Canadian Journal of Anesthesia, Vol 32, 105-111, Copyright © 1985 by Canadian Anesthesiologists' Society

Effects of Intubation on Coronary Blood Flow and Myocardial Oxygenation

¹ Department of Anaesthesia, Dalhousie University, Halifax, Nova Scotia and the Departments of Anesthesiology and Cardiovascular Surgery, Cedars-Sinai Medical Center, Los Angeles, California

Address correspondence to: Dr. E.A. Moffitt, Sir Charles Tupper Medical Building, University Avenue, Halifax, Nova Scotia, B3H 4H7.

Effects on haemodynamics and myocardial oxygenation of endotracheal intubation were examined in 17 patients after halothane induction and 12 after 1 mg·kg^-1 of IV morphine. Six patients having each anaesthetic were pretreated with IV propranolol (0.1 mg·kg^-1) 45 minutes earlier. Arterial and intracardiac pressures, cardiac output and total coronary sinus blood flow (CSBF), both by thermodilution, were determined plus arterial-coronary differences of oxygen, haemoglobin and lactate. Blood pressure (BP), heart rate and CSBF were recorded continuously during intubation. The subjects were candidates for coronary bypass grafts, but had good ventricular function (mean ejection fraction 0.68 ± 0.13 SD).

From their reduced levels after induction, BP, cardiac index and systemic vascular resistance increased to awake levels following intubation. Mean CSBF in non-betablocked patients increased to awake level along with BP. More myocardial oxygen was extracted and consumed after intubation, but lactate extraction continued: these data are evidence of adequate oxygen supply. Induction with either halothane or morphine effectively prevented the hypertensive response to intubation. Acute beta blockade led to less increase in heart rate from intubation.

Key Words: HEART: coronary artery disease, myocardial function, anaesthetics • ANAESTHETICS, VOLATILE: halothane • ANALGESICS: morphine • INTUBATION ENDOTRACHEAL: complications