Neuromuscular Blockade by d‐Tubocurarine in Children

The effect of the intravenous injection, 0.1 mg./pound, of d-tubocurarine on the compound muscle action potential of the hypothenar muscles was studied in 45 patients. The neuromuscular block produced by d-tubocurarine was indirectly and significantly related to age, weight, and to weight plus age. Weight plus age yielded the highest correlation coefficients, although these factors did not account for more than one-third of the variance among individuals. The younger and smaller children had a greater degree and duration of block. The variability in response among the children was large. In studies of the effect of indirect was tetanic stimulation we found, before reversal of block, that mean single action potential height was 85.7 per cent of control, while fade was increased from a control mean of 6.3 per cent to 30.6 per cent. Reversal at a mean time of 84.6 minutes improved mean single action potential height to 98.4 per cent of control; however, fade was decreased to 6.1 per cent. The implications of these results are discussed.