Comparison of the haemodynamic effects of mivacurium and atracurium during fentanyl anaesthesia.

We have measured the haemodynamic effects of mivacurium 0.15 and 0.2 mg kg-1, and atracurium 0.5 mg kg-1 administered over 10-15 s in patients undergoing coronary artery bypass surgery under fentanyl anaesthesia. There were no significant haemodynamic changes in the atracurium group, other than a transient decrease in pulmonary arterial wedge pressure. Changes in heart rate were small in all three groups. Mivacurium 0.15 mg kg-1 produced changes of only small magnitude (12% decrease in mean arterial pressure and 16% decrease in systemic vascular resistance index) however, mivacurium 0.2 mg kg-1 produced a 25% reduction in mean arterial pressure, a 14% increase in cardiac index and a 35% decrease in systemic vascular resistance index. Erythema developed in two, three and seven patients after atracurium, mivacurium 0.15 mg kg-1 and mivacurium 0.2 mg kg-1, respectively. One patient exhibited a 54% decrease in mean arterial pressure, generalized erythema and bronchospasm after mivacurium 0.2 mg kg-1. The haemodynamic changes with mivacurium suggested histamine release.

Attenuation of the cardiovascular responses to subcutaneous adrenaline in neurosurgical patients.

In 30 neurosurgical patients after induction of anaesthesia and random pretreatment with i.v. propranolol 1 mg or metoprolol 1 mg, heart rate and mean arterial pressure were measured at 30-s intervals after subcutaneous infiltration of adrenaline 1:200,000. While metoprolol prevented the cardiovascular effects of adrenaline infiltration, propranolol pretreatment was associated with a highly significant increase (P less than 0.01) in mean arterial pressure and a significant decrease (P less than 0.05) in heart rate. These results confirm the potentially serious interaction of propranolol and adrenaline during anaesthesia, and support the use of metoprolol instead, to obtund the cardiovascular effects of adrenaline infiltration.