Accurate monitoring of neuromuscular blockade using a peripheral nerve stimulator--a review.

For normal anaesthetic practice, monitoring of neuromuscular blockade is best performed by stimulation of the ulnar nerve at the wrist with a peripheral nerve stimulator and evaluation of the response of the thumb. Determination of the initial threshold for stimulation in the awake patient to allow estimation of the current required for supramaximal stimulation is an important set-up procedure to improve accuracy. The degree of paralysis of specific muscle groups such as the diaphragm can be inferred from their sensitivity to neuromuscular blocking agents relative to adductor pollicis. Monitoring with different stimulation patterns allows a wide spectrum of muscle paralyses to be evaluated.