Deep sedation is desirable during cardioversion performed to treat cardiac arrhythmias. Because this procedure is often performed in an emergency situation when the arrhythmia is causing patient instability, sedation must be quick and compatible with the possibility of a full stomach. Optimal sedation in these circumstances would include quick onset, low cardiopulmonary depression, and rapid recovery. Agents frequently used include propofol, etomidate, and midazolam (with or without flumazenil). Coll-Vinent and associates examined the sedative choices available for emergency cardioversion, comparing effectiveness, adverse events, and recovery time.

Adults undergoing cardioversion in an emergency department for atrial fibrillation or flutter, who were relatively hemodynamically stable and fasting for at least four hours, were included in the study. Patients were randomized to sedation, overseen by an anesthesiologist, of one of the following regimens: (1) etomidate in a dosage of 0.2 mg per kg; (2) propofol, 1.5 mg per kg; (3) midazolam, 0.2 mg per kg; or (4) midazolam followed by flumazenil, 0.5 mg in a bolus followed by 0.5 mg in intravenous perfusion over one hour, after the cardioversion was performed. If induction was not obtained with these doses within five minutes, additional doses of the same medication were given until the patient was sedated adequately. All patients received supplemental 50 percent oxygen before the procedure and during the procedure, if necessary. Awakening time was defined as spontaneous eye opening.

Of the 32 randomized patients enrolled in the study, the group receiving midazolam was most likely to require extra medication to achieve induction. Hemodynamic assessment was the same among all groups throughout the procedure. None of the patients required intubation. More patients receiving etomidate had transient episodes of myoclonus. No clinically consequential adverse events occurred.

Propofol provided the best response, including short induction, rapid awakening, rapid recuperation, and minimal adverse effects. No significant hypotension was noted, probably because of the hemodynamic stability of the patients and because of the slow drug administration. Transient apnea and hypoventilation occurred with all drugs, suggesting the need for available ventilatory support. Midazolam is known to be relatively hemodynamically safe, but recovery periods were longer. Flumazenil reduces this lengthened recovery period and the possibility of resedation, but there is general agreement that its use should be reserved for patients in whom the sedative response may compromise respiratory function.

The authors conclude that propofol is the superior sedative for emergency cardioversion of hemodynamically stable patients. They recommend that further studies be conducted.

Other articles in the same issue further document this support for propofol sedation. Basset and associates show that propofol sedation is effective and safe in children in emergency settings, assuming that monitoring is performed for transient cardiopulmonary depression. An accompanying editorial by Green and Krauss points out that the difficulty of appropriately titrating a fast-acting sedative like propofol requires anesthesiologist supervision to avoid potentially overshooting the sedation goal. The optimal use of propofol is probably for brief, intensely painful procedures. Further studies are encouraged.