The feasibility of the posterior tibial nerve-flexor hallucis brevis pathway applied in neuromuscular monitoring: a multicentric, controlled, and prospective clinical trial

This study aimed to investigate the clinical viability of utilizing the flexor hallucis brevis as an alternative site for neuromuscular monitoring compared to the conventional adductor pollicis. Patients were recruited from three medical centers. Cis-atracurium was administered, and two monitors were employed independently to assess neuromuscular blockade of the adductor pollicis and the ipsilateral flexor hallucis brevis, following a train of four (TOF) pattern until TOF ratios exceeded 0.9 or until the conclusion of surgery. Statistical analysis revealed significant differences in onset time, duration of no-twitch response, spontaneous recovery time, and total monitoring time between the two sites, with mean differences of -53.54 s, -2.49, 3.22, and 5.89 min, respectively (P < 0.001).The posterior tibial nerve-flexor hallucis brevis pathway presents a promising alternative for neuromuscular monitoring during anesthesia maintenance. Further investigation is warranted to explore its utility in anesthesia induction and recovery. Trial registration: The trial was registered at www.chictr.org.cn (20/11/2018, ChiCTR1800019651).

Effect of conditioning contraction intensity on postactivation potentiation is muscle dependent

We aimed to examine whether the influence of conditioning contraction intensity on the extent of postactivation potentiation (PAP) is muscle dependent. Eleven healthy males performed both thumb adduction and plantar flexion as a conditioning contraction. The conditioning contraction intensities were set at 20%, 40%, 60%, 80%, or 100% of the maximal voluntary isometric contraction (MVC). Before and after the conditioning contraction, twitch torque was measured for the respective joint to calculate the extent of PAP. In plantar flexion, the extent of PAP became significantly larger as the conditioning contraction intensity increased up to 80% MVC (p<0.05). In contrast, the extent of PAP in thumb adduction increased significantly only up to 60% MVC (p<0.05), but not at higher intensities. These results indicate that the influence of the conditioning contraction intensity on the extent of PAP is muscle dependent. Our results suggest that a conditioning contraction with submaximal intensity can sufficiently evoke sizable PAP in the muscle where most of muscle fibers are recruited at submaximal intensities, thereby attenuating muscle fatigue induced by the conditioning contraction.

Differential effects of vecuronium on the thumb and the big toe muscles evaluated by acceleration measurement

To clarify the differential effects of vecuronium on the thumb and on the big toe, train-of-four (TOF) stimuli were applied to the ulnar nerve at the wrist and the tibial nerve at the ankle in anesthetized patients using two acceleration transducers. Ten adult patients, aged 21-55 years, were studied. Anesthesia was induced by an intravenous injection of thiopental, and vecuronium 0.1 mg·kg^-1 was used for paralysis. Anesthesia was maintained with nitrous oxide (66%)-oxygen-sevoflurane (1 MAC). The duration of time to the maximal twitch depression on the thumb and the big toe was 136.5±32.5 s and 183.0±40.1 s (P<0.05), respectively. The time to 25% recovery of the twitch height on the thumb and the big toe was 48.1±17.3 min and 39.1±11.6 min, respectively; the time to 50% recovery of twitch height on the thumb and the big toe was 54.1±16.1 min and 40.0±9.2 min (P<0.05), respectively. When paralysis was reversed at 25% of TOF ratio on the thumb, the value of the TOF ratio on the big toe was 58.5±18.2% (P<0.01).