A survey of non-depolarising muscle relaxants used in cardiac anaesthesia and surgery

Abstract

Introduction: Residual neuromuscular blockade contributes to postoperative morbidity and mortality, and is more common with long-acting non-depolarising muscle relaxants (NDMRs) such as pancuronium [1]. This phenomenon may be a common occurrence in ‘fast-track’ managed cardiac patients administered long-acting NDMRs. We examine the usage of NDMRs in cardiac anaesthesia in the United Kingdom. Methods: A postal questionnaire was sent to 310 consultant cardiac anaesthetists in the United Kingdom. We asked which NDMRs are preferred (differentiating between ‘fast-track’ [FT] and ‘non-fast-track’ [NFT] management of patients), and what methods are used to assess neuromuscular function prior to extubation. Results: There was a 72.6% (225/310) response rate, of which 217 responses were valid. A single-agent NDMR technique is most prevalent for both NFT (92.2%) and FT patients (88.5%). Pancuronium (either as sole agent or in combination with another NDMR) was the first choice for NFT and FT patients, 73.7% and 52.1% respectively. For both management strategies, rocuronium is the next most popular agent. Benzylisoquinolinium derivatives are not in common usage. Forty-nine out of 211 anaesthetists (where a comparison could be made) changed their choice of NDMR between NFT and FT patients. The majority of these anaesthetists (85.7%) remove pancuronium from their practice for FT patients. Of respondents, 20.7% (45/217) indicated that an assessment of neuromuscular function was part of an extubation protocol; 75.6% (34/45) of these respondents detailed only clinical methods, whilst 6.7% (3/45) indicated use of a ‘neuromuscular function monitor’ alone, with 15.6% (7/45) indicating use of both methods. Amongst the responses indicating ‘neuromuscular function monitor’ methods, an assessment of the ‘train-of-four’ was the commonest response. Less than 10% monitor the neuromuscular junction during surgery. Conclusions: Pancuronium remains the most popular NDMR for all types of cardiac anaesthesia. Some anaesthetists modify their choice of NDMR for FT management, changing from pancuronium to a shorter acting NDMR as the commonest adaptation. A minority of respondents indicated that a protocol exists to routinely assess the neuromuscular function prior to extubation.