Effect of Pancuronium on Plasma Free‐Norepinephrine and Epinephrine in Adult Cardiac Surgical Patients

Since diazepam‐ketamine induction sequences in healthy humans cause no significant increase in plasma free‐norepinephrine and epinephrine, blood pressure and heart rate, we have frequently used a diazepam‐ketamine pancuronium sequence for induction of anesthesia in patients undergoing open‐heart surgery. In order to assess objectively the influence of pancuronium on sympathetic activity in cardiac patients, plasma free‐norepinephrine and free‐epinephrine were measured by Vend‐salu's method in the arterial blood of 12 patients who were to undergo valve replacement or coronary bypass. At the same time, arterial pressure measured by a strain‐gauge from the radial artery and heart rate measured by ECG were continuously recorded during induction with diazepam 0.3 mg/kg, followed 10 min later by ketamine 2.0 mg/kg. No significant changes occurred in these parameters before pancuronium administration. Plasma free‐norepinephrine and free‐epinephrine concentrations before and 5 min after pancuronium 0.1 mg/kg given over a 1‐min period were 0.42±0.05 (mean ± s.e.mean) and 0.45±0.05 ng/ml (P>0.1) and 0.01±0.003 and 0.02±0.009 ng/ml (P>0.1), respectively. A significant increase in heart rate followed pancuronium administration from 75.0±4.0 to 90.0±6.0 beatslmin (P<0.001). The corresponding systolic and diastolic direct arterial pressures were 148.0±9.4/74.0±6.0 and 153.0±8.3/81.0±5.2 mmHg (P>0.05). Although a statistically significant increase in heart rate was observed after pancuronium, no significant increase was found in plasma free‐norepinephrine, epinephrine or direct arterial pressure.