A comparative study of train-of-four (TOF) count at corrugator supercilii and at adductor pollicis reflecting abdominal muscles relaxation

Abstract

Introduction: Diaphragm and lateral abdominal muscles frequently show sparing effects to muscle relaxants. This study compared visual estimation of neuromuscular transmission of corrugator supercilii and adductor pollicis (AP) with electromyographic measurements of lateral abdominal wall muscles during recovery from vecuronium-induced intense neuromuscular block. Methods: 60 patients undergoing elective surgeries under general anesthesia  were included. Following loss of consciousness, supramaximal stimulations were applied using electrical nerve stimlators to left 10th intercostal, ulnar and facial nerves. Electromyographic activity (EMG) of abdominal wall muscles were measured. After Inj. Vecuronium 0.1 mg/kg, Electromyographic activity measurements counted the visually detectable train-of-four (TOF) responses at corrugator supercilii and adductor pollicis. The onset time, the duration of action and quantitative measurements of neuromuscular block were done. Observations: Clinical duration of action of vecuronium almost coincided with train-of-four response at corrugators supercilii where as train-of-four recovery at adductor policis occurred late during recovery stage. Corrugators supercilii had a stronger positive correlation with abdominal muscles relaxation as compared to the adductor policies. Corrugators supercilii had a stronger correlation coefficient (0.910 vs 0.417) than adductor policis with respect to abdominal muscle. It indicated that corrugator supercilii is a better predictor than AP to measure abdominal muscle relaxation.