Cardiovascular Effects of Non-depolarizing Neuromuscular Blockers in Patients with Coronary Artery Disease

To compare haemodynamic responses associated with equipotent doses of muscle relaxants and high dose fentanyl (50 micrograms X kg-1), 40 non-hypertensive patients who were receiving beta adrenergic and calcium channel blocker therapy and undergoing coronary bypass surgery were randomized to four study groups receiving the following: (1) atracurium: 0.4 mg X kg-1, (2) pancuronium: 0.12 mg X kg-1, (3) vecuronium: 0.12 mg X kg-1, or (4) pancuronium-metocurine mixture: (0.4 mg + 1.6 mg X ml-1):1 ml/10 kg. Neuromuscular blockers were injected with fetanyl at induction. Haemodynamics were recorded with the patients awake (baseline), at two minutes post-induction, and at two and five minutes after intubation. Pancuronium was the only drug associated with significant increases in HR; no other significant changes occurred within each group when compared to their respective baseline haemodynamics. HR increased more after induction with pancuronium when compared to atracurium (23 vs. 4 per cent, p less than 0.05) and to vecuronium (23 vs. 2 per cent, p less than 0.05), and when compared to vecuronium after intubation (29 vs. 7 per cent, p less than 0.05). The pancuronium-metocurine mixture caused tachycardia which was less than, though not significantly different than with pancuronium; however, HR returned to baseline by five minutes with the mixture, but remained elevated with pancuronium (3 vs. 18 per cent, p less than 0.05). SVR fell more on induction with atracurium when compared to vecuronium (-18 vs. 1 per cent, p less than 0.05). These changes in HR or SVR were not accompanied by ECG signs of ischaemia.(ABSTRACT TRUNCATED AT 250 WORDS)