Post written by Ala Sharara, MD, AGAF, FACG, FRCP, from the Division of Gastroenterology and Hepatology, American University of Beirut Medical Center, Beirut, Lebanon.

The target sedation level for endoscopic procedures is conscious sedation. However, patients might progress to deeper levels of sedation, such as deep sedation and general anesthesia. To our knowledge, no study has specifically investigated the degree of sedation achieved in clinical practice and the time spent at each level using a standardized conscious sedation regimen during these procedures.

Therefore, we conducted a prospective study to assess degree of sedation in patients undergoing propofol-based endoscopy. We used the bispectral index (BIS), a noninvasive tool that uses electroencephalographic monitoring to provide anesthesiologists with a numerical representation of the depth of sedation and the effects of anesthesia on patients.

The monitoring parameters required by the American Society of Anesthesiologists and the American Society for Gastrointestinal Endoscopy—heart rate, blood pressure, continuous electrocardiography, pulse oximetry, capnography, and patient reactivity—may not be accurate enough in assessing depth of sedation during GI endoscopy, even for experienced anesthesiologists. For some patients, any oversedation may result in delayed recovery, cognitive dysfunction, and other related adverse events.

Our finding that the line between conscious sedation and general anesthesia, as well as a deep hypnotic state, was frequently crossed is striking. Notably, 88% of patients spent more than one-third of the total sedation time in general anesthesia and more than 10% in a deep hypnotic state. Younger age was the only predictor for a BIS score below 60, and no significant predictors were identified for a BIS score below 40 in the multivariate analysis. Patients who experienced a BIS score below 40 had a higher incidence of postprocedural dizziness.

The number needed to harm was 6, indicating that one could expect prolonged dizziness in 1 of every 6 patients who experienced a deep hypnotic state during their procedural sedation. Thus, endoscopists and anesthesiologists should develop new objective and reliable depth-monitoring devices to limit oversedation and related adverse events.

To our knowledge, this study is the first to investigate time spent by patients undergoing propofol-based GI endoscopy in different stages of sedation using BIS monitoring.

Illustrative recording of dips in the bispectral index (BIS) recorded during endoscopy: A, BIS score <60; B, BIS score <40. The y axis denotes the BIS score and the x axis indicates time (in minutes).

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