Journal: Br J Anaesth 99(4):514-517, 2007. 28 References
Reprint: Department of Anaesthesia and Intensive Care, Copenhagen University Hospital, Rigshospitalet, Blegdamsvej 9, DK-2100 Copenhagen, Denmark (C Claudius, MD)
Faculty Disclosure: Abstracted by L. Easley, who has nothing to disclose.
It is a myth that postoperative residual curarization (PORC) can be avoided if only one single intubating dose of an intermediate-acting neuromuscular blocking agent is given, and the surgical procedure is longer than 1 - 1.5 hours. The authors report a case of severe residual blockade of more than 3 hours after a normal single intubating dose of rocuronium. The patient was an 84-yr-old woman undergoing hysterectomy and bilateral salpingo-oophorectomy. After induction, routine monitoring of neuromuscular block with train-of-four (TOF) stimulation of the left ulnar nerve at the wrist and recording of the response of the thumb was performed using acceleromyography. Rocuronium 0.6 mg/kg was injected and the trachea intubated. The uneventful laparotomy was completed after 1.5 hours. The level of neuromuscular block was evaluated using the post-tetanic count (PTC) method and TOF. The first response to TOF stimulation (T1) was recorded 193 minutes after the intubating dose of rocuronium. On arrival at the post-anesthetic care unit (PACU; 265 min after injection of rocuronium) clinical tests of residual block were performed. The patient showed no signs or symptoms of residual paralysis.
The two main messages of this case report are: PORC cannot be excluded with certainty although only one normal dose of an intermediate-acting neuromuscular blocking agent has been given for tracheal intubation; and it demonstrates the value of objective neuromuscular monitoring in diagnosis and treatment of PORC. Several factors may have contributed to the prolonged duration of action of rocuronium in this patient: the patient was 84 years old, and the duration of action of rocuronium is prolonged in elderly patients; the variation in duration of action of rocuronium is huge; the elimination of rocuronium is mainly due to biliary excretion, and liver cirrhosis may prolong the duration of action of steroid-based neuromuscular blocking agents; the sensitivity to neuromuscular blocking agents is higher in females than in males; and anesthesia in this patient was maintained with sevoflurane.
Recovery of a rocuronium block during sevoflurane anesthesia is markedly slower than recovery during a total IV anesthesia. The most probable explanation of the prolonged response seen in this elderly patient is a genetically increased sensitivity to rocuronium. Although there is good evidence that quantitative neuromuscular monitoring will decrease the risk of residual paralysis, many clinicians still do not monitor routinely in daily practice. In conclusion, this case illustrates the importance of quantitative neuromuscular monitoring. |
