Antifibrillatory effects of high dose bretylium and a lidocaine-bretylium combination during cardiopulmonary resuscitation.
Previous CPR studies from our laboratory have shown that a standard iv dose of lidocaine (2 mg/kg) has a rapid antifibrillatory effect, while a standard dose of bretylium (5 mg/kg) produces a delayed but more pronounced effect. In order to determine the optimal doses, we investigated the antifibrillatory effects of a) high dose bretylium (10 mg/kg) and b) a combination of lidocaine (2 mg/kg) and bretylium (5 mg/kg) during CPR in two groups of anesthetized dogs. Ventricular fibrillation threshold (VFT) was determined using a train method and CPR was performed by a pneumatic device. During both a control and drug phase, the VFT was determined in each dog before CPR, and after each of three consecutive 3-min CPR periods. The combination of lidocaine and bretylium (11 dogs) caused a significant increase in VFT compared to the control phase after each of the 3-min CPR periods and maintained this effect for greater than 2 h. Bretylium 10 mg/kg (eight dogs) significantly elevated the VFT only after the third 3-min CPR period. We conclude that the combination of standard doses of lidocaine and bretylium produces a rapid and prolonged antifibrillatory effect and may be the optimal regimen in the CPR setting. High dose bretylium has a delayed onset of effect and appears to produce no greater effect than standard doses of the drug.
D000818:Animals; D001794:Blood Pressure; D001949:Bretylium Compounds / Q000627:therapeutic use*; D002245:Carbon Dioxide / Q000097:blood; D004285:Dogs; D004338:Drug Combinations; D004554:Electric Countershock; D005260:Female; D006863:Hydrogen-Ion Concentration; D008012:Lidocaine / Q000627:therapeutic use*; D008297:Male; D010100:Oxygen / Q000097:blood; D012151:Resuscitation / Q000379:methods*; D014693:Ventricular Fibrillation / Q000517:prevention & control*
D001949:Bretylium Compounds; D004338:Drug Combinations; D002245:Carbon Dioxide; D008012:Lidocaine; C045166:bretylium; D010100:Oxygen