Patent Application
20100094173
The invention relates generally to medical devices such as low-pressure plumbing apparatus, and particularly to fluid-transporting structures arranged to transport fluid from a subject's bladder to a drain container.
Various plumbing arrangements have been used for draining the discharge received from a catheter installed in a subject (e.g., a medical or veterinary patient). Two undesired drain pressure states are commonly found in certain conventional embodiments of known urinary catheter drain conduits: either excessive suction or excessive back-pressure. Such pressure states may be exerted on the bladder with potentially detrimental effect.
Excessive suction can be caused by a siphon effect imparted by a continuous column of urine extending below the level of the bladder in a discharge conduit. Such column is particularly likely in drain conduits having a sufficiently small bore. A sufficiently small bore promotes what may be characterized as plug-flow of discharge fluid in the conduit. A sufficiently small bore effectively resists breakdown of a meniscus disposed at a leading edge of a fluid filling the bore. In such a sufficiently small bore, surface tension of the fluid is sufficient to maintain the meniscus intact, and in contact with the circumference of the bore, despite gravitational forces at work on the fluid. A plumbing arrangement effective to determine a maximum bore size to ensure plug-flow includes an arrangement in which the meniscus traverses a vertically disposed radius of curvature in the conduit along a drain path, e.g., during a change from horizontal to vertical fluid flow. Excessive suction can cause pressure ulcers in the bladder by suctioning the bladder's mucosal wall up against the catheter's drain entrance port.
One source of excessive back-pressure includes a vertical section disposed in a catheter's discharge tubing that is not routed along a straight path from the catheter to the fluid collection container. Back-pressure may be caused during the first filling of a section of drain conduit that is routed to increase elevation of fluid therein with respect to the bladder. A pressure-inducing vertical section may also be defined by a leg of a U-shaped bend in a conduit having a sufficiently large bore. A sufficiently large bore permits conversion of plug-flow to particle-flow by permitting breakdown of the meniscus at the leading edge of a fluid filling the bore, e.g., as the meniscus encounters a rapid decrease in slope of the conduit along the drain path. Particle flow, or alternatively, detached stream flow, may even result during horizontal flow of fluid in a bore of sufficiently large diameter. In any event, particle-flow fluid often will coalesce at bottoms of U-shaped sections of drain tubing, change to plug-flow, and cause a back-pressure as the reformed plug of fluid is elevated during its escape from the U-shape.
Pressure exerted from the urine drain assembly is reflected in the pressure measured in the bladder. Excessive back-pressure can cause bladder distension and attendant patient discomfort. Bladder pressure may sometimes be measured and monitored as an indicator of abdominal pressure. Back-pressure from the drain assembly undesirably leads to inaccuracy in abdominal pressure indication, frustrating the ability to monitor an important medical parameter. Furthermore, back-pressure in the urine drain tubing assembly has an effect on bladder discharge, and may undesirably reduce measurement accuracy of a patient's urine output over time. Urine retained in the bladder for an extended period of time provides an undesirable nidus for infection.
Static pressure in an open drain conduit can be calculated, as is known, using potential energy of a fluid column. It is believed not uncommon for a patient having an installed commercially available urinary catheter to experience sustained intervals of back-pressure in excess of eight inches (20 cm) of water, or about 15-20 mm Hg, and sometimes more.
U.S. Pat. No. 2,602,448, issued Jul. 8, 1952, to McKenna, the contents of which are incorporated herein by this reference, discloses a plumbing arrangement including an automatic valve effective to cause periodic infusion and evacuation of an intubated patient's bladder. An elevated fluid source is adjusted to supply a slow fluid flow through the automatic valve toward the patient's bladder. Fluid flows into the patient's bladder, and simultaneously accumulates in the valve, until the bladder is full, at which time the valve's siphon element is charged by a cascade of accumulated fluid. The valve then fully evacuates the bladder using siphonic action, and leaves a water trap to resist air flow into the patient through the catheter.
U.S. Pat. No. 2,860,636, issued Nov. 18, 1956 to Seitchik et al., the contents of which are incorporated herein by this reference, discloses an automatic siphonic valve arrangement similar to that disclosed in the aforementioned >448 patent. Seitchik et al. disclose that common practice includes disposing the intake end of the siphon element at an elevation that is at least six inches (15 cm) below the bladder.
U.S. Pat. No. 3,598,124, issued Aug. 10, 1971, to Andersen et al., the contents of which are incorporated herein by this reference, discloses a plumbing arrangement for a urinary catheter drain conduit that is adapted to alleviate both excessive suction and excessive back-pressure. Andersen et al.'s plumbing arrangement is also adapted to cause cyclical filling of the bladder to a threshold pressure, followed by substantially complete bladder emptying, representative of natural operation of the urinary system. The threshold pressure can be adjusted by defining a desired difference in elevation between the highest point in their drain conduit and the bladder elevation. Their disclosed plumbing arrangement includes a pressure relief valve, disposed near the catheter and upstream of the highest point in the drain conduit. The pressure relief valve is adapted to admit air into the drain conduit subsequent to an emptying cycle of the bladder, and is actuated by siphon-induced suction. The admitted air acts as a hydraulic cut-off switch to allow the column of fluid downstream from the pressure relief valve to fully drain into a collection container, thereby removing both the siphon-induced suction and threshold pressure.
U.S. Pat. No. 6,736,803, issued May 18, 2004, to Cawood, the contents of which are incorporated herein by this reference, discloses a urine collection bag for use with a catheter and including a self-retracting drain tube adapted to empty the collection bag. The collection bag is adapted to be worn by a catheterized ambulatory patient, typically over the abdomen region. The drain tube includes a valve at its discharge end, which may be closed to resist spilling urine as the tube retracts subsequent to its use when emptying the collection bag.
Other relevant United States patents, which disclose structures adapted to facilitate fluid control during use of a urinary catheter include: U.S. Pat. Nos. 3,298,370; 3,800,795; 3,901,235; 4,343,316; 4,349,029; 4,981,474; 5,019,059; 5,429,624; 5,451,218; 5,505,717; 5,616,138; 6,311,339; 6,482,190; 6,500,158; 6,673,051; 6,740,066; 7,008,407; and 7,150,740 (the contents of each of which are incorporated herein by this reference).
Urine production from a patient is an indicator having medical importance and that is commonly recorded during routine care of a urine-catheterized patient. Current conventional practice includes periodically ensuring the drain conduit spanning between the catheter and drain container is fully emptied into the drain container. Mid-span portions of such drain conduit are typically elevated by a health care provider to promote complete drainage of any fluid entrapped in gooseneck portions of the drain path prior to recording the level of fluid held in the drain container. Such recordings are typically made at regular intervals, such as hourly. However, the requirement to manually evacuate standing portions of discharged fluid inevitably results in variably complete evacuation, and leads to uncertainty in the patient's actual urine output. Furthermore, elevating a mid-span portion of drain tubing may undesirably cause retrograde urine flow, which could contaminate the bladder.
Despite the numerous advancements made to date (e.g., as disclosed in the aforementioned patents), and the significant period of time during which various plumbing arrangements have been used for draining the discharge received from a urinary catheter installed in a medical patient, a need still exists for a robust drain arrangement that resists undesired positive and/or negative drain pressure, and/or severe fluctuations in such drain pressure.
Embodiments structured according to certain aspects of the instant invention provide an apparatus, and method of use of that apparatus, for draining a fluid discharged from a medical patient's bladder into a drain container while avoiding undesired pressure states in that patient's bladder.
One operable assembly includes a siphon conduit disposed between a urinary catheter and a siphon-break device. The siphon conduit typically defines a fluid communicating lumen having a substantially constant cross-section disposed between its first end and second end. Desirably, the cross-section of the siphon conduit is configured and arranged to maintain plug-flow of a fluid flowing therethrough. In such case, and subsequent to a first filling with fluid, the siphon conduit is structured to maintain a substantially continuous column of fluid from its first end substantially to its second end. That is, any bubbles introduced at an entrance end of the siphon conduit, or off-gassed from the fluid flowing therethrough, will be transported to the discharge end without undergoing a meniscus breakdown that permits particle flow inside the siphon conduit.
Sometimes, a siphon conduit may include an extension structure to assist in tidy management of the conduit's path. One such extension structure includes a stretch of lumen coiled about an axis and adapted for extension along that axis effective to lengthen an effective drain path between the siphon conduit's first end and second end. Another operable extension structure includes a serpentine labyrinth of substantially in-plane curved flow sections adapted for extension by changing a length of lumen stretched between first and second curved flow sections. Similarly, a length adjustment may be effected in a serpentine labyrinth of such in-plane curved flow sections by changing a radius of curvature of at least one curved flow section. In certain cases, siphon conduit may be routed in combination with a hose management tool adapted to confine a serpentine labyrinth to a desired location in space. Desirably, such tool is configured for attachment to structure associated with a bed, to assist in disposing a siphon-break at a desired elevation. One operable such tool is adapted to permit transverse installation of a portion of the siphon conduit between gripping structure of the tool.
The siphon-break device is typically disposed at an elevation to cause a siphon-break to occur at a desired elevation with respect to a nominal location of the patient's bladder. The elevation of such siphon-break location may be selected irrespective of the elevation of fluid collected in a lower, or downstream, urine drain container. The siphon-break device, and any associated conduit disposed downstream of the siphon-break location, may be characterized as being effective to decouple the potential energy of fluid flowing downstream of the siphon-break (and along a path extending toward the drain container) from having an effect on fluid contained upstream of the siphon-break and in the siphon conduit. An operable siphon-break device includes a lumen having a cross-section that is larger than the cross-section inside of the siphon conduit and effective to promote particle-flow of fluid downstream from the siphon-break. In any case, a siphon-break device is desirably configured and arranged to cause particle-flow (or detached flow) commencing at a siphon-break location for a fluid flowing through the siphon-break device. The fluid flow path disposed downstream of the siphon-break location is typically arranged to define a path adapted to maintain particle-flow, or detached stream flow, of fluid between the siphon-break location and a container in which to receive drained fluid. Desirably, the drain path between the siphon-break location and container has a continuous downward slope.
In certain cases, a length of the siphon-break device (or alternatively, a drain conduit communicating from the siphon-break device) may be adjusted to accommodate a plurality of distances between the siphon-break location and drain container to permit disposing the siphon-break location at approximately the same elevation as a patient's bladder. Subsequent to completely charging the siphon conduit with fluid, the location of the siphon-break desirably controls the pressure at the entrance of a urinary catheter installed in the patient's bladder. Typically, the siphon-break is disposed within plus or minus 6 inches (15 cm) of a nominal bladder elevation of the patient. Preferably, the siphon-break elevation is disposed within positive 1 inch (2.5 cm) to about negative 6 inches (15 cm) of the patient's bladder elevation. In a more preferred arrangement, the siphon-break is disposed at an elevation to cause a substantially neutral or slightly negative pressure at the catheter's entrance, such as positive 1 inch (2.5 cm) to about negative 4 inches (10 cm) of the patient's bladder elevation. In a most desirable configuration, the siphon-break location is disposed to maintain the patient's bladder in an at least substantially evacuated state.
Sometimes, a shape of the siphon-break apparatus may be adjusted to accommodate a plurality of distances between a desired siphon-break location and a drain container. One operable shape for a siphon-break apparatus includes a telescopic structure adapted for extension along an axis effective to lengthen, or shorten, a drain path between the siphon conduit and drain container. Another operable shape includes a stretch of conduit coiled about an axis and adapted for extension, or retraction, along that axis. A further operable shape includes a serpentine labyrinth of substantially in-plane curved flow sections adapted for extension, or retraction, along an axis by changing a radius of curvature of at least one curved flow section.
In certain alternative embodiments, anchoring structure associated with the container is configured to permit making a vertical adjustment of the container with respect to suspension structure associated with the bed effective to facilitate disposing the siphon-break device at a desired elevation with respect to the bladder. Such embodiments avoid causing clinicians to perform a field operation including cutting a conduit to fit the spacing between a desired siphon-break location and an inlet to the drain container.
In some cases, a siphon-break device may be configured and arranged in harmony with the siphon conduit to visually indicate a corner approximately corresponding to the location of the siphon-break. It has been determined that the surface of the bed is a robust and reliable indicator of a desired location for a siphon-break to occur. Desirably, an anchor is also included, which is effective to maintain that corner in approximate registration with a top surface edge of a bed on which the drain apparatus may be installed.
A pressure indicator may sometimes be disposed in-circuit, desirably in relatively close proximity to the siphon-break device and in fluid communication with the siphon conduit. Such an indicator permits a clinician to visually verify a desired pressure state in drained fluid and near the siphon-break location. Feedback from such pressure indicating device may indicate a need to make an adjustment to the plumbing apparatus, including correction of the elevation of the siphon-break location with respect to the nominal location of the patient's bladder.
A method for placing a urinary catheter in fluid communication with a drain container using an embodiment structured according to certain principles of the instant invention includes: first, installing a urinary catheter in position to drain a patient's bladder. Second, a first end of a siphon conduit is placed into fluid communication with a discharge end of the catheter, with the siphon conduit being constructed to maintain plug-flow of a fluid flowing therethrough. Third, the siphon conduit is routed along a path disposed at approximately the same elevation to dispose the siphon conduit discharge end elevated above a drain container and to cause a siphon-break at an elevation in general agreement with the bladder. The siphon conduit may be routed over a leg, but generally follows the top surface of the bed in which the patient is disposed. In most cases, such siphon-break elevation desirably is selected to cause a small (e.g., 1 to 3 inches (2.5 to 8 cm) of water column) negative pressure in the bladder to promote complete evacuation. Most preferably, a substantially neutral, but slightly negative, pressure is induced (e.g., 1 to 2 cm water column). However, a small or neutral positive pressure may also be induced in certain alternative cases. Fourth, a first end of a siphon-break device is placed into fluid communication with the discharge end of the siphon conduit, where the siphon-break structure is constructed to resist plug-flow of a fluid flowing therethrough. And fifth, a second end of the siphon-break device is placed in fluid communication with the drain container.
In a method of using a drain apparatus structured according to certain principles of the instant invention, a urinary catheter is installed in a patient. A first end of a siphon drain conduit is placed in fluid communication with a discharge end of the catheter. A siphon-break apparatus, connected to the other end of the siphon conduit, is anchored at an elevation with respect to the bladder effective to induce a pressure between about positive 1 inch (2.5 cm) water column and about negative 6 inches (15 cm) water column at a drain entrance of the catheter. The discharge from the siphon-break apparatus is then placed in fluid communication with apparatus adapted to measure fluid flow rate.
In certain cases, the apparatus adapted to measure fluid flow rate may include an automated fluid flow rate determining device, such as a droplet counter. An alternative automated fluid flow rate determining device may include a data acquisition system adapted to estimate flow rate by measuring a difference in discharged fluid weight in one or more time periods, and performing appropriate conversion calculations.
In an alternative case, an embodiment of a drain apparatus adapted to manually measure discharged fluid flow rate may include a first container adapted to indicate a volume of fluid held therein. In the later case, the method may further include waiting for a first period of time during which a charge-volume at least fills drain structure disposed between the bladder and a siphon-break, and determining a first volume contained in the first container at the conclusion of the first period of time. After waiting for a second period of time, a second volume contained in the container at the conclusion of the second period of time is determined. Then, a flow rate can be calculated using the difference between first and second volumes divided by the second period of time. Of course, the last two steps can be repeated, with the flow rate being determined by dividing the difference in discharged volume by the corresponding time increment in which such volume was discharged. The measured volume at the end of each time period may sometimes be transferred to a bulk container. In such case, the fluid output can be calculated by dividing each measured volume by the period of time in which it was collected.
A first embodiment of a catheter drain assembly structured according to certain principles of the instant invention is illustrated in
Conduit 102 desirably includes extension structure, generally indicated at 112, operably arrangeable to change an effective length 114 between its first end 116 and second end 118. Extension structure of some sort is desirable to assist in tidy management of the drain path provided by conduit 102, and to resist routing of such path in a configuration that inherently produces an undesired pressure state in the patient's bladder. While other shapes and sorts of conduit structures are workable, conduit 102 is typically formed from a stretch of smooth-bored medical grade tubing providing an internal lumen with an approximately round cross-section bore.
The extension structure 112 illustrated in
An extension structure 112 may be arranged to form a portion of the conduit 102, or may essentially encompass the entire stretch of such conduit. In one configuration within contemplation, certain coils 120 may be self-biased toward a shorter length, and “stretched-out” to fit, as desired to accommodate a particular patient and bed arrangement. In another configuration, adjacent coils may be adhered to each other to form a compact group, and a desired stretch 114 may be accommodated by separating a sufficient length from the adhered group of coils 120. Such separated length may be stretched and substantially straightened, or may remain biased toward a coiled shape. Certain embodiments of workable extension structure may be, or include portions that are, plastically deformable, to assist in maintaining a certain shape and total length that may be imposed by a health practitioner. In such latter case, a siphon conduit 102 may advantageously be arranged so as to axially follow the course of the patient's leg, then be bent to transversely progress toward the edge of the bed. Sometimes, a malleable length of wire may be included in a conduit to help the conduit hold a desired deformed shape.
With reference still to
Fluid moves sufficiently slowly in conduit 102 during normal use that, as a practical matter, friction between the tubing and fluid may be disregarded when calculating pressures. However, as the conduit is first charged, stretches 128, 130 may, temporarily, have an effect on pressure exerted in the patient's bladder. As the conduit 102 is being initially charged, the corresponding pressure exerted in the patient's bladder will fluctuate as the leading edge of plug-flow fluid changes elevation relative to the bladder. Siphonic action as the leading edge of the column of fluid moves lower than the bladder causes a negative pressure, or suction, at the bladder. A positive pressure, or back-pressure effective to resist fluid flow from the bladder, is generated as the leading edge of the column of fluid in conduit 102 moves above the bladder's elevation 126.
The siphon conduit 102 may be manually charged to avoid, or minimize, holding time during siphon-induced pressure fluctuation in the patient's bladder during initial charging of such conduit. Such manual charging may conveniently be done using one fluid-communicating lumen of a three (or more)-way urinary catheter.
Once the conduit 102 is fully charged with fluid, the pressure exerted in the patient's bladder due to fluid in conduit 102 is desirably controlled entirely by the difference between the bladder elevation 126 and approximately the elevation of second end 118. It is currently preferred to induce a small negative pressure at drain aperture 110 to promote complete emptying of the bladder, such as by maintaining second end 118 at an elevation to cause a siphon-break elevation 132 that is about 2 to 4 inches (5 to 10 cm) lower than bladder elevation 126.
With continued reference to
Virtually any sort of drain container 138 may be used, so long as a suitable coupling with the discharge end of the siphon-break apparatus may be made. However, it is currently preferred that a drain container will include appropriate markings to facilitate monitoring the quantity of fluid discharged by the patient. Periodic monitoring of incremental such quantities permits calculation of a patient's fluid discharge rate. It is also preferred that the drain container 138, or some other structure included in the drain assembly, will provide a suitably protected vent, or other arrangement of structure, which is constructed to resist pressure build-up inside the container as fluid is discharged by the patient.
Alternative siphon-break structures 106′ and 106″ that include extension structure are illustrated in
Siphon-break structure 106′ includes a serpentine labyrinth of substantially in-plane curved flow sections 140 adapted for extension along an axis, as indicated by two-headed arrow 136, by changing a radius of curvature “R” of at least one of the curved flow sections to vertically lengthen or shorten a drain path between second end 118 and container 138. Siphon-break structure 106″ includes a stretch of conduit 140 coiled about an axis 142 and adapted for extension or retraction along axis 142, as indicated by two-headed arrow 136, effective to vertically lengthen or shorten a drain path between second end 118 and container 138. In any case, it is preferred that, downstream of the elevation 132 of the siphon-break itself, a continuous downward-sloping fluid drain path is provided, to resist pooling of fluid and consequent re-establishment of plug-flow, prior to emptying into container 138.
With reference now to
Still with reference to
As illustrated in
With reference now to
Organizing tool 170 may also serve as an anchor from which to locate the position for siphon-break elevation 132. Anchor structure (not illustrated) may be included in an association with certain tools 170 to assist in attaching a tool 170 to support structure, such as a bed rail 164, or stand 166. Such anchor structure may be adapted to orient the one or more anchored tool 170 in space effective to maintain the portion of conduit 102 associated with such tool(s) within a desired range of elevation.
In certain embodiments, the siphon-break device is configured and arranged to visually indicate an approximate location (and therefore elevation 132,
With continued reference to
Still with reference to
Hooks 212 suspend a base 220 and rail 222 at an elevation relative to the bed. A urine meter 225 is carried on the rail 222, and a bulk collection bag 227 is carried by the meter 225. After recording the volume collected in the meter during a first period of time, a valve may be manually opened to drain the measured fluid into the bag 227. Then, the valve is closed to permit collection and measurement of fluid in meter 225 for a subsequent period of time. In such case, the fluid output can be calculated by dividing each measured volume by the period of time in which it was collected. A similar and operable urine meter is available from Welford Medical, Inc., and includes a urine meter with a 500 mL measuring chamber and a 2000 mL downstream bulk collection bag.
In some cases, the hooks 212 may be vertically adjusted, relative to the base, to variably space the base 220 apart from the suspension structure. In some cases, the meter 225 is vertically adjustable along the rail to variably space the meter apart from the suspension structure. In any case, it is desirable to provide some adjustment in mounting the drain container to permit locating the siphon-break at a desired elevation with respect to the patient's bladder, and to maintain the drain conduit portion 229 in a configuration to resist formation of plug flow in fluid downstream of the siphon-break. Of course, the length of conduit 229 may simply be cut-to-fit in the field, to fit a particular installation. However, it is generally preferred to provide a urine drain assembly in pre-assembled kit-form, which requires minimal field assembly and is adjustable to accommodate anchoring a siphon-break location relative to different bed suspension structures.
A characteristic bore size of conduit 102 is generally determined by conflicting constraints. It is good for the characteristic size to be small as possible, to reduce the volume of urine contained between first and second ends of the conduit 102. A reasonable minimum characteristic cross-section size for a smooth-bore drain lumen might be about 0.040 inches (1 mm). In contrast, it is necessary for the characteristic size to be large enough to resist flow-blocking clot formation from debris build-up inside the drain lumen. An upper bound for a characteristic cross-section size is that size which is no longer capable of maintaining an intact meniscus at the fluid front as the fluid flows along a flow path that is curved from horizontal to vertical (or the size at which the lumen fails to maintain plug flow of fluid through the siphon conduit 102). It has been determined that a smooth-bore conduit sized about 0.160 inches (4.1 mm) is a compromise upper bound (including a margin of safety), beyond which particle flow may occur in a sterile saline reference fluid.
It is within contemplation to provide a siphon conduit 102 that has antimicrobial properties to resist build-up of biofilm and increased lubricity inside the drain lumen. An increase in lubricity corresponds to a decreased characteristic cross-section size capable of maintaining an intact meniscus. Therefore, an antimicrobial effect may serve to maintain a margin of safety against particle flow occurring in a siphon drain lumen. The antimicrobial property may be caused by application of a film agent to the lumen interior, or arise as a natural material property inherent in the conduit 102.
With reference now to
Because operating pressure of the fluid in the conduit 102 is very low during normal operation, the indicator 270 desirably provides a mechanical advantage by way of its larger working surface area, compared to the cross-section of drain conduit 102. It is within contemplation to couple small displacement of the large membrane area with a smaller cross-section to amplify travel of an indicator (not illustrated).
With continued reference to
An embodiment structured according to certain principles of the instant invention may be used in a method for placing a urinary catheter in fluid communication with a drain container. One such method includes installing a urinary catheter 104 in position to drain a patient's bladder. A first end 116 of a siphon conduit 102 is then placed into fluid communication with a discharge end of the catheter 104. The siphon conduit 102 may be characterized as being constructed to maintain plug-flow of a fluid 150 flowing therethrough. The bulk of the length of siphon conduit 102 is typically routed along a path disposed at approximately the same elevation to dispose the siphon conduit discharge end 118 elevated above a drain container 138 and to permit a siphon-break to occur at an elevation 132 in general agreement with the bladder's elevation 126. In most cases, such siphon-break elevation 132 desirably is selected to cause a small (e.g., 1 to 3 inches (2.5 to 7.5 cm) of water column, or more preferably, 1 to 2 cm water column) negative pressure in the bladder to promote complete evacuation. A siphon-break apparatus 106 is placed into fluid communication with the discharge end 118 of the siphon conduit 102. A currently preferred and operable siphon-break structure 106 is constructed to cause the siphon-break to occur at a desired elevation 132 and to resist plug-flow of a fluid 160 flowing further therethrough. The drain end of the siphon-break apparatus 106 is placed in fluid communication with the drain container 138. The method may include anchoring structure associated with the siphon-break apparatus 106 effective to dispose a siphon-break at any desired elevation 132.
Subsequent to complete fluid-filling of that portion of the drain conduit assembly disposed between the patient and the siphon-break apparatus 106, the siphon-break elevation 132 determines the amount of either back-pressure, or suction, imposed on the bladder by the instant drain assembly. The pressure effect of the drain assembly may be regarded as being applied to the bladder at the drain orifice of an installed catheter 104. Currently, it is preferred for siphon-break elevation 132 to be maintained between about 1 inch (2.5 cm) above, to about 4 inches (10 cm) below, the elevation of the patient's bladder. In theory, it is most desirable to position the siphon-break at an elevation to maintain a neutral pressure, or a substantially neutral negative pressure (e.g., 1 to 2 cm water column), at the catheter's drain entrance in the bladder to promote complete evacuation of the bladder. In practice, the elevation of a patient's bladder may be difficult to determine, and the patient may change position and consequent bladder elevation. Therefore, it is presently preferred to dispose siphon-break elevation 132 effective to err on the side of inducing negative pressure, to promote complete evacuation of the bladder and to permit measurement of bladder pressure that is truly reflective of abdominal pressure.
Bladder pressure can be measured, even real time, while draining urine from a bladder, as disclosed in United States patent application by Sugrue et al., Ser. No. 11/219,316, titled “Apparatus for monitoring intra-abdominal pressure,” filed Sep. 1, 2005, the contents of which are incorporated herein by this reference. A urine drain assembly structured according to certain principles of the instant invention permits measuring bladder pressure to infer abdominal pressure while permitting uninterrupted flow of urine draining from the patient's bladder. In such case, “uninterrupted flow” means that the drain tubing, such as the siphon tube 102, is not occluded as a condition to permit making a pressure measurement. It is recognized that the flow of fluid in the conduit 102 may cease due to lack of fluid entering the Catheter's drain orifice when the bladder is substantially empty (and the catheter's drain entrance may even be occluded by bladder wall structure), but such is not regarded as “interrupting the flow” within the context of this method of using the instant drain apparatus. In contrast, “interrupting the flow” requires a fluid flow-resisting device, such as a hose clamp, or valve, typically operated by a health care worker, effective to stop fluid flow through the drain conduit 102.
Interestingly, a positive pressure, or back-pressure caused by the drain assembly, would be added to the patient's abdominal pressure (in a pressure measurement made in the bladder), because fluid in the bladder would communicate such pressure between the drain system and measurement system. However, a negative pressure, or suction, does not necessarily effect measured bladder pressure, because the drain orifice (e.g., 110,
The instant urine drain system provides an important advance in the art of measuring urine output of a medical patient. The charge-volume of fluid in the conduit between the catheter 104 and end 118 (effectively the location of the siphon-break) can be determined. Such charge-volume can be supplied by the patient, or infused by medical personnel through an appropriate fluid coupling device (e.g., a 3-way valve, not illustrated, or a sample port associated with the catheter), disposed in association with the catheter 104. Assuming a small negative pressure (i.e., suction) is imposed by suitable location of the siphon-break elevation 132, and subsequent to filling such charge-volume, the patient's bladder will remain substantially empty. All urine produced by the patient will be removed substantially as it is produced, so the patient's fluid drain rate may be monitored with precision. The siphon conduit 102 remains filled with fluid, so no tiresome drain conduit manipulation is required to remove trapped pockets of fluid to ensure complete bladder draining prior to making a measurement. The change in volume contained in the drain container 138 may simply be determined at desired intervals of time to manually determine the patient's fluid discharge flow rate. Alternatively, an automated fluid flow rate determining device, such as the droplet counter disclosed in U.S. Pat. No. 6,640,649 issued Nov. 4, 2003 to Paz, et al., the contents of which are incorporated herein by this reference, may be used to determine the patient's discharge flow rate.
In any case, the instant drain assembly avoids need to manipulate the drain conduits to manually urge fluid motion in the drain conduit. The instant assembly can be configured and arranged to automatically ensure essentially complete evacuation of the bladder to reduce a nidus for infection. By avoiding fluid motion-inducing manipulations of the drain conduits, the instant assembly also avoids chance of inducing undesired retrograde urine flow into the bladder.
After being apprised of the instant disclosure, one of ordinary skill will be readily able to make the apparatus with materials and methods known in the art.
This application claims the benefit under 35 U.S.C. §119(e) of the filing date of U.S. Provisional Patent Application Ser. No. 60/918,386, filed Mar. 16, 2007, for “PRESSURE CONTROL FOR CATHETER DRAIN TUBING”, the contents of the entirety of which are incorporated by this reference.
| Filing Document | Filing Date | Country | Kind | 371c Date |
|---|---|---|---|---|
| PCT/US2008/003444 | 3/14/2008 | WO | 00 | 9/11/2009 |
| Number | Date | Country | |
|---|---|---|---|
| 60918386 | Mar 2007 | US |
