TITRATION OF INTRAVENOUS ANESTHETICS FOR CARDIOVERSION - A COMPARISONOF PROPOFOL, METHOHEXITAL, AND MIDAZOLAM

Objective. To compare propofol,methohexital, and midazolam administere d as titrated infusions for sedation during electrical cardioversion. Design: A prospective, randomized, single-blind comparative study. Set ting: Coronary care unit in a military teaching hospital. Patients: Th irty adult patients with atrial fibrillation, atrial flutter, or parox ysmal supraventricular tachycardia. Each patient required electrical c ardioversion. Patients were randomized to receive one of the three stu dy drugs. Ten patients composed one drug group. Measurements and Main Results. Demographic variables were similar between groups. Patients w ere randomized to receive propofol (10 mg/mL), methohexital (5 mg/mL), or midazolam (0.5 mg/mL) administered at 10 mL/min until the patients failed to follow verbal commands and demonstrated a degradation of th e lid response to stimulation. Dose requirements (mean +/- SD) were pr opofol 1.69 +/- 0.46 mg/kg, methohexital 1.07 +/- 0.34 mg/kg, and mida zolam 0.16 +/- 0.06 mg/kg. Hemodynamic assessment at baseline, after i nduction, after cardioversion, and at recovery demonstrated no differe nce in mean arterial pressure between the three groups. The time to aw akening was significantly prolonged in the group that received midazol am (33 +/- 11 mins,p < .05) as compared with the times of the groups t hat received propofol (11 +/- 4 mins) and methohexital (9 +/- 3 min). Side-effects were similar between groups, with the exception of an inc rease in pain on injection with propofol and an increased frequency of confusion in those patients receiving midazolam. Recall of the electr ical discharges at one hour after the procedure occurred in two patien ts in the propofol group. In both cases, there were technical problems which caused the duration of the procedure to extend into the anticip ated recovery period. Unit dose costs at our institution for a 70-kg p atient are: methohexitol, $3.14 (500-mg bottle); medazolam, $14.88 (5- mg vials x 3); and propofol, $6.60 (200-mg ampule). Conclusions: All t hree drugs are acceptable choices for use during elective direct-curre nt cardioversion. Titration of the agent results in a total drug dose which is usually less than the typical induction dose. There were no s ignificant differences in the hemodynamic actions of these drugs at an y time interval. Both propofol and methohexital proved superior in the ir ability to provide a more rapid anesthetic onset and recovery as co mpared with midazolam. Propofol offers the advantage of requiring no p remixing or dilution, and it is not a controlled substance, although i t does result in more pain on injection.