Repeatability and comparison of train-of-four responses at thoracic and pelvic limbs using electromyography in anesthetized dogs

Abstract

The aims of this study were to evaluate the repeatability of neuromuscular transmission (NMT) monitoring by electromyography and to compare train-of-four (TOF) responses of thoracic limbs to those of pelvic limbs in dogs after atracurium administration. Seven healthy dogs were enrolled in the study. The dogs were anesthetized with midazolam, morphine, propofol and isoflurane three times with a washout period of seven days. Two treatments of atracurium and electromyography-based neuromuscular monitoring were performed under each anesthesia. The dogs were randomly assigned to undergo either left or right side and either thoracic or pelvic limb for the first treatment and then allocated to the other for the second treatment. Ulnar and peroneal nerves were stimulated with a TOF pattern every 15 seconds. Onset time, time to recovery of the first (TOFcount1), second (TOFcount2), third (TOFcount3) and fourth (TOFcount4) twitches, and time to a TOF ratio of 0.9 (TOFR0.9) were recorded. Atracurium (0.2 mg/kg) was administered intravenously at time zero. Means and standard deviations of time to TOFR0.9 were used for coefficient of variation (CV) calculation. Statistical analyses revealed that the onset time was not different between the limbs. The times to TOFcount1-4 and TOFR0.9 were significantly shorter at the pelvic limbs (all P < 0.05). The CV of NMT monitoring at the thoracic and pelvic limbs were 14.87 and 11.03%, respectively. In conclusion, the NMT monitoring by electromyography at both limbs in dogs was repeatable with low CV. Nevertheless, the pelvic limb monitoring was prone to underestimate the residual neuromuscular blockade.