Neuromuscular monitoring: does it make a difference?

PURPOSE

The objective of the present prospective study was to evaluate the influence of neuromuscular monitoring on the level of neuromuscular blockade from induction of anaesthesia until extubation of the trachea.

METHODS

Forty-two patients aged between 18 and 73 yr undergoing a range of surgical procedures under general anaesthesia were randomly distributed into two groups of 21 patients each. In both groups a Datex NMT Monitor was used and electromyographic responses of the ulnar muscles to supramaximal stimulation of the ulnar nerve were recorded. In Group 1, the anaesthetist could see the movements of the stimulated hand, but not the monitor. In Group 2, the anaesthetist could see neither the stimulated hand nor the monitor. The same anaesthetist administered the neuromuscular relaxants which were succinylcholine 1.5 mg.kg-1 for tracheal intubation and vecuronium 0.1 mg.kg-1 for neuromuscular relaxation during surgery, followed by 1 to 2 mg maintenance injections. Possible residual curarization was evaluated in the recovery room by head life tests and pulse oximetry.

RESULTS

Patients in Group 1 had deeper neuromuscular block throughout surgery, despite the use of a comparable dose of vecuronium (10.1 mg for G1 vs 11.2 mg for G2). The EMG values of T1 and train-of-four values were not different at tracheal intubation or at extubation. No patients presented signs of residual curarization in the recovery room.

CONCLUSION

The study demonstrates that with the same amount of vecuronium the neuromuscular relaxation was deeper with the use of a simple neuromuscular monitoring (visual evaluation of the thumb movements). Despite the deeper neuromuscular block in the monitored group, there was no residual curarization in the recovery room.