Ventilation monitoring during moderate sedation in GI patients

Thomas J. Ebert, Austin H. Middleton, Nikhil Makhija

Sedation in locations outside the operating room (OR) is common. Guidelines for safe patient monitoring have been updated by the American Society of Anesthesiology to include monitoring of ventilation and/or carbon dioxide (CO2). Although technologies exist to monitor these variables, the quality and/or availability of these measurements in non-OR settings is not optimal. This quality improvement project assessed the value of impedance technology for monitoring minute ventilation (MV) compared to standard end-tidal monitoring of CO2 (ETCO2). Patients undergoing GI exams with moderate sedation provided by anesthesia providers were monitored for MV with a respiratory volume monitor (ExSpiron 1Xi, Respiratory Motion, Waltham, MA) and ETCO2 via nasal cannula (NC). Calibration and baseline data were collected prior to sedation. Continuous MV and ETCO2 data were collected and averaged, providing minute values after sedation medications throughout the procedure. Stable periods of reduced MV were averaged and used in comparison to ETCO2. Data from 20 patients were evaluated. After sedation, the expected decrease in MV after sedation was observed in 18 of 20 patients (average -47.82 %), while an increase in ETCO2 was observed in just 10 of 20 patients (average -5.17 mm Hg). The correlation coefficient between changes in MV and ETCO2 in response to sedation administration was positive and not significant, r = 0.223. Ventilation monitoring may provide an element of safety for earlier and more reliable detection of reduced ventilation compared to a surrogate for hypoventilation, ETCO2, in patients undergoing sedation for GI procedures outside of the OR.