title: Factors predicting atracurium reversal time.
abstract: BACKGROUND
  To identify individual factors and combination of factors predictive of reversal time (defined as time from neostigmine administration to train-of-four (TOF) ratio 0.70) from atracurium-induced neuromuscular block, the present study tested the following variables as possible predictors of reversal time: 1) degree of block at the time of antagonism as quantified by first response to TOF or double-burst stimulation (DBS); 2) time from last supplemental dose of atracurium to administration of neostigmine (pre-reversal time); and 3) time from administration of initial atracurium dose to T1 (the magnitude of the first twitch in TOF) recovered to 10% (duration of action of the initial dose of atracurium).
  
  
  METHODS
  The study population comprised 83 female patients, ASA physical status 1 or 2, anaesthetized with fentanyl, thiopental, halothane and nitrous oxide. Initial and supplemental doses of atracurium were 0.5 mg x kg(-1) and 0.15 mg x kg(-1), respectively. Evoked responses to TOF or DBS were recorded mechanomyographically. Neuromuscular block was antagonized with neostigmine, 0.07 mg x kg(-1), at varying time intervals (6-50 min) after the final atracurium dose.
  
  
  RESULTS
  Multiple linear regression analyses testing T1, D1 (the magnitude of the first twitch in DBS), pre-reversal time and duration of action of the initial dose of atracurium, demonstrated that with superficial block, T1 >15%, T1 is the only significant predictor for reversal time. With moderate block, 0< T1 < or =15%, both T1 and duration of action of the initial atracurium dose are significant predictors for reversal time. With profound block, T1=0, duration of action of the initial dose and pre-reversal time are significant predictors for reversal time.
  
  
  CONCLUSIONS
  1) T1 is a more important predictor for reversal time from atracurium-induced neuromuscular block than D1; 2) predictors differ with the degree of block: with T1 > 15%, T1 is the only significant predictor; with 0< T1 < or =15%, the duration of action of the initial dose and T1 are predictors for reversal time; with T1=0, the duration of action of the initial dose and pre-reversal time predict reversal time.
authors.affiliation: Department of Anaesthesia and Intensive Care, Odense University Hospital, Denmark.
authors.forename: H
authors.initials: H
authors.lastname: Kirkegaard-Nielsen
authors.forename: I K
authors.initials: IK
authors.lastname: Severinsen
authors.forename: H S
authors.initials: HS
authors.lastname: Pedersen
authors.forename: P
authors.initials: P
authors.lastname: Lindholm
mesh_terms: D000328:Adult; D000762:Anesthesia Recovery Period; D018685:Anesthetics, Inhalation / Q000008:administration & dosage; D018686:Anesthetics, Intravenous / Q000008:administration & dosage; D001279:Atracurium / Q000008:administration & dosage* / Q000037:antagonists & inhibitors; D002800:Cholinesterase Inhibitors / Q000627:therapeutic use; D004558:Electric Stimulation; D019054:Evoked Potentials, Motor / Q000187:drug effects; D005260:Female; D005283:Fentanyl / Q000008:administration & dosage; D005544:Forecasting; D006221:Halothane / Q000008:administration & dosage; D006801:Humans; D016014:Linear Models; D008875:Middle Aged; D009119:Muscle Contraction / Q000187:drug effects; D009388:Neostigmine / Q000627:therapeutic use; D019148:Neuromuscular Blockade; D003473:Neuromuscular Nondepolarizing Agents / Q000008:administration & dosage* / Q000037:antagonists & inhibitors; D009609:Nitrous Oxide / Q000008:administration & dosage; D013874:Thiopental / Q000008:administration & dosage; D013997:Time Factors; D014459:Ulnar Nerve / Q000187:drug effects
chemical_list: D018685:Anesthetics, Inhalation; D018686:Anesthetics, Intravenous; D002800:Cholinesterase Inhibitors; D003473:Neuromuscular Nondepolarizing Agents; D001279:Atracurium; D009388:Neostigmine; D013874:Thiopental; D009609:Nitrous Oxide; D005283:Fentanyl; D006221:Halothane