Mixed neuromuscular block. A re-assessment using train-of-four stimulation.

Suxamethonium was administered to patients during recovery from non-depolarising muscle relaxation. The effect of suxamethonium varied depending upon the degree of recovery from the non-depolarising block when it was administered. Early in recovery suxamethonium produced reversal of the non-depolarising block without paralysis whereas when administered later, initial recovery of the non-depolarising block was followed by paralysis. If administered after 50% recovery the predominant effect was paralysis without initial recovery. Assessment of neuromuscular blockade with train-of-four stimulation showed that the paralysis produced by suxamethonium under these circumstances, had depolarising and non-depolarising features.