CA1335708C - Tonometric catheter combination - Google Patents
Tonometric catheter combinationInfo
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- CA1335708C CA1335708C CA000609065A CA609065A CA1335708C CA 1335708 C CA1335708 C CA 1335708C CA 000609065 A CA000609065 A CA 000609065A CA 609065 A CA609065 A CA 609065A CA 1335708 C CA1335708 C CA 1335708C
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- sampling chamber
- catheter
- tube
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- Measuring And Recording Apparatus For Diagnosis (AREA)
Abstract
A tonometric catheter combination apparatus (20a) for measuring a fluid of interest indicative of the condition of an internal organ of a human or other mammal in vivo. The tonometric catheter combination (20a) provides for early detection of intestinal ischemia and/or stress ulceration and may also operate as a sump for draining fluid from an organ or for introducing fluid to the organ. The apparatus includes a tonometric catheter tube (68) which has a walled sampling chamber (40) thereon, which optionally may be in communication with the interior of the catheter tube. The wall (36) of the sampling chamber (40) is made of a material which is freely permeable to a gas or fluid property of interest but poorly permeable to other fluids. At least a second walled tube (66) is included for delivering fluids to or draining fluids from the internal organ.
Description
TONOM~-.KIC CA~n~ COMBINATION
Back~round and 8ummary of the Invention This invention relates to medical diagnostic equipment and methods and is particularly concerned with hollow viscus tonometry and remote electronic and optical sensing.
The prior art (see U.S. Patent No. 4,643,192) has recognized that intestinal ischemia, and to a lesser degree, stress ulceration, are two problems that plague physicians involved in th~ 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 completely and irreversibly compromised. 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 ~hat a fall in the intramucosal pH may precede the development of intestinal ischemia and stress ulceration. As I reported in my prior U.S. Patent No. 4,643,192, entitled "Hollow Viscus Tonometry" a fall in intramucosal pH also occurs within minutes of inducing intestinal ischemia in dogs. The fall in pH
in intestinal mucosa, and hence the likelihood of ischemia or stress ulceration, can be reliably calculated from a PC02 (partial pressure of CO2), or other indicia of pH, in luminal fluid and the bicarbonate concentration in arterial blood. The i method of calculating the pH in intestinal mucosal tissue, pursuant to principles of my prior patent, has been validated by directed measurements under a variety of conditions ~imulating clinical problems. A correlation coefficient in the order of 0.92 to 0.95 has been obtained in each of 16 dogs. The validity of the procedure is inherently extensible to humans, and indeed may also be useful in assessing the vitality of other hollow organs and tissue. See R.G. Fiddian-Green et al. "Splanchnic Ischemia and Multiple Organ Failure".
To measure the PC02 in the lumen of the gut it has heretofore been necessary to obtain and remove a ~ample 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 has now been observed that it i6 ~omewhat difficult to manually aspirate the ~ampling fluid or medium from a tonometric catheter located in the gut or other internal focus with any consistency. It is much easier to obtain such ~amples from the ~tomach, but samples obtained from the ~tomach frequently contain foreign material that can damage a gas analyzer.
As taught in my prior patent, the desired 6ample or ~amples can be obtained from the gut using a catheter tube (called a tonometric catheter) having a walled sampling chamber on the tube with the ~ampling chamber being in ~ample-specific communication with the hollow interior of the tube. The wall of the sampling chamber comprises a material which iB ~ubstantially impermeable to liquid yet is highly permeable to gas. One suitable material i5 polydimethylsiloxane elastomer.
In use the catheter is introduced into a patient to place the ~ampling chamber at a desired ~ite within the gut. An -~ ~ J
aspirating liquid or medium i8 employed to fill the interior of the gampling chamber. The sampling chamber i8 left in place at the desired sampling site long enough to allow the gases present to diffuse through the wall of the 6ampling chamber into the aspirating liguid. The time should be long enough for the gases t~ eguilibrate. The liguid impermeable nature of the sample 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 or desired amount of placement time has elapsed the aspirating liquid is aspirated along with the gases which have diffused into it. The ~ample 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 taught in my prior patent the PC02 measurement i8 utilized in conjunction with a measurement of the bicarbonate ion concentration (HC03 ) in an arterial blood ~ample 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 6amples may be taken at periodic intervals 60 that pH values may be periodically calculated. The procedure has a high reliability in accurately determining the adequacy of organ tissue oxygenation, and diagnosing intestinal ischemia in its incipient ~tages. Such determination or detection can be useful in treating the patient ~o that the potentially devastating consequences resulting from less timely detection may often be avoided.
While the sampling techniques taught in my prior patent have provided highly accurate and reliable results, it has now been observed that there are instances (in the care of the critically ill in intensive care units, for example) in which remote sensing of the organ or organ-wall condition and automatic calculation of the organ or organ-wall pH would be advantageous and easier to effectuate. This method would thus partially or totally eliminate the need for the Qomewhat cumbersome aspiration of the sampling fluid or medium which fills the sampling chamber;
it may also eliminate the need for the ~ampling chamber to be in Qampling-medium communication with any other part of the device.
There is also a need to extend the benefits of tonometric sampling and eensing to other internal hollow viscous organs. To thig end, there is a need for new and different tonometric devices 6pecifically adapted to allow my 6ensing and sampling techniques to be performed with ease in a clinical environment, and in combination with other procedures.
The importance and significance of determining the pH
of the wall of a given hollow visc~us organ has been recently 7~ dramatically magnified as a result of the recent r~cogn~tion that the pH of the wall of a given organ can be employed to accurately evaluate the vitality and/or ~tability of that organ as well as others; this is in contrast to merely determining whether such an organ is experiencing an ischemic event. Further, certain organs can be ~elected for monitoring, either alone or in combination, and evaluation of this organ or these organs can aid in predicting the overall condition of the patient, or the onset of a multitude of pathologies, including predicting or identifying ~uch events a6 multiple organ failure. Such a methodology can be employed to greatly enhance and ~upplement the monitoring of the critically ill, for example.
In one aspect, the pre~ent invention provides a new apparatus and method for remotely sensing organ condition and conveying an electromagnetic signal, e.g. an electrical current or optical 6ignal, to an electronic or optical apparatus located outside the organ under investigation. In one embodiment, a chemically sensitive electronic transducer (or plurality of transducers), 6uch a6 a field effect-tran6istor, i~ attached to a tonometric catheter for introduction into the organ along with the tonometric catheter. The first electronic sensor, preferably non-temperature, generates and conveys an electromagnetic signal indicative of 60me desired aspect of organ condition, e.g., indicative of the pC02, pH and/or P02 level of the organ or organ-wall. For example, in one preferred embodiment, mean ambient pC02, pH and/or P02 of lumenal fluid or the like is ~easured or monitored via wire or other suitable electromagnetic energy conveying ~eans to an electronic circuit which interprets the electromagnetic signal and produces a report of the organ condition.' The electronic circuit may includé an ~nput for receiving a ~eparately determined signal indicative of the blood pH of the patient. Using this pC02, pH and/or P02 measurement along with blood (preferably arterial) pH data, the electronic circuit determines the pH of the organ wall under test and thereby provides information for determining the organ'~ current condition or perhaps predicting the organ's future condition.
The electronic circuit may be 6uitably constructed from analog components, digital components or both.
In another embodiment, a pH, PC02 or P02 6ensitive colorimetric 6ubstance is injected into an area adjacent to the organ, e.g., into the sampling chamber of the tonometric catheter, and an optical 6ensor is employed to detect color change in order to determine the pH of the wall of that organ.
The optical sensor can either be disposed in or on the tonometric catheter for introduction into the area adjacent the organ or it may be disposed outside the organ with fiber optic cable optically coupling the 6ensor to the tonometric catheter 6ite at which the pH sensitive substance has been injected.
In another aspect the present invention provides a variety of new and different tonometric catheter devices for sensing and/or sampling a fluid or gas property (such as pH, Po2~
pC02, and the like) which is indicative of the condition of an internal organ, in conjunction or combination with a walled catheter tube adapted for delivery or draining fluids, such as nasogastric tubes, urinary catheters, ureteric catheters, intestinal feeding tubes, wound or abdominal drains (suction or regular) and biliary tubes, catheters and stents, with or without remote sensing means for pH, PC02 and/or Po2-In still another aspect or embodiment, the deviceemploys two separate walled catheter tubes, one tonometric catheter tube for the measurement of a fluid or gas property, that is in communication with the sampling chamber; and a second walled catheter tube adapted for delivering or draining fluids.
In yet another aspect or embodiment, the device employs a walled sampling chamber in communication with a sensing means, and a 6econd walled catheter tube adapted for delivering or draining fluids.
Optionally, when a non-temperature sensing-means is employed, a second sensing-means may be employed as well.
For a more complete understanding of the invention, its objects and advantages, reference may be had to the following specification and to the accompanying drawings. Also, see applicant's co-pending Canadian applications filed of even date herewith entitled "Remote Sensing Tonometric Catheter Apparatus and Method~ and "Hollow Viscus and Solid Organ Tonometry", bearing respective serial numbers 609,067 and 609,066.
Brief Doscription of the Dr~winqs Figure 1 is a plan view of a first embodiment of the tonometric catheter;
Figure 2A is a partial cross-~ectional view of the tonometric catheter illustrating a first means for attachment of an electronic field effect transistor sensor;
Figure 2B is a partial cross-sectional view of the tonometric catheter illustrating a ~econd means of attachment of the field effect transistor sensor;
Figure 3 illustrates the method of use of the tonometric catheter in measurement of the pH of the colon and also of the ~tomach, the specific embodiment illustrated for colonic measurement being that of Figure 5 and the specific tonometric catheter for ~astric measurement being that of Figure 4;
Figure 4 i6 another embodiment of the tonometric catheter with nasogastric tube;
Figure 4A i8 a cros6-~ectional view of the tonometric catheter of Figure 4 taken 6ubstantially along the line 4A-4A of Figure 4;
Figure 4B i6 a cros6-~ectional view of the tonometric catheter of Figure 4 taken substantially along the line 4B-4B of Figure 4;
Figure 5 i6 yet another embodiment of the tonometric catheter having multiple sensing/sampling portions;
Figure 5A is a cross-sectional view of the tonometric catheter of Fig~re 5, taken sub6tantially along the line 5A-5A of Figure 5;
Figure 6 is a detailed view illu6trating the tonometric catheter of Figure 4 in u6e within the stomach;
Figure 7 i8 a detailed view illu~trating the tonometric catheter of Figure 5 in use within the colon:
Figure 8 is a similar view illustrating the tonometric catheter of Figure 1 in use within the colon;
Figure 9 i6 an electrical schematic diagram illu6trating one embodiment of electronic circuit in accordance with the invention;
Figure 10 is an électrical schematic diagram illustrating another embodiment of the optical mea6urement of pH
in accordance with the invention;
Figure 11 i6 another embodiment of a tonometric catheter with a urinary catheter;
Figure llA i6 a cro66-sectional view of the tonometric catheter/urinary catheter of Figure 11, taken substantially along the line llA-llA of Figure 11.
n~cr~ption of the Proferred ~bodi~ents ~ igure 1 illustrates a fir6t embodiment of tonometric catheter 20. The tonometric catheter comprises a length of cuitable tubing 22, one end 32 of which i6 closed, and the opposite end of which has a connector ~uch as a luer-lock 24.
~uer-lock 24 is adapted to receive a complementary fitting 26, which in turn couples through a second length of tubing 28 to a three-way stopcock 30. Three-way 6topcock 30 may be used to 6electively connect tubing 28 to various ~ources of irrigation or a6piration.
Adjacent the closed end 32, tubing 22 i~ perforated as at 34. A balloon-like tonometric catheter membrane 36 is fitted over the closed end 60 that the perforations 34 are enclosed, as illu~trated. The tonometric catheter ~embrane 36 has an internal 61eeve diameter at 38 which forms a tight fit with tubing 22.
The preferred form of tonometric catheter ~embrane is polydimethylsiloxane elastomer. The membrane may be 6ealed to the tubing 22 with appropriate adhesive ~o that the tonometric catheter membrane i6 6ealed in a closed relationship to the outer wall of tubing 22, thereby forming ~ campling chamber 40 adjacent closed end 32. The tonometric catheter ~embrane has a certain elasticity to allow the membrane to expand when filled with an aspirating liquid in order to contact the wall of the organ under examination, as will be explained below.
The membrane 36 i8 preferably constructed such that at least a portion of it is selectively permeable to the gas or fluid property of interest. In a preferred embodiment, it is selectively permeable to hydrogen, oxygen, or H~, ~o that pH, PC02 and/or P02 can be measured. It i6 also preferably impermeable to other materials that would interfere with the desired measurements, such as other gases, proteins, and the like. In a highly preferred embodiment, an ion-~elective membrane is employed.
Bonded to either the inner wall or the outer wall of tubing 22 are one or more sensors 42 for detecting a property indicative of pH and/or temperature. Two such 6ensors are illustrated in Figure 1, bonded to the outside wall of tubing 22 with suitable adhesive. Figures 2A and 2B illu~trate two alternate means of sensor attachment, Figure 2A illustrating the sensor attached to the inner wall of tubinq 22 and ~igure 2B
illustratin~ the sen~or attached to the outer wall of tubing 22.
In a preferred embodiment, at least a portion of the tubing, but not all of it, i~ made of a C02 impermeable material, such a8 polyester elastomers derived from the reaction of dimethylterephtalate 1,4-butanediol ~nd -hydro- ~ -hydroxypoly (oxytetramethylene). In a highly preferred embodiment, this is a material such as Hytril, sold by DuPont.
For purposes of 6en~ing temperature, thermistor devices are presently preferred. For ~ens~ng properties indicative of pH
chemically responsive field effect transistors or ~Chemfets" may be employed. In this regard, Chemfet 6ensors 44 have been ~llustrated in Figures 2A and 2B. Chemfet sensor 44 comprises a field effect semiconductor device 46, which is encapsulated in a solution impervious material 48, such a8 a polymerized epoxy resin. The encapsulation material 48 in turn may be encapsulated in a housing 50 (~igure 2A). Semiconductor device 46 is electrically coupled by bonding wires 52 to a terminal 54.
Suitable electrical conductors such as conductor 56 are attached * Trade-mark 1 3357~8 to terminal 54 for electrically communicating between the Chemfet device 44 and the electronic circuitry described below in connection with Figure 9. Conductor 56 is preferably routed through tubing 22 and exits through ~ ~ealed aperture at or near the luer-lock end of tubing 22, as at 58. A more detailed description of a 6uitable electronic sensor may be found in U.S.
Patent ~o. 4,020,830 to JohnRon, entitled "Selective Chemical Sensitive FET Transducers ", In order to allow a solution to contact the chemically 6ensitive 6urface of sem~conductor device 46, tubing 22 may be provided with ~n ~perture 60 when implementing the embodiment of Figure 2A. Such an aperture i8 not needed in the embodiment of Figure 2B, since the semiconductor device 46 i6 exposed to ~ampling chamber 40 by virtue of the external mounting configuration.
The ~ampling ch~mher 40 can be filled with an ~spiration or sampling medium that i~ used to absorb or otherwise provide a means for incorporating and delivering or measuring the the fluids or gases of interest. Such a ~edium is selected depending upon many factors, incLuding the properties of the fluids or gases of interest, the type of sensor 42 employed, and the type of calibration that is necess~ry. Such mediums include bicarbonate ~olutions and saline solution. It might be noted that gases often behave as fluids and are therefore frequently considered to be fluids.
As noted above, when the sensor employed does not require frequent recalibration, the need for the sampling chamber 40 to be in communication with the proximate end of the tonometric catheter (that remains outside the patient) may be ~- i eliminated ~ince no aspiration is needed. However, in many instances ~uch communication may still be desirable as aspiration may be required to calibrate the 6ensor or ~ensors, to replace the aspirating or ~ampling medium with a fresh ~edium, and to incorporate the gas or gases of interest.
Another embodiment of the tonometric catheter ls illustrated in ~igures 4, 4A and 4B. As illustrated, the tonometric catheter i8 appropriately configured to also ~erve as a nasogastric 6ump, either with or without gastric suction. With reference to F~gure 4, the tonometric catheter 20a comprises a multipa~sage tubing 62 which defines three individual noncommunicating (between each other) pas6ageway6 or lumens, an air lumen 64, ~n optional suction lumen 66 and a tonometric catheter lumen 68. A tonometric catheter membrane, similar to that previously described, i6 attached at an intermediate location on tubing 62, allowing a portion of the tubing to extend beyond the end of membrane 36 to define the nasogastric sump 70.
Tubing 62 i6 provided with a plurality of perforations 72 which communicate between tonometric catheter lumen 68 and the 6ampling chamber 40 defined by membrane 36, If desired~, one or more ~ensors 42 can be included in ~ccordance with the above teachings, in which case a ~uitable conductor 56 may be routed through tonometric catheter lumen 68 to exit at ~ealed aperture 58.
The nasogastric ~ump portion 70 is suitably provided with a plurality of openings 74 through which the ~tomach may be aspirated.
At the opposite end of tubing 62 the tubing ~plits to form three separate connections. Air lumen 64 communicates with air lumen pas~ageway 76, 6uction lumen connects with 6uction lumen pa6sageway 78 and tonometric catheter lumen 68 communicates with tonometric catheter lumen pa6sageway 80. The tonometric catheter lumen pa66ageway is fitted with three-way stopcock 30, 6imilar in function and purpose to the three-way ~topcock 30 described in connection with Figure 1. If desired, a quick connect fitting 82 may be used to couple the suction lumen passageway 78 with an aspiration source. As illustrated, the quick connect fitting preferably has angularly cut ends and a 61ightly enlarged midsection, making it easy to insert into the end of passageway 78 and al60 into the ~6piration hose coupling (not 6hown). The enlarged midsection helps form a ceal with the adjoining pa~sageways. Preferably the quick connect fitting is fabricated of dispo6able plastic.
Yet another embodiment of the tonometric catheter i8 illustrated in Figures 5 and 5A. This embodiment is a multiple tonometric catheter embodiment employing ~ tubing 84 having a plurality of pa66ageways or lumen a6 shown ~n the cros6-Fectional view of Figure 5A. Specifically, tubing 84 includes an air lumen 86a which communicates ~ith the endmost tonometric i catheter 36a and three additional tonometric catheter lumens 86b, 86c and 86d, which communicate respectively with tonometric catheters 36b, 36c and 36d. As with the other embodiments, each tonometric catheter may be provided with one or more 6ensors such as ~ensor6 42. A radiopaque L~l,y~Len plug 88 i8 positioned within each of the three tonometric catheter lumen 86b, 86c and 86d adjacent the distal end of each tonometric catheter, ~erving to block the remainder of the tonometric catheter lumen passageway and thereby en~uring that fluid pres6ure introduced ~ 3357~8 into each tonometric catheter lumen will cause the ~ssociated tonometric catheter to balloon outwardly a~ required during use.
Similarly, a radiopaque tungsten rod 90 is fitted a8 a plug in the end of ~ir lumen 86a, serving to terminate the end of the air lumen passageway. Being radiopaque, the tungsten plugs and tungsten rod aid in properly positioning the tonometric catheters by being vi~ible under fluoroscope or x-ray. In addition, if desired, tubing 84 can be prov~ded with a radiopaque fitripe along all or part of its length.
At the proximal end of tubing 84 the lumen 86a-86d diverge to define four ~eparate tubes 92a-92d. Each tube i6 fitted with a three-way ~topcock ~imilAr to tho6e de~cribed ~bove. Each sampling connector may optionally be coded numerically by color, etc. While four approximately equally spaced tonometric catheter~ have been illustrated in ~igure 5, it will be under6tood that the invention can be modified to include a greater or fewer number of tonometric catheter6 at different 6pacing as reguired for a particular application. It will also be understood that ~ome or all of the tonometric catheters can include one or ~ore 6ensors coupled to conductors 56, each preferably routed through the co~-e_~onding lumen pas6ageway.
Referring now to Figure 9, a 6uitable electronic monitoring circuit will now be described. In Figure 9 CHEMFET
semiconductor device 46 has been shown ~chematically by the equivalent circuit model enclosed in dotted lines. The device 46 thus comprises drain electrode 150, source electrode 152 and reference electrode 154. The chemically selective system, ~uch as a ~embrane system is depicted diagrammatically at 156. The substrate i~ ~ou..ded as at 158.
1 33~708 Source electrode 154 is coupled to an input lead of operational amplifier 160 which includes feedback network diagrammatically depicted at 162. Operational amplifier 160 6enses the drain ~ource current flowing through device 46 and converts this 6ignal into a voltage signal which i8 output on lead 164. Tbe drain ~ource current changes in accordance with changes in the chemical system under test. More specifically, as the PC02 level changes in the fluid exposed to device 46, the drain ~ource current changes accordingly. Hence the output voltage signal on lead 164 is likewi6e an indication of the PC02 level of the organ under test. Thi6 voltage signal on lead 164 i8 coupled to an input of comparator 166 which also receives a reference voltage Vref, which ~ay be 6upplied using a voltage divider network (not shown) or which may ~lternatively be provided by a digitally controlled voltage source 168. The output of comparator 166 is fed to reference electrode 154 to provide a ~table reference bias voltage. If a digitally controlled voltage source i6 used, thi~ reference voltage can be ad~usted ~nd calibrated by a computer circuit yet to be ~i~c~sed. The voltage ~ignal o~lead 164 is also fed to an analog to digital convertor 170, which i6 in turn coupled to a microprocessor-based microcomputer 172.
In order to automatically determine the pH of the wall of the hollow viscous organ under test, a separate gas analyzer ~ensor 174 i6 used to determine the bicarbonate concentration in the arterial blood of the patient. The ou~ of sensor 174 is coupled through analog to digital convertor 176 to microcomputer 172. Microcomputer 172 is preprogrammed to calculate the pH of the organ wall u~ing the values provided by !
analog to digital convertors 170 and 176. Conversion of PC02 measurements can be converted into pH measurements automatically by microcomputer 172 using ~arious equations and references well-known in the art.
Although many different types of output devices may be employed, 6trip chart recorder 178 and CRT monitor 180 have been illustrated. Strip chart recorder 178 and monitor 180 are coupled as output devices to microcomputer 172. Strip chart recorder 178 offers the advantage of developing an easily readable, permanent record of the fluctuations in organ wall pH.
Monitor 180 offer6 the advantage of providing digital readout of the pH value as well as displaying the upper and lower excur6ions of pH fluctuation. If desired, microcomputer 172 can be preprogrammed using keyboard 182 to compare the instantaneous pH
value with doctor-selected upper and lower alarm limits. If the measured instantaneous pH fluctuates outside those limit6, microcomputer 172 can 60und an alarm to alert hospital staff.
While a 6ingle 6emiconductor device 46 has been illustrated in con~unction with the electronic circuit of Figure 9, the circuit may be readily adapted for use with a plurality of 6emiconductor devices in order to measure the pH at different locations substantially ~imultaneously. In 6uch an embodiment, the data coming from each 6ensor can be fed to a 6eparate I/0 port of microcomputer 172. In the alternative, a single I/O port can be used with the individual ~nput ~ignals being time multiplexed.
As an alternative to electronic pH sensors, the invention may also be practiced using optical sensor technology.
Referring to Figure 10, the presently preferred optical ~ensor embodiment use~ a first fiber optic cable 94 which i~ optically coupled through a series of lences 96, 6electable color filters 98 and heat absorber 100 to an illumination source 102, such as a 100 watt tungsten-halogen lamp. Fiber optic cable 94 is routed through the tonometric catheter lumen in a fashion similar to the conductor 56 of the above-described embodiments, with the end thereof protruding through the tubing and into the 6ampling chamber 40. A second fiber optic cable 104 is routed parallel to the fir6t fiber optic cable 94, with one end protruding through the tubing and held in place ad;acent the end of first cable 94 with a collar 106. Collar 106 may be adhesively bonded to the out~ide wall of the tubing. The oppo6ite end of second fiber optic cable 104 iB positioned for optically coupling with a phototran6i6tor 108 which i~
electrically connected to an operational amplifier circuit 110.
The operational amplifier circuit can be coupled to an analog to digital converter, 6uch as A/D converter 170 of ~igure 7.
~r~
In use, fiber optic cabye 94 ill-~minates a region within the ~ampling chamber 40 whi~h i6 fill~d with a ~ampling fluid containing ~ colorimetric pH~indicator~ The illumination from fiber optic cable 94 reflect6 from the molecules ~uspended in the pH indicator solution, with ~ome of the reflected illumination passing back through second fiber optic cable 104 to the phototransistor. By 6electing the appropriate filter 98, a monochromatic illumination or illumination of otherwise known spectral content is employed to illuminate the colorimetric pH
indicator solution. When the color of the filtered illumination matches that of the indicator, the illumination i6 absorbed and a low illumination signal i6 received at the phototransi~tor. When a pH change causes a color change in the indicator away from the color of the filtered illumination, more illumination is reflected back to the phototransistor, with an attendant increase in detected signal output. In this fashion, the proper selection of indicator dye and illumination filtration can be used to detect pH ranges. For a further description of fiber optic pH
sensor technology, refer to G. G. Vurek "A Fiber optic PC2 Sensor, n Annals of Biomedical ~nqineerinq, Vol. 11, pp. 499-510, 1983, which is available from Pergamon Press, Ltd.
While the preferred embodiments have been disclosed in connection with monitoring of the gastrointestinal tract and the urinary and ureteric tracts 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 several presently preferred detailed constructions for tonometric catheters have been disclosed, it will be appreciated that other constructions may be developed which are equally suitable. The disclosed constructions are presently preferred for the reason that they are readily fabricated using existing available materials. Other embodiments may include other, but equivalent materials for the tonometric catheter membrane and/or connective tubing. They may also differ in the specific fabrication details. As an example, the sampling chamber may be eccentric rather than symmetric about the connective tubing.
In still another embodiment, conventional gas analyzers may be employed externally. A device such as that shown in Figure 1 may be used in combination with a pump or aspiration means (not shown) for continuous or regular intermittent 1 3~708 aspiration of a 6ample of the aspirating liquid or medium that is used to fill the sampling chamber 40. The gample removed by pump or aspiration means via attachment to the luer-lock 24 can be optionally designed 80 that the sample a6pirated at each sampling interval can be brought in contact with an exterior, ~eparate gas analyzing means or sensor (not Fhown) to determine the pH, pO2~
PCO2 and/or the like, of the sample. Such automatic ~ampling can be conducted employing a sy6tem as ~hown in Figure 12. In the a6sembly a sampling ~ystem employs a personal computer to conduct evaluations and analysi6 of the ~amples withdrawn from the tonometric catheter 299.
Pump 203 i8 loaded with the ~ampling or aspirating ~edium such as 6aline. Next, valve 201 iB activated to withdraw a de~ired amount of the sampling fluid. The valve 201 is deactivated and pump 203 is u~ed to enforce the sampling chamber of the tonometric catheter 299 using a calibrated amount or optionally a pressure transducer 215. The sampling fluid or ~edium i~ allowed to come to equilibrium with the wall of the organ or area of interest. Next the ~dead space, n i.e., the ~rea of the lumlen filled with the ~4mpling fluid that is not in equilibrium, is removed by activating valve 205, activating pump 207, activating valve 209 and infusing pump 207; the waste 219 is discarded. A ~ample for analy~i6 is then withdrawn by deactivating valve 209, activating pump 207 to then deliver the sampling to a gas analyzer (not ~hown) that provides data from the sample to the PC 217, and the evaluation i~ conducted as described herein.
t The cample gas analyzer or a ~eparate gas analyzer may be employed to determine the bicarbonate concentration in the arterial blood of the patient, as described above.
Another embodiment of the tonometric catheter is illustrated in Figures 11 and llA. As illustrated, the tonometric catheter is appropriately configured to also serve as a urinary or ureteric catheter, either with or without ~uction, which optionally employs sensors. With reference to Figures 11 and llA, the tonometric catheter 220 comprises a multipassage tubing 262 whi~ch defines three individual noncommunicating (between each other) pas6ageways or lumen~, an optional air or irrigation lumen 264, a drainage or suction lumen 266 and a tonometric catheter lumen 268. A tonometric catheter membrane, 6imilar to that previously described, is attached at a distal location on tubing 262, allowing an intermediate portion of the tubing not exten~;ng beyond the end of membrane 236 to define the uretary or uretary catheter 270. Tubing 262 is provided with a plurality of perforations 272 which communicate between tonometric catheter lumen 268 ~nd the ~ampling chamber 240 defined by membrane 236. If desired, one or ~ore sensors 242 can be included in ~ccordance with the above teachings, in which case a suitable conductor 256 may be routed through tonometric catheter lumen 268 to exit at ~ealed aperture 258.
The urinary catheter or ureteric catheter portion 270 is suitably provided with a plurality of openings 274 throu~h which the bladder or ureters may be aspirated or lrrigated.
At the opposite end of tubing 262 the tubing 6plits to form three separate connections. Air or irrigation lumen 264 optionally communicates with air lumen passageway 276, urinary 1 3357û8 lumen connect6 with suction or drainage lumen pa6sageway 278 and tonometric catheter lumen 268 communicate6 with tonometric catheter lumen pa~sageway 280. The tonometric catheter lumen pa6sageway i~ fitted with three-way stopcock 230, similar in function and purpo6e to the three-way ~topcock 30 de6cribed in connection with Figure 1. If desired, a quick connect fitting 82 as seen in Figure 4 may be u~ed to couple the ~uction urinary passageway 278 with an aspiration source. As illustrated, the quick connect fitting preferably ~ag angularly cut ends and a slightly enlarged midsection, making it easy to in6ert into the end of passageway 278 and al~o into the a~piration ho6e coupling (not shown). ~he enlarged midsection help~ form a ~eal with the adjoining pa~ageway~. Preferably the quick connect fitting is fabricated of di6posable plastic.
Yet ~nother embodiment of the urinary catheter/tonometric catheter combination illustrated in Figures 11 and llA may employ a multiple tonometric catheter embodiment employing a tubing having a plurality of passageways or lumen a~ 6hown in the cro6s-sectional view of Figure 5A.
In ~nother embodiment of the present invention, a tonometric catheter may be ~dopted to deliver a pharmaceutically-active agent, either for sy~temic, local or topical activity, or a combination thereof. For example, an ~dditional lumen may be added such as that and for irrigation or ~piration, to deliver the active. For example, the irrigation/aspiration lumen 264 shown in Figure 11 ~nd llA, may be used to deliver an active agent. In another embodiment, a portion of the device may be modified ~o as to provide 6ustained release of the active aqent of interest.
Thus, for example, the problems of nosacomial infection associated with catheter insertion can be overcome by incorporating an antimicrobial into At least a portion of the polymeric material used to manufacture the tonometric catheter, or by coating at least a portion of the device with a sustained release composition, or by delivering the antimicrobial via the tonometric catheter. Such modifications are well known to those ~killed in the art. See U.S. Patent No. 4,677,143, Classes of useful agents include antimicrobial agents, nonsteroidal anti-inflammatory agents, topical anesthetics, topical vasodialators, ~etabolic suppressants, and other agents that could be delivered for absorption at the sites of the tonometric catheter.
Accordingly, while several preferred embodiments of the invention have been disclosed, it will be appreciated that principles of the invention, as set forth in the following claims, are applicable to other embodiments.
Back~round and 8ummary of the Invention This invention relates to medical diagnostic equipment and methods and is particularly concerned with hollow viscus tonometry and remote electronic and optical sensing.
The prior art (see U.S. Patent No. 4,643,192) has recognized that intestinal ischemia, and to a lesser degree, stress ulceration, are two problems that plague physicians involved in th~ 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 completely and irreversibly compromised. 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 ~hat a fall in the intramucosal pH may precede the development of intestinal ischemia and stress ulceration. As I reported in my prior U.S. Patent No. 4,643,192, entitled "Hollow Viscus Tonometry" a fall in intramucosal pH also occurs within minutes of inducing intestinal ischemia in dogs. The fall in pH
in intestinal mucosa, and hence the likelihood of ischemia or stress ulceration, can be reliably calculated from a PC02 (partial pressure of CO2), or other indicia of pH, in luminal fluid and the bicarbonate concentration in arterial blood. The i method of calculating the pH in intestinal mucosal tissue, pursuant to principles of my prior patent, has been validated by directed measurements under a variety of conditions ~imulating clinical problems. A correlation coefficient in the order of 0.92 to 0.95 has been obtained in each of 16 dogs. The validity of the procedure is inherently extensible to humans, and indeed may also be useful in assessing the vitality of other hollow organs and tissue. See R.G. Fiddian-Green et al. "Splanchnic Ischemia and Multiple Organ Failure".
To measure the PC02 in the lumen of the gut it has heretofore been necessary to obtain and remove a ~ample 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 has now been observed that it i6 ~omewhat difficult to manually aspirate the ~ampling fluid or medium from a tonometric catheter located in the gut or other internal focus with any consistency. It is much easier to obtain such ~amples from the ~tomach, but samples obtained from the ~tomach frequently contain foreign material that can damage a gas analyzer.
As taught in my prior patent, the desired 6ample or ~amples can be obtained from the gut using a catheter tube (called a tonometric catheter) having a walled sampling chamber on the tube with the ~ampling chamber being in ~ample-specific communication with the hollow interior of the tube. The wall of the sampling chamber comprises a material which iB ~ubstantially impermeable to liquid yet is highly permeable to gas. One suitable material i5 polydimethylsiloxane elastomer.
In use the catheter is introduced into a patient to place the ~ampling chamber at a desired ~ite within the gut. An -~ ~ J
aspirating liquid or medium i8 employed to fill the interior of the gampling chamber. The sampling chamber i8 left in place at the desired sampling site long enough to allow the gases present to diffuse through the wall of the 6ampling chamber into the aspirating liguid. The time should be long enough for the gases t~ eguilibrate. The liguid impermeable nature of the sample 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 or desired amount of placement time has elapsed the aspirating liquid is aspirated along with the gases which have diffused into it. The ~ample 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 taught in my prior patent the PC02 measurement i8 utilized in conjunction with a measurement of the bicarbonate ion concentration (HC03 ) in an arterial blood ~ample 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 6amples may be taken at periodic intervals 60 that pH values may be periodically calculated. The procedure has a high reliability in accurately determining the adequacy of organ tissue oxygenation, and diagnosing intestinal ischemia in its incipient ~tages. Such determination or detection can be useful in treating the patient ~o that the potentially devastating consequences resulting from less timely detection may often be avoided.
While the sampling techniques taught in my prior patent have provided highly accurate and reliable results, it has now been observed that there are instances (in the care of the critically ill in intensive care units, for example) in which remote sensing of the organ or organ-wall condition and automatic calculation of the organ or organ-wall pH would be advantageous and easier to effectuate. This method would thus partially or totally eliminate the need for the Qomewhat cumbersome aspiration of the sampling fluid or medium which fills the sampling chamber;
it may also eliminate the need for the ~ampling chamber to be in Qampling-medium communication with any other part of the device.
There is also a need to extend the benefits of tonometric sampling and eensing to other internal hollow viscous organs. To thig end, there is a need for new and different tonometric devices 6pecifically adapted to allow my 6ensing and sampling techniques to be performed with ease in a clinical environment, and in combination with other procedures.
The importance and significance of determining the pH
of the wall of a given hollow visc~us organ has been recently 7~ dramatically magnified as a result of the recent r~cogn~tion that the pH of the wall of a given organ can be employed to accurately evaluate the vitality and/or ~tability of that organ as well as others; this is in contrast to merely determining whether such an organ is experiencing an ischemic event. Further, certain organs can be ~elected for monitoring, either alone or in combination, and evaluation of this organ or these organs can aid in predicting the overall condition of the patient, or the onset of a multitude of pathologies, including predicting or identifying ~uch events a6 multiple organ failure. Such a methodology can be employed to greatly enhance and ~upplement the monitoring of the critically ill, for example.
In one aspect, the pre~ent invention provides a new apparatus and method for remotely sensing organ condition and conveying an electromagnetic signal, e.g. an electrical current or optical 6ignal, to an electronic or optical apparatus located outside the organ under investigation. In one embodiment, a chemically sensitive electronic transducer (or plurality of transducers), 6uch a6 a field effect-tran6istor, i~ attached to a tonometric catheter for introduction into the organ along with the tonometric catheter. The first electronic sensor, preferably non-temperature, generates and conveys an electromagnetic signal indicative of 60me desired aspect of organ condition, e.g., indicative of the pC02, pH and/or P02 level of the organ or organ-wall. For example, in one preferred embodiment, mean ambient pC02, pH and/or P02 of lumenal fluid or the like is ~easured or monitored via wire or other suitable electromagnetic energy conveying ~eans to an electronic circuit which interprets the electromagnetic signal and produces a report of the organ condition.' The electronic circuit may includé an ~nput for receiving a ~eparately determined signal indicative of the blood pH of the patient. Using this pC02, pH and/or P02 measurement along with blood (preferably arterial) pH data, the electronic circuit determines the pH of the organ wall under test and thereby provides information for determining the organ'~ current condition or perhaps predicting the organ's future condition.
The electronic circuit may be 6uitably constructed from analog components, digital components or both.
In another embodiment, a pH, PC02 or P02 6ensitive colorimetric 6ubstance is injected into an area adjacent to the organ, e.g., into the sampling chamber of the tonometric catheter, and an optical 6ensor is employed to detect color change in order to determine the pH of the wall of that organ.
The optical sensor can either be disposed in or on the tonometric catheter for introduction into the area adjacent the organ or it may be disposed outside the organ with fiber optic cable optically coupling the 6ensor to the tonometric catheter 6ite at which the pH sensitive substance has been injected.
In another aspect the present invention provides a variety of new and different tonometric catheter devices for sensing and/or sampling a fluid or gas property (such as pH, Po2~
pC02, and the like) which is indicative of the condition of an internal organ, in conjunction or combination with a walled catheter tube adapted for delivery or draining fluids, such as nasogastric tubes, urinary catheters, ureteric catheters, intestinal feeding tubes, wound or abdominal drains (suction or regular) and biliary tubes, catheters and stents, with or without remote sensing means for pH, PC02 and/or Po2-In still another aspect or embodiment, the deviceemploys two separate walled catheter tubes, one tonometric catheter tube for the measurement of a fluid or gas property, that is in communication with the sampling chamber; and a second walled catheter tube adapted for delivering or draining fluids.
In yet another aspect or embodiment, the device employs a walled sampling chamber in communication with a sensing means, and a 6econd walled catheter tube adapted for delivering or draining fluids.
Optionally, when a non-temperature sensing-means is employed, a second sensing-means may be employed as well.
For a more complete understanding of the invention, its objects and advantages, reference may be had to the following specification and to the accompanying drawings. Also, see applicant's co-pending Canadian applications filed of even date herewith entitled "Remote Sensing Tonometric Catheter Apparatus and Method~ and "Hollow Viscus and Solid Organ Tonometry", bearing respective serial numbers 609,067 and 609,066.
Brief Doscription of the Dr~winqs Figure 1 is a plan view of a first embodiment of the tonometric catheter;
Figure 2A is a partial cross-~ectional view of the tonometric catheter illustrating a first means for attachment of an electronic field effect transistor sensor;
Figure 2B is a partial cross-sectional view of the tonometric catheter illustrating a ~econd means of attachment of the field effect transistor sensor;
Figure 3 illustrates the method of use of the tonometric catheter in measurement of the pH of the colon and also of the ~tomach, the specific embodiment illustrated for colonic measurement being that of Figure 5 and the specific tonometric catheter for ~astric measurement being that of Figure 4;
Figure 4 i6 another embodiment of the tonometric catheter with nasogastric tube;
Figure 4A i8 a cros6-~ectional view of the tonometric catheter of Figure 4 taken 6ubstantially along the line 4A-4A of Figure 4;
Figure 4B i6 a cros6-~ectional view of the tonometric catheter of Figure 4 taken substantially along the line 4B-4B of Figure 4;
Figure 5 i6 yet another embodiment of the tonometric catheter having multiple sensing/sampling portions;
Figure 5A is a cross-sectional view of the tonometric catheter of Fig~re 5, taken sub6tantially along the line 5A-5A of Figure 5;
Figure 6 is a detailed view illu6trating the tonometric catheter of Figure 4 in u6e within the stomach;
Figure 7 i8 a detailed view illu~trating the tonometric catheter of Figure 5 in use within the colon:
Figure 8 is a similar view illustrating the tonometric catheter of Figure 1 in use within the colon;
Figure 9 i6 an electrical schematic diagram illu6trating one embodiment of electronic circuit in accordance with the invention;
Figure 10 is an électrical schematic diagram illustrating another embodiment of the optical mea6urement of pH
in accordance with the invention;
Figure 11 i6 another embodiment of a tonometric catheter with a urinary catheter;
Figure llA i6 a cro66-sectional view of the tonometric catheter/urinary catheter of Figure 11, taken substantially along the line llA-llA of Figure 11.
n~cr~ption of the Proferred ~bodi~ents ~ igure 1 illustrates a fir6t embodiment of tonometric catheter 20. The tonometric catheter comprises a length of cuitable tubing 22, one end 32 of which i6 closed, and the opposite end of which has a connector ~uch as a luer-lock 24.
~uer-lock 24 is adapted to receive a complementary fitting 26, which in turn couples through a second length of tubing 28 to a three-way stopcock 30. Three-way 6topcock 30 may be used to 6electively connect tubing 28 to various ~ources of irrigation or a6piration.
Adjacent the closed end 32, tubing 22 i~ perforated as at 34. A balloon-like tonometric catheter membrane 36 is fitted over the closed end 60 that the perforations 34 are enclosed, as illu~trated. The tonometric catheter ~embrane 36 has an internal 61eeve diameter at 38 which forms a tight fit with tubing 22.
The preferred form of tonometric catheter ~embrane is polydimethylsiloxane elastomer. The membrane may be 6ealed to the tubing 22 with appropriate adhesive ~o that the tonometric catheter membrane i6 6ealed in a closed relationship to the outer wall of tubing 22, thereby forming ~ campling chamber 40 adjacent closed end 32. The tonometric catheter ~embrane has a certain elasticity to allow the membrane to expand when filled with an aspirating liquid in order to contact the wall of the organ under examination, as will be explained below.
The membrane 36 i8 preferably constructed such that at least a portion of it is selectively permeable to the gas or fluid property of interest. In a preferred embodiment, it is selectively permeable to hydrogen, oxygen, or H~, ~o that pH, PC02 and/or P02 can be measured. It i6 also preferably impermeable to other materials that would interfere with the desired measurements, such as other gases, proteins, and the like. In a highly preferred embodiment, an ion-~elective membrane is employed.
Bonded to either the inner wall or the outer wall of tubing 22 are one or more sensors 42 for detecting a property indicative of pH and/or temperature. Two such 6ensors are illustrated in Figure 1, bonded to the outside wall of tubing 22 with suitable adhesive. Figures 2A and 2B illu~trate two alternate means of sensor attachment, Figure 2A illustrating the sensor attached to the inner wall of tubinq 22 and ~igure 2B
illustratin~ the sen~or attached to the outer wall of tubing 22.
In a preferred embodiment, at least a portion of the tubing, but not all of it, i~ made of a C02 impermeable material, such a8 polyester elastomers derived from the reaction of dimethylterephtalate 1,4-butanediol ~nd -hydro- ~ -hydroxypoly (oxytetramethylene). In a highly preferred embodiment, this is a material such as Hytril, sold by DuPont.
For purposes of 6en~ing temperature, thermistor devices are presently preferred. For ~ens~ng properties indicative of pH
chemically responsive field effect transistors or ~Chemfets" may be employed. In this regard, Chemfet 6ensors 44 have been ~llustrated in Figures 2A and 2B. Chemfet sensor 44 comprises a field effect semiconductor device 46, which is encapsulated in a solution impervious material 48, such a8 a polymerized epoxy resin. The encapsulation material 48 in turn may be encapsulated in a housing 50 (~igure 2A). Semiconductor device 46 is electrically coupled by bonding wires 52 to a terminal 54.
Suitable electrical conductors such as conductor 56 are attached * Trade-mark 1 3357~8 to terminal 54 for electrically communicating between the Chemfet device 44 and the electronic circuitry described below in connection with Figure 9. Conductor 56 is preferably routed through tubing 22 and exits through ~ ~ealed aperture at or near the luer-lock end of tubing 22, as at 58. A more detailed description of a 6uitable electronic sensor may be found in U.S.
Patent ~o. 4,020,830 to JohnRon, entitled "Selective Chemical Sensitive FET Transducers ", In order to allow a solution to contact the chemically 6ensitive 6urface of sem~conductor device 46, tubing 22 may be provided with ~n ~perture 60 when implementing the embodiment of Figure 2A. Such an aperture i8 not needed in the embodiment of Figure 2B, since the semiconductor device 46 i6 exposed to ~ampling chamber 40 by virtue of the external mounting configuration.
The ~ampling ch~mher 40 can be filled with an ~spiration or sampling medium that i~ used to absorb or otherwise provide a means for incorporating and delivering or measuring the the fluids or gases of interest. Such a ~edium is selected depending upon many factors, incLuding the properties of the fluids or gases of interest, the type of sensor 42 employed, and the type of calibration that is necess~ry. Such mediums include bicarbonate ~olutions and saline solution. It might be noted that gases often behave as fluids and are therefore frequently considered to be fluids.
As noted above, when the sensor employed does not require frequent recalibration, the need for the sampling chamber 40 to be in communication with the proximate end of the tonometric catheter (that remains outside the patient) may be ~- i eliminated ~ince no aspiration is needed. However, in many instances ~uch communication may still be desirable as aspiration may be required to calibrate the 6ensor or ~ensors, to replace the aspirating or ~ampling medium with a fresh ~edium, and to incorporate the gas or gases of interest.
Another embodiment of the tonometric catheter ls illustrated in ~igures 4, 4A and 4B. As illustrated, the tonometric catheter i8 appropriately configured to also ~erve as a nasogastric 6ump, either with or without gastric suction. With reference to F~gure 4, the tonometric catheter 20a comprises a multipa~sage tubing 62 which defines three individual noncommunicating (between each other) pas6ageway6 or lumens, an air lumen 64, ~n optional suction lumen 66 and a tonometric catheter lumen 68. A tonometric catheter membrane, similar to that previously described, i6 attached at an intermediate location on tubing 62, allowing a portion of the tubing to extend beyond the end of membrane 36 to define the nasogastric sump 70.
Tubing 62 i6 provided with a plurality of perforations 72 which communicate between tonometric catheter lumen 68 and the 6ampling chamber 40 defined by membrane 36, If desired~, one or more ~ensors 42 can be included in ~ccordance with the above teachings, in which case a ~uitable conductor 56 may be routed through tonometric catheter lumen 68 to exit at ~ealed aperture 58.
The nasogastric ~ump portion 70 is suitably provided with a plurality of openings 74 through which the ~tomach may be aspirated.
At the opposite end of tubing 62 the tubing ~plits to form three separate connections. Air lumen 64 communicates with air lumen pas~ageway 76, 6uction lumen connects with 6uction lumen pa6sageway 78 and tonometric catheter lumen 68 communicates with tonometric catheter lumen pa6sageway 80. The tonometric catheter lumen pa66ageway is fitted with three-way stopcock 30, 6imilar in function and purpose to the three-way ~topcock 30 described in connection with Figure 1. If desired, a quick connect fitting 82 may be used to couple the suction lumen passageway 78 with an aspiration source. As illustrated, the quick connect fitting preferably has angularly cut ends and a 61ightly enlarged midsection, making it easy to insert into the end of passageway 78 and al60 into the ~6piration hose coupling (not 6hown). The enlarged midsection helps form a ceal with the adjoining pa~sageways. Preferably the quick connect fitting is fabricated of dispo6able plastic.
Yet another embodiment of the tonometric catheter i8 illustrated in Figures 5 and 5A. This embodiment is a multiple tonometric catheter embodiment employing ~ tubing 84 having a plurality of pa66ageways or lumen a6 shown ~n the cros6-Fectional view of Figure 5A. Specifically, tubing 84 includes an air lumen 86a which communicates ~ith the endmost tonometric i catheter 36a and three additional tonometric catheter lumens 86b, 86c and 86d, which communicate respectively with tonometric catheters 36b, 36c and 36d. As with the other embodiments, each tonometric catheter may be provided with one or more 6ensors such as ~ensor6 42. A radiopaque L~l,y~Len plug 88 i8 positioned within each of the three tonometric catheter lumen 86b, 86c and 86d adjacent the distal end of each tonometric catheter, ~erving to block the remainder of the tonometric catheter lumen passageway and thereby en~uring that fluid pres6ure introduced ~ 3357~8 into each tonometric catheter lumen will cause the ~ssociated tonometric catheter to balloon outwardly a~ required during use.
Similarly, a radiopaque tungsten rod 90 is fitted a8 a plug in the end of ~ir lumen 86a, serving to terminate the end of the air lumen passageway. Being radiopaque, the tungsten plugs and tungsten rod aid in properly positioning the tonometric catheters by being vi~ible under fluoroscope or x-ray. In addition, if desired, tubing 84 can be prov~ded with a radiopaque fitripe along all or part of its length.
At the proximal end of tubing 84 the lumen 86a-86d diverge to define four ~eparate tubes 92a-92d. Each tube i6 fitted with a three-way ~topcock ~imilAr to tho6e de~cribed ~bove. Each sampling connector may optionally be coded numerically by color, etc. While four approximately equally spaced tonometric catheter~ have been illustrated in ~igure 5, it will be under6tood that the invention can be modified to include a greater or fewer number of tonometric catheter6 at different 6pacing as reguired for a particular application. It will also be understood that ~ome or all of the tonometric catheters can include one or ~ore 6ensors coupled to conductors 56, each preferably routed through the co~-e_~onding lumen pas6ageway.
Referring now to Figure 9, a 6uitable electronic monitoring circuit will now be described. In Figure 9 CHEMFET
semiconductor device 46 has been shown ~chematically by the equivalent circuit model enclosed in dotted lines. The device 46 thus comprises drain electrode 150, source electrode 152 and reference electrode 154. The chemically selective system, ~uch as a ~embrane system is depicted diagrammatically at 156. The substrate i~ ~ou..ded as at 158.
1 33~708 Source electrode 154 is coupled to an input lead of operational amplifier 160 which includes feedback network diagrammatically depicted at 162. Operational amplifier 160 6enses the drain ~ource current flowing through device 46 and converts this 6ignal into a voltage signal which i8 output on lead 164. Tbe drain ~ource current changes in accordance with changes in the chemical system under test. More specifically, as the PC02 level changes in the fluid exposed to device 46, the drain ~ource current changes accordingly. Hence the output voltage signal on lead 164 is likewi6e an indication of the PC02 level of the organ under test. Thi6 voltage signal on lead 164 i8 coupled to an input of comparator 166 which also receives a reference voltage Vref, which ~ay be 6upplied using a voltage divider network (not shown) or which may ~lternatively be provided by a digitally controlled voltage source 168. The output of comparator 166 is fed to reference electrode 154 to provide a ~table reference bias voltage. If a digitally controlled voltage source i6 used, thi~ reference voltage can be ad~usted ~nd calibrated by a computer circuit yet to be ~i~c~sed. The voltage ~ignal o~lead 164 is also fed to an analog to digital convertor 170, which i6 in turn coupled to a microprocessor-based microcomputer 172.
In order to automatically determine the pH of the wall of the hollow viscous organ under test, a separate gas analyzer ~ensor 174 i6 used to determine the bicarbonate concentration in the arterial blood of the patient. The ou~ of sensor 174 is coupled through analog to digital convertor 176 to microcomputer 172. Microcomputer 172 is preprogrammed to calculate the pH of the organ wall u~ing the values provided by !
analog to digital convertors 170 and 176. Conversion of PC02 measurements can be converted into pH measurements automatically by microcomputer 172 using ~arious equations and references well-known in the art.
Although many different types of output devices may be employed, 6trip chart recorder 178 and CRT monitor 180 have been illustrated. Strip chart recorder 178 and monitor 180 are coupled as output devices to microcomputer 172. Strip chart recorder 178 offers the advantage of developing an easily readable, permanent record of the fluctuations in organ wall pH.
Monitor 180 offer6 the advantage of providing digital readout of the pH value as well as displaying the upper and lower excur6ions of pH fluctuation. If desired, microcomputer 172 can be preprogrammed using keyboard 182 to compare the instantaneous pH
value with doctor-selected upper and lower alarm limits. If the measured instantaneous pH fluctuates outside those limit6, microcomputer 172 can 60und an alarm to alert hospital staff.
While a 6ingle 6emiconductor device 46 has been illustrated in con~unction with the electronic circuit of Figure 9, the circuit may be readily adapted for use with a plurality of 6emiconductor devices in order to measure the pH at different locations substantially ~imultaneously. In 6uch an embodiment, the data coming from each 6ensor can be fed to a 6eparate I/0 port of microcomputer 172. In the alternative, a single I/O port can be used with the individual ~nput ~ignals being time multiplexed.
As an alternative to electronic pH sensors, the invention may also be practiced using optical sensor technology.
Referring to Figure 10, the presently preferred optical ~ensor embodiment use~ a first fiber optic cable 94 which i~ optically coupled through a series of lences 96, 6electable color filters 98 and heat absorber 100 to an illumination source 102, such as a 100 watt tungsten-halogen lamp. Fiber optic cable 94 is routed through the tonometric catheter lumen in a fashion similar to the conductor 56 of the above-described embodiments, with the end thereof protruding through the tubing and into the 6ampling chamber 40. A second fiber optic cable 104 is routed parallel to the fir6t fiber optic cable 94, with one end protruding through the tubing and held in place ad;acent the end of first cable 94 with a collar 106. Collar 106 may be adhesively bonded to the out~ide wall of the tubing. The oppo6ite end of second fiber optic cable 104 iB positioned for optically coupling with a phototran6i6tor 108 which i~
electrically connected to an operational amplifier circuit 110.
The operational amplifier circuit can be coupled to an analog to digital converter, 6uch as A/D converter 170 of ~igure 7.
~r~
In use, fiber optic cabye 94 ill-~minates a region within the ~ampling chamber 40 whi~h i6 fill~d with a ~ampling fluid containing ~ colorimetric pH~indicator~ The illumination from fiber optic cable 94 reflect6 from the molecules ~uspended in the pH indicator solution, with ~ome of the reflected illumination passing back through second fiber optic cable 104 to the phototransistor. By 6electing the appropriate filter 98, a monochromatic illumination or illumination of otherwise known spectral content is employed to illuminate the colorimetric pH
indicator solution. When the color of the filtered illumination matches that of the indicator, the illumination i6 absorbed and a low illumination signal i6 received at the phototransi~tor. When a pH change causes a color change in the indicator away from the color of the filtered illumination, more illumination is reflected back to the phototransistor, with an attendant increase in detected signal output. In this fashion, the proper selection of indicator dye and illumination filtration can be used to detect pH ranges. For a further description of fiber optic pH
sensor technology, refer to G. G. Vurek "A Fiber optic PC2 Sensor, n Annals of Biomedical ~nqineerinq, Vol. 11, pp. 499-510, 1983, which is available from Pergamon Press, Ltd.
While the preferred embodiments have been disclosed in connection with monitoring of the gastrointestinal tract and the urinary and ureteric tracts 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 several presently preferred detailed constructions for tonometric catheters have been disclosed, it will be appreciated that other constructions may be developed which are equally suitable. The disclosed constructions are presently preferred for the reason that they are readily fabricated using existing available materials. Other embodiments may include other, but equivalent materials for the tonometric catheter membrane and/or connective tubing. They may also differ in the specific fabrication details. As an example, the sampling chamber may be eccentric rather than symmetric about the connective tubing.
In still another embodiment, conventional gas analyzers may be employed externally. A device such as that shown in Figure 1 may be used in combination with a pump or aspiration means (not shown) for continuous or regular intermittent 1 3~708 aspiration of a 6ample of the aspirating liquid or medium that is used to fill the sampling chamber 40. The gample removed by pump or aspiration means via attachment to the luer-lock 24 can be optionally designed 80 that the sample a6pirated at each sampling interval can be brought in contact with an exterior, ~eparate gas analyzing means or sensor (not Fhown) to determine the pH, pO2~
PCO2 and/or the like, of the sample. Such automatic ~ampling can be conducted employing a sy6tem as ~hown in Figure 12. In the a6sembly a sampling ~ystem employs a personal computer to conduct evaluations and analysi6 of the ~amples withdrawn from the tonometric catheter 299.
Pump 203 i8 loaded with the ~ampling or aspirating ~edium such as 6aline. Next, valve 201 iB activated to withdraw a de~ired amount of the sampling fluid. The valve 201 is deactivated and pump 203 is u~ed to enforce the sampling chamber of the tonometric catheter 299 using a calibrated amount or optionally a pressure transducer 215. The sampling fluid or ~edium i~ allowed to come to equilibrium with the wall of the organ or area of interest. Next the ~dead space, n i.e., the ~rea of the lumlen filled with the ~4mpling fluid that is not in equilibrium, is removed by activating valve 205, activating pump 207, activating valve 209 and infusing pump 207; the waste 219 is discarded. A ~ample for analy~i6 is then withdrawn by deactivating valve 209, activating pump 207 to then deliver the sampling to a gas analyzer (not ~hown) that provides data from the sample to the PC 217, and the evaluation i~ conducted as described herein.
t The cample gas analyzer or a ~eparate gas analyzer may be employed to determine the bicarbonate concentration in the arterial blood of the patient, as described above.
Another embodiment of the tonometric catheter is illustrated in Figures 11 and llA. As illustrated, the tonometric catheter is appropriately configured to also serve as a urinary or ureteric catheter, either with or without ~uction, which optionally employs sensors. With reference to Figures 11 and llA, the tonometric catheter 220 comprises a multipassage tubing 262 whi~ch defines three individual noncommunicating (between each other) pas6ageways or lumen~, an optional air or irrigation lumen 264, a drainage or suction lumen 266 and a tonometric catheter lumen 268. A tonometric catheter membrane, 6imilar to that previously described, is attached at a distal location on tubing 262, allowing an intermediate portion of the tubing not exten~;ng beyond the end of membrane 236 to define the uretary or uretary catheter 270. Tubing 262 is provided with a plurality of perforations 272 which communicate between tonometric catheter lumen 268 ~nd the ~ampling chamber 240 defined by membrane 236. If desired, one or ~ore sensors 242 can be included in ~ccordance with the above teachings, in which case a suitable conductor 256 may be routed through tonometric catheter lumen 268 to exit at ~ealed aperture 258.
The urinary catheter or ureteric catheter portion 270 is suitably provided with a plurality of openings 274 throu~h which the bladder or ureters may be aspirated or lrrigated.
At the opposite end of tubing 262 the tubing 6plits to form three separate connections. Air or irrigation lumen 264 optionally communicates with air lumen passageway 276, urinary 1 3357û8 lumen connect6 with suction or drainage lumen pa6sageway 278 and tonometric catheter lumen 268 communicate6 with tonometric catheter lumen pa~sageway 280. The tonometric catheter lumen pa6sageway i~ fitted with three-way stopcock 230, similar in function and purpo6e to the three-way ~topcock 30 de6cribed in connection with Figure 1. If desired, a quick connect fitting 82 as seen in Figure 4 may be u~ed to couple the ~uction urinary passageway 278 with an aspiration source. As illustrated, the quick connect fitting preferably ~ag angularly cut ends and a slightly enlarged midsection, making it easy to in6ert into the end of passageway 278 and al~o into the a~piration ho6e coupling (not shown). ~he enlarged midsection help~ form a ~eal with the adjoining pa~ageway~. Preferably the quick connect fitting is fabricated of di6posable plastic.
Yet ~nother embodiment of the urinary catheter/tonometric catheter combination illustrated in Figures 11 and llA may employ a multiple tonometric catheter embodiment employing a tubing having a plurality of passageways or lumen a~ 6hown in the cro6s-sectional view of Figure 5A.
In ~nother embodiment of the present invention, a tonometric catheter may be ~dopted to deliver a pharmaceutically-active agent, either for sy~temic, local or topical activity, or a combination thereof. For example, an ~dditional lumen may be added such as that and for irrigation or ~piration, to deliver the active. For example, the irrigation/aspiration lumen 264 shown in Figure 11 ~nd llA, may be used to deliver an active agent. In another embodiment, a portion of the device may be modified ~o as to provide 6ustained release of the active aqent of interest.
Thus, for example, the problems of nosacomial infection associated with catheter insertion can be overcome by incorporating an antimicrobial into At least a portion of the polymeric material used to manufacture the tonometric catheter, or by coating at least a portion of the device with a sustained release composition, or by delivering the antimicrobial via the tonometric catheter. Such modifications are well known to those ~killed in the art. See U.S. Patent No. 4,677,143, Classes of useful agents include antimicrobial agents, nonsteroidal anti-inflammatory agents, topical anesthetics, topical vasodialators, ~etabolic suppressants, and other agents that could be delivered for absorption at the sites of the tonometric catheter.
Accordingly, while several preferred embodiments of the invention have been disclosed, it will be appreciated that principles of the invention, as set forth in the following claims, are applicable to other embodiments.
Claims (55)
1. A tonometric catheter apparatus for measuring a fluid or gas property indicative of the condition of an internal organ of a human or other mammal in vivo which comprises:
(a) a tonometric catheter tube;
(b) a walled sampling chamber on said tube optionally in communication with the interior of said catheter tube, the wall of said walled sampling chamber comprising a material which is freely permeable to a gas or fluid property of interest but poorly permeable to other liquids or fluids: and (c) a second walled catheter tube adapted for delivering or draining fluids.
(a) a tonometric catheter tube;
(b) a walled sampling chamber on said tube optionally in communication with the interior of said catheter tube, the wall of said walled sampling chamber comprising a material which is freely permeable to a gas or fluid property of interest but poorly permeable to other liquids or fluids: and (c) a second walled catheter tube adapted for delivering or draining fluids.
2. An apparatus according to Claim 1 wherein the second walled catheter tube is suitable for draining fluid from or delivering fluid to the gut.
3. An apparatus according to Claim 1 wherein the second walled catheter tube is suitable for draining fluid from or delivering fluid to the bladder or kidney.
4. An apparatus according to Claim 1 wherein the device is a tonometric catheter/urinary catheter combination.
5. An apparatus according to Claim 1 wherein the device comprises a tonometric catheter/gastric suction combination.
6. An apparatus according to Claim 1 wherein the device comprises a tonometric catheter/nasogastric sump combination.
7. A tonometric catheter apparatus for remotely determining the condition of an internal organ of a human or other mammal in vivo which comprises:
a tonometric catheter having at least one sampling chamber for introduction into said organ or the area adjacent said organ;
said tonometric catheter having an electronic sensor in communication with said sampling chamber for developing a signal indicative of the condition of said organ;
means coupled to said sensor for conveying said signal to a location outside said organ whereby the condition of said organ may be remotely determined; and a second walled catheter tube suitable for delivering or draining fluid.
a tonometric catheter having at least one sampling chamber for introduction into said organ or the area adjacent said organ;
said tonometric catheter having an electronic sensor in communication with said sampling chamber for developing a signal indicative of the condition of said organ;
means coupled to said sensor for conveying said signal to a location outside said organ whereby the condition of said organ may be remotely determined; and a second walled catheter tube suitable for delivering or draining fluid.
8. A tonometric catheter apparatus for determining the pH of an internal organ of a human or other mammal in vivo comprising:
a tonometric catheter having at least one sampling chamber for introduction into said organ or the area adjacent said organ;
a sensor disposed on said tonometric catheter and in communication with said sampling chamber for introduction into said organ with said tonometric catheter;
said sensor comprising means responsive to a fluid property indicative of pH and for developing an electromagnetic signal indicative of said fluid property;
a means responsive to said signal for generating a pH
signal indicative of the pH of said organ; and a walled catheter tube suitable for delivering or draining fluids.
a tonometric catheter having at least one sampling chamber for introduction into said organ or the area adjacent said organ;
a sensor disposed on said tonometric catheter and in communication with said sampling chamber for introduction into said organ with said tonometric catheter;
said sensor comprising means responsive to a fluid property indicative of pH and for developing an electromagnetic signal indicative of said fluid property;
a means responsive to said signal for generating a pH
signal indicative of the pH of said organ; and a walled catheter tube suitable for delivering or draining fluids.
9. A tonometric catheter apparatus for remotely determining and reporting the condition of an internal organ of a human or other mammal comprising:
a tonometric catheter for introduction into said organ or the area adjacent said organ;
said tonometric catheter having a sensor for developing a first electromagnetic signal indicative of a fluid pressure condition within said organ;
a means for developing a second electromagnetic signal indicative of the blood pH of said mammal;
means receptive of said first and second signals for generating a third signal indicative of the condition of said organ;
means responsive to said third signal and located outside said organ for reporting said condition of said organ;
and a walled catheter tube suitable for delivering or draining fluids
a tonometric catheter for introduction into said organ or the area adjacent said organ;
said tonometric catheter having a sensor for developing a first electromagnetic signal indicative of a fluid pressure condition within said organ;
a means for developing a second electromagnetic signal indicative of the blood pH of said mammal;
means receptive of said first and second signals for generating a third signal indicative of the condition of said organ;
means responsive to said third signal and located outside said organ for reporting said condition of said organ;
and a walled catheter tube suitable for delivering or draining fluids
10. An apparatus according to Claim 7 wherein said sensor comprises a chemically sensitive electronic transucer.
11. An apparatus according to Claim 8 wherein said sensor comprises a chemically sensitive electronic transucer.
12. An apparatus according to Claim 9 wherein said sensor comprises a chemically sensitive electronic transducer.
13. The apparatus of Claim 7 wherein said sensor comprises a chemically sensitive field effect transistor transducer.
14. The apparatus of Claim 8 wherein said sensor comprises a chemically sensitive field effect transistor transducer.
15. The apparatus of Claim 9 wherein said sensor comprises a chemically sensitive field effect transistor transducer.
16. An apparatus according to Claim 8 wherein said electromagnetic signal is an electrical signal conveyed by wire to said means for generating a pH signal.
17. An apparatus according to Claim 9 wherein said first electromagnetic signal is an electrical signal conveyed by wire to said means for generating said third signal.
18. An apparatus according to Claim 9 wherein said means for reporting said condition includes analog circuit means for producing a report of said condition.
19. An apparatus according to Claim 9 wherein said means for reporting said condition includes digital circuit means for producing a report of said condition.
20. An apparatus according to Claim 7 wherein said tonometric catheter additionally comprises a second electronic sensor for determining the temperature of the sampling area adjacent said first sensor.
21. An apparatus according to Claim 8 wherein the gas property of interest is pCO2.
22. An apparatus according to Claim 8 wherein the gas property of interest is pO2.
23. An apparatus according to Claim 1 wherein at least a part of the catheter comprises .alpha.-hydro- .OMEGA. -hydroxy-poly (oxytetramethylene).
24. An apparatus according to Claim 7 wherein at least a part of the catheter comprises .alpha.-hydro- .OMEGA. -hydroxy-poly (oxytetramethylene).
25. An apparatus according to Claim 8 wherein at least a part of the catheter comprises .alpha.-hydro- .OMEGA. -hydroxy-poly (oxytetramethylene).
26. An apparatus according to Claim 9 wherein at least a part of the catheter comprises .alpha.-hydro- .OMEGA. -hydroxy-poly (oxytetramethylene).
27. An apparatus according to Claim 7 which additionally comprises a second sensor which measures temperature, said second sensor being in communication with the sampling chamber.
28. An apparatus according to Claim 8 which additionally comprises a second sensor which measures temperature, said second sensor being in communication with the sampling chamber.
29. An apparatus according to Claim 9 which additionally comprises a second sensor which measures temperature, said second sensor being in communication with the sampling chamber.
30. A combination tonometric catheter and nasogastric catheter apparatus for measuring a liquid fluid or gaseous fluid property indicative of the condition of an internal organ of a human or other mammal in vivo, comprising:
a) an elongated tube having a first lumen extending longitudinally therethrough, a portion of said tube being composed of a first flexible material that is substantially impermeable to one or more liquid fluids or gaseous fluids of interest, said fluids of interest including oxygen gases and carbon dioxide gases;
b) at least one walled sampling chamber on said tube in fluid communication with the interior of said first lumen, the wall of said sampling chamber being composed of a second flexible material that is freely and selectively permeable to said one or more liquid fluids or gaseous fluids of interest, said second material being substantially impermeable to other liquid fluids of gaseous fluids;
c) means for positioning said walled sampling chamber substantially adjacent a wall portion of said internal organ in order to allow at least one of said liquid fluids or gaseous fluids of interest from the tissue of the wall portion of the internal organ to permeate said walled sampling chamber; and d) said nasogastric catheter apparatus including at least one second lumen extending longitudinally through said tube and being adapted to be in fluid communication with the gastrointestinal tract.
a) an elongated tube having a first lumen extending longitudinally therethrough, a portion of said tube being composed of a first flexible material that is substantially impermeable to one or more liquid fluids or gaseous fluids of interest, said fluids of interest including oxygen gases and carbon dioxide gases;
b) at least one walled sampling chamber on said tube in fluid communication with the interior of said first lumen, the wall of said sampling chamber being composed of a second flexible material that is freely and selectively permeable to said one or more liquid fluids or gaseous fluids of interest, said second material being substantially impermeable to other liquid fluids of gaseous fluids;
c) means for positioning said walled sampling chamber substantially adjacent a wall portion of said internal organ in order to allow at least one of said liquid fluids or gaseous fluids of interest from the tissue of the wall portion of the internal organ to permeate said walled sampling chamber; and d) said nasogastric catheter apparatus including at least one second lumen extending longitudinally through said tube and being adapted to be in fluid communication with the gastrointestinal tract.
31. A combination apparatus according to claim 30, wherein said walled sampling chamber is substantially in direct contact with a wall portion of the internal organ.
32. A combination apparatus according to claim 30, further including temperature sensing means within said walled sampling chamber.
33. A combination apparatus according to claim 30, wherein said nasogastric catheter is a nasogastric sump apparatus.
34. A combination apparatus according to Claim 30, wherein at least a portion of said first flexible material is selected from the group of polyester elastomers derived from the reaction of dimethylterephthalate 1, 4-butanediol and 2-hydro-.omega.-hydroxypoly (oxytetramethylene).
35. A combination tonometric catheter and feeding tube apparatus for measuring a liquid fluid or gaseous fluid property indicative of the condition of an internal organ of a human or other mammal in vivo, comprising:
a) an elongated tube having a first lumen extending longitudinally therethrough, a portion of said tube being composed of a first flexible material that is substantially impermeable to one or more liquid fluids or gaseous fluids of interest, said fluids of interest including oxygen gases and carbon dioxide gases;
b) at least one walled sampling chamber on said tube in fluid communication with the interior of said first lumen, the wall of said sampling chamber being composed of a second flexible material that is freely and selectively permeable to said one or more liquid fluids or gaseous fluids of interest, said second material being substantially impermeable to other liquid fluids of gaseous fluids;
c) means for positioning said walled sampling chamber substantially adjacent a wall portion of said internal organ in order to allow at least one of said liquid fluids or gaseous fluids of interest from the tissue of the wall portion of the internal organ to permeate said walled sampling chamber; and d) said feeding tube apparatus including at least one second lumen extending longitudinally through said tube and being adapted to be in fluid communication with the gastrointestinal tract.
a) an elongated tube having a first lumen extending longitudinally therethrough, a portion of said tube being composed of a first flexible material that is substantially impermeable to one or more liquid fluids or gaseous fluids of interest, said fluids of interest including oxygen gases and carbon dioxide gases;
b) at least one walled sampling chamber on said tube in fluid communication with the interior of said first lumen, the wall of said sampling chamber being composed of a second flexible material that is freely and selectively permeable to said one or more liquid fluids or gaseous fluids of interest, said second material being substantially impermeable to other liquid fluids of gaseous fluids;
c) means for positioning said walled sampling chamber substantially adjacent a wall portion of said internal organ in order to allow at least one of said liquid fluids or gaseous fluids of interest from the tissue of the wall portion of the internal organ to permeate said walled sampling chamber; and d) said feeding tube apparatus including at least one second lumen extending longitudinally through said tube and being adapted to be in fluid communication with the gastrointestinal tract.
36. A combination apparatus according to claim 35, wherein said walled sampling chamber is substantially in direct contact with a wall portion of the internal organ.
37. A combination apparatus according to claim 35, further including temperature sensing means within said walled sampling chamber.
38. A combination apparatus according to Claim 35, wherein at least a portion of said first flexible material is selected from the group of polyester elastomers derived from the reaction of dimethylterephthalate 1, 4-butanediol and 2-hydro-.omega.-hydroxypoly (oxytetramethylene).
39. A combination tonometric catheter and wound drainage tube apparatus for measuring a liquid fluid or gaseous fluid property indicative of the condition of an internal organ of a human or other mammal in vivo, comprising:
a) an elongated tube having a first lumen extending longitudinally therethrough, a portion of said tube being composed of a first flexible material that is substantially impermeable to one or more liquid fluids or gaseous fluids of interest, said fluids of interest including oxygen gases and carbon dioxide gases;
b) at least one walled sampling chamber on said tube in fluid communication with the interior of said first lumen, the wall of said sampling chamber being composed of a second flexible material that is freely and selectively permeable to said one or more liquid fluids or gaseous fluids of interest, said second material being substantially impermeable to other liquid fluids of gaseous fluids;
c) means for positioning said walled sampling chamber substantially adjacent a wall portion of said internal organ in order to allow at least one of said liquid fluids or gaseous fluids of interest from the tissue of the wall portion of the internal organ to permeate said walled sampling chamber; and d) said wound drainage tube apparatus including at least one second lumen extending longitudinally through said tube and being adapted to be in fluid communication with the wound site.
a) an elongated tube having a first lumen extending longitudinally therethrough, a portion of said tube being composed of a first flexible material that is substantially impermeable to one or more liquid fluids or gaseous fluids of interest, said fluids of interest including oxygen gases and carbon dioxide gases;
b) at least one walled sampling chamber on said tube in fluid communication with the interior of said first lumen, the wall of said sampling chamber being composed of a second flexible material that is freely and selectively permeable to said one or more liquid fluids or gaseous fluids of interest, said second material being substantially impermeable to other liquid fluids of gaseous fluids;
c) means for positioning said walled sampling chamber substantially adjacent a wall portion of said internal organ in order to allow at least one of said liquid fluids or gaseous fluids of interest from the tissue of the wall portion of the internal organ to permeate said walled sampling chamber; and d) said wound drainage tube apparatus including at least one second lumen extending longitudinally through said tube and being adapted to be in fluid communication with the wound site.
40. A combination apparatus according to claim 39, wherein said walled sampling chamber is substantially in direct contact with a wall portion of the internal organ.
41. A combination apparatus according to claim 39, further including temperature sensing means within said walled sampling chamber.
42. A combination apparatus according to Claim 39, wherein at least a portion of said first flexible material is selected from the group of polyester elastomers derived from the reaction of dimethylterephthalate 1, 4-butanediol and 2-hydro-.omega.-hydroxypoly (oxytetramethylene).
43. A combination tonometric catheter and urinary catheter apparatus for measuring a liquid fluid or gaseous fluid property indicative of the condition of an internal organ of a human or other mammal in vivo, comprising:
a) an elongated tube having a first lumen extending longitudinally therethrough, a portion of said tube being composed of a first flexible material that is substantially impermeable to one or more liquid fluids or gaseous fluids of interest, said fluids of interest including oxygen gases and carbon dioxide gases;
b) at least one walled sampling chamber on said tube in fluid communication with the interior of said first lumen, the wall of said sampling chamber being composed of a second flexible material that is freely and selectively permeable to said one or more liquid fluids or gaseous fluids of interest, said second material being substantially impermeable to other liquid fluids of gaseous fluids;
c) means for positioning said walled sampling chamber substantially adjacent a wall portion of said internal organ in order to allow at least one of said liquid fluids or gaseous fluids of interest from the tissue of the wall portion of the internal organ to permeate said walled sampling chamber; and d) said urinary catheter apparatus including at least one second lumen extending longitudinally through said tube and being adapted to be in fluid communication with the bladder.
a) an elongated tube having a first lumen extending longitudinally therethrough, a portion of said tube being composed of a first flexible material that is substantially impermeable to one or more liquid fluids or gaseous fluids of interest, said fluids of interest including oxygen gases and carbon dioxide gases;
b) at least one walled sampling chamber on said tube in fluid communication with the interior of said first lumen, the wall of said sampling chamber being composed of a second flexible material that is freely and selectively permeable to said one or more liquid fluids or gaseous fluids of interest, said second material being substantially impermeable to other liquid fluids of gaseous fluids;
c) means for positioning said walled sampling chamber substantially adjacent a wall portion of said internal organ in order to allow at least one of said liquid fluids or gaseous fluids of interest from the tissue of the wall portion of the internal organ to permeate said walled sampling chamber; and d) said urinary catheter apparatus including at least one second lumen extending longitudinally through said tube and being adapted to be in fluid communication with the bladder.
44. A combination apparatus according to claim 43, wherein said walled sampling chamber is substantially in direct contact with a wall portion of the internal organ.
45. A combination apparatus according to claim 43, further including temperature sensing means within said walled sampling chamber.
46. A combination apparatus according to Claim 43, wherein at least a portion of said first flexible material is selected from the group of polyester elastomers derived from the reaction of dimethylterephthalate 1, 4-butanediol and 2-hydro-.omega.-hydroxypoly (oxytetramethylene).
47. A combination tonometric catheter and ureteric catheter apparatus for measuring a liquid fluid or gaseous fluid property indicative of the condition of an internal organ of a human or other mammal in vivo, comprising:
a) an elongated tube having a first lumen extending longitudinally therethrough, a portion of said tube being composed of a first flexible material that is substantially impermeable to one or more liquid fluids or gaseous fluids of interest, said fluids of interest including oxygen gases and carbon dioxide gases;
b) at least one walled sampling chamber on said tube in fluid communication with the interior of said first lumen, the wall of said sampling chamber being composed of a second flexible material that is freely and selectively permeable to said one or more liquid fluids or gaseous fluids of interest, said second material being substantially impermeable to other liquid fluids of gaseous fluids;
c) means for positioning said walled sampling chamber substantially adjacent a wall portion of said internal organ in order to allow at least one of said liquid fluids or gaseous fluids of interest from the tissue of the wall portion of the internal organ to permeate said walled sampling chamber; and d) said ureteric catheter apparatus including at least one second lumen extending longitudinally through said tube and being adapted to be in fluid communication with the ureter.
a) an elongated tube having a first lumen extending longitudinally therethrough, a portion of said tube being composed of a first flexible material that is substantially impermeable to one or more liquid fluids or gaseous fluids of interest, said fluids of interest including oxygen gases and carbon dioxide gases;
b) at least one walled sampling chamber on said tube in fluid communication with the interior of said first lumen, the wall of said sampling chamber being composed of a second flexible material that is freely and selectively permeable to said one or more liquid fluids or gaseous fluids of interest, said second material being substantially impermeable to other liquid fluids of gaseous fluids;
c) means for positioning said walled sampling chamber substantially adjacent a wall portion of said internal organ in order to allow at least one of said liquid fluids or gaseous fluids of interest from the tissue of the wall portion of the internal organ to permeate said walled sampling chamber; and d) said ureteric catheter apparatus including at least one second lumen extending longitudinally through said tube and being adapted to be in fluid communication with the ureter.
48. A combination apparatus according to claim 47, wherein said walled sampling chamber is substantially in direct contact with a wall portion of the internal organ.
49. A combination apparatus according to claim 47, further including temperature sensing means within said walled sampling chamber.
50. A combination apparatus according to Claim 47, wherein at least a portion of said first flexible material is selected from the group of polyester elastomers derived from the reaction of dimethylterephthalate 1, 4-butanediol and 2-hydro-.omega.-hydroxypoly (oxytetramethylene).
51. A combination tonometric catheter apparatus, nasogastric catheter, and feeding tube apparatus for measuring a liquid fluid or gaseous fluid property indicative of the condition of an internal organ of a human or other mammal in vivo, comprising:
a) an elongated tube having a first lumen extending longitudinally therethrough, a portion of said tube being composed of a first flexible material that is substantially impermeable to one or more liquid fluids or gaseous fluids of interest, said fluids of interest including oxygen gases and carbon dioxide gases;
b) at least one walled sampling chamber on said tube in fluid communication with the interior of said first lumen, the wall of said sampling chamber being composed of a second flexible material that is freely and selectively permeable to said one or more liquid fluids or gaseous fluids of interest, said second material being substantially impermeable to other liquid fluids of gaseous fluids;
c) means for positioning said walled sampling chamber substantially adjacent a wall portion of said internal organ in order to allow at least one of said liquid fluids or gaseous fluids of interest from the tissue of the wall portion of the internal organ to permeate said walled sampling chamber;
d) said nasogastric catheter apparatus including at least one second lumen extending longitudinally through said tube and being adapted to be in fluid communication with the gastrointestinal tract; and e) said feeding tube apparatus including at least one third lumen extending longitudinally through said tube and being adapted to be in fluid communication with the gastrointestinal tract.
a) an elongated tube having a first lumen extending longitudinally therethrough, a portion of said tube being composed of a first flexible material that is substantially impermeable to one or more liquid fluids or gaseous fluids of interest, said fluids of interest including oxygen gases and carbon dioxide gases;
b) at least one walled sampling chamber on said tube in fluid communication with the interior of said first lumen, the wall of said sampling chamber being composed of a second flexible material that is freely and selectively permeable to said one or more liquid fluids or gaseous fluids of interest, said second material being substantially impermeable to other liquid fluids of gaseous fluids;
c) means for positioning said walled sampling chamber substantially adjacent a wall portion of said internal organ in order to allow at least one of said liquid fluids or gaseous fluids of interest from the tissue of the wall portion of the internal organ to permeate said walled sampling chamber;
d) said nasogastric catheter apparatus including at least one second lumen extending longitudinally through said tube and being adapted to be in fluid communication with the gastrointestinal tract; and e) said feeding tube apparatus including at least one third lumen extending longitudinally through said tube and being adapted to be in fluid communication with the gastrointestinal tract.
52. A combination apparatus according to claim 51, wherein said walled sampling chamber is substantially in direct contact with a wall portion of the internal organ.
53. A combination apparatus according to claim 51, further including temperature sensing means within said walled sampling chamber.
54. A combination apparatus according to claim 51, wherein said nasogastric catheter is a nasogastric sump apparatus.
55. A combination apparatus according to Claim 51, wherein at least a portion of said first flexible material is selected from the group of polyester elastomers derived from the reaction of dimethylterephthalate 1, 4-butanediol and 2-hydro-.omega.-hydroxypoly (oxytetramethylene).
Applications Claiming Priority (2)
| Application Number | Priority Date | Filing Date | Title |
|---|---|---|---|
| US23728688A | 1988-08-26 | 1988-08-26 | |
| US237,286 | 1988-08-26 |
Publications (1)
| Publication Number | Publication Date |
|---|---|
| CA1335708C true CA1335708C (en) | 1995-05-30 |
Family
ID=22893105
Family Applications (1)
| Application Number | Title | Priority Date | Filing Date |
|---|---|---|---|
| CA000609065A Expired - Fee Related CA1335708C (en) | 1988-08-26 | 1989-08-23 | Tonometric catheter combination |
Country Status (2)
| Country | Link |
|---|---|
| CA (1) | CA1335708C (en) |
| ES (1) | ES2014889A6 (en) |
-
1989
- 1989-08-23 CA CA000609065A patent/CA1335708C/en not_active Expired - Fee Related
- 1989-08-25 ES ES8902940A patent/ES2014889A6/en not_active Expired - Lifetime
Also Published As
| Publication number | Publication date |
|---|---|
| ES2014889A6 (en) | 1990-07-16 |
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