CA1335709C - Hollow viscus and solid organ tonometry - Google Patents
Hollow viscus and solid organ tonometryInfo
- Publication number
- CA1335709C CA1335709C CA000609066A CA609066A CA1335709C CA 1335709 C CA1335709 C CA 1335709C CA 000609066 A CA000609066 A CA 000609066A CA 609066 A CA609066 A CA 609066A CA 1335709 C CA1335709 C CA 1335709C
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- organ
- catheter
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- adequacy
- fluid
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- A—HUMAN NECESSITIES
- A61—MEDICAL OR VETERINARY SCIENCE; HYGIENE
- A61B—DIAGNOSIS; SURGERY; IDENTIFICATION
- A61B5/00—Measuring for diagnostic purposes; Identification of persons
- A61B5/145—Measuring characteristics of blood in vivo, e.g. gas concentration, pH value; Measuring characteristics of body fluids or tissues, e.g. interstitial fluid, cerebral tissue
- A61B5/14542—Measuring characteristics of blood in vivo, e.g. gas concentration, pH value; Measuring characteristics of body fluids or tissues, e.g. interstitial fluid, cerebral tissue for measuring blood gases
-
- A—HUMAN NECESSITIES
- A61—MEDICAL OR VETERINARY SCIENCE; HYGIENE
- A61B—DIAGNOSIS; SURGERY; IDENTIFICATION
- A61B5/00—Measuring for diagnostic purposes; Identification of persons
- A61B5/145—Measuring characteristics of blood in vivo, e.g. gas concentration, pH value; Measuring characteristics of body fluids or tissues, e.g. interstitial fluid, cerebral tissue
- A61B5/14503—Measuring characteristics of blood in vivo, e.g. gas concentration, pH value; Measuring characteristics of body fluids or tissues, e.g. interstitial fluid, cerebral tissue invasive, e.g. introduced into the body by a catheter or needle or using implanted sensors
-
- A—HUMAN NECESSITIES
- A61—MEDICAL OR VETERINARY SCIENCE; HYGIENE
- A61B—DIAGNOSIS; SURGERY; IDENTIFICATION
- A61B5/00—Measuring for diagnostic purposes; Identification of persons
- A61B5/145—Measuring characteristics of blood in vivo, e.g. gas concentration, pH value; Measuring characteristics of body fluids or tissues, e.g. interstitial fluid, cerebral tissue
- A61B5/14539—Measuring characteristics of blood in vivo, e.g. gas concentration, pH value; Measuring characteristics of body fluids or tissues, e.g. interstitial fluid, cerebral tissue for measuring pH
-
- A—HUMAN NECESSITIES
- A61—MEDICAL OR VETERINARY SCIENCE; HYGIENE
- A61M—DEVICES FOR INTRODUCING MEDIA INTO, OR ONTO, THE BODY; DEVICES FOR TRANSDUCING BODY MEDIA OR FOR TAKING MEDIA FROM THE BODY; DEVICES FOR PRODUCING OR ENDING SLEEP OR STUPOR
- A61M25/00—Catheters; Hollow probes
- A61M25/10—Balloon catheters
-
- A—HUMAN NECESSITIES
- A61—MEDICAL OR VETERINARY SCIENCE; HYGIENE
- A61M—DEVICES FOR INTRODUCING MEDIA INTO, OR ONTO, THE BODY; DEVICES FOR TRANSDUCING BODY MEDIA OR FOR TAKING MEDIA FROM THE BODY; DEVICES FOR PRODUCING OR ENDING SLEEP OR STUPOR
- A61M25/00—Catheters; Hollow probes
- A61M25/01—Introducing, guiding, advancing, emplacing or holding catheters
- A61M2025/0177—Introducing, guiding, advancing, emplacing or holding catheters having external means for receiving guide wires, wires or stiffening members, e.g. loops, clamps or lateral tubes
-
- A—HUMAN NECESSITIES
- A61—MEDICAL OR VETERINARY SCIENCE; HYGIENE
- A61M—DEVICES FOR INTRODUCING MEDIA INTO, OR ONTO, THE BODY; DEVICES FOR TRANSDUCING BODY MEDIA OR FOR TAKING MEDIA FROM THE BODY; DEVICES FOR PRODUCING OR ENDING SLEEP OR STUPOR
- A61M25/00—Catheters; Hollow probes
- A61M25/10—Balloon catheters
- A61M2025/1043—Balloon catheters with special features or adapted for special applications
- A61M2025/1061—Balloon catheters with special features or adapted for special applications having separate inflations tubes, e.g. coaxial tubes or tubes otherwise arranged apart from the catheter tube
-
- A—HUMAN NECESSITIES
- A61—MEDICAL OR VETERINARY SCIENCE; HYGIENE
- A61M—DEVICES FOR INTRODUCING MEDIA INTO, OR ONTO, THE BODY; DEVICES FOR TRANSDUCING BODY MEDIA OR FOR TAKING MEDIA FROM THE BODY; DEVICES FOR PRODUCING OR ENDING SLEEP OR STUPOR
- A61M25/00—Catheters; Hollow probes
- A61M25/10—Balloon catheters
- A61M25/1011—Multiple balloon catheters
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- Health & Medical Sciences (AREA)
- Life Sciences & Earth Sciences (AREA)
- Physics & Mathematics (AREA)
- Heart & Thoracic Surgery (AREA)
- Animal Behavior & Ethology (AREA)
- Veterinary Medicine (AREA)
- Biophysics (AREA)
- Engineering & Computer Science (AREA)
- Biomedical Technology (AREA)
- Public Health (AREA)
- General Health & Medical Sciences (AREA)
- Pathology (AREA)
- Surgery (AREA)
- Molecular Biology (AREA)
- Medical Informatics (AREA)
- Optics & Photonics (AREA)
- Child & Adolescent Psychology (AREA)
- Pulmonology (AREA)
- Anesthesiology (AREA)
- Hematology (AREA)
- Measurement Of The Respiration, Hearing Ability, Form, And Blood Characteristics Of Living Organisms (AREA)
Abstract
Ischemia in a hollow internal organ can be detected in its incipient stages by obtaining a CO2 sample from within the organ of interest, measuring the partial pressure of CO2 sample, measuring the bicarbonate concentration of an arterial blood sample, and on the basis of these two measurements calculating the pH of the wall of the organ. The value of the pH is an indicator of the onset of ischemia in the organ. The CO2 sample is obtained by a novel catheter, multiple embodiments of which are disclosed. Also disclosed is a method for determining the vitality or adequacy of oxygenation of the whole body, or a solid internal organ, by the measurement of the pH of venous blood.
Description
HOLLO11 VI~CU~ AND 80LID ORGAN TONOMETRY
BACKGROUND AND SUMMARY OF THE I~V~;N 1~10N
This invention relates to medical diagnostic equipment and methods and is particularly concerned with hollow viscus tonometry, as well as determining the vitality or adequacy of oxygenation of the body or solid internal body organs.
Stress ulceration and intestinal ischemia are two serious problems that plague physicians involved in the management of patients in intensive care units. Intestinal ischemia, in particular, has an insidious onset and may not be detected until days after the intestine has become gangrenous. A delay in the diagnosis of intestinal ischemia may have devastating consequences for a patient. The availability of means for early diagnosis and management of patients with these problems would have immediate applicability in all intensive care units, especially where the procedure can be conveniently conducted with reasonable safety and reliability.
It has been established that a fall in the intramuscosal PH may precede the development of stress ulceration. One aspect of the invention involves the discovery, in the laboratory, that a fall in intrasmucosal pH also occurs within minutes of inducing intestinal ischemia in dogs. The fall in pH in intestinal mucosal, and hence the liklihood of stress ulceration or ischemia, can be reliably calculated from a PC02 (partial pressure of CO2) in luminal fluid and the bicarbonate concentration in arterial blood. The method of calculating the pH in intestinal muscosal tissue, pursuant to principles of the invention, has been validated by direct measurements under a variety of conditions simulating clinical problems. A
correlation coefficient in the order of 0.92 to 0.95 has been obtained in each of ~ixteen dogs. It will be readily recognized that the validity of the procedure is inherently extensible to humans.
To measure the PCO2 in the lumen of the gut it is necessary to obtain a sample of fluid that has been in contact with the wall of the gut for a certain time period, usually at least half an hour. It is difficult to aspirate fluid from the lumen of the gut with any consistency, for any fluid instilled into the lumen passes into distal and proximal regions. It is much easier to obtain samples from the stomach, but samples obtained from the 6tomach frequently contain foreign material that can damage a gas analyzer.
A particular aspect of the invention involves the creation of a new and unique catheter via which the desired ~ample or samples can be obtained without the complications of prior techniques. One embodiment of the new and unique catheter comprises a catheter tube having a walled ~ampling chamber on the tube with the sampling chamber being in communication with the hollow interior of the tube. The wall of the ~ampling chamber comprises a material which is substantially impermeable to liquid yet is highly permeable to gas. One suitable material is polydimethylsiloxane elastomer.
In use the catheter is introduced into a patient to place the sampling chamber at a desired site within the organ of interest. An aspirating liquid fills the interior of the sampling chamber. The sampling chamber is left in place at the - i ' desired sampling site lonq enough to allow the gases present to diffuse through the wall of the sampling chamber into the aspirating liquid. The time ~hould be long enough for the gases to equilibrate. The liquid impermeable nature of the sampling chamber wall material prevents both the aspirating liquid from leaking out of the chamber and also the intrusion of any liquids into the aspirating liquid. After the appropriate amount of placement time has elapsed the aspirating liquid is aspirated along with the gases which have diffused into it. The sample thus obtained is analyzed for gas content, in particular for pC02. In this way the PC02 within the lumen of the gut can be reliably measured with the fluid being free from lumenal debris.
In carrying out the diagnostic method of the invention the PC02 measurement is utilized in conjunction with a measurement of the bicarbonate concentration in an arterial blood sample of the patient for determining the pH of the tract wall.
Depending upon the particular condition of a given patient, the catheter may be left in place and samples may be taken at periodic intervals 80 that pH values may be periodically calculated. The procedure has a high reliability in accurately diagnosing intestinal ischemia in its incipient ~tages and such detection can be useful in treating the patient ~o that the potentially devastating consequences resulting from less timely detection may often be avoided.
The invention has applicability to many hollow internal organs although in the techniques described in detail herein the invention involves diagnosis within the gastrointestinal tract ~ystem. Depending upon the particular site or ~ites of interest within a patient, different types of catheters embodying principles of the invention may be appropriately used. One embodiment involves a catheter as described above. In that embodiment the catheter has a 6ingle sampling chamber and a 6ingle walled tube. Another embodiment contemplates the use of multiple individual single sampling chamber catheters of varying lengths bundled together to form a multiple sampling ~ite catheter. Still another embodiment involves the use of a sump-type nasogastric tube. Yet another embodiment comprises a pliable catheter with a mercury bag at its end which may be used for certain procedures. In use of an embodiment that employs multiple sampling chambers, the pH in intestinal mucosal tissue at one site may be calculated and compared with the calculated pH
values at other sites. This analysis can be a useful diagnostic aid to the atten~ing physician. In the case of an abdominal aortic resection a multiple sampling chamber type catheter may be placed intralumenally in series in the colon at the time of the resection, and it may be used to aid in the early detection of colonic ischemia that occurs insidiously in approximately five percent of the patients subjected to this major operation. A
mul*iple sampling chamber embodiment may also be introduced into the small intestine to monitor the pH and hence perfusion of the gut in patients with low flow states. In critically ill patients who require a nasogastric tube, a single ~ampling chamber embodiment may be incorporated into a conventional nasogastric tube and placed in the patient' 8 stomach.
It is further contemplated that the invention may be practiced in connection with diagnosis of the biliary tract, urinary tract and pancreas for monitoring pH and hence perfusion of the associated organs.
In connection with this invention, a preliminary novelty search developed the following U.S. patents 2,470,665; 3,227,154;
3,548,805; 3,572,315; 3,952,730; and 4,168,703, none of which are deemed pertinent to the claims of the present invention.
The foregoing features and benefits of the invention in its several aspects, along with additional features and benefits, will be ~een in the ensuing description and claims which should be considered in conjunction with the accompanying drawings. The drawings disclose presently preferred embodiments of catheters which embody principles of the invention and are used in the diagnostic aspects of the invention.
BRIEF DESCRIPTION OF THE DRAWINGS
Fig. 1 is a diagrammatic view of a catheter embodying principles of the invention.
Fig. 2 is another embodiment of catheter embodying principles of the invention.
Fig. 3 is yet another embodiment of catheter embodying principles of the invention.
Fig. 4 is still another embodiment of catheter embodying principles of the invention.
DESCRIPTION OF THE PREFERRED EMBODIMENT
Eig. 1 illustrates a first embodiment of catheter 10. The catheter comprises a length of suitable tubing 12 one end 14 of which is closed, and the opposite end of which contains a connector such as a luer-lock 16 or equivalent. A sampling chamber 18 is provided on the tube adjacent the clo~ed end 14.
The illustrated embodiment utilizes a tubular element 18a forming the ~ampling chamber wall. The preferred form of tubular __, element i5 polydemethylsiloxane elastomer. The tubular element has an internal diameter which allows it to be fitted over the tubing 12. The axial and segment6 of the tubular element 18a are secured to the outer wall of tube 12 at the locations indicated by the reference numerals 20 and 22. The attachment may be made in any suitable fashion with adhesive being a suitable attachment medium. Thus, the ends of the tubular element 18a are sealed in a closed relationship to the outer wall of the tube 12 thereby forming the sampling chamber 18 adjacent tube end 14. The wall material of the sampling chamber has a certain elasticity so as to allow the enclosure to assume a ~lightly ballooned or ovoidal shape when filled by aspirating liquid, as will be explained hereinafter.
Before the tubular element 18a i6 inserted over tube 12, ~uitable apertures 24 (shown on an enlarged scale in the drawing) are provided in the wall of tube 12 fiO that after assembly of the tubular element 18a the tube 12 the apertures 24 provide communication between the interior of tube 12 and the interior of the sampling chamber 18.
, The material of the tubular element 18a possesses a characteristic whereby it is poorly permeable to liquid fluid while it is freely permeable to gaseous fluid. This property is important in practice of the invention. The material is also substantially impervious to the contents of the intestinal tract.
In one form of use the catheter is introduced into a patient by being fed into the colon from the anus and positioned intraoperatively. A suitable aspirating fluid, 6uch as a saline ~olution, is introduced via the luer-lock 16, tube 12, and apertures 24 to fill the interior of the sampling chamber. The `
fluid passes through the apertures 24 filling the interior of the sampling chamber such that the 6ampling chamber assumes a balloon-like 6tate.
According to the method of the invention the catheter is placed 6uch that the sampling chamber is at a desired 6ampling site in the internal organ of interest. It is left at this site for a 6ufficient amount of time to allow gases, carbon dioxide being the particular gas of interest, to diffuse across the wall of the chamber into the aspirating liquid. Desirably the length of time should be sufficient to allow the gases to equilibrate.
For example, one half hour may be suitable in certain applications.
The aspirating liquid containing the carbon dioxide gas i8 then withdrawn via the luer end lock 16. The aspirated 6ample thus obtained is 6ubjected to analysis by a conventional gas analyzer to measure the PC02 content of the lumenal fluid. A
measurement of the bicarbonate concentration in the arterial blood of the patient i6 al60 obtained. These two measurements are then used to calculate the pH of the tract. Measurements may be *aken at periodic intervals in the same manner and in this way a record of pH values can be established.
The invention, in one respect, involves recognition of the principle that the partial pressure of gas in the lumen of the gastrointestinal tract is the same or very close to that in the wall of the gastrointestinal tract under a steady state condition and hence, can be used as a measure of the partial pressure of gas, especially C02, in the wall of that part of the gastrointestinal tract. The pH in the wall of the gastrointestinal tract can be calculated from this value if the bicarbonate concentration in arterial blood is also known. With the catheter of the invention the partial pressure of gas within the gastrointestinal tract can be readily measured because it allows a clear fluid sample, free of objectionable particulates and the like, to be obtained.
As explained earlier, a drop in the intramucosal pH has been found to accompany development of intestinal ischemia, and therefore the pH monitoring can be used to monitor for the incipiency of this potentially devastating condition. The earlier warning obtained with the invention offers the po~sibility of earlier treatment to counteract the condition.
Fig. 2 illustrates a further embodiment of the catheter 30. This embodiment is also useful in the colon. The catheter 30 comprises multiple sampling chambers 18 at 6paced locations along the length of the catheter. In this regard the catheter 30 is constructed as a bundle of individual catheters, such as the catheter 10 of Fig. 1, the individual catheters having various lengths. The illustrated example has five ~ampling chambers.
This allows measurements to be taken at five different sites within the organ of interest and is useful for monitoring pH
values not only in time at a particular sampling site but also in respect to concurrent pH measurements at different sites.
Fig. 3 illustrates a further embodiment of catheter 40 which comprises a tube 18a forming the wall of the sampling chamber; however, the tube 42 comprises a conventional double lumen nasogastric 6ump tube with a third lumen for the sampling chamber 18. The air and aspiration ports 44, 46 are of the nasogastric tube and the luer-end lock 16 iB for the third lumen which leads to the ~ampling chamber 18. The catheter 40 is intended for use in the stomach. In this regard the catheter may be inserted into a patient in the same manner as a nasogastric tube, and the aspirating fluid for obtaining the C02 measurement is introduced and aspirated via luer lock 16 in the same manner as that for the previously described catheters.
Fig. 4 illustrates a still further embodiment of catheter 50 which is the same as the embodiment 10 of Fig. 1 except that the end 14 includes a ~ealed mercury bag 52. This catheter is intended for use in the small intestine, and it should be very soft and pliable with the mercury bag allowing peri~talsis to position the tube in the cmall intestine. It should be long enough to reach the terminal ileum, and the same length as a colonscope would be more than adequate.
If desired, any of the embodiments of single catheter may be bundled together as in the manner of Fig. 2 ~o as to provide multiple sampling sites in any catheter construction.
Desirably the volume of the sampling chamber should be relatively small in order to facilitate rapid equilibration of gas yet it must be large enough 60 that a suitable sample of about one milliliter for use in the gas analyzer can be withdrawn via the element 16. For example, around two milliliters is a suitable volume. The tubes such as the tube 12 should be o~f small caliber to insure as cmall a dead space as possible within the patient when in use. Tube 12 should also have as small a fluid volume (say about two-tenths milliliter) cO that a minimum of aspirating liquid need be withdrawn at element 16 in advance of the sample from the chamber 18. The tube wall 12 ~hould also be impermeable to gas. The luer end locks are conventional for connection to a syringe when aspirating fluid is to be introduced or withdrawn. The catheters may also contain rapid opaque marker6 for use in verifying position of the 6ampling chambers in the gut.
Where the catheter is to be left in the lumen of the gut for an extended period of time, for example several days, it should be soft enough to be atlowed to remain in this position without damage to the wall of the gut. To facilitate insertion, for example into the colon, the catheter should be firm enough to allow for proper feeding. In this regard it may be appropriate to use a wire stent during insertion to facilitate positioning of the catheter with the wire stent being removed after proper positioning has been obtained.
While the preferred embodiment has been disclosed in connection with monitoring of the gastrointestinal tract it will be appreciated that its principles are applicable to other hollow internal organs to monitor pH and hence perfusion of those organs. Also while a preferred detailed construction for a catheter, such as described in Fig. 1, has been disclosed, it will be appreciated that other constructions may be developed which are equally as 6uitable. The disclosed construction however is presently preferred for the reason that it is readily fabricated using existing available materials. Other embodiments may include other, but equivalent materials for the sampling chamber wall. They may also differ in the specific fabrication details. As an example, the sampling chamber may be eccentric rather than symmetric about the tube 12.
It has now been further discovered that the pH of venous blood provides an excellent measure of the adequacy of tissue oxygenation of the whole body or organs, including solid organs, comparable to that achieved in hollow viscus organs by the method described herein, as well as that described in my co-pending and commonly assigned applications filed of even date herewith that relate to the use of a tonometric catheter to determine the adequacy of tissue oxygenation via the measurement of the pH of the wall of a hollow, viscus organ. Also, see applicant's co-pending Canadian applications filed of even date herewith entitled "Remote Sensing Tonometric Catheter Apparatus and Method" and "Tonometric Catheter Combination", bearing respective serial numbers 609,067 and 609,065.
For example, the methods of the present invention include the measure of the adequacy of whole-body oxygenation by measuring the pH of a central venous location. This may be done by tonometric sampling, or by the insertion of an electronic sensing means for measuring a fluid or gas property of the venous blood indicative of pH, or pH itself. This would include such means as a pH, PC02 or P02 electronic ~ensing means, ~uch as a probe, placed into a central venous location. A tonometric catheter which includes a sampling chamber may also be employed.
The sampling chamber is preferably constructed ~uch that at least a portion of it is permeable to a gas or fluid property indicative of the pH of the venous blood in which it is placed.
The sampling chamber of a tonometric catheter should also be impermeable to other materials that may interfere with the measurement of the desired gas or fluid property, ~uch as other gases, proteins and the like. In a highly preferred embodiment, an ion-selective membrane is employed. The sampling chamber may optionally include a first non-temperature censing means, and a ~ '.
second temperature sensing means, both in communication with said sampling chamber.
When no sensing means i6 employed, the tonometric catheter preferably employs a walled tonometric lumen, and said sampling chamber is in communication with said lumen. This provides the ability to carry out the aspiration of the 6ampling fluid or medium that is necessary when no remote sensing means is employed.
This method overcomes the problems associated with current methods of measuring whole-body oxygenation. Most methods currently employed to determine whole-body oxygenation include costly, time-consuming and error-prone measurements that typically include whole-body oxygen consumption and oxygen delivery. Another somewhat unreliable method currently employed is the frequently unreliable measurement of oxygen saturation in central venous blood.
The present method employing a central venous pH
measurement overcomes many of the disadvantages of the currently art-employed methods; it has the additional advantage of being extremely reliable and relatively inexpensive.
Thi6 method is also useful in measuring the vitality or adequacy of tissue oxygenation for a specific solid internal organ, such as the brain, liver, kidney, or a limb, by measuring the pH of a venous vessel draining that organ or limb.
The insertion of a pH, P02 or PC02 catheter in the jugular, hepatic or renal veins, or any other regional vein draining a limb or the kidney, can be employed to measure the adequacy of tissue oxygenation in regional solid organs. A pH
catheter and measurement is highly preferred.
Measurement of the adequacy of tissue oxygenation in the brain by the methods of the present invention is of particular interest because of the current lack of any art-disclosed or art-employed non-invasive, or minimally invasive, method of monitoring the adequacy of tissue oxygenation in this organ. The importance and significance of being able to make this measurement reliably and with minimum invasiveness and cost, especially in patient populations such as the elderly, patients having carotid artery surgery or patients with head trauma, with a reliable method cannot be over estimated.
In employing the methods of the present invention, the catheter may be inserted, for example, percutaneously into a jugular vein and advanced to monitor the venous drainage from the brain with great ease and minimal risk. Many patients in need of 6uch measurements already have a catheter in the jugular vein for other non-pH central venous measurements. Other methods currently employed in clinical 6etting used to measure vitality of the brain, or the adequacy of its oxygenation or that of its tissue, include (l) EEG measurements which are cumbersome, difficult to interpret, and subject to electrical interference;
BACKGROUND AND SUMMARY OF THE I~V~;N 1~10N
This invention relates to medical diagnostic equipment and methods and is particularly concerned with hollow viscus tonometry, as well as determining the vitality or adequacy of oxygenation of the body or solid internal body organs.
Stress ulceration and intestinal ischemia are two serious problems that plague physicians involved in the management of patients in intensive care units. Intestinal ischemia, in particular, has an insidious onset and may not be detected until days after the intestine has become gangrenous. A delay in the diagnosis of intestinal ischemia may have devastating consequences for a patient. The availability of means for early diagnosis and management of patients with these problems would have immediate applicability in all intensive care units, especially where the procedure can be conveniently conducted with reasonable safety and reliability.
It has been established that a fall in the intramuscosal PH may precede the development of stress ulceration. One aspect of the invention involves the discovery, in the laboratory, that a fall in intrasmucosal pH also occurs within minutes of inducing intestinal ischemia in dogs. The fall in pH in intestinal mucosal, and hence the liklihood of stress ulceration or ischemia, can be reliably calculated from a PC02 (partial pressure of CO2) in luminal fluid and the bicarbonate concentration in arterial blood. The method of calculating the pH in intestinal muscosal tissue, pursuant to principles of the invention, has been validated by direct measurements under a variety of conditions simulating clinical problems. A
correlation coefficient in the order of 0.92 to 0.95 has been obtained in each of ~ixteen dogs. It will be readily recognized that the validity of the procedure is inherently extensible to humans.
To measure the PCO2 in the lumen of the gut it is necessary to obtain a sample of fluid that has been in contact with the wall of the gut for a certain time period, usually at least half an hour. It is difficult to aspirate fluid from the lumen of the gut with any consistency, for any fluid instilled into the lumen passes into distal and proximal regions. It is much easier to obtain samples from the stomach, but samples obtained from the 6tomach frequently contain foreign material that can damage a gas analyzer.
A particular aspect of the invention involves the creation of a new and unique catheter via which the desired ~ample or samples can be obtained without the complications of prior techniques. One embodiment of the new and unique catheter comprises a catheter tube having a walled ~ampling chamber on the tube with the sampling chamber being in communication with the hollow interior of the tube. The wall of the ~ampling chamber comprises a material which is substantially impermeable to liquid yet is highly permeable to gas. One suitable material is polydimethylsiloxane elastomer.
In use the catheter is introduced into a patient to place the sampling chamber at a desired site within the organ of interest. An aspirating liquid fills the interior of the sampling chamber. The sampling chamber is left in place at the - i ' desired sampling site lonq enough to allow the gases present to diffuse through the wall of the sampling chamber into the aspirating liquid. The time ~hould be long enough for the gases to equilibrate. The liquid impermeable nature of the sampling chamber wall material prevents both the aspirating liquid from leaking out of the chamber and also the intrusion of any liquids into the aspirating liquid. After the appropriate amount of placement time has elapsed the aspirating liquid is aspirated along with the gases which have diffused into it. The sample thus obtained is analyzed for gas content, in particular for pC02. In this way the PC02 within the lumen of the gut can be reliably measured with the fluid being free from lumenal debris.
In carrying out the diagnostic method of the invention the PC02 measurement is utilized in conjunction with a measurement of the bicarbonate concentration in an arterial blood sample of the patient for determining the pH of the tract wall.
Depending upon the particular condition of a given patient, the catheter may be left in place and samples may be taken at periodic intervals 80 that pH values may be periodically calculated. The procedure has a high reliability in accurately diagnosing intestinal ischemia in its incipient ~tages and such detection can be useful in treating the patient ~o that the potentially devastating consequences resulting from less timely detection may often be avoided.
The invention has applicability to many hollow internal organs although in the techniques described in detail herein the invention involves diagnosis within the gastrointestinal tract ~ystem. Depending upon the particular site or ~ites of interest within a patient, different types of catheters embodying principles of the invention may be appropriately used. One embodiment involves a catheter as described above. In that embodiment the catheter has a 6ingle sampling chamber and a 6ingle walled tube. Another embodiment contemplates the use of multiple individual single sampling chamber catheters of varying lengths bundled together to form a multiple sampling ~ite catheter. Still another embodiment involves the use of a sump-type nasogastric tube. Yet another embodiment comprises a pliable catheter with a mercury bag at its end which may be used for certain procedures. In use of an embodiment that employs multiple sampling chambers, the pH in intestinal mucosal tissue at one site may be calculated and compared with the calculated pH
values at other sites. This analysis can be a useful diagnostic aid to the atten~ing physician. In the case of an abdominal aortic resection a multiple sampling chamber type catheter may be placed intralumenally in series in the colon at the time of the resection, and it may be used to aid in the early detection of colonic ischemia that occurs insidiously in approximately five percent of the patients subjected to this major operation. A
mul*iple sampling chamber embodiment may also be introduced into the small intestine to monitor the pH and hence perfusion of the gut in patients with low flow states. In critically ill patients who require a nasogastric tube, a single ~ampling chamber embodiment may be incorporated into a conventional nasogastric tube and placed in the patient' 8 stomach.
It is further contemplated that the invention may be practiced in connection with diagnosis of the biliary tract, urinary tract and pancreas for monitoring pH and hence perfusion of the associated organs.
In connection with this invention, a preliminary novelty search developed the following U.S. patents 2,470,665; 3,227,154;
3,548,805; 3,572,315; 3,952,730; and 4,168,703, none of which are deemed pertinent to the claims of the present invention.
The foregoing features and benefits of the invention in its several aspects, along with additional features and benefits, will be ~een in the ensuing description and claims which should be considered in conjunction with the accompanying drawings. The drawings disclose presently preferred embodiments of catheters which embody principles of the invention and are used in the diagnostic aspects of the invention.
BRIEF DESCRIPTION OF THE DRAWINGS
Fig. 1 is a diagrammatic view of a catheter embodying principles of the invention.
Fig. 2 is another embodiment of catheter embodying principles of the invention.
Fig. 3 is yet another embodiment of catheter embodying principles of the invention.
Fig. 4 is still another embodiment of catheter embodying principles of the invention.
DESCRIPTION OF THE PREFERRED EMBODIMENT
Eig. 1 illustrates a first embodiment of catheter 10. The catheter comprises a length of suitable tubing 12 one end 14 of which is closed, and the opposite end of which contains a connector such as a luer-lock 16 or equivalent. A sampling chamber 18 is provided on the tube adjacent the clo~ed end 14.
The illustrated embodiment utilizes a tubular element 18a forming the ~ampling chamber wall. The preferred form of tubular __, element i5 polydemethylsiloxane elastomer. The tubular element has an internal diameter which allows it to be fitted over the tubing 12. The axial and segment6 of the tubular element 18a are secured to the outer wall of tube 12 at the locations indicated by the reference numerals 20 and 22. The attachment may be made in any suitable fashion with adhesive being a suitable attachment medium. Thus, the ends of the tubular element 18a are sealed in a closed relationship to the outer wall of the tube 12 thereby forming the sampling chamber 18 adjacent tube end 14. The wall material of the sampling chamber has a certain elasticity so as to allow the enclosure to assume a ~lightly ballooned or ovoidal shape when filled by aspirating liquid, as will be explained hereinafter.
Before the tubular element 18a i6 inserted over tube 12, ~uitable apertures 24 (shown on an enlarged scale in the drawing) are provided in the wall of tube 12 fiO that after assembly of the tubular element 18a the tube 12 the apertures 24 provide communication between the interior of tube 12 and the interior of the sampling chamber 18.
, The material of the tubular element 18a possesses a characteristic whereby it is poorly permeable to liquid fluid while it is freely permeable to gaseous fluid. This property is important in practice of the invention. The material is also substantially impervious to the contents of the intestinal tract.
In one form of use the catheter is introduced into a patient by being fed into the colon from the anus and positioned intraoperatively. A suitable aspirating fluid, 6uch as a saline ~olution, is introduced via the luer-lock 16, tube 12, and apertures 24 to fill the interior of the sampling chamber. The `
fluid passes through the apertures 24 filling the interior of the sampling chamber such that the 6ampling chamber assumes a balloon-like 6tate.
According to the method of the invention the catheter is placed 6uch that the sampling chamber is at a desired 6ampling site in the internal organ of interest. It is left at this site for a 6ufficient amount of time to allow gases, carbon dioxide being the particular gas of interest, to diffuse across the wall of the chamber into the aspirating liquid. Desirably the length of time should be sufficient to allow the gases to equilibrate.
For example, one half hour may be suitable in certain applications.
The aspirating liquid containing the carbon dioxide gas i8 then withdrawn via the luer end lock 16. The aspirated 6ample thus obtained is 6ubjected to analysis by a conventional gas analyzer to measure the PC02 content of the lumenal fluid. A
measurement of the bicarbonate concentration in the arterial blood of the patient i6 al60 obtained. These two measurements are then used to calculate the pH of the tract. Measurements may be *aken at periodic intervals in the same manner and in this way a record of pH values can be established.
The invention, in one respect, involves recognition of the principle that the partial pressure of gas in the lumen of the gastrointestinal tract is the same or very close to that in the wall of the gastrointestinal tract under a steady state condition and hence, can be used as a measure of the partial pressure of gas, especially C02, in the wall of that part of the gastrointestinal tract. The pH in the wall of the gastrointestinal tract can be calculated from this value if the bicarbonate concentration in arterial blood is also known. With the catheter of the invention the partial pressure of gas within the gastrointestinal tract can be readily measured because it allows a clear fluid sample, free of objectionable particulates and the like, to be obtained.
As explained earlier, a drop in the intramucosal pH has been found to accompany development of intestinal ischemia, and therefore the pH monitoring can be used to monitor for the incipiency of this potentially devastating condition. The earlier warning obtained with the invention offers the po~sibility of earlier treatment to counteract the condition.
Fig. 2 illustrates a further embodiment of the catheter 30. This embodiment is also useful in the colon. The catheter 30 comprises multiple sampling chambers 18 at 6paced locations along the length of the catheter. In this regard the catheter 30 is constructed as a bundle of individual catheters, such as the catheter 10 of Fig. 1, the individual catheters having various lengths. The illustrated example has five ~ampling chambers.
This allows measurements to be taken at five different sites within the organ of interest and is useful for monitoring pH
values not only in time at a particular sampling site but also in respect to concurrent pH measurements at different sites.
Fig. 3 illustrates a further embodiment of catheter 40 which comprises a tube 18a forming the wall of the sampling chamber; however, the tube 42 comprises a conventional double lumen nasogastric 6ump tube with a third lumen for the sampling chamber 18. The air and aspiration ports 44, 46 are of the nasogastric tube and the luer-end lock 16 iB for the third lumen which leads to the ~ampling chamber 18. The catheter 40 is intended for use in the stomach. In this regard the catheter may be inserted into a patient in the same manner as a nasogastric tube, and the aspirating fluid for obtaining the C02 measurement is introduced and aspirated via luer lock 16 in the same manner as that for the previously described catheters.
Fig. 4 illustrates a still further embodiment of catheter 50 which is the same as the embodiment 10 of Fig. 1 except that the end 14 includes a ~ealed mercury bag 52. This catheter is intended for use in the small intestine, and it should be very soft and pliable with the mercury bag allowing peri~talsis to position the tube in the cmall intestine. It should be long enough to reach the terminal ileum, and the same length as a colonscope would be more than adequate.
If desired, any of the embodiments of single catheter may be bundled together as in the manner of Fig. 2 ~o as to provide multiple sampling sites in any catheter construction.
Desirably the volume of the sampling chamber should be relatively small in order to facilitate rapid equilibration of gas yet it must be large enough 60 that a suitable sample of about one milliliter for use in the gas analyzer can be withdrawn via the element 16. For example, around two milliliters is a suitable volume. The tubes such as the tube 12 should be o~f small caliber to insure as cmall a dead space as possible within the patient when in use. Tube 12 should also have as small a fluid volume (say about two-tenths milliliter) cO that a minimum of aspirating liquid need be withdrawn at element 16 in advance of the sample from the chamber 18. The tube wall 12 ~hould also be impermeable to gas. The luer end locks are conventional for connection to a syringe when aspirating fluid is to be introduced or withdrawn. The catheters may also contain rapid opaque marker6 for use in verifying position of the 6ampling chambers in the gut.
Where the catheter is to be left in the lumen of the gut for an extended period of time, for example several days, it should be soft enough to be atlowed to remain in this position without damage to the wall of the gut. To facilitate insertion, for example into the colon, the catheter should be firm enough to allow for proper feeding. In this regard it may be appropriate to use a wire stent during insertion to facilitate positioning of the catheter with the wire stent being removed after proper positioning has been obtained.
While the preferred embodiment has been disclosed in connection with monitoring of the gastrointestinal tract it will be appreciated that its principles are applicable to other hollow internal organs to monitor pH and hence perfusion of those organs. Also while a preferred detailed construction for a catheter, such as described in Fig. 1, has been disclosed, it will be appreciated that other constructions may be developed which are equally as 6uitable. The disclosed construction however is presently preferred for the reason that it is readily fabricated using existing available materials. Other embodiments may include other, but equivalent materials for the sampling chamber wall. They may also differ in the specific fabrication details. As an example, the sampling chamber may be eccentric rather than symmetric about the tube 12.
It has now been further discovered that the pH of venous blood provides an excellent measure of the adequacy of tissue oxygenation of the whole body or organs, including solid organs, comparable to that achieved in hollow viscus organs by the method described herein, as well as that described in my co-pending and commonly assigned applications filed of even date herewith that relate to the use of a tonometric catheter to determine the adequacy of tissue oxygenation via the measurement of the pH of the wall of a hollow, viscus organ. Also, see applicant's co-pending Canadian applications filed of even date herewith entitled "Remote Sensing Tonometric Catheter Apparatus and Method" and "Tonometric Catheter Combination", bearing respective serial numbers 609,067 and 609,065.
For example, the methods of the present invention include the measure of the adequacy of whole-body oxygenation by measuring the pH of a central venous location. This may be done by tonometric sampling, or by the insertion of an electronic sensing means for measuring a fluid or gas property of the venous blood indicative of pH, or pH itself. This would include such means as a pH, PC02 or P02 electronic ~ensing means, ~uch as a probe, placed into a central venous location. A tonometric catheter which includes a sampling chamber may also be employed.
The sampling chamber is preferably constructed ~uch that at least a portion of it is permeable to a gas or fluid property indicative of the pH of the venous blood in which it is placed.
The sampling chamber of a tonometric catheter should also be impermeable to other materials that may interfere with the measurement of the desired gas or fluid property, ~uch as other gases, proteins and the like. In a highly preferred embodiment, an ion-selective membrane is employed. The sampling chamber may optionally include a first non-temperature censing means, and a ~ '.
second temperature sensing means, both in communication with said sampling chamber.
When no sensing means i6 employed, the tonometric catheter preferably employs a walled tonometric lumen, and said sampling chamber is in communication with said lumen. This provides the ability to carry out the aspiration of the 6ampling fluid or medium that is necessary when no remote sensing means is employed.
This method overcomes the problems associated with current methods of measuring whole-body oxygenation. Most methods currently employed to determine whole-body oxygenation include costly, time-consuming and error-prone measurements that typically include whole-body oxygen consumption and oxygen delivery. Another somewhat unreliable method currently employed is the frequently unreliable measurement of oxygen saturation in central venous blood.
The present method employing a central venous pH
measurement overcomes many of the disadvantages of the currently art-employed methods; it has the additional advantage of being extremely reliable and relatively inexpensive.
Thi6 method is also useful in measuring the vitality or adequacy of tissue oxygenation for a specific solid internal organ, such as the brain, liver, kidney, or a limb, by measuring the pH of a venous vessel draining that organ or limb.
The insertion of a pH, P02 or PC02 catheter in the jugular, hepatic or renal veins, or any other regional vein draining a limb or the kidney, can be employed to measure the adequacy of tissue oxygenation in regional solid organs. A pH
catheter and measurement is highly preferred.
Measurement of the adequacy of tissue oxygenation in the brain by the methods of the present invention is of particular interest because of the current lack of any art-disclosed or art-employed non-invasive, or minimally invasive, method of monitoring the adequacy of tissue oxygenation in this organ. The importance and significance of being able to make this measurement reliably and with minimum invasiveness and cost, especially in patient populations such as the elderly, patients having carotid artery surgery or patients with head trauma, with a reliable method cannot be over estimated.
In employing the methods of the present invention, the catheter may be inserted, for example, percutaneously into a jugular vein and advanced to monitor the venous drainage from the brain with great ease and minimal risk. Many patients in need of 6uch measurements already have a catheter in the jugular vein for other non-pH central venous measurements. Other methods currently employed in clinical 6etting used to measure vitality of the brain, or the adequacy of its oxygenation or that of its tissue, include (l) EEG measurements which are cumbersome, difficult to interpret, and subject to electrical interference;
(2) near-infrared-spectroscopy, which is costly, cumbersome and currently only applicable to neonates or premature babies with uncalcified sku116: (3) the Richmond-bolt, which requires that a hole be drilled into the ~kull and only measures pressure, thus providing no information about the adequacy of tissue oxygenation; and (4) NMR or nuclear magnetic resonance, which is still somewhat experimental, extremely costly and difficult to interpret. None of the above methods provide the precise information required to determine whether tissue oxygenation of the brain is adequate.
Measurement of the adequacy of tissue oxygenation in the liver is also of particular interest because of the importance of the liver in metabolizing drugs; the disturbance in drug metabolism precipitated by disturbances in hepatic perfusion; and because of the increasing frequency of liver transplants. For example, the measurements of pH in hepatic venous blood according to the instant invention provides a precise, reliable and relatively inexpensive method of monitoring the adequacy of hepatic oxygenation in all patents who are critically ill, including those having liver transplants. Other techniques that attempt to measure the vitality of adequacy of oxygenation of the liver include open biopsy of the liver. Some work has been attempted which involves intrahepatic tissue pH probes. The problem with tissue pH probes is the artefact created by the invasive insertion of the probe, and the difficulty of probe placement and of maintaining its position in the liver tissue as the liver moves with respiration. Measurements of hepatic venous pH according to the methods of the present invention do not have these shortcomings.
Accordingly, the present invention relates to a method for determining the vitality or adequacy of whole-body oxygenation of a human or other mammal in vivo comprising:
(i) providing a means for measuring a fluid or gas property indicative of pH, such as an arterial pH
catheter, suitable for insertion into a central venous location;
(ii) inserting said means such as a pH catheter into a central venous location;
(iii) measuring the pH of the blood at said central venous location either directly or from the selected fluid or gas property; and (iv) determining the vitality or adequacy of whole-body oxygenation of said human or mammal from said pH
measurement.
This method may also be employed to determine the vitality or adequacy of oxygenation of a solid internal organ. It therefore comprises the steps of:
(i) providing a means for measuring a fluid or gas property indicative ~f pH, such a6 an arterial pH
catheter, suitable for insertion into a venous vessel at least partially draining an organ of interest;
(ii) inserting said means or catheter into said venous vessel draining said organ;
(iii) measuring the pH of the blood in said venous vessel, either directly or from the selected fluid or gas property; and (iv) determining the vitality or adequacy of oxygenation of said organ from said pH measurement.
While a preferred embodiment of the invention has been disclosed, it will be appreciated that principles of the invention, as set forth in the following claims, are applicable to other embodiments.
Measurement of the adequacy of tissue oxygenation in the liver is also of particular interest because of the importance of the liver in metabolizing drugs; the disturbance in drug metabolism precipitated by disturbances in hepatic perfusion; and because of the increasing frequency of liver transplants. For example, the measurements of pH in hepatic venous blood according to the instant invention provides a precise, reliable and relatively inexpensive method of monitoring the adequacy of hepatic oxygenation in all patents who are critically ill, including those having liver transplants. Other techniques that attempt to measure the vitality of adequacy of oxygenation of the liver include open biopsy of the liver. Some work has been attempted which involves intrahepatic tissue pH probes. The problem with tissue pH probes is the artefact created by the invasive insertion of the probe, and the difficulty of probe placement and of maintaining its position in the liver tissue as the liver moves with respiration. Measurements of hepatic venous pH according to the methods of the present invention do not have these shortcomings.
Accordingly, the present invention relates to a method for determining the vitality or adequacy of whole-body oxygenation of a human or other mammal in vivo comprising:
(i) providing a means for measuring a fluid or gas property indicative of pH, such as an arterial pH
catheter, suitable for insertion into a central venous location;
(ii) inserting said means such as a pH catheter into a central venous location;
(iii) measuring the pH of the blood at said central venous location either directly or from the selected fluid or gas property; and (iv) determining the vitality or adequacy of whole-body oxygenation of said human or mammal from said pH
measurement.
This method may also be employed to determine the vitality or adequacy of oxygenation of a solid internal organ. It therefore comprises the steps of:
(i) providing a means for measuring a fluid or gas property indicative ~f pH, such a6 an arterial pH
catheter, suitable for insertion into a venous vessel at least partially draining an organ of interest;
(ii) inserting said means or catheter into said venous vessel draining said organ;
(iii) measuring the pH of the blood in said venous vessel, either directly or from the selected fluid or gas property; and (iv) determining the vitality or adequacy of oxygenation of said organ from said pH measurement.
While a preferred embodiment of the invention has been disclosed, it will be appreciated that principles of the invention, as set forth in the following claims, are applicable to other embodiments.
Claims (16)
1. A method for determining the vitality or adequacy of oxygenation of a human or other mammal in vivo comprising:
(i) providing a means for determining a fluid or gas property indicative of pH suitable for insertion into a central venous location;
(ii) inserting said means into a central venous location;
(iii) measuring said fluid or liquid property;
(iv) determining the pH of the blood at said central venous location from said fluid or gas property; and (v) determining the vitality or adequacy of whole-body oxygenation of said human or mammal from said pH
measurement.
(i) providing a means for determining a fluid or gas property indicative of pH suitable for insertion into a central venous location;
(ii) inserting said means into a central venous location;
(iii) measuring said fluid or liquid property;
(iv) determining the pH of the blood at said central venous location from said fluid or gas property; and (v) determining the vitality or adequacy of whole-body oxygenation of said human or mammal from said pH
measurement.
2. A method for determining the vitality or adequacy of oxygenation of a human or other mammal in vivo comprising (i) providing a pH catheter suitable for insertion into a central venous location;
(ii) inserting said catheter into a central venous location;
(iii) measuring the pH of the blood at said central venous location; and (iv) determining the vitality or adequacy of whole-body oxygenation of said human or mammal from said pH
measurement.
(ii) inserting said catheter into a central venous location;
(iii) measuring the pH of the blood at said central venous location; and (iv) determining the vitality or adequacy of whole-body oxygenation of said human or mammal from said pH
measurement.
3. A method for determining the vitality or adequacy of oxygenation of a solid internal organ comprising:
(i) providing a means for determining a fluid or gas property indicative of pH suitable for insertion into a venous vessel at least partially draining a solid internal organ of interest;
(ii) inserting said means into said venous vessel;
(iii) measuring said fluid or gas property;
(iv) determining the pH of the blood in said venous vessel from said fluid or gas property; and (v) determining the vitality or adequacy of oxygenation of said organ from said pH measurement.
(i) providing a means for determining a fluid or gas property indicative of pH suitable for insertion into a venous vessel at least partially draining a solid internal organ of interest;
(ii) inserting said means into said venous vessel;
(iii) measuring said fluid or gas property;
(iv) determining the pH of the blood in said venous vessel from said fluid or gas property; and (v) determining the vitality or adequacy of oxygenation of said organ from said pH measurement.
4. A method according to Claim 3 wherein said organ is the liver.
5. A method according to Claim 4 wherein said venous vessel is the hepatic vein.
6. A method according to Claim 3 wherein said organ is the kidney.
7. A method according to Claim 6 wherein said venous vessel is a renal vein.
8. A method according to Claim 3 wherein said organ is the brain.
9. A method according to Claim 8 wherein said venous vessel is the jugular vein.
10. A method as set forth in claim 3 in which the material of the wall of said walled sampling chamber is a polydimethylsiloxane elastomer.
11. A method according to Claim 10 wherein said organ is the liver.
12. A method according to Claim 18 wherein said venous vessel is the hepatic vein.
13. A method according to Claim 10 wherein said organ is the kidney.
14. A method according to Claim 13 wherein said venous vessel is a renal vein.
15. A method according to Claim 10 wherein said organ is the brain.
16. A method according to Claim 15 wherein said venous vessel is the jugular vein.
Applications Claiming Priority (2)
| Application Number | Priority Date | Filing Date | Title |
|---|---|---|---|
| US23728888A | 1988-08-26 | 1988-08-26 | |
| US237,288 | 1988-08-26 |
Publications (1)
| Publication Number | Publication Date |
|---|---|
| CA1335709C true CA1335709C (en) | 1995-05-30 |
Family
ID=22893112
Family Applications (1)
| Application Number | Title | Priority Date | Filing Date |
|---|---|---|---|
| CA000609066A Expired - Fee Related CA1335709C (en) | 1988-08-26 | 1989-08-23 | Hollow viscus and solid organ tonometry |
Country Status (3)
| Country | Link |
|---|---|
| AU (1) | AU4204689A (en) |
| CA (1) | CA1335709C (en) |
| WO (1) | WO1990001896A1 (en) |
Families Citing this family (1)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| US7291502B2 (en) | 2006-03-15 | 2007-11-06 | Franco Wayne P | Method for performing a non-invasive blood gas test |
Family Cites Families (7)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| US3658053A (en) * | 1969-08-28 | 1972-04-25 | Scient Research Instr Corp | Catheter for use in detecting dissolved gas in fluids such as blood |
| DE2734247C2 (en) * | 1977-07-29 | 1984-07-19 | Fresenius AG, 6380 Bad Homburg | Device for continuous chemical analysis in the living body |
| US4221567A (en) * | 1977-12-23 | 1980-09-09 | Intermountain Health Care | Sampling and determination of diffusible chemical substances |
| US4516580A (en) * | 1981-12-28 | 1985-05-14 | Polanyi Michael L | Continuous blood gas monitoring |
| US4643192A (en) * | 1982-03-22 | 1987-02-17 | Regents Of The University Of Michigan | Hollow viscus tonometry |
| US4671287A (en) * | 1983-12-29 | 1987-06-09 | Fiddian Green Richard G | Apparatus and method for sustaining vitality of organs of the gastrointestinal tract |
| US4576590A (en) * | 1983-12-29 | 1986-03-18 | Fiddian Green Richard G | Intraluminal membrane oxygenator method for a tubular organ of the gastrointestinal tract |
-
1989
- 1989-08-23 CA CA000609066A patent/CA1335709C/en not_active Expired - Fee Related
- 1989-08-24 AU AU42046/89A patent/AU4204689A/en not_active Abandoned
- 1989-08-24 WO PCT/US1989/003664 patent/WO1990001896A1/en unknown
Also Published As
| Publication number | Publication date |
|---|---|
| WO1990001896A1 (en) | 1990-03-08 |
| AU4204689A (en) | 1990-03-23 |
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