Method and device for assessing perfusion failure in a patient

• US 6,216,024 B1
• Filed: 09/24/1998
• Issued: 04/10/2001
• Est. Priority Date: 07/06/1995
• Status: Expired due to Term

• Current Assignee: Weil Institute Of Critical Care Medicine
• Original Assignee: Institute of Critical Care Medicine
• Inventors: Tang, Wanchun, Weil, Max Harry, Bisera, Jose
• Primary Examiner(s): Nasser, Robert L.
• Application Number:
  US09/160,224
• Time in Patent Office: 929 Days
• Field of Search: 300/345-350, 300/309, 300/300-301, 300/529, 300/587, 300/353-4
• US Class Current: 600/353
• CPC Class Codes: A61B 5/0261 using optical means, e.g. infrared light
• CPC Class Codes: A61B 5/14542 for measuring blood gases A61B5/14551 takes precedence
• CPC Class Codes: A61B 5/1473 invasive, e.g. introduced into the body by a catheter A61B5/1482 takes precedence
• CPC Class Codes: A61B 5/412 Detecting or monitoring sepsis
• CPC Class Codes: A61B 5/42 Detecting, measuring or recording for evaluating the gastrointestinal, the endocrine or the exocrine systems A61B1/00, A61B5/4857, A61B5/486, A61B5/4866, A61B5/4869 take precedence
• CPC Class Codes: A61B 5/682 Mouth, e.g., oral cavity; tongue; Lips; Teeth

Abstract

Methods and devices are provided for assessing impairment of blood circulation in a patient, such as that in perfusion failure, by measurement of pCO₂ (partial pressure of carbon dioxide) in the upper digestive and/or respiratory tract of the patient. The method comprises introducing a carbon dioxide sensor into the upper digestive and/or respiratory tract of a patient, without passing the sensor down through or beyond the patient'"'"'s epiglottis. Specifically, a carbon dioxide sensor is placed adjacent a mucosal surface within the upper digestive and/or respiratory tract, preferably within the patient'"'"'s mouth or inside the patient'"'"'s nose. By avoiding passage through the mouth into the throat and esophagus, discomfort is substantially avoided and the potential for injury minimized. Previously, the belief in the art was that increased partial pressure of carbon dioxide was a localized phenomenon during perfusion failure; however, applicants have now discovered that increases in tissue CO₂ occur throughout the body during perfusion failure, and the method and device of the invention are premised on this discovery.

Claims

1. A device for assessing perfusion failure in a patient in a minimally invasive manner, the device comprising:

a carbon dioxide sensor means for detecting for a partial pressure of carbon dioxide (pCO2), the sensor means being adapted for lying adjacent a mucosal surface of the upper respiratory/digestive tract above the epiglottis of a patient and measuring carbon dioxide at the mucosal surface;

an isolating means for inhibiting air flow around the mucosal surface in a region surrounding the sensor means; and

an indicating means operably connected to the sensor means, wherein the indicating means indicates a degree of perfusion failure of the patient associated with the detected partial pressure of carbon dioxide.

2. The device of claim 1, wherein the isolating means includes a sealing part of elastomeric material positioned to form a seal against a perimeter of the mucosal surface surrounding the sensor.

3. The device of claim 1, wherein the isolating means is a holder, the holder being designed to fit within the mouth of the patient and hold the sensor in place adjacent the mucosal surface.

4. The device of claim 3, wherein the holder is designed to contact the bottom of the tongue and the floor of the mouth of the patient, and to lie substantially against an intersection region where the bottom surface of the tongue emerges from the floor of the mouth, wherein during detecting the sensor means is positioned within the holder and adjacent a sublingual mucosal surface.

5. The device of claim 3, wherein the holder is constructed to fit between the inside of a lip and gum of the patient, wherein during detecting the sensor means is positioned within the holder and adjacent a mucosal surface isolated by the holder.

6. The device of claim 1, wherein the isolating means is a holder, the holder being designed to fit within a nares of the patient and hold the sensor in place adjacent the mucosal surface.

7. The device of claim 1, wherein the device further comprises a moisturizing means for supplying moisture to the mucosal surface adjacent the sensor.

8. The device of claim 1, wherein the sensor is a fiber optic carbon dioxide sensor.

9. The device of claim 1, wherein the indicating means comprises a circuit for generating a signal indicating a rate of change of pCO₂ with time.

10. A method for assessing perfusion failure of a patient, the method comprising:

placing a carbon dioxide sensor adjacent a mucosal surface of an upper digestive/respiratory tract of a patient; and

measuring a partial pressure of carbon dioxide at the mucosal surface;

wherein a partial pressure of carbon dioxide at the mucosal surface of the upper digestive/respiratory tract that is substantially greater than a normal partial pressure of carbon dioxide is indicative of perfusion failure in the patient.

11. The method of claim 10, wherein the mucosal surface is within the mouth of the patient.

12. The method of claim 10, wherein the mucosal surface is within the nose of the patient.

13. The method of claim 10, wherein the partial pressure of carbon dioxide is measured using a fiber optic carbon dioxide sensor.

14. The method of claim 10, wherein said measuring step comprises:

positioning a carbon dioxide sensor means for detecting a partial pressure of carbon dioxide (pCO₂) adjacent the mucosal surface; and

inhibiting air flow around the mucosal surface in a region surrounding the sensor means.