Clinical evaluation of reflectance spectrophotometry for the measurement of gastric microvascular oxygen saturation in patients undergoing cardiopulmonary bypass

Objective: To evaluate the impact of cardiopulmonary bypass (CPB) on gastric mucosal oxygen saturation assessed by reflectance spectrophotometry in patients undergoing coronary artery bypass graft surgery. Design: Prospective, observational study. Setting: A division of cardiothoracic anesthesia in a university hospital. Participants: Twelve consecutive patients undergoing CPB. Interventions: Monitoring, anesthesia, surgical procedure, and CPB for the patients followed routine clinical protocol as established in the departments. Microvascular oxygen saturation in gastric mucosa was assessed by reflectance spectrophotometry before, during, and after CPB. Measurements and Main Results: Gastric mucosal oxygen saturation averaged 65 ± 7% (mean ± SD) before CPB, decreased significantly to 57 ± 9% during CPB (p < 0.01), and was 59 ± 8% after CPB. These changes in regional oxygen saturation were not mirrored in variables of systemic oxygenation. Gastric mucosal oxygen saturation always showed instantaneous reactions to various surgical and pharmacologic interventions. Conclusion: Reflectance spectrophotometry allowed the authors to assess gastric mucosal oxygen saturation with a high repetition rate, regardless of spontaneous circulation with pulsatile flow or nonpulsatile flow during CPB. This technique provided the means to monitor on-line the course of tissue oxygen saturation throughout the operative procedure. Reflectance spectrophotometry is an appropriate and sensitive assessment tool to monitor gastric mucosal oxygen saturation in patients undergoing CPB.