[Signs of a severe myocardial ischemia following peritonsillar infiltration with ornipressin (POR 8)]

Ornipressin (OR), a synthetic derivative of natural vasopressin, is widely used in combination with local anaesthetics in order to reduce surgical bleeding and systemic absorption of the local anaesthetic. As shown previously in experimental studies, OR causes severe coronary vasoconstriction. The myocardial oxygen balance is compromised by an increase in myocardial oxygen demand due to hypertension and impaired oxygen delivery following coronary vasoconstriction. We describe the case of a 19-year-old male who was admitted to the hospital for elective tonsillectomy. There was no evidence of systemic or cardiovascular disease (ASA I). Following the induction of anaesthesia with thiopentone 4 mg/kg and ventilation with N2O/O2 (FiO2:0.25), vecuronium was administered to facilitate orotracheal intubation. Anaesthesia was maintained with N2O/O2 (FiO2:0.33) and 2 MAC isoflurane. After reaching an anaesthetic steady state with stable haemodynamic conditions, peritonsillar infiltration with a prilocaine solution containing a total of 0.8 IU OR (0.1 IU/ml) produced marked tachycardia and hypertension. Concomitantly, distinct ST-segment-depression was observed in a lead II ECG. Hypertension and tachycardia occurred within 3 min after the local infiltration with prilocaine/OR. Maximum ST-segment depression and haemodynamic changes were recorded 11 min after infiltration, with an increase in heart rate from 58 to 136 min and a rise in blood pressure from 115/50 to 217/130 mmHg. Considering experimental results, the ECG changes in this case show clear evidence that even in healthy humans OR-induced systemic haemodynamic changes may be complicated by severe myocardial ischaemia due to coronary vasoconstriction.(ABSTRACT TRUNCATED AT 250 WORDS)