Air tonometry method and apparatus for measuring intraluminal gastrointestinal pCO.sub.2 and pO.sub.2
First Claim
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1. A method for measuring partial pressure of one or more gases in the gastrointestinal lumen of a patient comprising the steps of:
- A. defining an intraluminal region as a region-of-interest within the gut of a patient by inserting a catheter into said patient, said catheter having a distal end and a proximal end, whereby said distal tip is located in a desired intraluminal region in the gut of said patient and said proximal end is external to said patient, and wherein said catheter further includes an open-faced chamber defined near the distal end of said catheter, and a gas permeable membrane spanning said open-faced chamber to define a closed gas-filled gas sensing region therein, said closed gas sensing region having substantially no fluidic communication with said proximal end, and includes a detector, said detector including a CO2 sensor affixed to said catheter near said distal end and including selectively operative sensor means for generating at said proximal end a signal representative of the concentration of CO2 in said intraluminal region adjacent to said distal end,B. sensing in said gut the concentration of said gases in said region-of-interest, andC. generating a signal representative of said concentration, said signal being representative of the partial pressure of said gases in said region-of-interest, wherein said sensing step and said generating step include the step of operating said sensor means.
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Abstract
A method and apparatus for measuring or monitoring pCO2, and optionally pO2, on a real-time basis, in the stomach or the intestine using air tonometry. The intraluminal measurements are made using a catheter having a CO2 sensor, and optionally a pO2 sensor, at its tip for in situ measurements, or by circulating a fixed amount of air through the catheter with measurement occurring at the proximal end of the catheter. Instrumentation supporting the sensor may be adapted for location within a patient or external to a patient.
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Citations
16 Claims
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1. A method for measuring partial pressure of one or more gases in the gastrointestinal lumen of a patient comprising the steps of:
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A. defining an intraluminal region as a region-of-interest within the gut of a patient by inserting a catheter into said patient, said catheter having a distal end and a proximal end, whereby said distal tip is located in a desired intraluminal region in the gut of said patient and said proximal end is external to said patient, and wherein said catheter further includes an open-faced chamber defined near the distal end of said catheter, and a gas permeable membrane spanning said open-faced chamber to define a closed gas-filled gas sensing region therein, said closed gas sensing region having substantially no fluidic communication with said proximal end, and includes a detector, said detector including a CO2 sensor affixed to said catheter near said distal end and including selectively operative sensor means for generating at said proximal end a signal representative of the concentration of CO2 in said intraluminal region adjacent to said distal end, B. sensing in said gut the concentration of said gases in said region-of-interest, and C. generating a signal representative of said concentration, said signal being representative of the partial pressure of said gases in said region-of-interest, wherein said sensing step and said generating step include the step of operating said sensor means. - View Dependent Claims (2, 3, 4)
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5. An intraluminal gastrointestinal gas measuring system, comprising:
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A. an elongated catheter having a distal end and a proximal end, B. one or more gas sensors affixed to said catheter near said distal end, wherein at least one of said gas sensors includes an open-faced chamber defined near the distal end of said catheter, and a gas permeable membrane spanning said open-faced chamber to define a closed gas-filled gas sensing region therein, said closed gas sensing region having substantially no fluidic communication with said proximal end, and wherein at least one of said gas sensors is adjacent to said closed gas sensing region and in optical communication with said proximal end, and C. sensor means for generating at said proximal end a signal representative of the partial pressure of said gases external to said catheter and adjacent to said gas sensors. - View Dependent Claims (6, 7, 8, 9, 10, 11, 12)
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13. An intraluminal gastrointestinal gas measuring system, comprising:
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A. an elongated catheter having a distal end and a proximal end, and having; i. an open-faced chamber near said distal end and a gas permeable membrane spanning said chamber to define a gas-filled gas sensing region, ii. a first lumen extending from said proximal end to said sensing region, and iii. a second lumen extending from said proximal end to said gas sensing region B. means as for coupling said first and second lumens at said proximal end to establish a closed gas flow path through said first and second lumens and said gas sensing regions, C. flow means for establishing a continuously recirculating flow of gas in said gas flow path, and D. detector means for determining the gas concentration in said gas flow path. - View Dependent Claims (14, 15, 16)
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Specification