A comparison of rocuronium and pancuronium in adult patients scheduled for 'fast-track' elective open heart surgery involving hypothermic cardiopulmonary bypass

Introduction

The non-depolarising muscle relaxant (NDMR) pancuronium continues to be used for fast-track cardiac anaesthesia despite its declining popularity elsewhere. Its duration of action can be unpredictable and prolonged, leading to an increased incidence of residual neuromuscular block [1]. We examined whether pancuronium remains an appropriate NDMR for 'fast-track' patients and include comparison with rocuronium, which has been suggested as an alternative agent.

Methods

Twenty patients eligible for 'fast-track' cardiac surgery were prospectively randomised to receive either pancuronium 0.1 mg/kg or rocuronium 1 mg/kg in a double-blind study design. Neuromuscular function was assessed by acceleromyography and the time to recovery of train-of-four (TOF) ratio of 0.9 was measured. A standardised anaesthetic technique was employed which avoided the use of volatile anaesthetic gases and vapours.

Results

Both groups had similar demographic makeup and were well matched for confounding variables. No patient required supplementary doses of NDMR.

The median times (in minutes) for pancuronium and rocuronium, respectively, to recovery of TOF 0.9 were 472.5 (SD, 103.7) and 217.5 (SD, 56.6). The observed difference in TOF 0.9 medians was 255 (95% CI, 150–320). The Mann–Whitney test was highly significant at P = 0.0003.

No patient in the rocuronium group and 7/10 patients in the pancuronium group had their extubations delayed as a consequence of residual paralysis.

Conclusions

We have demonstrated that pancuronium lasts approximately twice as long and has approximately double the inter-individual variation compared with rocuronium. We recommend that pancuronium is no longer an acceptable NDMR in such patients. Although rocuronium has potential as an alternative agent, we recommend that due to variation in its duration of action post-hypothermic cardiopulmonary bypass, patients should routinely have their neuromuscular function monitored prior to extubation.