Continuous Capnometry Should be Standard Practice for Moderate-Deep Procedural Sedation
Continuous capnometry has been consistently proven to identify patients undergoing moderate-deep procedural sedation who have impaired ventilation well before hypoxia develops. There have been at least 8 studies that have demonstrated that continuous capnometry identifies airway obstruction, apnea, or hypoventilation prior to both clinical detection of airway issues or the development of hypoxia.1,2,3,4,5,6,7,8 Because of this, continuous capnometry should be added to traditional oximetry and ECG monitoring for moderate-deep procedural sedation.
In one study using propofol for ED procedures in children, capnometry detected apnea or airway obstruction in 11 of 15 occurrences well before it was detected by either clinical observation or oximetry. 7 In another study using midazolam and fentanyl in adult patients, clinical observation failed to identify any of the 28 patients who developed hypoventilation based on capnometry monitoring. 8Oxygen desaturation is a late sign of medication-induced hypoventilation so we should not become first aware of respiratory depression when they become hypoxic.
The only downside to continuous capnometry is that you may have more false-positive alarms in patients with subclinical hypoventilation. However, it does provide the opportunity to further assess the patient’s level of consciousness and ventilation if an capnometry alarm signals. In general, a significant rise of the end tidal CO2 above 50 mmHg or 10 mmHg above the patient’s baseline warrants an evaluation for impaired ventilation, airway obstruction, or apnea.
The bottom line is that any clinician performing moderate-deep procedural sedation in the ER or ICU should be using continuous capnometry with continuous ECG and oximetry monitoring to optimize patient safety.
2 Miner JR, Biros M, Krieg S, et al. Randomized clinical trial of propofol versus methohexital for procedural sedation during fracture and dislocation reduction in the emergency department. Acad Emerg Med. 2003;10:931-937.
8 Deitch K, Chudnofsky CR, Domenici P. The utility of supplemental oxygen during emergency department procedural sedation and analgesia with midazolam and fentanyl: a randomized controlled trial. Ann Emerg Med. 2007;49:1-8.