DOES THE CHOICE OF ANTIHYPERTENSIVE THERAPY INFLUENCE HEMODYNAMIC-RESPONSES TO INDUCTION, LARYNGOSCOPY AND INTUBATION

We have measured haemodynamic responses to induction of anaesthesia, l aryngoscopy and intubation 103 mild-moderate patients patients (diasto lic less than or equal to 110 mm Hg) currently receiving one of four m onotherapies (ACE inhibitors, group A; P adrenoceptor blocking drugs, group B; calcium channel antagonists, group C; diuretics, group D) and 24 were untreated hypertensive patients). Anaesthesia was induced wit h fentanyl 1.5-2.0 mu g kg(-1) and thiopentone 3-5 mg kg(-1). Tracheal intubation was facilitated by vecuronium 0.1 mg kg(-1) and anaesthesi a maintained with enflurane and nitrous oxide in oxygen. Systolic and diastolic pressures (SAP, DAP) were measured at 1-min intervals by a n oninvasive oscillometric method and cardiac output (CO) and stroke vol ume (SV) by thoracic bioimpedance. Induction of anaesthesia was associ ated with a decrease in SAP, DAP and CO in groups A-D (P < 0.05). Hear t rate (HR) decreased in groups A and D (P < 0.01) and systemic vascul ar resistance (SVR) decreased in groups A and B (P < 0.05). SAP and H R increased in all groups after laryngoscopy and intubation (P < 0.01) as did SVR in groups A, B and D (P < 0.02). CO was unaltered. Similar changes occurred in the untreated hypertensive patients, although nin e of 24 patients exhibited HR greater than or equal to, 100 beat min-1 after laryngoscopy and intubation. Comparison of the changes in SAP, DAP, CO and SVR with time showed no differences in the five treatment groups; changes in HR were significantly less in group B compared with the other groups (P < 0.01). We conclude that the presser responses t o laryngoscopy and intubation are unaffected by concurrent medication in mild moderate hypertensive patients and changes of a similar magnit ude are observed also in untreated hypertensive patients.