In off-pump cardiac surgery, neuromuscular monitoring should be mandatory and immediate extubation is feasible

EDITOR: We read with great interest the article by Cammu et al.[1] investigating the effect of neuromuscular monitoring on the feasibility of immediate extubation after off-pump cardiac surgery. They examined whether the use of neuromuscular transmission monitoring results in differences in the incidence of postoperative residual curarization, the endotracheal extubation rate and outcome after continuous infusion of rocuronium in patients undergoing off-pump coronary artery bypass surgery. They performed a study of two groups of patients undergoing off-pump cardiac surgery, one group of patients with neuromuscular monitoring, one without neuromuscular monitoring. They state that they found no additional benefit of using neuromuscular transmission monitoring, and conclude that it is not wise to perform immediate postoperative extubation in off-pump coronary artery bypass surgery. We would like to raise a number of points. We are concerned about the application of a neuromuscular blocking drug without the concomitant use of any neuromuscular monitoring device. A recent editorial [2] made it clear that it is time to routinely use quantitative neuromuscular monitoring whenever a neuromuscular blocking drug is used. The authors did not use a quantitative or a qualitative method to monitor neuromuscular blockade and we believe that this represents an uncommon practice. Furthermore, the authors argue that continuous infusions of neuromuscular blocking drugs are commonly used during coronary artery bypass grafting. There is no explanation advanced as to why a profound neuromuscular block is necessary for cardiac surgery. In our opinion, profound neuromuscular block in cardiac surgery stems from a time when cardiac anaesthesia was based more on relaxation and analgesia than actual anaesthesia. However, in recent years, concerns about intraoperative awareness and a general change of practice towards the more liberal use of volatile anaesthetics, such as sevoflurane, have greatly diminished the use of neuromuscular blocking drugs. We routinely use neuromuscular monitoring to control the intermittent application of rocuronium during cardiac surgery and we try to maintain a train of four ratio of 0.25-0.5 during surgery. Sufficiently deep anaesthesia seems to be the main strategy in order to avoid not only patient movement but also intraoperative awareness. Finally, the authors suggest that 'immediate postoperative extubation has been made realistic due to strong analgesics'. We cannot support this hypothesis. They have discounted all of the recent advances in early and immediate extubation after different types of cardiac surgery which have been made possible by using regional techniques, especially high thoracic epidurals [3-5]. In their study, the authors did not present postoperative pain scores but stated that significant postoperative pain was the main problem which lead to failure of immediate extubation. This is not surprising when one considers their intraoperative analgesic regimen where patients received remifentanil infusions during surgery and, as pre-emptive analgesia, 15 mg pirinitramide (piritramide). Due to the ultra-short action of remifentanil, we would contend that 15 mg of pirinitramide would not provide sufficient analgesia to allow the immediate extubation of any patient after any form of major surgery. Pre-emptive analgesia using opioids such as morphine during solely remifentanil-based analgesia is associated with significant pain immediately after major surgery and can lead to postoperative respiratory depression in the acute or intermediate postoperative period [6]. We (and others [4]) have successfully extubated patients immediately after cardiac surgery using conventional, fentanyl-based analgesia, with average pain scores of 4 [5]. However, thoracic epidural analgesia is superior to conventional opioid-based analgesia for pain control and provides significantly lower pain scores. We believe that thoracic epidural analgesia provides the best chance of success for immediate extubation with a practically pain-free, comfortable patient. The conclusion that routine immediate postoperative extubation in off-pump cardiac surgery is not wise seems biased and shows that the author's strategy of analgesia is not adequate. The fact that 8 out of 16 of their patients could not be extubated because of an inadequate analgesic regimen should not lead the reader to think that immediate extubation is impossible or dangerous after cardiac surgery. Routine immediate extubation after off-pump cardiac surgery is possible as long as normothermia is maintained and sufficient analgesia is provided (preferably by thoracic epidural analgesia). Neuromuscular monitoring should be applied whenever neuromuscular blocking drugs are used and profound neuromuscular block is not necessary for cardiac surgery when a sufficient level of anaesthesia is provided. J. F. Olivier T. M. Hemmerling Department of Anesthesiology; Centre Hospitalier de l'Université de Montréal (CHUM); Université de Montréal; Montréal, Québec, Canada

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