Esophageal pulse oximetry is more accurate and detects hypoxemia earlier than conventional pulse oximetry during general anesthesia.

The esophagus is perfused directly by prominent arteries and may provide a more consistent tissue source for pulse oximetry. The goal of this study was to evaluate the sensitivity and accuracy of an esophageal pulse oximetry probe on patients during controlled hypoxemia in comparison to measurements obtained with conventional pulse oximetry (SpulseO(2)). Forty-five ASA I-II adult patients were included in this prospective observational study. Nellcor digital oximetric probes were placed on finger tips for SpulseO(2) before anesthesia. After tracheal intubation, an esophageal probe was placed in the lower segment of the esophagus for esophageal oximetric monitoring (SoesO(2)). All patients were disconnected from the breathing circuit to establish a controlled hypoxemia, and were re-connected to the breathing circuit and ventilated with 100% oxygen immediately when SoesO(2) dropped to 90%. Matched SoesO(2) and SpulseO(2) readings were recorded when SoesO(2) measurements were at 100%, 95%, 90% and the lowest reading. The time for SoesO(2) and SpulseO(2) to drop from 100% to 95%, 90% and return to 100% was recorded. Oxygen saturation from arterial blood samples (SartO(2)) was also measured at each time point respectively. The linear correlation coefficient of the regression analysis between SartO(2) and SoesO(2) was 0.954. The mean ± 2SD of the difference was 0.3% ± 4.3% for SoesO(2) vs. SartO(2) and 6.8% ± 5.6% for SpulseO(2) vs. SartO(2) (P < 0.001). The 95% confidence interval for the absolute difference between SoesO(2) and SartO(2) was 0.3% to 0.7% and 6.2% to 7.4% between SpulseO(2) and SartO(2). The time to reach 90% saturation measured with SoesO(2) was approximately 94 seconds earlier than the SpulseO(2) (P < 0.001). In conclusion, SoesO(2) is more accurate and enables earlier detection of hypoxemia when compared to conventional pulse oximetry during hypoxemia for patients undergoing general anesthesia.