BRIEF DESCRIPTION OF THE DRAWINGS
The drawings illustrate the best mode presently contemplated of carrying out the invention. In the drawings:
FIG. 1 is an illustration of a prior art system for determining the intra-abdominal pressure of a patient utilizing a collected volume of fluid from the patient;
FIG. 2 is an illustration of the prior art system shown in FIG. 1 illustrating the manual measurement of the IAP of the patient utilizing markings on a manometer tube;
FIG. 3 is an illustration of the intra-abdominal pressure measuring device of the present invention as attached to a patient monitoring device having a display;
FIG. 4 is an illustration of the pressure measuring device in a position ready to determine the intra-abdominal pressure of the patient;
FIG. 5 is an illustration similar to FIG. 4 illustrating the venting of the drainage conduit to atmosphere and the determination of the intra-abdominal pressure; and
FIG. 6 is a second, alternate configuration of the intra-abdominal pressure measuring device in accordance with the present invention.
DETAILED DESCRIPTION OF THE INVENTION
FIG. 1 illustrates a prior art intra-abdominal pressure (IAP) measuring apparatus as being used on a patient 12 in a post-operative or intensive care environment. The IAP measuring apparatus 10 shown in FIGS. 1 and 2 generally represents the device shown and described in U.S. Pat. No. 6,503,208. As illustrated in FIG. 1, the patient is in a supine position with a catheter 14, such as a urinary (Foley) catheter positioned to drain the patient's bladder 16 into a collection container 18. In the apparatus shown in FIGS. 1 and 2, a drainage conduit 20 is connected to one end 22 of the catheter 14 and provides a drainage path to the collection container 18. In the embodiment shown in FIGS. 1 and 2, the drainage conduit 20 is received within a Y-connector 24. The Y-connector 24 provides a fluid path to a second drainage conduit 26 that eventually leads to the collection container 18, as best shown in FIG. 1.
Referring now to FIG. 2, the Y-connector 24 includes a venting conduit 28 having a sterile air filter 30 and a clamping device 32. During normal operation, the clamping device 32 is in a closed position to prevent the patient's urine from coming into contact with the filter and forming deposits that may block the air filter 30 from its venting function. When the clamping device 32 is in the closed position, fluid drained from the patient 12 passes through the drainage conduit 20, the Y-connector 24 and the second drainage conduit 26 and is collected within the collection container 18.
In the embodiment shown in FIG. 2, the discharge conduit 20 is a manometer tube that includes a series of measurement markings that are calibrated in either cm H2O or mmHg. When it is desired to make a pressure measurement for the intra-abdominal pressure for the patient 12, the Y-connector 24 is elevated above the mid-axillary line 34 of the patient 12 until the zero pressure marking line 36 is even with the mid-axillary line 34. Once the drainage conduit 20 is properly elevated, the clamping device 32 is opened, thus venting the entire drainage conduit to atmosphere. Once the drainage conduit 20 is vented to atmosphere, a measuring volume of the drained fluid from the patient returns to the patient through the catheter 14.
Once the fluid returns to the patient, the level of the fluid remaining within the discharge conduit 20 above the zero marking 36 indicates the pressure within the bladder of the patient. Since the specific gravity of the collected fluid, and specifically urine, is very close to 1.0, the bladder pressure is equivalent to the height of the urine contained within the discharge tube 20 above the zero marking 36.
Although the apparatus shown in FIGS. 1 and 2 has proven effective to determine the intra-abdominal pressure of a patient, the measurement process requires a manual viewing of the level of fluid within the discharge conduit 20 and a subsequent recording of this pressure within an automated system within the treatment environment.
FIGS. 3-5 illustrate a first preferred embodiment of the IAP measuring apparatus 38 of the present invention, where the same reference numerals for similar components to those shown in the prior art system of FIGS. 1-2 are utilized to facilitate understanding of the present invention. As illustrated in FIG. 3, the apparatus 38 includes the drainage conduit 20 connected to the catheter 14 such that fluid from the patient 12, and specifically urine from the bladder 16, can be collected within the collection container 18. In the embodiment of the invention shown in FIG. 3, a sensing conduit 40 is positioned in fluid communication with the drainage conduit 20 through a T-shaped connector 42. The connector 42 is positioned within the drainage conduit 20 and receives a first end 44 of the sensing conduit 40. Specifically, the first end 44 of the hollow, tubular sensing conduit 40 is connected to and in fluid communication with the T-shaped connector 42. In the embodiment illustrated in FIG. 3, the sensing conduit 40 includes an air filter 46 positioned between the first end 44 and a second end 48. The second end 48 includes a coupling 50 that receives a mating coupling 52 of a pressure transducer 54. The pressure transducer 54 is a conventional component, such as the TrueWave disposable pressure transducer available from Edwards Lifesciences, and generates a signal along an output line 56 that relates to the air pressure sensed by the pressure transducer 54. The output line 56 can be received by an input 58 of a patient monitor 60 such that the patient monitor can display the pressure measurements from the transducer 54 on a display 62 on an intermittent basis when the drainage conduit is elevated above the patient and the clamping device 32 is opened to allow venting to atmospheric pressure.
As can be understood in FIG. 3, when the pressure transducer 54 is attached to the second end 48 of the sensing conduit 40, a volume of air is entrapped within the sensing conduit 40. The fluid within the discharge conduit 20 can flow into the sensing conduit 40 and compress the air therein. The trapped volume of air within the sensing conduit 40 allows the pressure transducer 54 to make a pressure determination of the fluid in the discharge conduit 20 that is determined by the air-to-liquid junction within the sensing conduit 40.
Referring now to FIG. 4, when an intra-abdominal pressure measurement is to be made utilizing the IAP measuring apparatus 38, the Y-connector 24 is elevated until the T-connector 42 is generally aligned with the mid-axillary line 34 for the patient 12. As described previously, the mid-axillary line for the patient 12 is generally level with a horizontal axis extending through the pubic bone of the patient 12 when the patient is in a supine position. As illustrated in FIG. 4, when the Y-connector 24 is initially elevated and the clamping device 32 remains closed, both the drainage conduit 20 and second drainage conduit 26 are filled with fluid collected from the patient.
Once the drainage conduit 20 and Y-connector 24 are properly elevated, the clamping device 32 is opened, causing the drainage conduit 20 to be vented to atmospheric pressure through the air filter 30. Once the drainage conduit 20 has been vented to atmosphere, a measurement volume of fluid contained within the drainage conduit 20 flows back into the patient bladder 16 through the catheter 14. Since the specific gravity of urine is very close to 1.0, the bladder pressure is equivalent to the height of the fluid contained within the discharge tube 20 provided that the liquid-to-air junction in the sensing conduit is positioned at the mid-axillary line.
As the measurement volume of the patient fluid returns to the bladder 16, a small volume of the fluid enters into the sensing conduit 40. As the fluid enters into the sensing conduit 40, the fluid meets the volume of air at a liquid-to-air junction point 64 (FIG. 5). When the volume of fluid enters the sensing conduit 40, the fluid compresses the air trapped between the pressure transducer 54 and the point 64, which is the air-to-fluid junction within the sensing conduit 40. The pressure transducer 54 senses the pressure of air within the sensing conduit 40 and generates a signal based upon the sensed pressure.
The IAP for a patient has been demonstrated to be identical to the intra-gastric pressure when the patient is supine and the patient's mid-axillary line is used as the zero pressure reference level. The greater the IAP for the patient, the further the fluid solution will travel up the sensing conduit 40. The compression of the air within the sensing conduit 40 will thus be sensed by the pressure transducer 54, which provides a signal to the patient monitor 60 that is related to the IAP for the patient 12.
In the embodiment of the invention shown in FIGS. 4 and 5, the volume of the drainage conduit 20 is sufficient to return the required measuring volume of fluid back to the patient's bladder 16 and still provide a column of fluid within the drainage conduit 20. The specific volume of the drainage conduit 20 can vary as long as the volume is sufficient to return the measurement volume to the patient during the measurement procedure.
As can be understood in FIGS. 4 and 5, once the pressure measurement has been taken, the patient monitor 60 can display the measurement as well as transmit the measurement to various other locations within a healthcare facility. The electronic registration and documentation of the IAP for the patient utilizing the system 38 of the present invention is a significant improvement over the manual measurement techniques shown in the prior art drawings of FIGS. 1 and 2.
Referring now to FIG. 6, thereshown is a second embodiment of the IAP measuring apparatus, as referred to by reference numeral 66. In the second embodiment shown in FIG. 6, the apparatus includes a pressure monitor 68 that is operable to determine and display the intra-abdominal pressure for the patient 12.
As illustrated in FIG. 6, the patient 12 includes the catheter 14 connected to a single drainage conduit 70. The drainage conduit 70 drains fluid from the patient into the collection container 18 as in the first embodiment previously described.
The pressure monitor 68 includes a main housing 72 that includes a display 74. The pressure monitor is configured to connect with the air filter 46 at the second end of the sensing conduit 40. The first end 44 of the sensing conduit 40 is received by the T-connector 42 and is thus in fluid communication with the drainage conduit 70. Preferably, the air filter 46 is part of a disposable assembly including the sensing conduit 40 and has a connector that mates with the pressure monitor 68.
As illustrated in FIG. 6, the pressure monitor 68 includes an internal pressure transducer 76 that is in fluid communication through an internal passageway with the sensing conduit 40, via the air filter 46. In this manner, the pressure transducer 76 can determine the air pressure within the sensing conduit 40 in a similar manner as previously described.
The pressure monitor 68 further includes a clamping device 78 that can be selectively operated to occlude the flow of fluid through the drainage conduit 70. Specifically, the clamping device 78 is an automated device that can be operated between a first position and a second position to selectively allow fluid to flow through the drainage conduit 70.
The pressure monitor 68 includes an air dosing pump 80 that is also in fluid communication with the sensing conduit 40 through an internal passageway within the pressure monitor 68.
When the pressure monitor 68 desires to make a pressure measurement, the pressure monitor 68 initially activates the clamping device 78 to occlude the drainage conduit 70. Once the clamping device 78 has been actuated, the air pump 80 will inject a pre-set volume of air into the drainage conduit through the filter 46 and the sensing conduit 40. Since the clamping device 78 occludes the drainage conduit, the pre-set volume of air injected into the drainage conduit 70 will fill the drainage conduit and force a volume of the drained fluid collected in the drainage conduit 70 back into the bladder. Specifically, the air pump 80 will inject a volume of air sufficient to cause the fluid-to-air junction in the conduit 70 to be at the mid-axillary line 34. As illustrated, the drainage conduit 70 is held in place by a pair of adhesive strips 81 at the mid-axillary line 34. In accordance with the second embodiment shown in FIG. 6, the pressure transducer 76 can obtain a pressure measurement related to the IAP for the patient, which then can be displayed on the integral display 74.
As can be understood by the above description, the method and apparatus of the present invention utilize the pressure within the discharge conduit upon the return of a volume of fluid to a patient to determine the IAP for the patient 12. The pressure transducer senses the air pressure within a sensing conduit, which is directly related to the IAP for the patient. The pressure transducer provides a pressure signal to the patient monitor 60 or display 74, which can then display the IAP for the patient on an intermittent basis. Although two embodiments of the present invention have been shown and described in the Figures, it is contemplated by the inventor that various other methods and apparatus can be utilized for sensing the inter-abdominal pressure of the patient utilizing the pressure of the collective fluids from the patient.