Does End‐tidal Carbon Dioxide Monitoring Detect Respiratory Events Prior to Current Sedation Monitoring Practices?

Objectives: The value of ventilation monitoring with end‐tidal carbon dioxide (ETCO₂) to anticipate acute respiratory events during emergency department (ED) procedural sedation and analgesia (PSA) is unclear. The authors sought to determine if ETCO₂ monitoring would reveal findings indicating an acute respiratory event earlier than indicated by current monitoring practices. Methods: The study included a prospective convenience sample of ED patients undergoing PSA. Clinicians performed ED PSA procedures with generally accepted patient monitoring, including oxygen saturation (SpO₂), and clinical ventilation assessment. A study investigator recorded ETCO₂ levels and respiratory events during each PSA procedure, with clinical providers blinded to ETCO₂ levels. Acute respiratory events were defined as SpO₂≤92%, increases in the amount of supplemental oxygen provided, use of bag‐valve mask or oral/nasal airway for ventilatory assistance, repositioning or airway alignment maneuvers, and use of physical or verbal means to stimulate patients with depressed ventilation or apnea, and reversal agent administration. Results: Enrollment was stopped after independent review of 20 acute respiratory events in 60 patient sedation encounters (33%). Abnormal ETCO₂ findings were documented in 36 patients (60%). Seventeen patients (85%) with acute respiratory events demonstrated ETCO₂ findings indicative of hypoventilation or apnea during PSA. Abnormal ETCO₂ findings were documented before changes in SpO₂ or clinically observed hypoventilation in 14 patients (70%) with acute respiratory events. Conclusions: Abnormal ETCO₂ findings were observed with many acute respiratory events. A majority of patients with acute respiratory events had ETCO₂ abnormalities that occurred before oxygen desaturation or observed hypoventilation.