Neuromuscular blockade and minimal monitoring

Abstract

The debate regarding the use of peripheral nerve stimulators in the assessment of neuromuscular blockade is long overdue. It is therefore gratifying to read a balanced appraisal of the status quo from recognised experts in the field [1, 2]. Why is it opportune to reconsider the current guidelines? For two reasons: firstly, the evidence concerning the widespread occurrence of postoperative residual curarisation is undeniably overwhelming and this has now been supplemented by strong evidence that harm may occur in some patients. Secondly, the survey that we carried out of current practice across the UK [3] with regard to assessment of reversal status following neuromuscular blockade is entirely consistent with the above; that is to say, current practice is at best questionable and at worst dangerous. In the conclusion to our survey we stated that there was great confusion regarding the use of tests currently being used by our colleagues. For example, if anaesthetists genuinely believe that eye opening, tongue protrusion or a normal pattern of breathing or normal saturation is really consistent with full reversal from neuromuscular blockade it reflects sadly not only on current practice but also on the current training of our juniors. Regrettably, there is also a lack of clarity regarding the suitability or lack of suitability of clinical testing both in current publications and in the Association of Anaesthetists of Great Britain and Ireland guidelines on minimal monitoring; does anyone really perform head lift or hand grip before extubation? Perhaps those who have the benefit of desflurane/remifentanil anaesthesia are able to have a meaningful rapport with their patients immediately at the end of surgery and before making the decision to extubate or not. Those of us who routinely work with longer acting agents do not have this luxury; there is presumably no concern among these individuals regarding awareness during anaesthesia since the patient is presumably compos mentis and knows that the operation is complete despite the presence of a tracheal tube. Nevertheless, one must question the supposition that patients are not distressed by being woken up with a tracheal tube in place, and being asked to perform some of these tests. Alternatively, the tests presumably can be done after extubation. Are those patients who remain partially paralysed gently reassured before being re-anaesthetised? What is required now at the very least is an unambiguous statement that all clinical tests are flawed and that the only unequivocal test of reversal is an objective measurement of train-of-four ratio. As already mentioned, there are some patients with co-morbidity in whom measurement of train-of-four should be indicated if not mandatory. One group in particular who increasingly cause problems are the morbidly obese and I would strongly recommend that this group should be added to the list.