Electrophysiologic and hemodynamic effects of sodium bicarbonate in a canine model of severe cocaine intoxication.
OBJECTIVE
Cocaine toxicity causes myocardial depression, malignant dysrhythmias, and sudden death, partially due to cocaine-related myocardial sodium channel blockade. Because of cocaine's ability to block cardiac sodium channels, sodium bicarbonate (NaHCO3) has been proposed as an antidote. The hypothesis of this study was that NaHCO3 would correct cocaine-induced conduction abnormalities and resultant hemodynamic compromise in an animal model simulating severe cocaine intoxication.


METHODS



METHODS
Prospective, controlled, experimental study in which 15 anesthetized dogs were given three successive boluses of cocaine (7 mg/kg) and then randomized to receive NaHCO3, 2 mEq/kg (n = 8) or placebo (n =7).


METHODS
Arterial, left ventricular, and pulmonary artery pressures; cardiac output (CO); electrocardiogram (ECG); blood gases; and serum concentrations of cocaine were measured at baseline, at fixed time intervals after each bolus of cocaine, and then after administration of NaHCO3 or placebo. Statistical significance was determined by analysis of variance (ANOVA) for repeated measures.


RESULTS
Seven dogs experienced significant arrhythmias, including VT, pulseless electrical activity, and third-degree atrioventricular block; 2 of these dogs expired prior to receiving NaHCO3 and were excluded. Immediately after administering NaHCO3, QRS duration decreased by 30% (p < 0.001), returning to baseline more quickly than in the control group. This effect was associated with a brief 30% decrease in MAP (p = NS). After NaHCO3, CO increased 78% and remained increased for 5 min (p < 0.007). One dog converted from complete heart block to sinus rhythm shortly after NaHCO3 administration.


CONCLUSIONS
NaHCO3 improved ECG changes secondary to cocaine toxicity and improved myocardial function.
Wilson
Lance D
LD
Department of Emergency Medicine, MetroHealth Medical Center, Cleveland, Ohio 44109, USA. ldwilson@pol.net
Shelat
Chandresh
C
D000818:Animals; D000931:Antidotes; D001145:Arrhythmias, Cardiac / Q000139:chemically induced / Q000188:drug therapy / Q000503:physiopathology; D001784:Blood Gas Analysis; D001794:Blood Pressure / Q000187:drug effects; D002302:Cardiac Output / Q000187:drug effects; D003042:Cocaine / Q000037:antagonists & inhibitors* / Q000633:toxicity*; D004285:Dogs; D004562:Electrocardiography / Q000187:drug effects; D004594:Electrophysiology; D006339:Heart Rate / Q000187:drug effects; D006439:Hemodynamics / Q000187:drug effects*; D017693:Sodium Bicarbonate / Q000494:pharmacology*; D026941:Sodium Channel Blockers / Q000633:toxicity*; D016277:Ventricular Function, Left / Q000187:drug effects
D000931:Antidotes; D026941:Sodium Channel Blockers; D017693:Sodium Bicarbonate; D003042:Cocaine