European Journal of Anaesthesiology 1996, 13, 483–484 Extended neuromuscular blockade with mivacurium following pancuronium J. R. Sneyd Anesthesiology Department, 1G323 University Hospital, 1500 E Med Center Drive, Ann Arbor, MI 48109-0048, USA Present Address: Department of Anaesthesia, Derriford Hospital, Derriford Road, Plymouth, PL6 8DH, UK. J. R. Sneyd (1996) European Journal of Anaesthesiology, 13, 483–484 Extended neuromuscular blockade with mivacurium following pancuronium Summary (2X ED95) produced extended paralysis with no re- sponse to train-of-four stimulation for 85min. The A 21-year-old female weighing 55 kg was an- prolonged effect of mivacurium may have been be- aesthetized for facial reconstruction. After an initial cause of inhibition of plasma cholinesterase by pan- bolus of pancuronium 5mg and top-up doses of 2mg curonium. The serum cholinesterase activity 12 h after at 135 min and 1 mg at 290 min and 335 min, no further surgery was 0.38 units mL -1 (normal range 0.65–1.0 relaxant was given for 130min at which time neuro- units mL -1 ). There was no evidence of atypical cho- muscular transmission appeared fully recovered with linesterase. a full train-of-four twitches and a sustained response to 50Hz stimulation of the posterior tibial nerve. Sub- Keywords:  , pancuronium, mivacurium, interaction. sequently, a single dose of mivacurium 8mg Introduction which lasted 490 min. Estimated blood loss was under 500 mL and a total of 4 litres of crystalloid and colloid Mivacurium isarecently introduced short-acting,non- were infused. depolarizing skeletal muscle relaxant which is broken Suxamethonium 100mg was given at induction fol- down by plasma cholinesterase. A case is described lowed by pancuronium 5mg. Neuromuscular function in which administration of mivacurium to a patient was not tested between the suxamethonium and the who had already received pancuronium led to pro- first dose of pancuronium. Subsequent doses of pan- longed paralysis. curonium were 2mg at 135min and 1mg at 290min and 335min. At 465min, 130min after the last dose Case report of pancuronium, surgery was almost complete with only somedelicate suturing around theeye remaining. A 21-year-old Japanese female weighing 55kg re- Stimulation of the posterior tibial nerve gave a full ceived extensivefacial injuriesin aroad trafficaccident train-of-four twitches and a sustained response to and underwent facial reconstruction 12h later. She 50 Hz stimulation. In order to ensure no movement of had previously been in good health and had never a patient who was by now very lightly anaesthetized, undergone surgery. Anaesthesia was induced with a single dose of mivacurium 8mg (2XED95) was thiamylal 300mg and maintained with isoflurane in given.Subsequently,neuromuscular function failed to oxygen and nitrous oxide (F I O 2 0.33–0.47) delivered return and the patient was ventilated with 50% nitrous via a circle system with fresh gas flow of 3 l min -1 and oxidein oxygen.Oesophageal temperaturewas36.6°C an isoflurane vapourizer setting of 1–3%. Fentanyl at this time. Intravenous (i.v.) cefuroxime 1.5g had 500 g and morphine 4mg were given during surgery been given after induction of anaesthesia, no other antibiotics were given. After 85min, a single twitch Accepted May 1995 Correspondence: Dr J. R. Sneyd. could be seen in reponse to train-of-four stimulation  1996 European Academy of Anaesthesiology 483