Capnography Improves Detection of Apnea During Procedural Sedation for Percutaneous Transhepatic Cholangiodrainage

Abstract

Capnography provides noninvasive monitoring of ventilation and can enable early recognition of altered respiration patterns and apnea. To compare the detection of apnea and the prediction of oxygen desaturation and hypoxemia using capnography versus clinical surveillance during procedural sedation for percutaneous transhepatic cholangiodrainage (PTCD). Twenty consecutive patients scheduled for PTCD were included in the study. All patients were sedated during the procedure using midazolam and propofol. Aside from standard monitoring, additional capnographic monitoring was used and analyzed by an independent observer. The mean (± SD) cumulative duration of apnea demonstrated by capnography was significantly longer than the mean cumulative duration of clinically detected apnea (207.5 ± 348.8 s versus 8.2 ± 17.9 s; P=0.015). The overall number of detected episodes of apnea was also significantly different (113 versus seven; P=0.012). There were 15 events of oxygen desaturation (decrease in oxygen saturation [SaO2] ≥ 5%), which were predicted in eight of 15 cases by capnography and in one of 15 cases by clinical observation. There were three events of hypoxemia (SaO2 <90%) that were predicted in three of three cases by capnography and in one of three cases by clinical observation. Capnographic monitoring was superior to clinical surveillance in the detection of apnea and in the prediction of oxygen desaturation during procedural sedation for PTCD.