REPEATED EPISODES OF MYOCARDIAL-ISCHEMIA DURING COMBINED THORACIC EPIDURAL-ISOFLURANE ANESTHESIA

A patient with a history of coronary artery diseasedeveloped new ST se gment depressions in the ECG registration during a low dose (0.7%) iso flurane anaesthesia that was combined with a continuous thoracic epidu ral analgesia. Simultaneously a small decrease in mean arterial blood pressure (MAP) was noted. During the next 5 min these changes were fol lowed by a severe drop in MAP (from 88 to 60 mmHg) and in cardiac outp ut from 5.5 to 3.2 L/min. When isoflurane was discontinued both the EC G and the cardiovascular changes returned to the previous condition. L ater, when 0.5% isoflurane was restarted, the ECG changes reappeared w ithin ten min, but disappeared once again when isoflurane administrati on was discontinued. Thus, this patient had repeated episodes of myoca rdial ischaemia which were associated with the use of low dose isoflur ane. Although isoflurane-induced ''coronary steal'' may appear as a li kely cause of these ischaemic episodes, it is possible that the thorac ic epidural had synergistic action and rendered the patient exceptiona lly sensitive to minor changes in perfusion pressure.