Studies of Anaesthesia in Relation to Hypertension. Ii

The electrocardiographic and haemodynamic responses to the induction of anaesthesia, followed by laryngoscopy and endotracheal intubation have been studied in a group of 16 untreated hypertensive patients, and a group of 20 patients receiving antihypertensive therapy up to and including the day of operation. The influence of five different induction agents, thiopentone, methohexitone, propanidid, diazepam, and neuroleptanalgesia induced by a combination of phenoperidine and droperidol were compared. Neuroleptanalgesia caused less arterial hypotension than any of the other agents, but afforded only marginally more protection than other agents against hypertension, tachycardia and dysrhythmia associated with laryngoscopy and tracheal intubation. Both propanidid and diazepam caused dramatic but transient hypotension in a small number of patients and were not investigated further. Unlike its effects in normotensive subjects, methohexitone caused greater hypotension than thiopentone in hypertensive patients. The rationale is presented for the prophylactic blockade of beta-adrenergic receptors to prevent hypertensive crises during laryngoscopy and intubation in both treated and untreated hypertensive patients.