Introduction: The pharmacodynamics and pharmacokinetics of nondepolarising neuromuscular blocking agent rocuronium (R) with short-onset time, is well studied in noncardiac surgery . The aim of this study was to compare haemodynamic responses and neuromuscular profile of R and cisatracurium (C) and evaluate tracheal intubating conditions in cardiac surgical patients with coronary artery disease.
Method: 26 adult ASA physical status class 3-4 patients undergoing CABG surgery were studied. All patients were taking nitrates and β-blockers and were premedicated with diazepam 10 mg, trimeperidine 20 mg and atropine 0.3 mg. In all patients anaesthesia was induced with midazolam 0.1-0.15 mg kg−1, fentanyl 6 μg kg−1 and ketamine 1 mg kg−1. The patients were randomly allocated to two groups: group one (13 patients) received rocuronium 0.9 mg kg−1 (3ED×95) and group two (13 patients) received cis-atracurium 0.15 mg kg−1 (3ED×95) for tracheal intubation. Haemodynamic data (HR, MAP, CVP, MPAP, SVR, PVR, CI) were registered before and 10 min after relaxant injection. Accelerometric control of neuromuscular transmission was carried out by the TOF-Guard device (Organon Teknika) by train-of-four stimulation of the ulnar nerve. Statistical analysis was performed using Student's t-test (mean ± SD).
Results: Comparison of the dynamics of T1 suppression for 10 min after drugs injection (Figure 1) showed that maximal neuromuscular blockade was observed 1.5 ± 0.1 min after administration of R and 3.3 ± 0.8 min after C injection (P < 0.05). Clinical and neuromuscular blockade (90 ± 5%) after injection of R and C persisted for 62.1 ± 8 min and 54.1 ± 10 min accordingly (P > 0.05). In group 1 the conditions for tracheal intubation at 2 min were evaluated as excellent in all patients. In group 2 excellent conditions of intubation of trachea at 4 min were assessed in 12 patients. In one patient tracheal intubation was accompanied by moderate coughing. During 10 min after R and C administration minor changes in all the measured or derived haemodynamic variables within and between the two groups did not attain statistical significance.
Discussion: Both the new neuromuscular blocking agents provided high efficacy and haemodynamic stability in β-blocked patients with coronary artery disease during induction of anaesthesia. However, adequate neuromuscular blockade for tracheal intubation was achieved 2 times faster after R injection. Because of the short-onset time, rocuronium appears to be a more suitable agent for muscle relaxation during induction of anaesthesia in cardiosurgical patients especially in the case of emergency.
1 Robertson EN, Hull JM, Verbeek AM, et al.
A comparison of rocuronium and vecuronium: the pharmacodynamic, cardiovascular and intra-ocular effects. Eur J Anaesthesiol
1994; 9 (Suppl)