Authors: van Loon K et al., Anesth Analg 2014 Jul 119:49
Hypoxic events occurred in similar numbers of patients with and without CO2 monitoring.
Undetected hypoventilation is associated with complications in propofol sedation. To evaluate whether capnography reduces episodes of hypoxia during propofol sedation, researchers in the Netherlands randomized 427 healthy women undergoing deep sedation for minor gynecologic procedures to receive a standard protocol of pulse oximetry and visual monitoring of breathing versus the standard protocol plus continuous capnography.
Hypoxemia was defined as an oxygen saturation of less than 91% for any duration. There were no significant differences between the capnography and control groups in number of patients with hypoxemia (26% and 25%), profound (less than 81% SaO2) hypoxemia (3% in each), or prolonged (greater than 60 seconds) hypoxemia (4% and 1%). Significantly more airway interventions were performed in the capnography group (50% vs. 32%).
This study showed no clear benefit for capnography, but patients did not receive supplemental oxygen, so the time between capnographic indication of ventilator compromise and hypoxemia was short, thereby limiting the “early warning” aspect of capnography. Capnography is now readily available and easily deployed. Both the American Society of Anesthesiologists and the American College of Emergency Physicians recommend its use during procedural sedation. Pending further refinement of these recommendations and larger studies, it is hard to argue against the use of capnography and supplemental oxygen during deep sedation.