Train-of-four and double burst stimulation fade at the great toe and thumb.

PURPOSE: We compared probabilities of tactile detection of fade in response to train-of-four (TOF), double burst stimulation3.3 (DBS3.3), and DBS3.2 at the great toe with those at the thumb.

METHODS

One hundred and thirty adult patients anaesthetized with nitrous oxide, oxygen, isoflurane, and fentanyl were studied. At varying degrees of neuromuscular block caused by vecuronium, an observer determined the presence or absence of fade in response to TOF DBS3.3, or DBS3.2 at the great toe and that at the thumb. The relationship between T1/T0 or TOF ratio (T4/T1) measured at the great toe and that at the thumb was also examined.

RESULTS

When TOF ratios were 0-0.10, 0.11-0.20, 0.21-0.30, 0.31-0.40, 0.41-0.50, 0.51-0.60, 0.61-0.70, and 0.71-1.00, the probabilities of detection of fade in response to TOF at the great toe (thumb) were 77 (100), 66 (100), 58 (96), 52 (77), 39 (38), 26 (23), 2(4), and 0(0)%, respectively (P < 0.05 at TOF ratio 0-0.40). Similarly, the probabilities of detection of fade in response to DBS3.3 at the great toe were lower than at the thumb when TOF ratios were 0.21-0.80, and those in response to DBS3.2 at the great toe were lower than at the thumb when TOF ratios were 0.61-0.80. A dose relationship was observed between T1/T0 or TOF ratio at the great toe and that at the thumb.

CONCLUSION

This study suggests that the probability of tactile detection of fade in response to TOF, DBS3.3, or DBS3.2 at the great toe is less than that at the thumb. The present results may be because the flexor hallucis brevis muscle is more resistant to non-depolarizing neuromuscular relaxant than the adductor pollicis muscle and that the ratio of fade in response to neurostimulation at the great toe is higher than at the thumb.