Summary

Background and objective: The amide-linked local anaesthetics, bupivacaine and ropivacaine, can cause depression of cardiac contractility and dysrhythmias. In a previous study, we observed decreased contractility and ST segment depression following ropivacaine administration in anaesthetized dogs. The efficacy of intravenous (i.v.) and intracoronary nicorandil (30 and 100 μg kg−1), i.v. nitroglycerin (glyceryl trinitrate) (5 μg kg−1) and calcium chloride (1, 2 and 4 mmol) in reversing the cardiotoxic effects of intracoronary ropivacaine were studied following the administration of intracoronary ropivacaine.

Methods: Six dogs were studied. The dogs were anaesthetized with i.v. pentobarbital (30 mg kg−1). A left-sided thoracotomy was performed and the left circumflex coronary was cannulated. For each dog, the dose of ropivacaine was identified, which produced measurable cardiotoxicity. In each case, ropivacaine was followed by one of the three resuscitation drugs. The effects of each resuscitation drug on ST segments and left ventricular contractility (dP/dt) produced by ropivacaine alone were compared with those produced by ropivacaine followed by each of the three resuscitation drugs using Fisher's exact test.

Results: The doses of ropivacaine required to produce depression of left ventricular dP/dt and ST segments ranged from 1 to 8 mg. Ropivacaine-induced depression of left ventricular contractility (dP/dt) was more rapidly and completely reversed by calcium chloride than by either nitroglycerin or nicorandil (P = 0.008).

Conclusions: Calcium chloride may be effective in the treatment of inadvertent intravascular administration of amide local anaesthetic agents.