VASOPRESSIN INSTEAD OF EPINEPHRINE ENHANCES EFFICACY OF CPR WITHOUT CAUSING TACHYCARDIA

Survival from cardiac arrest is highly dependent on the arterial pressure generated by cardiopulmonary resuscitation (CPR). To increase efficacy of precordial compressions, the potent vasoconstrictor epinephrine (EPI) is administered. However, EPI also elicits a robust, β1-adrenoceptor-mediated tachycardia following defibrillation, depleting the myocardium of the energy reserves it requires for recovery. We proposed that the adrenoceptor-independent vasoconstrictor vasopressin (AVP) increases arterial pressure as effectively as EPI without producing tachycardia. After 6 min pacing-induced cardiac arrest, domestic swine (25-35 kg; 10 boars, 11 sows) received precordial compressions (100/min) for 4 min, and either EPI (0.1 mg; n=5) or AVP (10 U; n=24) was injected iv at 1 min CPR. EPI and AVP similarly increased mean arterial pressure from 31±3 to 66±4 mmHg vs. 34±3 to 59±3 mmHg after 4 min CPR. The AVP-treated pigs required less countershock energy (12±2 J) to achieve defibrillation vs EPI-treated pigs (16±4 J). Post-arrest tachycardia was less intense in AVP- (133±11 bpm) than EPI-treated (174±14 bpm) pigs. Thus, AVP is as effective as EPI at enhancing CPR, but avoids EPI-induced tachycardia. Purpose (a): The purpose of this study was to test the hypothesis that the adrenoceptor-independent vasoconstrictor vasopressin increases arterial pressure as effectively as epinephrine without producing tachycardia during cardiopulmonary resuscitation (CPR). Methods (b): After 6 min pacing-induced cardiac arrest, domestic swine (25-35 kg; 10 boars, 11 sows) received precordial compressions (100/min) for 4 min, and either epinephrine (0.1 mg; n=5) or vasopressin (10 U; n=24) was injected iv at 1 min CPR. Results (c): Epinephrine and Vasopressin similarly increased mean arterial pressure from 31±3 to 66±4 mmHg vs. 34±3 to 59±3 mmHg after 4 min CPR. The vasopressin-treated pigs required less countershock energy (12±2 J) to achieve defibrillation vs epinephrine-treated pigs (16±4 J). Post-arrest tachycardia was less intense in vasopressin- (133±11 bpm) than epinephrine-treated (174±14 bpm) pigs. Conclusions (d): Vasopressin is as effective as epinephrine at enhancing CPR, but avoids epinephrine-induced tachycardia.