Urine output monitor apparatus

Abstract

Apparatus for monitoring the output of urine from a catheterised patient comprising: a two-part elongate pipe, one part having an upstream end and the other part having a downstream end which ends are open for inline connection into a urine channel carrying urine away from the bladder of a patient, the parts each having open inner ends; a housing having an open neck inside the housing and extending in a direction towards an open mouth at an outer surface of the housing; two pipe stems extending from the housing in a direction substantially perpendicular to the direction the open neck extends, the inner ends of the two-part elongate pipe between the upstream and downstream ends being fitted over the pipe stems, and a flexible bag which has an open mouth, in which the open mouth of the flexible bag is attached to the open neck of the housing inside the housing and in which the flexible bag is arranged so as to be able to inflate and deflate within the housing, the elongate pipe, housing and flexible bag forming a semi rigid conduit which is substantially airtight between the upstream and downstream ends and which, when the open upstream and downstream ends are connected to the urine channel, may be filled with urine.

Description

[0001] Urine Output Monitor Apparatus

[0002] FIELD OF THE INVENTION

[0003] The present invention relates to apparatus for monitoring the output of urine.

[0004] BACKGROUND ART

[0005] Volumetric measurement of urine output is an important process for catheterised patients admitted to hospital for medical or surgical care. It can be used to guide therapy as well as offering an early indication of deterioration in clinical status and renal function. KDIGO, an international organisation dedicated to evidence based guidelines in kidney disease, uses urine output as a key criterion in defining acute kidney injury.

[0006] The most common method of measuring urine output involves collecting the urine in a graduated container or bag connected to the catheter, a nurse or paramedic noting the total volume of urine at regular intervals before opening a valve to empty the urine in the bag through a drain pipe into a larger reservoir; the flow rate of urine can be calculated according to the volume collected in the bag over the time period between measurements. The apparatus used in this method (a catheter, the graduated bag, a valve, a drain pipe and a reservoir) is relatively inexpensive, which is important as all the parts which come into contact with the urine or the patient have to be disposed of between uses to maintain hygiene and prevent patient contamination; however, this is not a reliably accurate method, as it requires regular nursing input to take the recordings, and it is not always possible in a busy hospital ward for a nurse to take the reading at the exact time. There have been many attempts to automate the process of urine output measurement and monitoring, some of which are described in WO 2022 / 219578. A problem with conventional automated urine output monitors is that they are usually configured with a pump, valves and pressure sensors as an integral whole with the necessary urine conduits which means that the disposable elements of the apparatus are significantly more expensive than those of the common, non-automated method, and many hospitals cannot afford to use automated urine output monitors for every patient for whom urine output monitoring is a medical requirement. There is a need for a simple and less expensive form of urine output monitor apparatus.

[0007] SUMMARY OF THE INVENTION

[0008] The present invention therefore provides apparatus for monitoring the output of urine from a catheterised patient comprising: a two-part elongate pipe, one part having an upstream end and the other part having a downstream end which ends are open for inline connection into a urine channel carrying urine away from the bladder of a patient, the parts each having open inner ends; a housing having an open neck inside the housing and extending in a direction towards an open mouth at an outer surface of the housing; two pipe stems extending from the housing in a direction substantially perpendicular to the direction the open neck extends, the inner ends of the two-part elongate pipe between the upstream and downstream ends being fitted over the pipe stems, and a flexible bag which has an open mouth, in which the open mouth of the flexible bag is attached to the open neck of the housing inside the housing and in which the flexible bag is arranged so as to be able to inflate and deflate within the housing, the elongate pipe, housing and flexible bag forming a semi rigid conduit which is substantially airtight between the upstream and downstream ends and which, when the open upstream and downstream ends are connected to the urine channel, may be filled with urine.

[0009] With such an arrangement, the assembly forming the semi rigid conduit may be the only part of the urine output measuring apparatus which need be disposable, and this assembly is relatively inexpensive and simple in its operation. Moreover, the semi rigid conduit may be shaped and configured so that its installation in a urine output monitoring system is intuitive, and therefore quick and easy to achieve.

[0010] The pipe in the vicinity of, near or adjacent the upstream and downstream ends of the elongate pipe is preferably elastically flexible. This enables the elongate pipe to be pinched closed, thus forming a cheap and simple stop valve, and also to be retained in place when fitted over the pipe stems.

[0011] The open neck of the housing being oriented substantially transversely to the pipe stems enables an operator to see how the housing and the elongate pipe is to be fitted into the urine output monitoring system, and makes incorrect installation extremely unlikely; it also allows the semi rigid conduit to be fitted into the urine output monitoring system in a one-directional movement (essentially, perpendicular to the elongate pipe), as will be explained below.

[0012] The housing is preferably rigid, and the flexible bag is preferably formed of an elastic material. The semi rigid conduit may be provided with or integral with a downstream urine collection tube and a urine collection bag, allowing the resulting combination to be used on its own where accurate urine output monitoring is not required, but easily and rapidly reconfigured for accurate monitoring by combining with the elements described below.

[0013] The urine output monitoring system may further comprise an air pump having an air outlet tube which is releasably attachable to the open mouth of the housing for selectively inflating or deflating the flexible bag, an air pressure sensor coupled to the air outlet tube and configured to generate a signal related to the air pressure sensed in the air outlet tube, and a controller configured to control the air pump responsively to the signal.

[0014] The controller can be adapted to control the air pump to increase the air pressure in the flexible bag so as to inflate it, thereby forcing urine out of the elongate pipe, and the controller may be adapted to calculate a volume of urine that was forced out of the pipe, based on the controlling of the pump.

[0015] The urine output monitoring system may further comprise two pinch valves adapted to operate on a flexible portion of the elongate pipe, one pinch valve adjacent or in the vicinity of each of the upstream and downstream ends of the elongate pipe. The pinch valves are actuated to open or close by the controller. The air pump may be a reciprocating piston pump.

[0016] The urine output monitoring system may comprise an enclosure containing the air pump, pressure sensor, controller and the pinch valves, and having an opening into which the semi rigid conduit can be releasably inserted and an air outlet fitting, so that the elongate pipe is received within the opening and the open neck of the housing engages with the air outlet fitting in one movement, in a snap fit arrangement allowing an operator to receive haptic feedback that the semi rigid conduit is correctly installed. The opening in the enclosure preferably has a door, the door closing in a snap fit, the act of closing the door with the semi rigid conduit inside the opening locking the open neck of the housing to the air outlet tube.

[0017] When the term "semi rigid" is used herein in relation to a thing, it should be understood to mean that the thing so described is rigid in some places or parts, and non-rigid, or flexible, in other places or parts.

[0018] BRIEF DESCRIPTION OF THE DRAWINGS

[0019] The invention will now be described by way of example and with reference to the accompanying figures, in which;

[0020] Figure 1 is a schematic diagram illustrating the principles of operation of a urine output monitoring apparatus in accordance with the present invention;

[0021] Figure 2 is a schematic diagram illustrating the operation of the apparatus in accordance with the present invention;

[0022] Figure 3 is a perspective view of an embodiment of urine output monitoring apparatus in accordance with the present invention;

[0023] Figure 4 is a perspective view in partial cross-section of part of the apparatus of Figure 2, and

[0024] Figure 5 is a schematic view of the pinch valve arrangement of Figure 3 illustrating the operation of the urine flow valves shown in Figure 2.

[0025] DETAILED DESCRIPTION OF THE EMBODIMENTS

[0026] In Figure 1, a patient's catheterised bladder is fitted with a catheter 4 with the foley catheter balloon inflated to retain the catheter in the bladder, and which leads via urine channel 6a, 6b to a urine collection container 8 (such as a flexible bag) which has volumetric markings 10 allowing the total volume of urine passed by the patient since the last time the container 8 was empty to be measured. Connected in-line with the upstream channel 6a and the downstream channel 6b is a urine output monitoring apparatus 12 inside an enclosure shown by a dotted line. The monitoring apparatus comprises a small bore conduit 14 connecting the upstream channel 6a to the downstream channel 6b, a small bore branch tube 16 which leads to a pressure sensor P and a pump 18; either side of the branch line 16 are stop, or pinch, valves 20a, 20b for selectively closing the conduit 14 against the flow of urine or opening to permit the flow of urine through the conduit 14. A controller M (such as a suitably programmed microprocessor) is connected to the sensor P, the pump 18 and the pinch valves 20a, 20b.

[0027] In operation, initially the downstream stop valve 20b is closed, allowing urine to flow into the conduit 14 upstream of the stop valve 20b and the branch tube 16; as urine flows, the pressure sensed by the sensor P increases until it reaches a first threshold pressure indicative of urine being present; this prompts the controller M to actuate the pump 18 and lower the pressure in the conduit 14 so as to draw urine from the bladder 2 into the conduit. As the conduit fills, the pressure in the conduit 14 increases. When the sensor P senses a pressure rise indicating that the conduit 14 has filled sufficiently, this is communicated to the controller M, which reacts to close the upstream pinch valve 20a, to open the downstream pinch valve 20b, and to actuate the pump 18 to increase pressure in the conduit and drive the urine from the conduit 14 downstream of the stop valve 20a and the branch tube 16, through the downstream channel 6b and to the urine collection container 8. This continues for a predetermined time and / or until the conduit 14 is substantially empty of urine, at which point the system returns to the initial state, allowing urine to flow into and fill the conduit 14 again. The controller is adapted to determine the urine flow rate according to the timings of the cycle described above, and the sensed pressure values as the conduit fills with urine.

[0028] Figure 2 shows an elongate pipe comprising two, elastic upstream and downstream end pipes 22a, 22b, one inner end of each end pipe is fitted over one of two short, parallel pipe stems which extend from opposite sides of a rigid housing 24. The housing 24 thus has two pipe stems for inline connection with the end pipes 22a, 22b; the housing also has an open neck which extends from an open mouth 26 at the external surface of the housing 24 inside the housing in a direction perpendicular to the inline pipe stems, and which is sealed with a flexible bag, or elastic balloon, 28 which is illustrated in Figure 2 in its inflated state; the flexible bag has a single mouth, or opening, which is connected to the open neck inside the housing as will be described below. Collectively, the upstream and downstream end pipes 22a, 22b, housing 24 and flexible bag 28 form a semi rigid conduit which is substantially airtight between the upstream and downstream end pipes 22a, 22b and which can fill with urine drawn from the bladder and direct it to flow to the urine collection container 8 when the upstream and downstream end pipes 22a, 22b are connected inline with the upstream urine channel 6a and the downstream urine channel 6b, respectively. The urine output monitoring apparatus 12 comprises a branch line 16, pressure sensor P and pump 18 (here a reciprocating piston pump) as described above; there is also an air outlet fitting 30 which is shaped and configured to fit snugly within the open mouth 26 of the open neck of the rigid housing 24 in a snap fit when the housing 24 is moved in the direction of arrow C towards the outlet fitting 30, with an O-ring 32 providing an airtight seal. It will be understood that in a first pinch valve configuration urine flows into the semi rigid conduit when the upstream pinch valve 20a is open and the downstream pinch valve 20b is closed (the closure direction of the pinch valves is indicated by the arrows B) and that urine flows out of the semi rigid conduit in a second pinch valve configuration, when the upstream pinch valve 20a is closed and the downstream pinch valve 20b is open, as described above.

[0029] The apparatus of Figure 2 normally waits in the first pinch valve configuration until a rise in pressure sensed by sensor P indicates the presence of urine; this prompts the controller to actuate the pump 18 to lower the pressure in the semi rigid conduit to draw urine into the semi rigid conduit; as the amount of urine in the semi rigid conduit increases, the flexible bag 28 is gradually deflated, either until the stroke limit of the pump is reached, or the bag has been deflated to a predetermined extent (the flexible bag 28 should never be too collapsed down, it must at all times remain compliant and have minimal pressure difference across its thin walls; any pressure difference either side of the bag would be an error the controller would have to deal with). At this point, the controller switches the pinch valves to the second configuration and reverses the pump to raise the pressure and discharge urine from the semi rigid conduit into the urine collection container 8, gradually inflating the bag 28. The flexible bag 28 is inflated by the piston pump until the stroke limit of the pump is reached or the flexible bag is inflated to its initial state (if the bag were fully inflated inside the housing 24 it might press against the housing and become damaged; but if this were to occur the pressure sensed by sensor P would start to rise so the controller can be programmed to stop the pump if this is detected). The discharge cycle can happen quickly - several seconds perhaps. The apparatus would then return to the intake cycle with an inflated bag ready to draw in a fresh batch of urine as it is produced in the bladder. So, the device would spend most of its life in the intake state, in the first pinch valve configuration, and the pump would make small movements to draw urine in based on the measured pressure.

[0030] Urine is removed in one or more of the above cycles until the bladder 2 empties and collapses down against itself and the foley catheter 4. At this point the urine pressure would rapidly fall and go negative with any further removal of urine, similar to sucking the air out of a balloon. This makes a very obvious pressure transition point to detect when the bladder is empty and to cease pumping.

[0031] Figure 3 shows the semi rigid conduit of Figure 2 in the process of being installed in an enclosure 40 containing the air pump, pressure sensor, controller and the pinch valves. The enclosure 40 has an opening 42 which is shaped and configured to receive the semi rigid conduit; the opening has a central portion adapted to receive the rigid housing 24 (and this contains the outlet fitting 30 of Figure 2 to which the open neck 26 of the housing is fitted) and two rectangular end portions adapted to receive a square end piece 44 which is a push fit into the ends of upstream and downstream end pipes 22a, 22b distant from the housing 24 and which help locate the semi rigid conduit in the opening 42. The transverse alignment of the open neck with the pipe stems and end pipes allows the conduit to be installed easily by moving it in one direction, into the enclosure 40, or removed quickly in the opposite direction. When the semi rigid conduit is properly located within the opening, closing of the door 46 retains the semi rigid conduit within the opening 42, inside the enclosure 40. Also shown in Figure 3 are two cam-operated pinch valves 48 which pinch the elastic upstream and downstream end pipes 22a, 22b under the control of the controller M. The enclosure 40 also has a display 50 which displays the urine output over time as a graph of volume against time, giving a person attending the patient a graphic display from which any changes in urine output can be easily discerned. The display 50 could be a GUI, and / or there could be switches and the like for changing the display and programming the controller. It will be understood that, because the only part of the illustrated apparatus which comes into contact with urine is the semi rigid conduit, this is the only part of the apparatus which needs to be disposed of between patients. The semi rigid conduit is easily replaced by opening the door 46, removing the semi rigid conduit from the opening 42, disconnecting the end pieces 44 from the upstream and downstream urine channels 6a, 6b, and then inserting a new semi rigid conduit into the opening 42 and closing the door. As mentioned above, the upstream and downstream end pipes 22a, 22b are made of a surgical grade flexible, preferably elastic material, the housing 24 and the end pieces 44 are made of a suitable rigid material such as a surgical grade plastic. The flexible bag 28 is made of a surgical grade plastic film.

[0032] Figure 4 shows a cross-section along lines 4-4 of Figure 2 the housing 24; this comprises an outer part 24a and an inner part 24b which snap fit together. The inner part 24b has a neck portion 25 which extends inside the lower part 24a when the inner part 24b is fitted to the lower part 24a of the housing 24; the flexible bag 28 is held around the neck 25 by an elastic band 27 to form an airtight and urine-tight seal. It is important that the flexible bag 28 makes an air and urine tight seal with the neck 25. This may be best achieved with an elastic band 27 as shown, with glue or alternatively by designing the flexible bag to tightly stretch and secure itself onto the neck (if using elasticity alone, the neck 25 may need a lip or ringed portion to assist with securing the neck of the bag). Figure 5 shows the operation of a pinch valve 20 which reciprocates and, when in the "pinch" state (as shown), squeezes the walls of the elastic end pipe 22 together and prevents the flow of urine U through the end pipe 22. Although plastics are cheap, it may be that the rigid elements could be made of a more robust and durable material such as metal / alloy.

[0033] It will of course be understood that many variations may be made to the abovedescribed embodiment without departing from the scope of the present invention. For example, we envisage the semi rigid conduit as being transparent, so that it can be readily observed if urine is present and flowing, but it could be that some or all of the parts forming the semi rigid housing could be opaque. The drawings show an arrangement in which the semi rigid housing is inserted in one direction only, and the act of insertion automatically ensures that the open end of the housing engages on the outlet pipe (so that the open end is transverse to the general length direction of the semi rigid conduit), but in a modification outside the scope of the invention the open end could be parallel with the general length direction of the semi rigid conduit. The use of the word "substantially" in Claim 1 is intended to encompass arrangements in which the two pipe stems extend from the housing in a direction exactly perpendicular to the direction the open neck extends, and also at a small angle (e.g. 5° to 10°, up to 15°) away from the perpendicular such that an arrangement where the angle is not exactly perpendicular achieves substantially the same result, in the same way, as the claimed invention. The semi rigid conduit could be made as one unit with the downstream channel 6b and the urine collection container 8 to create a one-piece urine collection bag which is compatible with the enclosure 40 of Figure 4 but does not have to be used for accurate urine flow monitoring; the monitoring apparatus of Figure 4 could then be combined with the compatible urine collection bag only when a patient needs more accurate monitoring. Although the valves are preferably pinch valves, other forms of valves could be used, such as diaphragm valves, ball valves, piston valves, rotary valves or the like, and the valves could be of different types upstream and downstream of the housing 24.

[0034] Where different variations or alternative arrangements are described above, it should be understood that embodiments of the invention may incorporate such variations and / or alternatives in any suitable combination.

Claims

CLAIMS1. Apparatus for monitoring the output of urine from a patient comprising: a two-part elongate pipe, one part having an upstream end and the other part having a downstream end which ends are open for inline connection into a urine channel carrying urine away from the bladder of a patient, the parts each having open inner ends; a housing having an open neck inside the housing and extending in a direction towards a mouth at an outer surface of the housing; and two pipe stems extending from the housing in a direction substantially perpendicular to the direction the open neck extends, the inner ends of the two-part elongate pipe between the upstream and downstream ends being fitted over the pipe stems, and a flexible bag which has an open mouth, in which the open mouth of the flexible bag is attached to the open neck of the housing inside the housing and the flexible bag is arranged so as to be able to inflate and deflate within the housing, the elongate pipe, housing and flexible bag forming a semi rigid conduit which is substantially airtight between the upstream and downstream ends and which, when the open ends are connected to the urine channel, may be filled with urine.

2. Apparatus according to Claim 1, in which the pipe adjacent of the upstream and downstream ends is elastically flexible.

3. Apparatus according to any preceding claim, in which the housing is rigid.

4. Apparatus according to any preceding claim, in which the flexible bag is formed of an elastic material.

5. Apparatus according to any preceding claim, in which the semi rigid conduit is integral with a downstream urine collection tube and a urine collection bag.

6. Apparatus according to any preceding claim, further comprising an air pump having an air outlet tube which is releasably attachable to the open mouth of the housing for selectively inflating or deflating the flexible bag, an air pressure sensor coupled to theair outlet tube and configured to generate a signal related to the air pressure sensed in the air outlet tube, and a controller configured to control the air pump responsively to the signal.

7. Apparatus according to Claim 6, in which the controller is adapted to control the air pump to increase the air pressure in the flexible bag so as to inflate it, thereby forcing urine out of the elongate pipe, and the controller is adapted to calculate a volume of urine that was forced out of the pipe, based on the controlling of the pump.

8. Apparatus according to Claim 7, further comprising two pinch valves adapted to operate on a flexible portion of the elongate pipe, one pinch valve in the vicinity of each of the upstream and downstream ends of the elongate pipe.

9. Apparatus according to Claim 8, in which the air pump is a reciprocating piston pump.

10. Apparatus according to any of Claims 6 to 9, further comprising an enclosure containing the air pump, pressure sensor, controller and any pinch valves, and having an opening into which the semi rigid conduit can be releasably inserted and an air outlet fitting, so that the elongate pipe is received within the opening and the open neck of the housing engages with the air outlet fitting in one movement.

11. Apparatus according to Claim 10, in which the opening in the enclosure has a door, the door closing in a snap fit, and in which the act of closing the door with the semi rigid conduit inside the opening locks the open neck of the housing to the air outlet tube.

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