CEREBRAL OXYGENATION MONITORING IN PATIENTS UNDERGOING ERCP UNDER DEEP SEDATION: A PROSPECTIVE OBSERVATIONAL STUDY

Aims Unintentional prolongation of time under deep sedation increases the risk for sedation-related complications during endoscopic retrograde cholangiopancreatography (ERCP). Cerebral oximetry provides early detection of cerebral hypoxia and hypoperfusion by demonstrating the regional hemoglobin oxygen saturation (rSO2) in the cerebral cortex. In the first study to date, we aimed to evaluate whether cerebral oxygenation is affected during deep sedation in ERCP and determine whether cerebral desaturation events (CDEs) are associated with deeper levels of sedation and cardiopulmonary complications.

Methods Consecutive patients who underwent ERCP between July and October 2019 were included prospectively. Propofol was used as monotherapy. Sedation depth was assessed with bispectral index (BIS) and values between 40 and 60 were defined as deep sedation. Participants were monitored continuously along with INVOS 5100 C cerebral oximeter (Covidien-Medtronic, Boulder, Colorado, USA). RSO2 values were registered prior to sedation (baseline value), every 5 minutes until ERCP termination and at recovery of consciousness. BIS values were simultaneously recorded. Cerebral desaturation was defined as a greater than 10% drop from individual baseline rSO2.

Results Sixty patients, mean age 67.9 years, were enrolled. BIS values ranged from 18 to 84. No significant correlation was observed between rSO2 and BIS measurements throughout the recordings. Data from patients ≥ 65 years (n = 37) were analyzed separately with similar results. Time course of mean rSO2 and BIS recordings exhibited little variability throughout the sedation period and no association between percent changes of rSO2 and BIS was observed (r = −0.086, p = 0.44). Overall, CDEs were detected in 4.8% of INVOS recordings but none was associated with clinical manifestations. Eight cardiopulmonary complications (hypoxia, hypotension) occurred without the presence of cerebral desaturation.

Conclusions Cerebral oxygenation and depth of sedation remained uncorrelated at every time-point of the procedure while they exhibited little variability throughout the sedation period. Cerebral oximetry did not detect complications earlier than standard monitors.