Capnography during procedural sedation has rapidly become standard practice in the interests of “safety” – despite decades of Emergency Medicine experience safely performing sedation without. The theory: earlier detection of inadequate ventilation allows for intervention and prevention of hypoxemic episodes. In the most prominent randomized trial, there was a 17% absolute reduction in transient hypoxemic events. Critics appropriately point out, however, that transient events are hardly a meaningful patient-oriented outcome.
This trial, in which sedation was performed by nurses in an outpatient gynecology setting in the Netherlands, describes 427 patients randomized either to capnography or “routine monitoring”. Supplemental oxygen was not used in this setting, as these practioners considered it to obscure the additive value of pulse oximetry. Essentially by definition, all patients were female, and the median age was 24 with few co-morbidities.
Overall, 25.7% of patients in the capnography group developed hypoxemic episodes versus 24.9% of patients in the control group. There were also no differences in numbers of patients with profound hypoxemia (<81%) or prolonged hypoxemia (>60 seconds), although patients with hypoxemia in the capnography group had more frequent prolonged episodes than the control group (14.0% vs. 3.7%). Likely as a result, patients in the capnography group underwent airway positioning maneuvers more frequently (49.5% vs. 32.1%).
It’s a stretch to say this is information is generalizable to Emergency Department sedation. It is, at least, a useful window into what many skeptics have been saying all along – the additive value of capnography in sedation is low, and, rather, the extra information leads to additional interventions and procedural interruptions without measurable benefit. Procedural success in this setting was not adversely impacted by the frequent interruptions, however.
“Capnography During Deep Sedation with Propofol by Nonanesthesiologists: A Randomized Controlled Trial”