Haemodynamic interactions of muscle relaxants and sufentanil in coronary artery surgery

The haemodynamic interactions between sufentanil (S) and muscle relaxants (MR) were studied in 40 ASA physical status III or IV patients (four groups of ten) scheduled for coronary artery bypass grafting (ABG). Group I received pancuronium (P) 0.08 mg.kg-1, Group II received vecuronium (V) 0.1 mg.kg-1, Group III received atracurium (A) 0.5 mg.kg-1 and Group IV metocurine 0.1 mg.kg-1 plus pancuronium 0.02 mg.kg-1 (M-P). Sufentanil, 20 micrograms.kg-1 was administered before sternotomy, 10 micrograms.kg-1 being injected before tracheal intubation and 10 micrograms.kg-1 afterwards. Heart rate (HR), ECG leadII and V5, systolic, diastolic and mean arterial and pulmonary blood pressures, central venous pressure (CVP) and pulmonary capillary wedge pressure (W) were measured and recorded at the time of seven strategic events between the pre-induction of anaesthesia period and sternotomy. Cardiac output (CO) and systemic vascular resistances (SVR) were also measured before induction of anaesthesia and after the administration of S 10 micrograms.kg-1 plus the MR. The HR decreased from baseline values in the post-tracheal intubation period in all groups except in P group. The mean arterial pressure also decreased significantly in all groups except in the P group. The CO did not change from baseline values but SVR decreased in all groups. There was no evidence of new myocardial ischaemia according to the ECG monitoring and there was no significant difference in the HR changes between patients who had or who had not received beta-blockers in any group. We conclude that within the present study conditions and design, HR and blood pressure changed least with pancuronium.