Succinylcholine causes profound hyperkalemia in hemorrhagic, acidotic rabbits

Two recent clinical reports suggested that succinylcholine (SCh) may cause severe hyperkalemia in hemorrhagic, acidotic humans. To investigate this, we anesthetized rabbits with halothane and N2O, and inserted venous and arterial catheters. Control rabbits (Group C, n = 4) remained anesthetized and undisturbed. Hemorrhage/profound acidosis (HPA) was accomplished by withdrawal of 25-30 mL/kg of blood and waiting until pHa approximately 7.05 (Group HPA, n = 5). Hemorrhage/minimal acidosis (HMA) was accomplished by withdrawal of 25-30 mL/kg of blood, but acidosis was minimized by not waiting for it to occur and by administering NaHCO3 0-1.4 mEq/kg (Group HMA, n = 4). In a metabolic acidosis group (n = 4), HCl was infused until pHa approximately 7.05. Respiratory acidosis (n = 4) was accomplished by partial obstruction of the endotracheal tube until PaCO2 approximately 120 mm Hg and pHa approximately 7.05. Potassium levels were determined before the above interventions (baseline), immediately before (pre-SCh), and 1, 3, 5, 7, 10, and 13 min after SCh 1 mg/kg intravenously. In Group C, potassium gradually increased from 3.5 +/- 0.2 mEq/L to 4.8 +/- 0.2 mEq/L 13 min after SCh. In Group HPA, potassium increased from 3.8 +/- 0.3 to 7.0 +/- 1.8 mEq/L after hemorrhage/acidosis and then to 11.4 +/- 1.7 mEq/L at 13 min after SCh. The metabolic acidosis group was significantly different from Group C at 7, 10, and 13 min after SCh (maximum at 13 min, 6.8 +/- 1.2 mEq/L).(ABSTRACT TRUNCATED AT 250 WORDS)