Heart-rate slowing and junctional rhythm following intravenous succinylcholine with and without intramuscular atropine preanesthetic medication.

The incidence of heart-rate slowing (greater than 15 percent) and junctional rhythm after two injections of succinylcholine (1 mg/kg), separated by 5 minutes, was determined in adult patients. All patients received intramuscular morphine as preanesthetic medication 60 to 90 minutes before intravenous thiamylal anesthetic induction. Intramuscular atropine (mcg/kg) 60 to 90 or 15 to 20 minutes before anesthetic induction did not alter the incidence of first or second succinylcholine dose heart-rate slowing or junctional rhythm as compared with patients receiving only morphine premedication.