Haemodynamic responses to antagonism of pancuronium and alcuronium block

Using non-invasive methods, haemodynamic responses to antagonism of pancuronium (Pc) and alcuronium (Ac) block were compared in patients anaesthetized with thiopental-N2O-fentanyl and undergoing minor surgery. Neuromuscular block (90%) was maintained with Pc in 10 patients and Ac in 10 patients. After surgery, atropine 0.015 mg kg-1 and neostigmine 0.03 mg kg-1 (AN) were given simultaneously. The rate of reversal of the block was equal in the two groups. Between 4 and 16 min after AN, the decrease of heart rate (HR) was more pronounced in patients who had received Pc. The mean of the lowest HR was 43.2 beats min-1 in the Pc group, compared with 62.0 beats min-1 in the Ac group. The bradycardia was associated with a moderate decrease in arterial pressure in patients treated with Pc. However, due to an increase in stroke volume, mean cardiac output (CO) was not lower in the Pc group. Some patients treated with Pc developed a temporary nodal rhythm after AN and this was associated with a considerable decrease in CO. It is concluded that, in spite of marked bradycardia during antagonism of Pc block, circulation is well maintained, provided that sinus rhythm is present.