THE INFLUENCE OF DRUGS USED IN NEUROLEPTANALGESIA ON CARDIOVASCULAR AND VENTILATORY FUNCTION BY

The circulatory and ventilatory influences of various combinations of the narcotic analgesics phenoperidine and fentanyl, and the neuroleptics haloperidol and dehydro-benzperidol, were investigated during nitrous oxide anaesthesia in 230 patients. Measurements of cardiac output and other haemodynamic variables in nine patients supported the general findings that the cardiovascular effects of the analgesics were modified by alterations of ventilation, in particular the haemodynamic effects of concurrent hypercapnia. Serious circulatory disturbances were not found following premedication with neuroleptic drugs. Mechanisms of ventilatory depression following the use of the analgesics have been evaluated, and indices of ventilation and arterial oxygenation show that postoperative values after neuroleptanalgesia are comparable to those- after other methods of anaesthesia. The rationale of neuroleptanalgesia combined with light general anaesthesia is explored and the pharmacology of the drugs is reviewed. Since the inception of a technique of anaesthesia which combined the neuroleptic properties of certain butyrophenones, with the profound anal-gesia produced by potent, short-acting analgesics, the concept of neuroleptanalgesia (De Castro and Mundeleer, 1959; Delay and Deniker, 1961; Alder, 1961) has attracted much attention but has also been greeted with considerable scepticism. As an alternative to general anaesthesia (Nilsson and Janssen, 1961) it has only found application in the relatively specialized fields of neurosurgery (Brown, 1964), ophthalmic surgery (Trifogli and Manni, 1964), and for repeated burns dressings (Smith and Hollis, 1966). Recent developments in the use of both neuroleptics and analgesics have followed the trend set by Brown, Horton and Macrae (1963), and have been directed toward their inclusion with nitrous oxide and a muscle relaxant as part of a balanced anaesthetic tech-nique. It is perhaps unfortunate that the original term "neuroleptanalgesia " should still be used in Based on papers delivered to the Second British Symposium on the use of neuroleptanalgesia in anaes-thetic practice, and to a meeting of the Yorkshire Society of Anaesthetists held jointly with the Hickma