Consistent with clinical practice, the authors reported that the arterial oxygen saturation was the most important physiological measurement to assess sedation risk. (Image source: Thinkstock)

Consistent with clinical practice, the authors reported that the arterial oxygen saturation was the most important physiological measurement to assess sedation risk. (Image source: Thinkstock)

Lying on a stretcher awaiting a procedure, one cannot help but have some anxiety about the potential for complications. To anyone trained in anesthesiology, the serious complications related to sedation are very real. It is essential that as we change care paradigms for procedural sedation, we find methods for evaluating the risk of adverse events.

Dr. Paul J. Niklewski, Ethicon Endo-Surgery, Inc., Cincinnati, Ohio, and the Department of Neuroscience, University of Cincinnati, Cincinnati, Ohio, and colleagues from Ethicon Endo-Surgery and the Department of Anesthesiology, University of Cincinnati Medical Center, Cincinnati, Ohio, identified physiologic parameters that can be used to assess sedation risk. Their article titled “A Novel Index of Hypoxemia for Assessment of Risk During Procedural Sedation” was published in this month’s edition of Anesthesia & Analgesia.

The authors had 13 practicing anesthesiologists review records, including detailed oximetry and capnometry data, from 204 procedures for risk of oversedation where patients had been sedated with the SEDASYS® System, a new paradigm for sedation during endoscopy. Each anesthesiologist assigned a Likert score from 1-10 to each record grading the risk of oversedation-related sequelae from no risk to highest risk. Definitions were established for complications of oxygen desaturation, apnea, hypercarbia, hypotension, and bradycardia. The relationship of these scores to five physiologic variables–saturation, respiration rate, end-tidal carbon dioxide (EtCO2), heart rate, and arterial blood pressure–was assessed. In addition, a new parameter named area under the curve for desaturation (AUCDesat) was evaluated for association with the risk of oversedation.

AUCDesat is an integrated numerical value that represents the total area under 90% arterial oxygen saturation. Because it is an integral of desaturation over time, it incorporates depth, duration, and incidence of desaturation.

The authors reported that arterial oxygenation was the most important physiological parameter for assessing sedation risk. Of possible measures of desaturation, the authors found that AUCDesat best correlated to the mean Likert score indicating the risk of oversedation. The authors recognize that there is no information about outcome, and that AUCDesat needs to be evaluated relative to outcome rather than the anesthesiologist’s perception to validate its utility in assessing sedation risk.The SEDASYS System represents a new paradigm in procedural sedation and insuring patient safety is paramount. Outcome studies are difficult and require objective measures of risk. AUCDesat may turn out to be useful as a tool for assessing risk. It is similar to the SatSeconds™ (Covidien, Boulder, CO) alarm management system, which is also designed to assess the depth and duration of desaturation.

Procedural sedation will continue to be performed for large numbers of patients and paradigms for medications and care models are likely to evolve. Hopefully these new care models will be sufficiently tested before adoption to alleviate concerns about safety.