title: The effects of age on maintenance of intense neuromuscular block with rocuronium.
abstract: BACKGROUND
  Increasing age is associated with a longer duration of action of neuromuscular block. The aim of this study was to determine the influence of ageing on the recovery of the post-tetanic count (PTC) from rocuronium-induced neuromuscular block.
  
  
  METHODS
  Twenty-two younger (20-60 years) and 22 older (> 70 years) patients were enrolled in this study. After induction of anaesthesia with fentanyl and propofol, all patients initially received 1 mg/kg rocuronium and neuromuscular block were evaluated by contractions of the adductor pollicis muscle to ulnar nerve train-of-four stimulation using an acceleromyograph. Subsequently, intense rocuronium-induced block was determined every 6 min using the PTC during 1.0-1.5% sevoflurane and remifentanil anaesthesia. When the first response to the PTC stimulus was detected, 0.2 mg/kg rocuronium was additionally administered, and again, spontaneous recovery of neuromuscular function was monitored until the first response to the PTC reappeared.
  
  
  RESULTS
  Median values (range) of the times from the administration of 1 mg/kg and 0.2 mg/kg rocuronium until recovery of the first detectable PTC were significantly longer in the older [51.0 (27-100) min, P < 0.0001 and 30.0 (12-66) min, P = 0.0036, respectively] than the younger patients [31.5 (21-45) min and 18.0 (12-36) min, respectively].
  
  
  CONCLUSIONS
  The times from rocuronium injection to reappearance of the first response to PTC stimulation are approximately twofold longer and more variable in older than younger patients. Hence, the dosing interval of rocuronium should be adjusted using neuromuscular monitoring when maintaining intense neuromuscular block, especially in older patients.
authors.affiliation: Department of Anaesthesiology, Nihon University School of Medicine, Tokyo, Japan.
authors.forename: T
authors.initials: T
authors.lastname: Furuya
authors.forename: T
authors.initials: T
authors.lastname: Suzuki
authors.forename: A
authors.initials: A
authors.lastname: Kashiwai
authors.forename: J
authors.initials: J
authors.lastname: Konishi
authors.forename: M
authors.initials: M
authors.lastname: Aono
authors.forename: N
authors.initials: N
authors.lastname: Hirose
authors.forename: J
authors.initials: J
authors.lastname: Kato
authors.forename: S
authors.initials: S
authors.lastname: Ogawa
mesh_terms: D000328:Adult; D000368:Aged; D000369:Aged, 80 and over; D000375:Aging / Q000502:physiology*; D000732:Androstanols; D000768:Anesthesia, General; D004558:Electric Stimulation; D005260:Female; D006801:Humans; D008297:Male; D008875:Middle Aged; D016343:Monitoring, Intraoperative; D009119:Muscle Contraction / Q000187:drug effects / Q000502:physiology; D019148:Neuromuscular Blockade; D003473:Neuromuscular Nondepolarizing Agents; D000077123:Rocuronium; D018401:Sample Size; D055815:Young Adult
chemical_list: D000732:Androstanols; D003473:Neuromuscular Nondepolarizing Agents; D000077123:Rocuronium