title: Muscle relaxation and increasing doses of propofol improve intubating conditions.
abstract: OBJECTIVE
  Muscle relaxants and anesthetics are usually associated during intubation. However, their relative role to facilitate the process is not clearly defined. This study was designed to determine, during intubation: i). the relative role of anesthetics and atracurium-induced neuromuscular block and; ii). the effect of different doses of propofol in the presence of complete muscle block.
  
  
  METHODS
  Patients were randomized to four groups and received fentanyl and a standardized anesthetic procedure. Patients from groups high (H; n = 45), medium (M; n = 48) and low (L; n = 47) received 2.5 mg x kg(-1), 2.0 mg x kg(-1), and 1.5 mg x kg(-1) of propofol respectively. Atracurium (0.5 mg x kg(-1)) was then injected and tracheal intubation performed once complete block was achieved at the orbicularis oculi. Patients from group without atracurium (WA; n = 20) received propofol as in group H. Intubation was performed at the expected onset time of action of atracurium.
  
  
  RESULTS
  Using the same dose of propofol, the incidence of good or excellent intubating conditions was 35% without atracurium and 95% with atracurium (P < 0.0001). In patients receiving atracurium, clinically acceptable intubating conditions were more frequently achieved in groups receiving the highest propofol doses (group H or M vs group L; P < 0.03).
  
  
  CONCLUSIONS
  Our study confirms the interaction between anesthesia and muscle relaxation to produce adequate intubating conditions. In the conditions described, intubating conditions were more dependent on atracurium-induced neuromuscular blockade than on anesthetics, but both atracurium and propofol improved intubating conditions.
authors.affiliation: Départements d'anesthésie, Institut Gustave Roussy, Villejuif. CHU de Poitiers, Poitiers, France.
authors.forename: Thomas
authors.initials: T
authors.lastname: Lieutaud
authors.forename: Valérie
authors.initials: V
authors.lastname: Billard
authors.forename: Huguette
authors.initials: H
authors.lastname: Khalaf
authors.forename: Bertrand
authors.initials: B
authors.lastname: Debaene
mesh_terms: D000293:Adolescent; D000328:Adult; D000368:Aged; D018686:Anesthetics, Intravenous / Q000008:administration & dosage; D001279:Atracurium; D003371:Cough / Q000503:physiopathology; D004305:Dose-Response Relationship, Drug; D004311:Double-Blind Method; D005260:Female; D006801:Humans; D007442:Intubation, Intratracheal; D007828:Laryngoscopy; D008297:Male; D008875:Middle Aged; D003473:Neuromuscular Nondepolarizing Agents; D015742:Propofol / Q000008:administration & dosage
chemical_list: D018686:Anesthetics, Intravenous; D003473:Neuromuscular Nondepolarizing Agents; D001279:Atracurium; D015742:Propofol