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 (ETCO 2 ) to anticipate acute respiratory events during emergency department (ED) procedural sedation and analgesia (PSA) is unclear. The authors sought to determine if ETCO 2 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 (SpO 2 ), and clinical ventilation assessment. A study investigator recorded ETCO 2 levels and respiratory events during each PSA procedure, with clinical providers blinded to ETCO 2 levels. Acute respiratory events were defined as SpO 2 ≤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 ETCO 2 findings were documented in 36 patients (60%). Seventeen patients (85%) with acute respiratory events demonstrated ETCO 2 findings indicative of hypoventilation or apnea during PSA. Abnormal ETCO 2 findings were documented before changes in SpO 2 or clinically observed hypoventilation in 14 patients (70%) with acute respiratory events.Conclusions:Abnormal ETCO 2 findings were observed with many acute respiratory events. A majority of patients with acute respiratory events had ETCO 2 abnormalities that occurred before oxygen desaturation or observed hypoventilation.