Capnography for procedural sedation in the ED: a systematic review

Introduction: Procedural sedation and analgesia (PSA) is commonplace in the ED. Previous studies have identified capnography as a reliable indicator of PSA-induced respiratory depression. This review investigates the potential effect on patient safety of the use of capnography in addition to standard monitoring for adult patients undergoing PSA in the ED.

Methods: MEDLINE, Embase, Scopus, CINAHL and Google Scholar were searched systematically for ED studies using capnography during PSA. Data extraction was performed by two independent authors. Using MedCalc V.13.3.3 and Meta-DiSc V.1.4, data were aggregated under the random-effects model and heterogeneity was assessed using Cochran's Q-test and the I² statistic.

Results: Of the 737 studies that were screened, 7 studies met the eligibility criteria, representing a total of 662 patients. The aggregate diagnostic accuracy for capnography identifying an adverse event included a diagnostic OR of approximately 6 (OR: 5.87; 95% CI 2.41 to 14.3; p<0.001), sensitivity 0.82 (95% CI 0.76 to 0.87), specificity 0.6 (95% CI 0.55 to 0.64), negative likelihood ratio 0.3 (95% CI 0.12 to 0.75) and positive likelihood ratio 1.89 (95% CI 1.53 to 2.34). There was a lack of statistical evidence for a difference in the proportion of adverse events detected when capnography was used in addition to standard monitoring (48.8% (95% CI 32.85 to 64.92)) compared with chance alone (50%).

Conclusions: There is no firm evidence that capnography provides additional safety compared with standard monitoring alone during PSA in adults in the ED. There is a paucity of published research involving preoxygenated patients who remain on high-flow oxygen throughout PSA. Well-powered randomised controlled trials, employing an accepted adverse event reporting tool in such patients, are required. Until then, we advocate continued compliance with current professional recommendations for the use of capnography during PSA in adults in the ED.