Post-tetanic count at adductor pollicis is a better indicator of early diaphragmatic recovery than train-of-four count at corrugator supercilii

Abstract

Background. Because the intensity of neuromuscular block at the diaphragm (DIA) is indirectly assessed, the electromyographic measurements of the DIA (DIAEMG) from surface electrodes were related to information provided by visual estimation of neuromuscular transmission at the adductor pollicis (AP) and the corrugator supercilii (CSC) during recovery from vecuronium block. Methods. Twelve adult patients were studied during balanced anaesthesia. After induction of anaesthesia and tracheal intubation without neuromuscular blocking agent, supramaximal stimulations were applied to phrenic, ulnar and facial nerves. During recovery from vecuronium 0.1 mg kg-1 an independent observer blinded to DIAEMG counted visually detectable train-of-four (TOF) at CSC (TOFCSC) and post-tetanic AP (PTCAP) responses. Times to recovery of PTCAP=1, <5, <10 and >10, and TOFCSC=1-4 responses were related to DIAEMG. Values are means (sd). Results. Reappearance of the first response to PTCAP occurred significantly (P<0.05) earlier and for a lower recovery of DIAEMG than that of TOFCSC [24 (8) min vs 33 (9) min, and 10 (10)% vs 25 (8)%, respectively]. With PTCAP 5 response, DIAEMG recovery was 21 (11)%. Recovery of TOFCSC=1 and 2 coincided with DIAEMG recovery of 25 (8)% and 47 (9)%, respectively. Conclusions. PTCAP may better reflect early recovery of vecuronium-induced DIA paralysis than TOFCSC. The findings suggested that PTCAP5 warranted deep neuromuscular block of the DIA. © The Board of Management and Trustees of the British Journal of Anaesthesia 2007. All rights reserved.