Using continuous quantitative capnography for emergency department procedural sedation: a systematic review and cost-effectiveness analysis

End-tidal CO₂ has been advocated to improve safety of emergency department (ED) procedural sedation by decreasing hypoxia and catastrophic outcomes. This study aimed to estimate the cost-effectiveness of routine use of continuous waveform quantitative end-tidal CO₂ monitoring for ED procedural sedation in prevention of catastrophic events. Markov modeling was used to perform cost-effectiveness analysis to estimate societal costs per prevented catastrophic event (death or hypoxic brain injury) during routine ED procedural sedation. Estimates for efficacy of capnography and safety of sedation were derived from the literature. This model was then applied to all procedural sedations performed in US EDs with assumptions selected to maximize efficacy and minimize cost of implementation. Assuming that capnography decreases the catastrophic adverse event rate by 40.7% (proportional to efficacy in preventing hypoxia), routine use of capnography would decrease the 5-year estimated catastrophic event rate in all US EDs from 15.5 events to 9.2 events (difference 6.3 prevented events per 5 years). Over a 5-year period, implementing routine end-tidal CO₂ monitoring would cost an estimated $2,830,326 per prevented catastrophic event, which translates into $114,007 per quality-adjusted life-year. Sensitivity analyses suggest that reasonable assumptions continue to estimate high costs of prevented catastrophic events. Continuous waveform quantitative end-tidal CO₂ monitoring is a very costly strategy to prevent catastrophic complications of procedural sedation when applied routinely in ED procedural sedations.