Lipid emulsion is superior to vasopressin in a rodent model of resuscitation from toxin-induced cardiac arrest.

Objectives: Lipid emulsion infusion is an emerging antidotal therapy for toxin-induced cardiac arrest. To compare the efficacy of resuscitation from bupivacaine-induced asystole using lipid emulsion infusion vs. vasopressin, alone and with epinephrine. Design: Prospective, randomized, animal study. Setting: University research laboratory. Subjects: Adult, male Sprague-Dawley rats. Interventions: Instrumented rats were given an intravenous bolus of 20 mg/kg bupivacaine to induce asystole (zero time). Rats (n 6 for all groups) were ventilated with 100% oxygen, given chest compressions, and randomized to receive 30% lipid emulsion (L, 5 mL/kg bolus then 1.0 mL/kg/min infusion) and vasopressin 0.4 U/kg bolus alone (V) or combined with epineph- rine, 30 g/kg (V E); boluses (L, V, or V E) were repeated at 2.5 and 5 minutes for a rate–pressure product (RPP) less than 20% baseline. Measurements and Main Results: The arterial blood pressure and electrocardiogram were measured continuously for 10 min- utes when blood was drawn for arterial blood gas analysis, lactate content, and central venous oxygen saturation (ScvpO2). Hemodynamic parameters of the L group at 10 minutes (30,615 4782 mm Hg/min; 151 19.1 mm Hg; 197 8.6 min1; RPP, systolic blood pressure and heart rate, respectively) exceeded those of the V group (5395 1310 mm Hg/min; 85.8 12 mm Hg; 61 10.8 min1) and the V E group (11,183 1857 mm Hg/min1; 75.5 12.9 min1, RPP and heart rate, respectively; systolic blood pressure was not different). Metrics indicated better tissue perfusion in the L group (7.24 0.02; 83% 3.5%; 2.2 0.36 mmol/L; pH, ScvpO2, lactate, respectively) than V (7.13 0.02; 29.9% 4.4%; 7.5 0.6 mmol/L) and V E groups (7.07 0.03; 26.2% 8.9%; 7.7 1 mmol/L). Wet-to-dry lung ratios in V (8.3 0.6) and V E (8.7 0.2) were greater than that in the L group (6.2 05) (mean SEM; p < 0.05 for all shown results). Conclusions: Lipid emulsion in this rat model provides superior hemodynamic and metabolic recovery from bupivacaine-induced cardiac arrest than do vasopressors. Systolic pressure was not a useful metric in the vasopressor groups. Vasopressin was asso- ciated with adverse outcomes.