Comparison of haemodynamic effects of morphine and fentanyl in patients with coronary artery disease.

The haemodynamic effects of morphine (2.5 mg kg-1) and fentanyl (16.7 and 25 micrograms kg-1) were compared in patients undergoing coronary artery bypass surgery. Morphine or fentanyl in combination with pancuronium, nitrous oxide and a small dose of thiopentone produced some deterioration of myocardial performance. Both analgesics failed to block haemodynamic responses to noxious stimulation including tracheal intubation and sternotomy. Heart rate increased following tracheal intubation and systemic vascular resistance increased after sternotomy. However, the larger dose of fentanyl (25 micrograms kg-1) was accompanied by the smallest haemodynamic changes. Supplementary anaesthetic agents were often required to maintain haemodynamic stability during sternotomy. It is suggested here that larger doses of fentanyl, or the addition of other intravenous or inhalation anaesthetics might be employed for patients with severe coronary artery disease and good left ventricular function. On the other hand, in patients with poor left ventricular function, the myocardial depressant properties of thiopentone and nitrous oxide may be detrimental.