Accelographic and mechanical post-tetanic count and train-of-four ratio assessed at the great toe

We examined post-tetanic count (PTC) and train-of-four (TOF) ratios at the great toe assessed accelographically or mechanically and compared these with post-tetanic count and train-of-four ratios evaluated mechanically at the thumb in 24 patients who were given vecuronium. An acceleration transducer was attached to the right great toe, a force transducer to the left great toe and another force transducer to the thumb of the left hand. In the PTC group (n = 12) and TOF group (n = 12), post-tetanic count and train-of-four ratios were simultaneously recorded using the two great toes and the thumb of the left hand respectively. Accelographic post-tetanic count at the great toe was greater than the post-tetanic count at the thumb; however, mechanical post-tetanic count at the great toe was lower than the mechanical post-tetanic count at the thumb. Accelographic and mechanical train-of-four ratios at the great toe were greater than the mechanical train-of-four ratios at the thumb. But mechanical train-of-four ratios at the great toe became similar to mechanical train-of-four ratios at the thumb as the degree of neuromuscular block lessened. In conclusion, the mechanical post-tetanic count at the great toe is lower than the mechanical post-tetanic count at the thumb. In contrast, mechanical train-of-four ratios at the great toe are greater than the mechanical train-of-four at the thumb. Nevertheless, as the mechanical train-of-four ratios at the great toe became comparable with the mechanical train-of-four ratios at the thumb, mechanical assessment of the train-of-four ratio at the great toe may be useful for the evaluation of residual neuromuscular block.