Detection of ischemia by a biosensor measuring tissue carbon dioxide tension

Abstract

ObjectiveWe investigated a miniaturized biomedical sensor that can be inserted into any tissue or organ to measure partial gas pressure of carbon dioxide (pCO2) and temperature continuously in real time. Numerous animal studies have shown that pCO2 is a sensitive and specific marker of ischemia. The present study was designed to examine the feasibility and safety of the device in patients scheduled for limb (arm/leg) surgery with tourniquet. MethodsWe performed an observational, prospective, cohort study at a single center in Norway. The primary and secondary endpoints were to evaluate the ability of the biosensor to measure partial gas pressure of carbon dioxide and corresponding temperature levels in ischemic and non-ischemic limb musculature and subcutaneous tissue. Additional secondary objectives were to assess the safety/efficacy of using the device. ResultsForty-five patients received the sensor in this study from May 2020 to June 2022. The mean difference between the partial gas pressure of carbon dioxide levels in ischemia and non-ischemia limbs was 4.7 kPa, 95% CI [3.7; 5.8], p<0.001. Combining intramuscular and subcutaneous tissue, the mean total difference between the partial gas pressure of carbon dioxide levels in ischemic and non-ischemic limb was 3.9 kPa; 95% CI [3.4; 4.4], p<0.001. The mean difference between the temperature levels in intramuscular and subcutaneous tissue in ischemic and non-ischemic limb was 2.5oC; 95% CI [2.040; 2.9], p<0.001 and 2.6oC; 95 %CI [2.1; 3.2], p<0.001 respectively. Four patients experienced minor bleeding (less than 5 ml) during insertion of the sensors. No other bleeding was reported during the study period. None of the subjects experienced any kind of clinical infections/inflammations or pain (Numeric Rating Scale score 0) at the insertion sites during the entire study period. No serious adverse events related to the study procedure or device were noted. ConclusionsThe device provides a safe and dependable way to continuously and instantly track partial gas pressure of carbon dioxide levels in muscular and subcutaneous tissues, thereby offering a means to monitor ischemia.