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

Background. Because the intensity of neuromuscular block at the diaphragm (DIA) is indirectly assessed, the electromyographic measurements of the DIA (DIA_EMG) 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 DIA_EMG counted visually detectable train-of-four (TOF) at CSC (TOF_CSC) and post-tetanic AP (PTC_AP) responses. Times to recovery of PTC_AP=1, <5, <10 and >10, and TOF_CSC=1-4 responses were related to DIA_EMG. Values are means (^sd). Results. Reappearance of the first response to PTC_AP occurred significantly (P<0.05) earlier and for a lower recovery of DIA_EMG than that of TOF_CSC [24 (8) min vs 33 (9) min, and 10 (10)% vs 25 (8)%, respectively]. With PTC_AP 5 response, DIA_EMG recovery was 21 (11)%. Recovery of TOF_CSC=1 and 2 coincided with DIA^EMG recovery of 25 (8)% and 47 (9)%, respectively. Conclusions. PTC_AP may better reflect early recovery of vecuronium-induced DIA paralysis than TOF_CSC. The findings suggested that PTC_AP5 warranted deep neuromuscular block of the DIA.