Efficacy of End-Tidal Capnography Monitoring during Flexible Bronchoscopy in Nonintubated Patients under Sedation: A Randomized Controlled Study

Abstract

Background: Although appropriate sedation is recommended during flexible bronchoscopy (FB), patients are at risk for hypoventilation due to inadvertent oversedation. End-tidal capnography is expected as an additional useful monitor for these patients during FB. Objectives: The aim of this study was to evaluate the benefit of additional end-tidal capnography monitoring in reducing the incidence of hypoxemia during FB in patients under sedation. Methods: Patients undergoing FB under moderate sedation without tracheal intubation were randomly assigned to receive standard monitoring including pulse oximetry or additional capnography monitoring. Bronchoscopy examiners for the only capnography group were informed of apnea events by alarms and display of the capnography monitor. Results: A total of 185 patients were enrolled. Patient characteristics were well balanced between the two groups. Hypoxemia (at least one episode of pulse oximeter oxygen saturation [SpO₂] < 90%) was observed in 27 out of 94 patients in the capnography group (29%) and in 42 out of 91 patients in the control group (46%; p = 0.014), resulting in an absolute risk difference of −17.4% (95% confidence interval, −31.1 to −3.7). In the capnography group, hypoxemia duration was shorter (20.4 vs. 41.7 s, p = 0.029), severe hypoxemic events (SpO₂ < 85%) were observed less frequently (16 [17%] vs. 29 [32%], p = 0.019), and the mean lowest SpO₂ value was higher (90.5 vs. 87.6%, p = 0.002). Conclusion: End-tidal capnography monitoring can reduce the incidence and duration of hypoxemia during FB in nonintubated patients under sedation.