liquid.
For some of these applications, when liquid column container 118 is oriented in the aligned orientation, the inner cross-sectional area at the plurality of axial locations along liquid column container 118 corresponding to the pressure of the gas in fluid reservoir 120 at the respective plurality of pressures in relevant pressure range 127 equals at least 200% of an average inner cross-sectional area of liquid column container 118, measured in horizontal plane 135, at most or all axial locations along liquid column container 118 corresponding to a pressure of the gas in fluid reservoir 120 of between 5 and 15 cm H2O. For some applications, the average inner cross-sectional area is less than 0.16 cm2, such as less than 0.09 cm2, at most or all axial locations along liquid column container 118 corresponding to a pressure of the gas in fluid reservoir 120 of between 5 and 15 cm H2O, when liquid column container 118 is oriented in the aligned orientation.
For some applications, liquid column container 118 is wider (i.e., has a greater cross-sectional area) in (a) a buffer fluid compartment 124 that reflects pressures of the gas in fluid reservoir 120 of greater than 28 cm H2O, e.g., greater than 30 cm H2O that includes relevant pressure range 127 than in (b) relevant-range fluid compartment 123 that includes relevant pressure range 127. In other words, when liquid column container 118 is oriented in the aligned orientation, an average inner cross-sectional area at all axial locations along liquid column container 118 corresponding to the pressure of the gas in fluid reservoir 120 at the respective plurality of pressures in the relevant range is less than the inner cross-sectional area of liquid column container 118, measured in horizontal plane 135, at at least one axial location along liquid column container 118 corresponding to a pressure of the gas in fluid reservoir 120 of between 28 cm and 35 cm H2O. The wider liquid column container 118 in buffer fluid compartment 124 substantially reduces increases in pressure if the pressure should exceed the lower end of the pressure range of buffer fluid compartment 124, because buffer fluid compartment 124 can hold a greater volume of liquid per unit of height than can relevant-range fluid compartment 123.
For some applications, liquid 121 has a density of between 0.8 and 12 g/cm3 at 4 degrees Celsius at 1 atm, and/or a density of between 0.8 and 12 g/cm3 at 20 degrees Celsius at 1 atm. Typically, the density (whether at 4 degrees or at 20 degrees) is between 1.5 and 5 g/cm3, such as between 2 and 4 g/cm3, e.g., between 2.5 and 3.5 g/cm3 (all of these values are more dense than water and less dense than mercury). For some applications, liquid 121 comprises a tungstate-based liquid, e.g., selected from the group consisting of: sodium polytungstate, sodium metatungstate, lithium polytungstate, and lithium metatungstate. Alternatively or additionally, liquid 121 may have any of the characteristics described hereinbelow with reference to
To the extent that the density d of liquid 121 is greater than that of water, i.e., greater than 1 g/cm3 at 4 degrees Celsius at 1 atm, a shorter liquid column container 118 can be used to measure and regulate pressures, and pressure indicia markings 126 are closer together. Assuming a container of uniform cross section and a liquid column of uniform cross section, it follows from Equation 1 (ΔP=(ΔV/A)*d) that, if using a liquid of density d compared with using water, the distance between pressure indicia markings 126 for indicating a 1 cm H2O change in pressure equals the quotient of (a) 1 cm divided by (b) the density of liquid 121 at 4 degrees Celsius at 1 atm. For some applications, a distance between a highest point 136 of liquid column container 118 and a lowest point 137 of fluid reservoir 120 is between 10 and 20 cm, when liquid column container 118 is oriented in an aligned orientation. The highest point is measured with respect to the center of gravity of the Earth.
For some applications, as shown in the figures and labeled in
Typically, liquid column container 118 is open to atmosphere 99 at at least one site 139 along liquid column container 118. Liquid column container 118 has first and second ends 143 and 144 at opposite ends of liquid column container 118. For some applications, liquid column container 118 is in fluid communication with fluid reservoir 120 via first end 143, the at least one site 139 is at second end 144, and liquid column container 118 is open to atmosphere 99 at second end 144. For some applications, liquid column container 118 defines an opening 142 having an area of between 0.09 and 1 mm2, and liquid column container 118 is open to atmosphere 99 via opening 142. For some applications, cuff pressure stabilizer 100 further comprises a sealing element 145 (e.g., a plug or screw-cap) that is removably disposed so as to seal opening 142 (shown removed in
For some applications, when liquid column container 118 is oriented in the aligned orientation, at least 2 cc, no more than 10 cc, and/or between 2 and 10 cc (e.g., between 2 and 8 cc, such as between 2 and 6 cc, e.g., between 2 and 4 cc) of liquid 121 are contained in fluid reservoir 120 at a lower height than first end 143 of liquid column container 118. For some applications, an upper surface area of liquid 121 in fluid reservoir 120 is at least 2 cm2, no more than 8 cm2, and/or between 2 and 8 cm2 (e.g., between 2 and 6 cm2, such as between 2 and 4 cm2), when (a) liquid column container 118 is oriented in the aligned orientation and (b) the pressure of the gas in fluid reservoir 120 is 25 cm H2O.
For some applications, cuff pressure stabilizer 100 further comprises:
Typically, inflation inlet port 130 comprises a valve, such as a directional valve. Inflation inlet port 130 isolates the system such there is no exchange of gas (air) between inflatable cuff 11 and atmosphere 99 (ambient air) after initial inflation by external inflation source 20.
For some applications, cuff pressure stabilizer 100 further comprises an inlet junction 131, which comprises inflation inlet port 130, and which couples in fluid communication inflation inlet port 130, first connector tube 133, and second connector tube 132.
For some applications, when (a) inflation lumen proximal port connector 134 forms the air-tight seal with inflation lumen proximal port 15 of tracheal ventilation tube 10 and (b) a pressure of the gas of the gas in fluid reservoir 120 is 10 cm H2O, (i) a first combined air-flow resistance between inflation inlet port 130 and an interior of inflatable cuff 11 equals between 80% and 120% of (ii) a second combined air-flow resistance between inflation inlet port and fluid reservoir 120, such as between 90% and 110%, e.g., between 95% and 105%. Typically, in order to achieve these relative air-flow resistances, the relative lengths of first and second connector tubes 133 and 132 are set such that the resistance of second connector tube 132 equals the sum of the resistance of first connector tube 133 and a fixed constant resistance of all elements of tracheal ventilation tube 10 in the flow path. This approximately equal air-flow resistance prevents transient false pressure readings immediately following inflation or reinflation of inflatable cuff 11 via inflation inlet port 130, without being dependent on the technique of the healthcare worker. For example, if the resistance from inflation inlet port 130 were lower in second connector tube 132 (to cuff pressure stabilizer 100) than in first connector tube 133 (to inflatable cuff 11), during inflation initially a majority of the air would flow toward cuff pressure stabilizer 100. As a result, level 129 of fluid in liquid column container 118 would indicate a higher pressure than the true pressure of inflatable cuff 11. If external inflation source 20 were to be disconnected at this point in time, the pressure shown by liquid column container 118 would gradually decrease as pressure equilibrium between inflatable cuff 11 and fluid reservoir 120 is gradually reached.
For some applications, cuff pressure stabilizer 100 further comprises one or more connector tubes, which couple inflation lumen proximal port connector 134 in fluid communication with gas inlet 141. When inflation lumen proximal port connector 134 forms the air-tight seal with inflation lumen proximal port 15 of tracheal ventilation tube 10, a combined air-flow resistance between an interior of inflatable cuff 11 and fluid reservoir 120 is such that a transient pressure difference of 5 cm H2O between the interior of inflatable cuff 11 and fluid reservoir 120 results in less than a 0.1 cc per second, e.g., less than a 0.05, a 0.02, or a 0.01 cc per second, fluid flow from inflatable cuff 11 into fluid reservoir 120. The slow rate of flow delays the automatic pressure-regulation response from cuff pressure stabilizer 100. A too rapid pressure-regulation response might underinflate inflatable cuff 11 during transient, short-term increases in pressure in the inflatable cuff, such as during the positive pressure phase of the ventilation cycle when high-pressure ventilation (generally greater than 25 cm H2O) is applied to the patient, generally for only a few seconds, typically less than 3 seconds.
For patients ventilated at high peak inspiratory pressure (PIP), i.e., greater than 25 cm H2O and sometimes even up to 40 cm H2O, there is a need to both maintain the high ventilation pressure during the peak ventilation and to maintain on average the balloon pressure near 25 cm H2O. For these patients only, it is advantageous to limit the fluid flow between inflatable cuff 11 and fluid reservoir 120, as described immediately above, at the expense of increasing the pressure regulation response time of cuff pressure stabilizer 100.
Generally, high PIP is applied to less than 30% of patients. For the remaining 70% of patients there is no need for flow limitation. To the contrary, the longer response time due to flow limitation compromises the desired fast response to low cuff pressures. To best accommodate these differing patient needs, in some applications, cuff pressure stabilizer 100 comprises a switch that sets flow states of cuff pressure stabilizer 100, including (a) a flow-limiting state (e.g., via a flow-limiting channel, as described immediately above, and (b) a fast-flow state (e.g., via a fast-flow channel, which is sized so as to substantially not limit flow, e.g., such that a transient pressure difference of 5 cm H2O between the interior of inflatable cuff 11 and fluid reservoir 120 results in greater than a 0.02 cc per second, e.g., more than a 0.05 cc per second, fluid flow from inflatable cuff 11 into fluid reservoir 120). A healthcare worker selects which of these two channels to enable according to the individual patient's ventilation needs. In addition, the healthcare worker may select the fast-flow channel during inflation of inflatable cuff 11.
For some applications, the flow resistance is placed not between inflatable cuff 11 and fluid reservoir 120, but instead at the at least one site 139 along liquid column container 118 at which liquid column container 118 is open to atmosphere 99, as described hereinabove. Flow resistance anywhere along the fluid communication from inflatable cuff 11 all the way to atmosphere 99 is sufficient to create the desired effect.
For some applications, liquid column container 118 is arranged such that, when (a) liquid column container 118 is oriented in the aligned orientation and (b) the pressure of the gas in fluid reservoir 120 is 25 cm H2O: an increase in a volume of the gas in fluid reservoir 120 of up to 2 cc results in less than a 10 cm H2O increase in the pressure of the gas in fluid reservoir 120, such as less than a 6 cm H2O increase in the pressure of the gas in fluid reservoir 120, e.g., less than a 5 cm H2O or less than a 4 cm H2O increase. Alternatively or additionally, for some applications, liquid column container 118 is arranged such that, when (a) liquid column container 118 is oriented in the aligned orientation, and (b) the pressure of the gas in fluid reservoir 120 is 25 cm H2O: a decrease in the volume of the gas in fluid reservoir 120 of up to 1 cc results in less than a 6 cm H2O decrease in the pressure of the gas in fluid reservoir 120, e.g., less than a 5 cm H2O or less than a 4 cm H2O decrease. For some applications, liquid column container 118 is shaped so as to provide asymmetric regulation of pressure; for example, liquid column container 118 may be conical. Alternatively or additionally, for some applications, pressure indicia markings 126 are arranged to indicate a pressure of 25 cm H2O at an axial location of relevant-range fluid compartment 123 other than an axial center of relevant-range fluid compartment 123.
Typically, cuff pressure stabilizer 100 does not comprise any membranes in contact with liquid 121, and does not comprise any membranes in a fluid path between liquid 121 and atmosphere 99.
Typically, cuff pressure stabilizer 100 does not comprise a spring for measuring the pressure of the gas in fluid reservoir 120.
For some applications, cuff pressure stabilizer 100 further comprises an orientation-sensitive valve assembly 150, which comprises a valve 156 (e.g., a solenoid valve, or an elastically biased gate). Orientation-sensitive valve assembly 150 is arranged to automatically assume:
Typically, the constant equals between 5 and 45 degrees, such as between 5 and 20 degrees.
Valve 156 is configured to reduce fluid communication thereacross by at least 90% when in the reduced-flow state compared to when in the open state, such as to entirely block fluid communication thereacross when in the reduced-flow state. Such reduced fluid communication serves as a safety feature and/or to prevent spillage of the fluid during storage and shipment of the device. For some applications, valve 156 is arranged in a fluid path between inflation lumen proximal port connector 134 and fluid reservoir 120.
For some applications, orientation-sensitive valve assembly 150 comprises electronic components, such as an orientation sensor 155 (e.g., comprising an accelerometer), which is configured to sense the orientation of cuff pressure stabilizer 100, and a battery 151. For some applications, orientation-sensitive valve assembly 150 further comprises one or more alignment indicators 152 and 153 (e.g., LEDs).
Reference is now made to
For some applications, cuff pressure stabilizer 200 comprises an orientation-sensitive valve assembly 250 that is mechanical and non-electrical. For some applications, orientation-sensitive valve assembly 250 comprises:
When cuff pressure stabilizer 100 differs from the aligned orientation by more than the constant number of degrees mentioned above with reference to
When cuff pressure stabilizer 100 differs from the aligned orientation by no more than the constant number of degrees, moving weight 261 slides or rolls away from opening 267, such that moving weight 261 does not press on the second end of press-switch 266, such as shown in
Reference is now made to
Liquid column container 118 is shaped so as to define a wider portion 323 and a narrower portion 322 axially between wider portion 323 and fluid reservoir 120. Wider portion 323 has an average cross-sectional area, measured in (a) horizontal plane 135, described hereinabove with reference to
Typically, all axial locations along liquid column container 118 corresponding to the pressure of the gas in fluid reservoir 120 at the respective plurality of pressures in relevant pressure range 127 fall within wider portion 323. However, this may not be the case if a healthcare worker axially adjusts wider portion 323 beyond normal clinical limits (in configurations in which cuff pressure stabilizer 300 is arranged to provide an adjustable distance between wider portion 323 and fluid reservoir 120, such as described hereinbelow with reference to
For some applications, wider portion 323 has a length of:
For some applications, when liquid column container 118 is oriented in the aligned orientation, wider portion 323 has an inner cross-sectional area, measured in horizontal plane 135 and/or the above-mentioned plane, at a plurality of (such as at most or all) axial locations along wider portion 323, of (a) at least 0.16 cm2 (e.g., at least 0.25 cm2, 0.5 cm2, or 1 cm2), (b) at least the product of 0.16 cm2 (e.g., at least 0.25 cm2, 0.5 cm2, or 1 cm2) and a specific gravity of liquid 121 with reference to water at 4 degrees Celsius at 1 atm, (c) at least the product of 0.16 cm2 (e.g., at least 0.25 cm2, 0.5 cm2, or 1 cm2) and a specific gravity of liquid 121 with reference to water at 20 degrees Celsius at 1 atm, and/or (d) less than 2 cm2. For some applications, when liquid column container 118 is oriented in the aligned orientation, wider portion 323 has an average inner cross-sectional area, measured in horizontal plane 135 and/or the above-mentioned plane, of (a) at least 0.16 cm2 (e.g., at least 0.25 cm2, 0.5 cm2, or 1 cm2), (b) at least the product of 0.16 cm2 (e.g., at least 0.25 cm2, 0.5 cm2, or 1 cm2) and a specific gravity of liquid 121 with reference to water at 4 degrees Celsius at 1 atm, (c) at least the product of 0.16 cm2 (e.g., at least 0.25 cm2, 0.5 cm2, or 1 cm2) and a specific gravity of liquid 121 with reference to water at 20 degrees Celsius at 1 atm, and/or (d) less than 2 cm2. For some applications, when liquid column container 118 is oriented in the aligned orientation, narrower portion 322 has an inner cross-sectional area, measured in horizontal plane 135 and/or the above-mentioned plane, of less than 0.16 cm2, such as less than 0.09 cm2, at most or all axial locations along narrower portion 322.
Reference is now made to
For some applications, cuff pressure stabilizer 300 is arranged such that the adjustable distance can vary by at least 1 cm. Alternatively or additionally, for some applications, cuff pressure stabilizer 300 is arranged such that the adjustable distance can vary by (a) at least the quotient of (i) 3 cm divided by (ii) the specific gravity of liquid 121 with reference to water at 4 degrees Celsius at 1 atm, and/or (b) at least the quotient of (i) 3 cm divided by (ii) the specific gravity of liquid 121 with reference to water at 20 degrees Celsius at 1 atm.
For some applications, cuff pressure stabilizer 300 comprises a mechanical user control element 360, which is arranged to set the adjustable distance, for example by rotation, e.g., with respect to a threaded connector 361 that is fixed to wider portion 363. Alternatively, mechanical user control element 360 may axially slide with respect to casing 110 upon application of a sufficient force to overcome friction preventing such sliding.
For some applications, such as shown in
For other application (configuration not shown), fluid reservoir 120 is axially-slidably coupled to casing 110. Typically, for these applications, wider portion 323 of liquid column container 118 is fixed to casing 110.
For some applications, wider portion 323 of liquid column container 118 has a target-pressure indicator marker 369 (e.g., a horizontal line), which is axially slidable with respect to pressure indicia markings 126, which, as mentioned above, are typically provided on casing 110. The healthcare worker may set target-pressure indicator marker 369 to indicate a desired target pressure in inflatable cuff 11, and then inflate inflatable cuff 11 at least approximately to this target pressure. Such setting of target-pressure indicator marker 369, by axially moving target-pressure indicator marker 369 with respect to pressure indicia markings 126, has the effect of adjusting the adjustable distance between wider portion 323 of liquid column container 118 and fluid reservoir 120.
Target-pressure indicator marker 369 is disposed on wider portion 323 so as to delineate (a) an upper portion of wider portion 323 above target-pressure indicator marker 369 and (b) a lower portion of wider portion 323 below target-pressure indicator marker 369. For some applications, the volume of the upper portion equals:
For some applications, at least an axial portion of narrower portion 322 of liquid column container 118 is flexible, so as to provide a variable axial length to narrower portion 322. For some of these applications, the at least an axial portion of narrower portion 322 of liquid column container 118 is elastic. For other applications, at least an axial portion of narrower portion 322 of liquid column container 118 is telescopically adjustable, so as to provide a variable axial length to narrower portion 322.
Reference is still made to
For some applications, at each of all axial locations along narrower portion 322 of liquid column container 118, liquid column container 118:
For some applications, the largest inner dimension D1 equals at least 4 mm at most or all of the axial locations along narrower portion 322 of liquid column container 118, such as at least 6 mm, e.g., at least 8 mm Alternatively or additionally, for some applications, the diameter D2 of circle 326 is no more than 4 mm at most or all of the axial locations along narrower portion 322 of liquid column container 118, such as no more than 2 mm, e g , no more than 1 mm, such as no more than 0.5 mm
For some applications, at most or all of the axial locations along narrower portion 322 of liquid column container 118, liquid column container 118 has a non-circular cross-sectional shape, such as a rectangle, an oblong shape, an ellipse, or a crescent. For applications in which the cross-sectional shape is a rectangle, a length L of the rectangular typically equals at least 200% of a width W of the rectangle, such as at least 300% or at least 400%. For applications in which the cross-sectional shape is an ellipse, a length of the major axis of the ellipse typically equals at least 200% of a length of the minor axis of the ellipse, such as at least 300% or at least 400%.
Alternatively or additionally, for some applications, at each of the axial locations along narrower portion 322 of liquid column container 118, at least 80% of the inner cross-sectional area is within 1 mm of an inner surface 328 of liquid column container 118, such as within 0.75 mm, e.g., within 0.5 mm, such as within 0.2 mm, of inner surface 328. For some applications, at each of the axial locations along narrower portion 322 of liquid column container 118, less than 10% of the inner cross-sectional area is within 0.1 mm, such as within 0.2 mm, of inner surface 328 of liquid column container 118. For some applications, the inner cross-sectional area is less than 0.09 cm2 at most or all axial locations along narrower portion 322 of liquid column container 118, when liquid column container 118 is oriented in the aligned orientation.
Reference is made to
Reference is now made to
Cuff pressure stabilizer 500 comprises a fluid reservoir 524 and a liquid column container 518. Liquid column container 518 is (a) open to atmosphere 99 at at least one site along liquid column container 518, (b) in fluid communication with fluid reservoir 524, and (c) in communication with the inflation lumen proximal port connector 134 via fluid reservoir 524. Cuff pressure stabilizer 500 comprises a buffer module 550, which is configured to provide automatic pressure regulation of inflatable cuff 11, while simultaneously continuously displaying the pressure in inflatable cuff 11. Cuff pressure stabilizer 500 further comprises an indicator module 520, which continuously displays the pressure in inflatable cuff 11.
Cuff pressure stabilizer 500 further comprises liquid 121, which is contained (a) in fluid reservoir 524, (b) in liquid column container 518, or (c) partially in fluid reservoir 524 and partially in liquid column container 518. Like cuff pressure stabilizer 100, cuff pressure stabilizer 500 has a plurality of pressure indicia markings 126 distributed along liquid column container 518 for measuring a height of liquid 121 in liquid column container 518. Typically, pressure indicia markings 126 are distributed evenly throughout at least relevant pressure range 127 of 23-27 cm H2O.
Typically, liquid 121 has (a) a density of between 1.5 and 5 g/cm3 at 4 degrees Celsius at 1 atm, such as less than 3.5 g at 4 degrees Celsius at 1 atm, e.g., less than 3 g at 4 degrees Celsius at 1 atm, e.g., between 1.5 and 3.5 g/cm3, such as between 1.5 and 3 g/cm3, and/or (b) a density of between 1.5 and 5 g/cm3 at 20 degrees Celsius at 1 atm, such as less than 3.5 g at 20 degrees Celsius at 1 atm, e.g., less than 3 g at 20 degrees Celsius at 1 atm, e.g., between 1.5 and 3.5 g/cm3, such as between 1.5 and 3 g/cm3. Such a density provides high resolution pressure readings in the above-mentioned relevant pressure range 127 of 23-27 cm H2O, without requiring liquid column container 518 to be very long and unwieldy, such as if liquid 121 was H2O.
For some applications, liquid 121 has (a) a viscosity of no more than 25 times a viscosity of water at 4 degrees Celsius at 1 atm, such as no more than 15, no more than 10, or no more than 5 times the viscosity of water at 4 degrees Celsius at 1 atm, and/or (b) a viscosity of no more than 25 times a viscosity of water at 20 degrees Celsius at 1 atm, such as no more than 15, no more than 10, or no more than 5 times the viscosity of water at 20 degrees Celsius at 1 atm. For some applications, liquid 121 comprises a solution of crystals (solute) dissolved in a liquid solvent (typically water), having a mass percent of between 65% and 85% (e.g., between 75% and 85%) (i.e., the mass of the liquid solvent (typically water) is only between 15% and 35% of the total mass of the solution). The dilution is selected based on the desired density of the liquid.
Typically, liquid 121 is non-toxic. As used in the present application, including in the claims, “non-toxic” has the meaning generally understood in the medical arts, i.e., that the full quantity of liquid 121 of the cuff pressure stabilizer, even if it is swallowed by the patient or comes in contact with the patient's skin, will not produce personal injury or illness to the patient. (The liquid is still “non-toxic” if it causes mild irritations upon coming contact in with the eyes (which is not an intended use of the liquid).) For example, criteria for ascertaining whether a substance is “toxic” are provided in the U.S. Federal Hazardous Substances Act (FHSA) and the Chemicals Act of Germany (Chemikaliengesetz—ChemG), as amended in 2008.
Typically, liquid 121 is non-flammable. Typically, liquid 121 is odorless. For some applications, liquid 121 comprises a tungstate-based liquid, e.g., selected from the group consisting of sodium polytungstate, sodium metatungstate, lithium polytungstate, and lithium metatungstate. For some applications, liquid 121 comprises at least two liquids, at least one of which has the density of between 1.5 and 5 g/cm3 at 4 degrees Celsius at 1 atm, and at least one of which has a density of less than 1.5 g/cm3 at 4 degrees Celsius at 1 atm. For some applications, liquid 121 comprises at least two liquids, at least one of which has the density of between 1.5 and 5 g/cm3 at 20 degrees Celsius at 1 atm, and at least one of which has a density of less than 1.5 g/cm3 at 20 degrees Celsius at 1 atm.
For some applications, a volume of liquid 121 is at least 0.5 cc, no more than 4 cc, and/or between 0.5 and 4 cc, such as at least 1 cc, no more than 2 cc, and/or between 1 and 2 cc.
For some applications, liquid column container 518 is in pressure communication with inflation lumen proximal port connector 134 via fluid reservoir 524. For some of these applications, fluid reservoir 524 comprises at least one wall 521 that comprises a pressure-communicating movable wall 554, and liquid column container 518 is in pressure communication with inflation lumen proximal port connector 134 via pressure-communicating movable wall 554 of fluid reservoir 524. For some applications (as shown), pressure-communicating movable wall 554 comprises a flexible membrane, which typically is elastic or pliable, while for other applications (not shown), pressure-communicating movable wall 554 comprises another movable structure, such as bellows.
For some applications, cuff pressure stabilizer 500 comprises a gas container 523, which (a) extends to inflation lumen proximal port connector 134, (b) contains some of the gas, (c) is not in liquid communication with fluid reservoir 524, and (d) comprises at least one wall that comprises a volume-compensation movable wall 552, which is in pressure communication with atmosphere 99 on the other side of the movable wall. For some applications (as shown), volume-compensation movable wall 552 comprises a flexible membrane, which typically is elastic or pliable, while for other applications (not shown), volume-compensation movable wall 552 comprises another movable structure, such as bellows. When inflatable cuff 11 is squeezed and its volume therefore decreases, gas is pushed from the inflatable cuff into gas container 523. As a result, volume-compensation movable wall 552 moves (e.g., stretches, for applications in which the movable wall comprises a flexible membrane) and thereby increases the total volume of gas container 523 to accommodate the addition gas. In addition, a liquid upper surface 529 of liquid 121 in liquid column container 518 moves upward, also increasing the volume of gas container 523.
For some of these applications, fluid reservoir 524 comprises the at least one wall 521 that comprises pressure-communicating movable wall 554, and liquid column container 518 is in pressure communication with gas container 523 via pressure-communicating movable wall 554 of fluid reservoir 524. Pressure-communicating movable wall 554 thus prevents fluid communication between fluid reservoir 524 and gas container 523, while allowing pressure communication therebetween. Typically, pressure-communicating movable wall 554 is disposed at least partially within gas container 523.
Pressure-communicating movable wall 554 is typically deformable (e.g., elastic and/or pliable). As a result, when the gas pressure increases in gas container 523, the gas presses and moves pressure-communicating movable wall 554, thereby pushing liquid 121 in fluid reservoir 524 upward within liquid column container 518, and thus also elevating liquid upper surface 529 of liquid 121 in liquid column container 518. For some applications, pressure-communicating movable wall 554 is supported at its bottom by a rigid platform 556, which maintains the lowest point of liquid 121 at a fixed reference height.
For some applications, gas container 523 comprises a buffer chamber 564, which is shaped so as to define a chamber inlet port 558 that is in fluid communication with inflation lumen proximal port connector 134, such as via gas inlet 141. For some applications, buffer chamber 564 has a volume of at least 1 cc when a pressure of the gas in buffer chamber 564 is 25 cm H2O. For some applications, a volume of buffer chamber 564 increases by at least 1 cc, such as by at least 2 cc, and/or by no more than 5 cc, when a pressure of gas 559 in buffer chamber 564 increases from 25 cm H2O to 30 cm H2O. For some applications, at least one wall of buffer chamber 564 comprises volume-compensation movable wall 552, described above.
Buffer chamber 564 typically comprises a buffer chamber casing 537. For some applications, pressure-communicating movable wall 554 is disposed at least partially within buffer chamber 564, e.g., within buffer chamber casing 537. For some of these applications, buffer chamber casing 537 is shaped so as to define, in addition to buffer chamber 564, an enclosed volume-compensation movable wall expansion space 553, into which volume-compensation movable wall 552 can expand. For such applications, buffer chamber casing 537 typically is shaped so as to define a buffer chamber air environment port 557 between enclosed volume-compensation movable wall expansion space 553 and atmosphere 99.
For some applications, liquid column container 518 comprises a dissolvable wall portion 560 that is dissolvable in water. Typically, dissolvable wall portion 560 defines a perforation therethrough that is configured to become permeable to liquid 121 through the perforation after total time of at least 3 days, e.g., at least 7 days, at least 10 days, or at least 14 days, and/or less than 30 days of contact with liquid 121. Typically, dissolvable wall portion 560 remains impermeable to liquid 121 for at least 48 hours, e.g., at least 1 week, at least 2 weeks, or at least 3 weeks, of contact between liquid 121 and dissolvable wall portion 560. For some applications, before the first use of cuff pressure stabilizer 500, an elongate plug is disposed in liquid column container 518 (typically through opening 142) and reaches below the bottom end of dissolvable wall portion 560, thereby preventing liquid 121 from coming into contact with dissolvable wall portion 560 until the plug is removed. Dissolvable wall portion 560 may preserve sterility of cuff pressure stabilizer 500 by preventing reuse of the stabilizer for more than one patient.
For some applications, when liquid column container 518 is oriented in an aligned orientation in which pressure indicia markings 126 reflect, to within 1 cm H2O, pressure of the gas in buffer chamber 564 at least in relevant pressure range 127 of 23-27 cm H2O: dissolvable wall portion 560 is disposed at least partially below an axial location along liquid column container 518 corresponding to a pressure of the gas in buffer chamber 564 of 23 cm H2O. For some applications, when liquid column container 518 is oriented in the aligned orientation and the pressure of the gas in buffer chamber 564 equals ambient air pressure, dissolvable wall portion 560 is disposed above liquid upper surface 529 of liquid 121 in liquid column container 518.
Reference is now made to
As illustrated in
Reference is now made to
Cuff pressure stabilizer 600 comprises a fluid reservoir 624, and a liquid column container 618, which is (a) open to atmosphere 99 at at least one site along liquid column container 618, (b) in fluid communication with fluid reservoir 624, and (c) in communication with the inflation lumen proximal port connector 134 via fluid reservoir 624. Cuff pressure stabilizer 600 comprises a buffer module 650, which is configured to provide automatic pressure regulation of inflatable cuff 11, while simultaneously continuously displaying the pressure in inflatable cuff 11. Cuff pressure stabilizer 600 further comprises an indicator module 620, which continuously displays the pressure in inflatable cuff 11.
Typically, fluid reservoir 624 contains some of gas 559, and liquid column container 618 is in fluid communication with inflation lumen proximal port connector 134 via fluid reservoir 624. Consequently, gravity causes gas 559 in fluid reservoir 624 to be above the portion of liquid 121 in fluid reservoir 624.
For some applications, fluid reservoir 624 extends to inflation lumen proximal port connector 134, and comprises at least one wall 630 that comprises a volume-compensation movable wall 652, which is in pressure communication with atmosphere 99. For some applications, fluid reservoir 624 comprises a buffer chamber 664, which is shaped so as to define a chamber inlet port 658 that is in fluid communication with inflation lumen proximal port connector 134, such as via gas inlet 141. For some of these applications, buffer chamber 664 comprises the at least one wall 630 that comprises volume-compensation movable wall 652. For some applications, buffer chamber 664 has a volume of at least 2 cc when gas 559 in buffer chamber 664 is at a pressure of 25 cm H2O.
In the resting state illustrated in
As illustrated in
For some applications, fluid reservoir 624 contains some of gas 559, and when liquid column container 618 is oriented in an aligned orientation in which pressure indicia markings 126 reflect, to within 1 cm H2O, pressure of the gas in fluid reservoir 624 at least in relevant pressure range 127 of 23-27 cm H2O: dissolvable wall portion 560 is disposed at least partially below an axial location along liquid column container 618 corresponding to a pressure of the gas in fluid reservoir 624 of 23 cm H2O. For some applications, when liquid column container 618 is oriented in an aligned orientation and the pressure of gas 559 in fluid reservoir 624 equals ambient air pressure, dissolvable wall portion 560 is disposed above liquid upper surface 529 of liquid 121 in liquid column container 618.
Reference is now made to
For some applications, buffer chamber 664 comprises a buffer chamber casing 837. For some applications, volume-compensation movable wall 652 is disposed at least partially within buffer chamber 664, e.g., within buffer chamber casing 837. Buffer chamber casing 837 typically is shaped so as to define buffer chamber air environment port 557 between enclosed volume-compensation movable wall expansion space 553 and atmosphere 99.
Typically, cuff pressure stabilizer 800 comprises a coupling element 828, which may comprise, for example, a strap (as shown), a gripper (not shown), or a clamp (not shown), which is coupleable to a vertical pole (e.g., a vertical IV pole), such as shown for the prototypes in
For some applications, buffer chamber 664 is shaped so as to define an internal spill-prevention element 880, which may be shaped as an inverted bottle neck. Spill-prevention element 880 creates a pool such that if the device is laid on its side or even turned upside down, liquid 121 will not spill by gravity through buffer chamber air environment port 557.
For some applications, cuff pressure stabilizer 800 comprises an on/off valve 885, which enables/disables fluid communication between buffer chamber 664 and liquid column container 618. In the illustrated configuration, valve 885 is switched on/off by rotation around the vertical axis, e.g., upon turning by 180 degrees, a fluid passage 887 to liquid column container 618 is turned away and instead a wall 886 seals the fluid communication between buffer chamber 664 and liquid column container 618.
For some applications, cuff pressure stabilizer 800 comprises a pressure-release chamber 890. Pressure-release chamber 890 is typically sized to have a volume larger than that of the full liquid content. If the pressure rises to a level above that of a level of the bottom of pressure-release chamber 890, liquid 121 is collected within pressure-release chamber 890. Liquid 121 is the only gas-seal that prevents escape of gas from the cuff to atmosphere 99. Therefore, if the cuff pressure rises to a pressure substantially above the level of the bottom of pressure-release chamber 890, all of liquid 121 is collected in pressure-release chamber 890, and gas escapes from the cuff to atmosphere 99, thereby releasing the excess pressure. The level of liquid 121 then falls again to recreate the gas seal so as to prevent further gas leakage from the cuff to atmosphere 99. Altogether, pressure-release chamber 890 operates as an effective pressure-release valve in which the pressure limit is set by the height of pressure-release chamber 890.
Reference is now made to
Reference is now made to
Although cuff pressure stabilizers 100, 200, 300, 500, 600, and 800 have been described as being used with inflatable cuff 11 of tracheal ventilation tube 10, cuff pressure stabilizers 100, 200, 300, 500, 600, and 800 may alternatively be used with other inflatable chambers of other medical devices or non-medical devices. For example, the inflatable chamber may be a Foley catheter balloon, a gastric balloon, a balloon of colonoscope, or a balloon of an endoscope.
In the description and claims of the present application, each of the verbs, “comprise,” “include” and “have,” and conjugates thereof, are used to indicate that the object or objects of the verb are not necessarily a complete listing of members, components, elements or parts of the subject or subjects of the verb. The articles “a” and “an” are used herein to refer to one or to more than one (i.e., to at least one) of the grammatical object of the article. By way of example, “an element” means one element or more than one element. The term “including” is used herein to mean, and is used interchangeably with, the phrase “including but not limited to.” The term “or” is used herein to mean, and is used interchangeably with, the term “and/or,” unless context clearly indicates otherwise. The term “such as” is used herein to mean, and is used interchangeably, with the phrase “such as but not limited to.”
All publications, patent applications, patents, and other references mentioned herein are incorporated by reference in their entirety. In case of conflict, the present patent specification, including definitions, will prevail. In addition, the materials, methods, and examples are illustrative only and not intended to be limiting.
For brevity, some explicit combinations of various features are not explicitly illustrated in the figures and/or described. It is now disclosed that any combination of the method or device features disclosed herein can be combined in any manner—including any combination of features—any combination of features can be included in any embodiment and/or omitted from any embodiments.
As used in the present application, including in the claims, a “fluid” comprises liquid and/or gas.
Although applications of the present invention have generally been described as for use with tracheal ventilation tube 10, they may also be used with other catheters, such as tracheostomy catheters.
The scope of the present invention includes embodiments described in the following applications, which are assigned to the assignee of the present application and are incorporated herein by reference. In an embodiment, techniques and apparatus described in one or more of the following applications are combined with techniques and apparatus described herein:
PCT Publication WO/2012/131626 to Einav et al.
GB 2482618 A to Einav et al.;
UK Application GB 1119794.4, filed Nov. 16, 2011;
U.S. Provisional Application 61/468,990, filed Mar. 29, 2011;
U.S. Provisional Application 61/473,790, filed Apr. 10, 2011;
U.S. Provisional Application 61/483,699, filed May 8, 2011;
U.S. Provisional Application 61/496,019, filed Jun. 12, 2011;
U.S. Provisional Application 61/527,658, filed Aug. 26, 2011;
U.S. Provisional Application 61/539,998, filed Sep. 28, 2011;
U.S. Provisional Application 61/560,385, filed Nov. 16, 2011;
U.S. Provisional Application 61/603,340, filed Feb. 26, 2012;
U.S. Provisional Application 61/603,344, filed Feb. 26, 2012;
U.S. Provisional Application 61/609,763, filed Mar. 12, 2012;
U.S. Provisional Application 61/613,408, filed Mar. 20, 2012;
U.S. Provisional Application 61/635,360, filed Apr. 19, 2012;
U.S. Provisional Application 61/655,801, filed Jun. 5, 2012;
U.S. Provisional Application 61/660,832, filed Jun. 18, 2012;
U.S. Provisional Application 61/673,744, filed Jul. 20, 2012;
PCT Publication WO 2013/030821 to Zachar et al.;
U.S. Pat. No. 8,999,074 to Zachar et al.;
U.S. Provisional Application 62/305,567, filed Mar. 9, 2016;
U.S. Provisional Application 62/402,024, filed Sep. 30, 2016; and
U.S. Provisional Application 62/405,115, filed Oct. 6, 2016
It will be appreciated by persons skilled in the art that the present invention is not limited to what has been particularly shown and described hereinabove. Rather, the scope of the present invention includes both combinations and subcombinations of the various features described hereinabove, as well as variations and modifications thereof that are not in the prior art, which would occur to persons skilled in the art upon reading the foregoing description.
The present patent application is a continuation of U.S. patent application Ser. No. 16/078,545 which is incorporated herein by reference. U.S. patent application Ser. No. 16/078,545 is a national-stage entry of PCT/IL2017/050284 filed on Mar. 8, 2017 which is incorporated herein by reference. PCT/IL2017/050284 claims priority from (a) U.S. Provisional Application 62/305,567, filed Mar. 9, 2016, (b) U.S. Provisional Application 62/402,024, filed Sep. 30, 2016, (c) U.S. Provisional Application 62/405,115, filed Oct. 6, 2016, and (d) U.S. Provisional Application 62/448,254, filed Jan. 19, 2017, all of which are assigned to the assignee of the present application and are incorporated herein by reference.
| Number | Date | Country | |
|---|---|---|---|
| 62305567 | Mar 2016 | US | |
| 62402024 | Sep 2016 | US | |
| 62405115 | Oct 2016 | US | |
| 62448254 | Jan 2017 | US |
| Number | Date | Country | |
|---|---|---|---|
| Parent | 16078545 | Aug 2018 | US |
| Child | 17146038 | US |
