The Effect of Lidocaine and Bretylium on the Defibrillation Threshold during Cardiac Arrest and Cardiopulmonary Resuscitation

Abstract

The effect of intravenous lidocaine, 2 mg/kg, and bretylium, 5 mg/kg, on defibrillation threshold (DFT) was investigated in a-chloralose anesthetized dogs undergoing conventional closed chest cardiopulmonary resuscitation (CPR) following induced ventricular fibrillation. Ventricular fibrillation was induced electrically and CPR was performed by a pneumatic device set to compress the chest 60 times and inflate the lung 12 times a minute. Defibrillation was achieved using underdamped sinusoidal current shocks from a special defibrillator which allowed determination of delivered energy. The DFT was defined as the peak current which defibrillated, but no more than 20% higher than a current which did not defibrillate. All DFTs were obtained within 5 min of CPR. The mean k SD current and energy thresholds required for defibrillation during lidocaine-CPR (seven dogs) were 17.0 k 8.9 A and 53.0 k 40.7 J as compared to 12.5 k 6.2 A and 34.3 k 30.7 J, respectively during control-CPR (P < 0.05). The mean f SD current and energy thresholds during bretylium-CPR were 1 1 .O f 3.4 A and 24.1 k 1.3 J as compared to 1 1.8 k 1.7 A and 29.4 f 9.6 J, respectively, during control-CPR (NS). These results show that lidocaine acutely elevated defibrillation threshold whereas bretylium did not produce such an effect. The effect on DFT along with other pharmacologic properties should be considered when lidocaine or bretylium is used in the setting of cardiac arrest and CPR. o

Effect of epinephrine and lidocaine therapy on outcome after cardiac arrest due to ventricular fibrillation.

“…Lidocaine is also often used to treat persistent ventricular fibrillation because the drug has been shown in some studies to prevent the emergence of ventricular fibrillation during the early hours of acute myocardial infarction.9 -Other studies, however, have shown that lidocaine increases defibrillation energy level requirements and is relatively ineffective in terminating ventricular tachyarrhythmias after they have been established. [12][13][14][15][16][17] Ventricular fibrillation persists after initial defibrillation attempts in 25-40% of patients discovered in cardiac arrest and may present a condition quite different from either acute myocardial infarction or experimental resuscitation, and thus may have dif-Methods The Seattle Emergency Medical System is a tiered response system. The first level of care is provided by firefighters.…”

European Resuscitation Council Guidelines 2000 for Adult Advanced Life Support

“…Early studies suggested that lignocane/lidocaine increased the ventricular defibrillation threshold in animals, [71][72][73][74] but this may have been influenced by experimental techniques. 75 In humans the administration of lignocaine/lidocaine before defibrillation may not increase the energy requirements for defibrillation.…”

Treatment of tachyarrhythmias

“…17 One trial of fair quality (LOE 3) showed no statistically significant differences in outcome between victims of cardiac arrest who received lidocaine and patients in a historical control group who received no antiarrhythmic medications, 115 and 2 randomized studies (LOE 2) comparing lidocaine and bretylium demonstrated no difference in outcome. 95,96 Studies opposing the use of lidocaine include 1 randomized study of good quality (LOE 1) comparing amiodarone and lidocaine that showed a greater likelihood of successful resuscitation with use of amiodarone, 116 1 randomized study of good quality (LOE 2) comparing lidocaine and epinephrine that demonstrated a higher incidence of asystole with the use of lidocaine and no difference in return of spontaneous circulation, 117 1 retrospective, uncontrolled trial of good quality (LOE 4) suggesting that lidocaine reduced the short-term success of resuscitation, 118 numerous animal studies (LOE 6) demonstrating a lower rate of short-term survival after administration of lidocaine and elevation in the defibrillation threshold after treatment, [119][120][121][122][123][124][125][126] and meta-analyses and recent retrospective cohort studies suggesting increased mortality with the prophylactic use of lidocaine in patients with acute myocardial infarction. [18][19][20][21] Support for the use of bretylium in patients who have had a cardiac arrest comes from 1 randomized trial of fair quality (LOE 2) demonstrating a marginally significant benefit in patients treated for VF or asystole (no benefit in those treated for VF alone) who had been provided with only basic life support before arrival in the emergency department 94 and 2 randomized (LOE 2) trials comparing lidocaine and bretylium in patients treated for cardiac arrest that demonstrated no difference in outcome between the On the basis of discussions at the Evidence Evaluation and Guidelines 2000 conferences, scientists believe that evidence supports the use of IV amiodarone following epinephrine to treat shock-refractory cardiac arrest due to VF or pulseless VT (Class IIb).…”