Monitoring of neuromuscular block

page 42 Update in Anaesthesia | www.anaesthesiologists.org There is increasing evidence that residual neuromuscular block is common, and also that it may adversely affect patient outcome. A study by Debaene and colleagues1 found that 45% of patients had residual curarization (train-offour [TOF] ratio<0.9) in the postoperative recovery room after a single intubating dose of the intermediate-acting drugs atracurium, vecuronium or rocuronium. Another study found residual curarization (TOF ratio<0.7) in 42% of patients in the postoperative recovery room after vecuronium.2 Neuromuscular block was not antagonized in either study and the use of neuromuscular monitoring was not recorded, as anaesthetists were encouraged to carry out their practice routinely during these investigations. Although there is no evidence that residual neuromuscular block leads to increased mortality, significant pulmonary morbidity has been demonstrated after using longer-acting agents such as pancuronium.3 As well as interfering with pulmonary mechanics, residual neuromuscular block impairs the ventilatory response to hypoxia.4 At low doses, these drugs significantly impair pharyngeal function and lead to an increased risk of tracheal aspiration and airway obstruction.5