EtCO2 已是 standard of care？

Does Capnography Add Benefit During Emergency Department Propofol Sedation?
All patients who became hypoxemic demonstrated respiratory depression by capnography before developing hypoxemia.

Capnography has been used as a real-time adjunct to procedural sedation monitoring in intensive care units and operating rooms for decades, yet it is not commonly used in the emergency department (ED) for this purpose. These authors determined whether adding capnography to standard monitoring (pulse oximetry, pulse rate, and blood pressure) during ED procedural sedation decreases the incidence of hypoxic events. In a prospective trial, 132 consecutive adults undergoing propofol sedation with standard monitoring and capnography at a single tertiary-care hospital ED were randomized to a study group, in which treating physicians could view the capnography monitoring screen, or to a control group, in which physicians could not view the screen.

Procedural sedation was initiated with a bolus of 1 mg/kg of propofol, followed by additional boluses of 0.5 mg/kg. All patients received opioids (0.5 µg/kg of fentanyl or 0.05 mg/kg of morphine) at least 30 minutes before administration of propofol. Hypoxia was defined as a pulse oximetry oxygen saturation (SpO2) level <93%.>/= 50 mm Hg, an ETCO2 absolute increase or decrease from baseline of >/= 10%, or loss of the waveform for >/= 15 seconds.

Patient characteristics were similar in the two groups. The rate of capnography-detected respiratory depression was similar between groups, but hypoxia was more frequent in the control group (42% vs. 25%). Capnographic evidence of respiratory depression was 100% sensitive for predicting hypoxia. Overall, 64% of patients with capnographic evidence of respiratory depression developed hypoxia.

Comment:
This study and myriad others from the anesthesia and intensive care literature provide convincing evidence that capnography is extremely useful for detecting respiratory depression and preventing hypoxia in patients undergoing procedural sedation. Its use should be standard for emergency department patients receiving deep procedural sedation.

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Richard D. Zane, MD, FAAEM
Published in Journal Watch Emergency Medicine March 12, 2010
Citation(s): Deitch K et al. Does end tidal CO2 monitoring during emergency department procedural sedation and analgesia with propofol decrease the incidence of hypoxic events? A randomized, controlled trial. Ann Emerg Med 2010 Mar; 55:258.