Patent Application
20250144354
The present disclosure relates to a positive pressure breathing circuit and a method for ventilating a patient. The breathing circuit can be used in any type of pressurized breathing therapy including, for example, continuous positive air (way) pressure (CPAP) therapy and bilevel positive air pressure therapy where the inspiratory and expiratory pressures differ.
Breathing circuits can help a patient to breath by opening up their airways and/or supplying specific breathing gases for a particular medicinal purpose. The breathing gases may be supplied at a flow rate that is higher than an average inspiratory flow rate to ensure there is no shortage of breathing gases. In the case of CPAP therapy, the flow supplied to the patient is usually higher than the peak inspiratory flow, rather than the average inspiratory flow.
Some traditional breathing circuits use a mixed breathing gas including a blend of air and oxygen gas that is supplied to a patient via an inspiratory tube. The required oxygen saturation levels in the patient's blood can be achieved by adjusting the ratio of the oxygen in the oxygen/air blend. However, a problem with this breathing circuit is the positive pressure experienced by the patient is the result of a continuous supply of the mixed breathing gas during both inhalation and exhalation, which results in a significant wastage of the oxygen gas. There is therefore a need for an improved breathing circuit.
An embodiment relates to a positive pressure breathing circuit for ventilating a patient, the breathing circuit including:
An embodiment relates to a positive pressure breathing circuit for ventilating a patient, the breathing circuit including:
An advantage provided by the second gas entering the inspiratory member distally is that the inspiratory member has few or no additional components proximal to the patient interface making the breathing circuit lighter which makes the patient interface more comfortable than if the second gas entered the inspiratory member closer to the patient interface. The inspiratory member may include an inspiratory tube.
The breathing circuit may include an expiratory member which receives the exhaled gas from the patient interface.
The expiratory member may include an expiratory tube extending away from the patient interface. In one example, the expiratory member may be connected to the patient interface. In another example, proximal portions of the expiratory member and the inspiratory member may be connected adjacent to the patient interface.
The expiratory member is configured so that the excess supply of the first gas in the expiratory member downstream of the second non-return valve and the exhaled gas in the expiratory member downstream of the second non-return valve are vented from the breathing circuit
The inspiratory member may include a first non-return valve and the first gas enters the inspiratory member upstream of the first non-return valve and the second gas enters the inspiratory member downstream of the first non-return valve. That is to say, the first non-return valve is located between the first gas and the second gas entering the inspiratory member.
Throughout this specification, the first non-return valve inhibits the exhaled gas from passing upstream of the first non-return valve. The first non-return valve inhibits the exhaled gas from passing upstream of the first non-return valve, but this does not necessarily mean that the first non-return valve completely blocks the flow. The first non-return valve may of course block the flow.
In addition, by locating the first non-return valve distally, the inspiratory member has few or no additional components proximal to the patient interface, allowing the distal portion of the breathing circuit attached to the patient interface to be lighter than if the first non-return valve was proximal to the patient interface and the second gas entered the inspiratory member closer to the patient interface.
The first non-return valve is configured to inhibit the second gas flowing upstream toward the first gas entering the inspiratory member.
The inspiratory member is configured so that a volume of the second gas can enter and flow toward the patient interface during patient exhalation and be stored in the inspiratory member.
The expiratory member may have a second non-return valve to inhibit the exhaled gas from re-entering the patient interface.
Throughout this specification, the second non-return valve inhibits the flow of the excess supply of the first gas passing upstream of the second non-return valve, but this does not necessarily mean that the second non-return valve completely blocks the flow. The second non-return valve may of course block the flow.
The internal volume of the inspiratory member for receiving the volume of the second gas can be changed by changing the length of the inspiratory member to accommodate a desired volume of the second gas during patient exhalation. For example, the inspiratory member may be expandible and contractible in an axial direction of the tube to change the length of the member. In another example, the breathing circuit may have a set of the inspiratory members of different internal volume, and the member of desired internal volume can be chosen from the set. In yet another example, the inspiratory member may have a set of markings thereon signifying the internal volume at particular lengths. In use, a user may select the desired internal volume by cutting the inspiratory member at one of the markings.
The internal volume may be changed by changing the diameter of the inspiratory member. For example, the inspiratory member may have an expandable diameter over part or all of the length of the inspiratory member.
The pressure regulation device may be configured to regulate pressure in the breathing circuit.
In one example, the pressure regulation device may be directly connected to the patient interface. For example, the pressure regulation device may be integrally formed with the patient interface, connected to an outlet port of the patient interface, or connected to the patient interface, for example, by a connector such as Y-piece. In the situation where the pressure regulation device is on the patient interface, there may be no need for an expiratory member.
In another example, the pressure regulation device may be connected to the expiratory member and vent the exhaled gas from the expiratory member. In one example, the pressure regulation device may be connected to an end of the expiratory member. In this example, the expiratory member is not connected to the inspiratory member.
For instance, the pressure regulation device may include a pressure relief valve, such as a positive end expiratory pressure valve (expiratory tube PEEP valve) for venting exhaled gas.
In another example, the pressure regulation device may be configured to regulate pressure in the inspiratory member. For instance, the pressure regulation device in the inspiratory member may include a pressure relief valve, such as a positive end expiratory pressure valve (inspiratory member PEEP valve) for venting the first gas supplied in excess to the breathing circuit.
In another example, the pressure regulation device may include a first control valve for controlling the pressure of the first gas supplied to the breathing circuit.
In another example, the pressure regulation device may include a second control valve for controlling the pressure of the second gas supplied to the breathing circuit.
The inspiratory member may be connectable to the expiratory member so that any excess of the first gas supplied to the inspiratory member passes (from the inspiratory member) to the expiratory member without passing through the patient interface. That is to say the inspiratory member and the expiratory member are connected in a loop configuration and the excess supply of the first gas is conveyed from the inspiratory member to the expiratory member in the loop configuration remote from the patent interface.
The distal portion of the expiratory member and the distal portion of the inspiratory member may be connected to form the loop configuration. That is to say, they are connected remotely from the patent interface.
The expiratory member may include a second non-return valve to inhibit the first gas from entering the patient interface from the expiratory member.
The expiratory member is configured so that the first gas and the exhaled gas in the expiratory member downstream of the second non-return valve are vented from the breathing circuit. Specifically, the expiratory member is configured to vent the first gas supplied in excess to the breathing circuit that flows to the expiratory member and the exhaled gas received by the expiratory member.
The second non-return valve also inhibits the exhaled gas from being rebreathed.
The expiratory member may have a substantially constant volume. That is to say in one example, the expiratory member may not have a volume changing structure volume such as a bellows, collapsible chamber, or flexible walled passage or alike. The volume of the expiratory member may fluctuate by a small amount due to pressure changes, but the macro structure of the expiratory member is not configured to change with changes in pressure.
The expiratory member may have a constant volume upstream of the second non-return valve.
The expiratory member may have a constant volume downstream of the second non-return valve.
The inspiratory member may be connected to the expiratory member downstream of the second non-return valve.
In one example, the breathing circuit comprises a bypass member interconnecting the inspiratory member and the expiratory member that conveys the excess supply of the first gas from the inspiratory member to the expiratory member.
The bypass member may include a bypass tube.
The bypass member may interconnect distal portions of the inspiratory and expiratory members.
The bypass member may connect to the expiratory member downstream of the second non-return valve.
In another example, the inspiratory member and the expiratory member are directly interconnected.
The inspiratory member and the expiratory member may have a continuous open line so the first gas can pass from the inspiratory member to the expiratory member in one direction.
The first gas received by the expiratory member is vented from the breathing circuit unobstructed, and the expiratory member is configured so that the exhaled gas passes through the second non-return valve and is vented from the breathing circuit.
The expiratory member may be configured so that the excess supply of the first gas and the exhaled gas downstream of the second non-return valve are vented from the breathing circuit without re-entering the inspiratory member. This can be achieved by the first gas and the second gas being supplied to the inspiratory member, and the patient exhaling the exhaled gas at an exhaled pressure.
The pressure regulation device may include a positive end expiratory pressure valve (PEEP valve) on the distal portion of the expiratory member.
The positive end expiratory pressure valve of the expiratory member may have a pressure setting ranging from about 2.5 to 35.0 cmH2O, about 4.5.0 to 25.0 cmH2O, about 6.5 to 15 cmH2O, or about 8.0 to 12.0 cmH2O, or about 10.0 cmH2O.
The pressure regulation device of the expiratory member may have a higher pressure setting than the pressure regulation device of inspiratory member. The difference in pressure may inhibit flow of the breathing gas from the inspiratory member to the expiratory member other than that caused by the patient.
The pressure regulation devices of at least one of the expiratory member and the inspiratory member may be a positive end expiratory pressure valve (PEEP valve).
The pressure regulation devices of at least one of the expiratory member and the inspiratory member may be a restriction orifice.
The pressure regulation device may include an over pressure relief valve that is intended to release the pressure from the breathing circuit. The over pressure relief valve may have a higher setting than the pressure relief valve of the expiratory member, and if present, the pressure relief valve of the inspiratory member. The over pressure relief valve may be located on the inspiratory member. The over pressure relief valve may be located on the expiratory member. If the bypass member interconnecting the inspiratory and expiratory members is present, the over pressure relief valve may be located on the bypass member. The over pressure relief valve may be located on any one or a combination of the inspiratory member, the expiratory member and the bypass member.
The breathing circuit may include a humidification device for humidifying part of, or all of, the breathing gas. For example, the humidification device may be humidifying the first gas. In this instance, the humidification device may be located upstream of the second gas entering the inspiratory member, such as upstream of the first non-return valve.
In another example, the humidification device may humidify the first gas and the second gas. In this instance, the humidification device will be located downstream of the second gas entering the inspiratory member. In this position, the humidification device would be located downstream of the first non-return valve if present. An advantage in this arrangement is that the first non-return valve is kept dry which is better for achieving reliable functionality. In addition, any secretions from the patient are unlikely to contact the first non-return valve due to its position upstream of the second gas entering the inspiratory member.
The humidification device may have a humidification chamber in which the water and the breathing gas contact, and the chamber has a volume in which the second gas can accumulate. Especially when the patient is exhaling. This further increases the likelihood of the patient inhaling the second gas at the start of their breath.
As the second gas can be stored in the humidifier device while the patient is exhaling in addition to the inspiratory member, the volume of the humidification chamber should be considered when equating the tidal volume to the inspiratory member.
The second gas may be supplied at a constant flow rate.
The first gas may be supplied at a constant flow rate.
The breathing circuit may include the first source of the first gas in which the first source includes a variable flow generator that is operable for supplying a high pressure during patient inhalation and a low pressure during patient exhalation for the first gas. The variable flow generator may also be operable to provide constant pressure. That is to say, the inspiratory pressure or the IPAP is higher, relative to the expiratory pressure or the EPAP which is lower. The flow generator may cycle between the high pressure during patient inhalation and the low pressure during patient exhalation during continuous patient breathing. For example, the variable flow generator may be a non-invasive ventilation or a PAP device that has a variable speed blower. The variable flow generator may also supply the first gas at a constant positive air pressure during patient inhalation and patient exhalation.
The breathing circuit may include a sensor for detecting when a patient inhales and/or exhales. Typically, the gas flow generator operates at the high pressure when the patient inhales, and at the low pressure when the patient exhales. In the situation in which the first gas is air, the variable speed blower may include an inspiratory positive airway pressure (IPAP) and an expiratory positive airway pressure (EPAP).
The sensor may be a flow sensor for detecting the flow of the first gas in the breathing circuit. The flow sensor may be located within the flow generator upstream or downstream of a blower of the flow generator. For example, the flow sensor may be located at the inlet or outlet of the flow generator. In another example, the flow sensor may be located at the inspiratory member to detect when the patient inhales. An output from the flow sensor can be used to determine when the patient starts and/or ends inhaling, and can be used to operate the flow generator in high pressure flow and low pressure, such as between IPAP or EPAP.
In another example, the flow sensor may be located in the expiratory member to detect when the patient exhales. An output from the flow sensor can be used to determine when the patient starts and/or ends exhaling, and can be used to operate the pressure regulation device in high pressure flow and low pressure, such as between IPAP or EPAP.
The sensor may include a pressure sensor for detecting the pressure of the first gas in the breathing circuit downstream of the flow generator. In one example, the pressure sensor may be located on the inspiratory member downstream of the flow generator and upstream of the second gas entering the inspiratory member. In another example, the pressure sensor may be within the flow generator and downstream of a blower of the flow generator. In yet another example, the pressure sensor may be located at the patient interface.
When the breathing circuit includes a variable flow generator, the pressure regulation device of the breathing circuit may, in one example, include a pressure relief valve, such as a PEEP valve. The pressure relief valve may be located in the expiratory member for venting the exhaled gas.
In another example, the pressure regulation device may include a restriction orifice having an aperture of fixed opening size.
In another example, the pressure regulation may include a constant flow valve
In further examples, the internal volume may range from about 315 ml to 760 ml for adult patients, or range from about 400 to 600 ml. For pediatric patients, the internal volume may range from about 100 ml to 450 ml, or range from about 200 to 400 ml. For neonatal patients, the internal volume may range from about 50 to 200 ml, or range from about 100 to 150 ml.
The pressure of exhaled gas in the expiratory member may be greater than the pressure of the breathing gas in inspiratory member.
The first gas may be pressurized air. The first gas may be pressurized air enriched with oxygen.
In one example, the second gas may be pressurized oxygen gas.
In another example, the second gas may be a pressurized gas including one or any combination of: oxygen gas, heliox, or an anaesthetic gas. The anaesthetic gas could be nitrous oxide or a 50:50 mixture of nitrous oxide and oxygen gas.
Pressurized oxygen gas may be supplied from a liquified oxygen source, a bottled oxygen source or from an oxygen concentrator source.
The breathing circuit may include a patient interface. The patient interface may be a sealed patient interface. For example, the patient interface includes either one or any combination of a full-face mask (also known as an oro-nasal mask), a sealed nasal cannula, a sealed oral mask, a sealed nasal mask, a nasal pillows interface, or a tracheostomy member. The first non-return valve may be arranged on the patient interface.
The patient interface may have an inlet connection that connects to the inspiratory member, and an outlet connection that connects to the expiratory member.
The patient interface may have a coupling to which a Y-piece, is or can be connected, in which one leg of the Y-piece is an inlet connection that connects to the inspiratory member, and another leg is an outlet connection that connects to the expiratory member.
The positive end expiratory pressure valve of the expiratory member may be fitted directly to the outlet connection of the Y-piece.
The inspiratory member may be directly connected to the patient interface either with or without a Y-piece. That is to say, there may be no intervening operations such as humidifiers, heat and moisture exchangers or other items that have the potential to increase dead space in the breathing circuit between the inspiratory member and the patient interface.
An embodiment relates to a positive pressure breathing circuit for ventilating a patient, the breathing circuit including:
The breathing circuit may include a pressure regulation device configured to regulate pressure in the breathing circuit, including venting exhaled gas.
The breathing circuit may have an expiratory member configured to vent the exhaled gas from the patient interface.
In one example, the flow generator may be a variable flow generator that is operable to provide high pressure during patient inhalation and low pressure during patient exhalation. The variable flow generator may also be operable to provide constant pressure. That is to say, the inspiratory pressure or the IPAP is higher, relative to the expiratory pressure or the EPAP which is lower.
One of the advantages of this embodiment is that variable flow generator is operable to supply the first gas at set pressures, and in turn, controls the total pressure in the breathing circuit. This may include the option of the inspiratory member not having a separate venting device. In this instance, the inspiratory member may be closed, that is without a vent.
In another example, the flow generator may be a constant flow generator. That is the flow generator can be used for CPAP, which delivers a constant pressure for a given setting. It will be appreciated that a user may change the setting as desired.
The breathing circuit may have a pressure regulation device for regulating the pressure in the expiratory member.
The pressure regulation device for regulating the pressure in the expiratory member may be set to slightly higher pressure than the target pressure of the variable flow generator. For example 0.5 to 2.0 cmH20 higher than the target pressure of the flow generator. This inhibits the second gas continuously flowing through the regulation device, which will then vent when the patient exhales.
The inspiratory member may be configured so that the second gas enters a proximal portion of the inspiratory member. In this situation, the inspiratory member may include a first non-return valve downstream of the second gas entering the inspiratory member.
In this situation in which the second gas enters the proximal portion, the breathing circuit may include a humidification device for humidifying the second gas prior to entering the inspiratory member.
The inspiratory member may be configured so that the second gas enters a distal portion of the inspiratory member. In this situation, the inspiratory member may include a first non-return valve upstream of the second gas entering the inspiratory member. That is to say, the first non-return valve may be located between the first gas and the second gas entering the inspiratory member.
Elements of the breathing circuit may be connected together or pre-assembled into a module. The module may be connected to other elements by a user to complete the breathing circuit, or two or more modules may be connected together, which in turn may form the breathing circuit or be connected to other elements. Examples of possible modules may include any one or a combination of the following:
An embodiment relates to a method for ventilating a patient, the method including:
An embodiment relates to a method for ventilating a patient, the method including:
The positive pressure breathing circuit may include any one or a combination of the features of the breathing circuit described herein. For example, the breathing circuit provided may include an expiratory member configured to vent exhaled gas from the patient interface.
The method may include selecting an internal volume of the inspiratory member in which the second gas can be stored. Selecting the internal volume may include adjusting the volume so that a therapeutic amount of the second gas can be stored in the inspiratory member. Selecting the internal volume may include determining where to severe the inspiratory member based on volume markings spaced along the length of the member. The method may include adjusting the internal volume by severing the inspiratory member at one of the markings.
The method may include a step of regulating the pressure in the breathing circuit which may include venting exhaled gas from the expiratory member. The venting may be achieved using a restriction device, such as a pressure relief valve, a PEEP valve, an orifice, and constant flow device that maintains a constant flow irrespective of the pressure differential across the device.
In the situation in which the distal portions of the inspiratory member and the expiratory member are interconnected to form a loop configuration, the method may include the first gas being supplied to the inspiratory member and any excess supply of the first gas is conveyed from the inspiratory member to the expiratory member by the interconnection of the inspiratory member and the expiratory member without passing through the patient interface.
The breathing circuit provided may be configured with a bypass member interconnecting the inspiratory member and the expiratory member. In this situation, the step of regulating the pressure may include conveying the excess supply of the first gas from the inspiratory member to the expiratory member via the bypass member.
The method may include releasing overpressure from the circuit using an overpressure relief valve.
The method may include humidifying the breathing gas. For example, humidifying the first and the second gas.
The second gas may be supplied at a substantially constant flow rate.
In one example, the first gas may be supplied at a constant flow rate.
In another example, the first gas may be supplied at a variable flow rate. For example, the method may include operating a variable flow generator to supply the first gas at a high pressure flow during patient inhalation and a low pressure flow during patient exhalation, such as between IPAP or EPAP.
The step of operating the variable flow generator may include sensing flow in the breathing circuit and using output data of a sensor sensing the flow to operate the variable flow generator. The output data of the sensor may respond to when the patient inhales and/or exhales. The sensor may include a flow sensor, for example, in the expiratory member. The sensor may include a pressure sensor, for example, in the expiratory member.
An embodiment relates to a method for ventilating a patient, the method including:
The step of providing a positive pressure breathing circuit including providing a pressure regulation device configured to regulate pressure in the breathing circuit, including venting exhaled gas
The embodiments described in the paragraphs [0004], [0005], [0091], [0102], [0103], [0104] and [0116] may include any one or a combination of the features described herein.
Throughout this specification the term “excess supply of the first gas”, or variations thereof, refers to an amount of the first gas supplied by the flow generator that is not delivered to the patient interface.
The components of the breathing circuit described herein, including the inspiratory tube and the expiratory tube may be made of any suitable medical grade materials, including flexible plastic tubing that is substantially non-stretchable. Moreover, suitably the inspiratory and the expiratory tubes meet the ISO-5367 standard for compliance.
These and other features, aspects, and advantages of the present disclosure are described with reference to the drawings of certain embodiments, which are intended to schematically illustrate certain embodiments and not to limit the disclosure.
An embodiment will now be described in the following text which includes reference numerals that correspond to features illustrated in the accompanying Figures. To maintain clarity of the Figures, however, not all reference numerals are included in each Figure. Although certain examples are described herein, those of skill in the art will appreciate that the disclosure extends beyond the specifically disclosed examples and/or uses manually connected to a connection port of the interface 21 or a length of the tubing can interconnect the tube connector and a connection portion of the patient interface 21. In another example, not illustrated in the Figures, the inspiratory tube 11 and the expiratory tube 12 may be directly connected to an inlet connection of the patient interface 21 and an outlet connection of the patient interface 21 respectively.
With reference to
The breathing circuit 10 includes a pressure regulation device 22 for regulating the pressure of the breathing gas within the breathing circuit 10. In the case of
During patient inhalation and exhalation the first gas 16 is supplied to the inspiratory tube 11 upstream of the first non-return valve 19 and the second gas 18 is supplied at a constant flow rate to the inspiratory tube 11 downstream of the first non-return valve 19. That is to say, both the first gas 16 and the second gas 18 enter the distal portion 26 of the inspiratory tube 11.
At the start of patient exhalation, that is to say spontaneous exhalation, or during a pause between inhalation ending and exhalation starting, the first non-return valve 19 closes and the second gas 18 fills the gas passageway of the inspiratory tube 11 in a direction from the distal portion 26 toward the proximal portion 27, that is, in a direction toward the user. Although the first non-return valve 19 may be biased to a closed position, ideally the second gas 18 is supplied at a slightly higher pressure, for example in the range of about 1 to 300 cmH2O greater than the pressure of the first gas 16, suitably about 1 to 250 cmH2O greater, more suitably about 1 to 200 cmH2O greater, more suitably about 1 to 150 cmH2O greater, more suitably about 1 to 100 cmH2O greater, more suitably about 1 to 50 cmH2O greater, more suitably about 2 to 10 cmH2O greater. While the first non-return valve 19 is closed, the first gas 16 is conveyed from the inspiratory tube 11 to the expiratory tube 12 via the bypass tube 23.
During patient exhalation, the second gas 18 flows along the inspiratory tube 11, displacing the first gas 16 and the second gas 18, or a mixture thereof, downstream of the second gas 18 entering the inspiratory tube 11, and thereby storing a volume of the second gas 18 in the inspiratory tube 11 during patient exhalation. The first gas 16 and the second gas 18 displaced from the inspiratory tube can be conveyed from the inspiratory tube 11 into the expiratory tube 12 with exhaled gas(es) 28. Exhaled gas(es) 28 flow from the patient interface 21 into the expiratory tube 12 and away from the patient interface 21. Once the exhaled gas(es) 28 pass the second non-return valve 20 they can be vented from the breathing circuit 10. Similarly, excess supply of the first gas 16 flowing from the inspiratory tube 11 to the expiratory tube 12 can also be vented.
During patient inhalation, that is to say spontaneous inhalation, the second non-return valve 20 closes and the first non-return valve 19 opens. In a situation in which the internal volume of the inspiratory tube 11 between the first non-return valve 19 and the patient interface 21 approximates the tidal volume of the user, during inhalation the user initially receives a dose of the second gas 18 which is drawn into the alveoli of the user's lungs. In the event that the internal volume of the inspiratory tube 11 is less than the tidal volume of the user, or the flow rate of the second gas 18 into the inspiratory tube 11 is insufficient to fill the inspiration tube 11 with a tidal volume of the user, after the initial inhalation phase, the user may receive a combination of the first and second gases 16 and 18. This may not be disadvantageous as the first and second gases 16 and 18 may not go beyond the upper respiratory passage of the user where no gas transfer occurs. Conversely in the event that the internal volume of the inspiratory tube 11 is larger than the tidal volume of the user, and indeed, a volume of the second gas 18 loaded into the inspiratory tube 11 during the exhalation phase is greater than the tidal volume of the user, not all of the second gas 18 that is loaded/stored in the inspiratory tube 11 during exhalation will be inhaled. At the start of inhalation by the user, the first non-return valve 19 opens, allowing both the first gas and the second gas 16 and 18 to be supplied into the distal portion 26 of the inspiratory tube 11 which flows in a direction toward the user.
One of the advantages of this embodiment is that the second gas 18 fills the inspiratory tube 11 from the distal portion 26 and any patient interface leak that occurs during exhalation comprises the first gas 16 and a small amount of the second gas 18 that filled the inspiratory tube 11 at the end of the previous inhalation. This minimises any patient interface leak of the second gas 18 from the breathing circuit 10 and allows a lower flow rate of the second gas 18 to achieve an effective therapy.
During patient inhalation, that is to say spontaneous inhalation, the first non-return valve 19 opens. The user initially receives a dose of the second gas 18 that was loaded into the inspiratory tube 11 during exhalation and is drawn into the alveoli of the user's lungs. In addition, at the start of inhalation by the user, the first non-return valve 19 opens, allowing both the first gas 16 and the second gas 18 to be supplied into the distal portion 26 of the inspiratory tube 11 which flows in a direction toward the user, and in the event that the volume of the second gas 18 loaded into the inspiratory tube 11 is less than the tidal volume, a mixture of the first and second gases 16 and 18 can be supplied and received by the user. The first and second gases 16 and 18 supplied to the user toward the end of the inhalation cycle is usually received within the upper regions of the inspiratory passage where gas transfer does not occur.
Although not shown in the Figures, the breathing circuit 10 may also include a sensor to detect the amount of oxygen gas being inhaled by the patient. An example of a suitable sensor is a galvanic oxygen sensor to determine the fraction of inspired oxygen gas (FiO2) over 15 seconds or more, as this would effectively filter the FiO2 to a stable, indicative value of the FiO2 over the entire breath. Adjustments can then be made to the flow rates of the first and second gases 16 and 18 to the inspiratory tube 11. Alternatively, an ultrasonic sensor can be used to take rapid readings for detecting FiO2 during the course of each breath. The sensor may be located at any suitable location in the breathing circuit. Suitable locations include the patient interface or immediately upstream of the patient interface.
The pressure regulation device 22 of the breathing circuit 10 shown in
In addition, the pressure regulation device 22 of the breathing circuit 10 shown in
One of the advantages in locating the humidification device 37 downstream of the second gas inlet 17 is that both the first and second gases 16 and 18 are humidified by the humidification device 37. One of the benefits of this configuration is that the first non-return valve 19 is located upstream of the humidification device 37 meaning that the first non-return valve 19 will remain dry and therefore the humidification device 37 will not potentially affect the reliability of the first non-return valve 19. In addition, any secretions from the user are unlikely to pass through the humidification device 37 and reach the first non-return valve 19. In other words, the humidification device 37 provides a further obstacle to secretions from the user reducing the reliability of the breathing circuit 10.
If desired, the first and second gases 16 and 18 could be humidified in separate humidification devices. For example, although not shown in the drawings, a humidification device could be located in the inspiratory member 11 between the first and second gas inlets 15 and 17 for humidifying the first gas 16. A separate humidification device generator 33. The pressure sensor 36 could also be located at or close to the patient interface 21 and/or anywhere in the inspiratory tube 11 downstream of the flow generator 33, it may also be downstream of a blower within the flow generator.
In addition, a flow sensor 34 may be located at or close to the inlet of the flow generator 33, which enables the flow generator 33 to be arranged as a single self-contained module. Although not illustrated, the flow sensor 34 could also be located at the outlet of the flow generator 33. Moreover, the flow sensor 34 can be located anywhere in the inspiratory tube 11, expiratory tube 12, or upstream or downstream of a blower within the flow generator 33. In any event, outputs from the sensors 34, 36 can be used to operate the flow generator 33, including increasing or decreasing the speed of the flow generator 33 as desired. However, in the case of the respiratory therapy, it is desirable to control the pressure at the patient interface. In one example, the variable flow regulator 33 can be used to provide an inspiratory pressure, such as an inspiratory positive airway pressure (IPAP) and an expiratory pressure, such as an expiratory positive airway pressure (EPAP), or continuous positive airway pressure (CPAP), in which IPAP equals EPAP. The inspiratory pressure and expiratory pressure can be preselected using an operating interface on the variable flow generator 33 and the pressure and flow sensors 36, 34 located at the flow generator 33 can be used to determine when the patient begins inhalation and exhalation.
A controller can also be used to estimate pressure drop within sections of the breathing circuit 10, which may be a function of the flow rate, to estimate the pressure at the patient interface based on the signal outputs of the flow sensor 34 and the pressure sensor 36 of the variable flow generator 33. For instance, the controller can estimate the pressure drop in the inspiratory tube 11 based on pre-determined components for specific breathing circuits 10. That is to say, different pre-determined functions, such as humidification devices 37, non-return valves 19, length of the inspiratory tube 11, internal diameter of the inspiratory tube 11 and so forth. In any event, the pressure drop will be a function of the various components and layout of the breathing circuit 10 and the components can be selected as desired.
The variable flow generator 33 enables the pressure requirements for effective therapy to be delivered whilst reducing or minimizing the excess supply of the first gas to specific operating ranges. This means that pressure regulation of the breathing circuit 10 can be achieved using devices that are less pressure dependent or are not pressure dependent at all. For instance, one of the advantages in using a variable flow generator 33 as a first gas source 13 is that the pressure regulation device 22 can be modified by replacing pressure relief valves, such as a PEEP valve with a simpler structure such as a flow restrictor, an orifice of fixed area or a constant flow valve. A constant flow valve may have a variable orifice that changes with the application of pressure so that flow rate through the valve remains substantially constant despite change in pressure across the orifice.
In another example, the flow sensor 34 may be located on the inspiratory tube 11 to detect the flow being inhaled by the patient. An output of the flow sensor 34 may then be used to determine when inhalation starts and ends which can be used to operate the variable flow generator 33 at either the inspiratory pressure or the expiratory pressure.
In another example, the flow sensor 34 may be located on the expiratory tube 12 to detect the flow being exhaled by the patient. An output of the flow sensor 34 may then be used to determine when exhalation starts and ends which can be used to operate the variable flow sensor 34 at either the inspiratory pressure or the expiratory pressure.
Advantages in using a variable flow generator 33 and a simplified pressure regulation device 22 include the following:
During patient inhalation and exhalation, the second gas 18 enters the proximal portion 27 of the inspiratory tube 11 via the second gas inlet 17 at a constant rate, and the first gas 16 enters the distal portion 26 via the first gas inlet 15. Control valve 32B can be used to control the flow and/or pressure of the second gas 18 at the second gas inlet 17. At the start of patient exhalation, or during a pause between inhalation ending and exhalation starting, the first non-return valve 19 closes and the second gas back fills the gas passageway of the inspiratory tube 11 in a direction from the proximal portion 27 toward the distal portion 26. During patient exhalation, the second gas 18 and the first gas 16 forms a gas/gas interface that moves along the gas passageway away from the second gas inlet 17 toward the distal portion 26, thereby storing a volume of the second gas 18 in the inspiratory tube 11 during patient exhalation. An amount of the first gas 16 may be vented from the inspiratory tube 11 during this stage by, for example, the variable flow generator 33. The volume of the second gas 18, such as oxygen, that enters the inspiratory tube 11 during exhalation may be equal to, or less than, a tidal volume of the user, thereby minimizing wastage of the second gas 18 by avoiding venting the first gas 16 during exhalation.
During patient inhalation, the first non-return valve 19 opens, and the second gas 18 that has been stored in the inspiratory tube 11 flows into the patient interface 21. If all of the second gas 18 is inhaled, the user will begin to inhale a mixture of the first gas 16 and the second gas 18. The total volume of the second gas 18 loaded and stored in the inspiratory tube 11 may be adjusted and controlled based on the internal volume of the inspiratory tube 11 and the flow rate of the second gas 18.
The variable flow generator 33 can be operated so that pressure output of the flow generator 33 more closely corresponds to the inspiratory pressure requirement and the expiratory pressure requirement of the user. The breathing circuit has a pressure regulation device 22 including a flow restrictor 38 in a distal portion of the expiratory tube 12 for venting exhaled gas 28 and any excess supply of the first gas. The flow restrictor 38 may include an orifice that can regulate venting of the first gas 16 and the exhaled gas from the expiratory tube 12. In the event that the first and second gases 16 and 18 are supplied at the required amounts, the excess supply of the first gas 16 will be minimized and little or no excess first gas will be conveyed by the bypass tube 23 and vented.
The flow of the first and second gases 16 and 18 in the inspiratory tube 11 in
During inhalation, the first non-return valve 19 opens and the user initially inhales the volume of the second gas 18 loaded and stored in the inspiratory tube 11 during exhalation. Once the volume of the second gas 18 has been inhaled, and if the patient continues to inhale the user receives a mixture of the second gas 18 and the first gas 16 that simultaneously enters the inspiratory tube 11.
One of the elements of the breathing circuit 10 shown in
Module A shown in
As shown by one of the dashed outlines in
Although not illustrated in
Specifically, during patient exhalation the second flow generator 33B is operated to provide a back pressure, for example 10 cmH20, that provides EPAP for the patient. The first flow generator 33A is operated at a lower pressure set point, or at a lower controlled flow, such that the first non-return valve 19 in the inspiratory tube 11 remains closed. This allows the second gas 18 to enter via second gas inlet 17 and accumulate and be stored in the inspiratory tube 11 by flowing in a direction away from the patient interface 21. The second gas 18 may also be stored in the reservoir, which as mentioned may optionally be placed upstream of the first flow generator 33A. Exhaled gas(es) 28 are vented from the expiratory tube 12 via pressure regulation device 22 located in the proximal portion of the expiratory tube 12.
If there is any mask leak during expiration, the gas leaking is made up of either exhaled gas(es), and/or gas delivered by the second flow generator 33B. This means that no oxygen will leak during expiration, as the first non-return valve remains closed due to the lower pressure or flow provided by the first flow generator 33A. Exhaled gas that are not leaked from the patient interface vent from the circuit 10 to atmosphere proximal to the patient via a pressure regulation device 22, such as restricted orifice. The pressure regulation device may also include a bacterial filter as illustrated. An advantage this provides is that no carbon dioxide builds up in the expiratory tube. That is to say the expiratory tube 12 can be flushed during patient exhalation.
During patient inspiration, the first non-return valve opens, and the first gas, suitably air enters the distal portion of the inspiratory tube which displaces the second gas, suitably oxygen gas, to deliver the second gas to the patient, at the pressure (IPAP) set by the first flow generator 33A. During patient inhalation, the first flow generator 33A may have an increased or increasing pressure set point or controlled flow and the second flow generator 33B may have a reduced or decreasing pressure set point or controlled flow, so that the first flow generator 33A is at a higher pressure or flow setting than the second flow generator 33B. This ensures that the patient breathes in the first and second gases delivered from the inspiratory tube and not any gases from the second flow generator 33B.
Although not shown in
The first non-return valve 19 may be any suitable valve, including a one-way flap valve, a biased valve that is biased into a closed position, or a diaphragm valve. The first non-return valve 19 closes when the gas pressure downstream of the first non-return valve 19, for instance in the patient interface during exhalation, is greater than the pressure upstream in the inspiratory tube 11. The first non-return valve 19 opens, suitably automatically, when the patient spontaneously inhales.
The breathing circuit 10 includes a pressure regulation device 22 having first and second pressure relief valve located in the expiratory tube 11 and in the distal portion 26 of the inspiratory tube 11 respectively. The first pressure relief valve is a first positive end expiratory pressure valve (first PEEP valve) and the second pressure relief valve is a second positive end expiratory pressure valve (second PEEP valve). The second PEEP valve has setting marginally above the setting of the first pressure relief valve, for example, 0.5 to 2.0 cmH2O greater.
The second PEEP valve and the overpressure relief valve 39 may be connected to the inspiratory tube 11 using any suitable tube joiner including a T-shaped joiner and Y-shaped joiner.
Proximal portions 25 and 27 of the expiratory tube 12 and the inspiratory tube 11 are connected to the patient interface 21 by a tube joiner having three limbs, such as a T-piece or a Y-piece, in which one of the limbs connects to the expiratory tube 12, another limb connects to the inspiratory tube 11, and a third limb of the tube connector couples to an inlet/outlet port on the patient interface 21 to conduct breathing gas as it is inhaled and exhaled. The tube joiner may be integrally formed with the patient interface 21. In another example, not illustrated in the Figures, the inspiratory tube 11 and the expiratory tube 12 may be directly connected to an inlet connection and outlet connection on the patient interface 21 respectively.
During patient inhalation and exhalation, the first gas 16 enters the distal portion 26 via the first gas inlet 15 at a constant rate controlled by the first control valve, and the second gas 18 enters the proximal portion 27 of the inspiratory tube 11 via the second gas inlet 17 at a constant rate, suitably controlled by a second control valve. At the start of patient exhalation, or during a pause between inhalation ending and exhalation starting, the first non-return valve 19 closes and the second gas 18 back fills the gas passageway of the inspiratory tube 11 in a direction from the proximal portion 27 toward the distal portion 26, that is away from the user. During patient exhalation, the second gas 18 and the first gas 16 forms a gas/gas interface that moves along the gas passageway away from the second gas inlet 17 toward the distal portion 26, thereby storing a volume of the second gas 18 in the inspiratory tube 11 during patient exhalation. The volume of the second gas 18, such as oxygen, that enters the inspiratory tube 11 during exhalation may be equal to, or less than, a tidal volume of the patient, thereby minimizing wastage of the second gas 18 by avoiding venting the first gas 16 during exhalation.
During patient inhalation, the first non-return valve 19 opens and the user initially receives a dose of the second gas 18 that was loaded into the inspiratory tube 11 during exhalation and is drawn into the alveoli of the user's lungs. In addition, the first gas 16 supplied into the distal portion 26 of the inspiratory tube 11 flows in a direction toward the patient, and the second gas 18 continues to be supplied to the proximal portion 27 of the inspiratory tube 11. In the event that the volume of the second gas 18 loaded into the inspiratory tube 11 is less than the tidal volume, a mixture of the first and second gases 16 and 18 can be supplied and received by the user. The first and second gases 16 and 18 supplied to the patient toward the end of the inhalation cycle is usually received within the upper regions of the inspiratory passage where gas transfer to the patient does not occur.
The pressure regulation device 22 also includes a third pressure relief device including an overpressure valve 39 for venting breathing gases from the breathing circuit 10 in the event of a blockage or malfunction. The overpressure valve 39 has a setting that is greater than the operating pressure of the first and second pressure relief devices and is located downstream of the second pressure relief valve.
Moreover, the breathing circuits 10 shown in any one of the Figures of the present specification may include the overpressure valve 39. The overpressure valve 39 is ideally located in the inspiratory tube 11, but it may also be located on the patient interface or even on the expiratory tube 12.
Set out below in Table 2 are exemplary volumes and tidal volumes of adult, paediatric and neonatal patients.
As described above the inspiratory member, includes an inspiratory tube and other components such as reservoir, humidification device and so forth. Similarly, the expiratory member includes an expiratory tube and other components such as bacterial filters and so forth. The inspiratory tube and the expiratory tube may include tubing of any suitable structure. For example, the inspiratory tube and the expiratory tube may be separate tubes. In one example, the tubes may be unconnected along their length, or they may be connected side-by-side using connector clips, a permanent adhesive, or be integrally formed. An integrally formed structure may be extruded.
In another example, the inspiratory and the expiratory tubes may be provided at least in part by a multi-lumen tube, in which separate lumens provide passageways of the inspiratory and the expiratory tubes. For example, the structure of a multi-lumen tube may have side-by-side passageways, in which a partition along the tube defines in part the passageways of the inspiratory and the expiratory tubes. The multi-lumen tube may have side-by-side passageways, which has for example, been made by extrusion. In another example, the structure of the multi-lumen tube may be a coaxial structure, in which one passageway is arranged centrally, and the other passageway is arranged about the periphery of the central passageway, such as in a co-axial structure.
In yet another example, the inspiratory and the expiratory tubes may be arranged as a single conduit formed from a spirally wound hollow body. The conduit may comprise a first elongate member having a hollow body spirally wound to form at least in part an elongate tube having a hollow wall surrounding the conduit lumen. The conduit may also include a second elongate member spirally wound and joined between adjacent turns of the first elongate member. The spirally wound hollow body may provide either one of the inspiratory and the expiratory tubes, and the conduit lumen formed by the spirally wound hollow body provides the other tube.
Alternatively, the conduit lumen may be the inspiratory tube and the second gas inlet may be provided into the spirally wound hollow body. The second gas enters a distal portion of the spirally wound hollow body, and flows into a proximal portion of the conduit lumen. This allows a proximal second gas inlet without needing an additional conduit near the patient interface.
Examples of suitable spiral wound hollow bodies and multi lumen tubes are disclosed in International patent publication WO2012/164667 (PCT/IB2012/001786) filed 30 May 2012, the full contents of which are hereby incorporated into this specification.
With reference to
The first and second gases 16 and 18 may be supplied at a constant rate, as shown in
In order to provide the best therapeutic benefit, it is desirable to optimize the amount of the therapeutic gas being delivered to the patient whilst minimizing wastage. This can be achieved by selecting 43 the internal volume of the inspiratory tube 11 based on the tidal volume of the patient, and changing the internal volume by changing the length of the tube 11 in which the second gas 18 is stored between inhalation cycles.
Humidification of the breathing gas can be carried out by humidifying 44 one or both of the first gas and the second gas 16 and 18 downstream of the second gas 18 entering the inspiratory tube 11.
Finally, irrespective of whether the first gas 16 is supplied at a fixed rate or at a variable rate, the method may also include regulating 45 the pressure in the breathing circuit 10. For example, the expiratory tube may include a pressure relief valve, such as PEEP valve as shown in
Conditional language used herein, such as, among others, “can,” “might,” “may,” “for example,” and the like, unless specifically stated otherwise, or otherwise understood within the context as used, is generally intended to convey that certain embodiments include, while other embodiments do not include, certain features, elements and/or states. Thus, such conditional language is not generally intended to imply that features, elements and/or states are in any way required for one or more embodiments or that one or more embodiments necessarily include logic for deciding, with or without author input or prompting, whether these features, elements and/or states are included or are to be performed in any particular embodiment. The terms “comprising,” “including,” “having,” and the like are synonymous and are used inclusively, in an open-ended fashion, and do not exclude additional elements, features, acts, operations, and so forth. Also, the term “or” is used in its inclusive sense (and not in its exclusive sense) so that when used, for example, to connect a list of elements, the term “or” means one, some, or all of the elements in the list. Further, the term “each,” as used herein, in addition to having its ordinary meaning, can mean any subset of a set of elements to which the term “each” is applied.
Disjunctive language such as the phrase “at least one of X, Y and Z,” unless specifically stated otherwise, is to be understood with the context as used in general to convey that an item, term, etc. may be either X, Y, or Z, or a combination thereof. Thus, such conjunctive language is not generally intended to imply that certain embodiments require at least one of X, at least one of Y and at least one of Z to each be present.
Unless otherwise explicitly stated, articles such as “a” or “an” should generally be interpreted to include one or more described items. Accordingly, phrases such as “a device configured to” are intended to include one or more recited devices. Such one or more recited devices can also be collectively configured to carry out the stated recitations. For example, “a processor configured to carry out recitations A, B and C” can include a first processor configured to carry out recitation A working in conjunction with a second processor configured to carry out recitations B and C.
While the above detailed description has shown, described, and pointed out novel features as applied to various embodiments, it will be understood that various omissions, substitutions, and changes in the form and details of the devices or methods illustrated can be made without departing from the spirit of the disclosure. As will be recognized, certain embodiments of the inventions described herein can be embodied within a form that does not provide all of the features and benefits set forth herein, as some features can be used or practiced separately from others.
| Filing Document | Filing Date | Country | Kind |
|---|---|---|---|
| PCT/NZ2022/050019 | 2/11/2022 | WO |
