title: Awareness during laryngoscopy and intubation: quantitating incidence following induction of balanced anesthesia with etomidate and cisatracurium as detected with the isolated forearm technique.
abstract: OBJECTIVE
  To measure the incidence of awareness during induction of anesthesia with etomidate and fentanyl, and to model its frequency as a function of dose of etomidate.
  
  
  METHODS
  Prospective cohort study.
  
  
  METHODS
  Anesthesia department of a university hospital.
  
  
  METHODS
  30 ASA physical status I, II, and III patients undergoing elective general surgery.
  
  
  METHODS
  Patients were assigned to one of three groups of etomidate (0.2 mg/kg, 0.3 mg/kg, 0.4 mg/kg) and received fentanyl (2 microg/kg) and 2 x ED(95) of cisatracurium (0.1 mg/kg). Neuromuscular block was monitored with a peripheral nerve stimulator. Intubation was performed after maximum T(1)-depression. To identify awareness, the isolated forearm technique (IFT) was used. The IFT was performed by prompting the patient every 20 seconds. Only a verified response was considered a positive IFT response. Anesthesia was maintained with isoflurane in oxygen/air and fentanyl.
  
  
  RESULTS
  Maximum neuromuscular block occurred after 352 +/- 96 seconds and intubation was performed 424 +/- 86 seconds after loss of consciousness (LOC). Awareness was dose dependent: 80% of patients receiving 0.2 mg/kg etomidate, 70% of patients receiving 0.3 mg/kg etomidate, and 20% of patients receiving 0.4 mg/kg etomidate had a positive IFT response. Awareness occurred in one patient 3 minutes after LOC, in 65% during laryngoscopy, and in 30% within the following 120 seconds. One patient had explicit recall without finding awareness unpleasant. Hemodynamic parameters did not differ between patients with a positive or a negative IFT response.
  
  
  CONCLUSIONS
  The incidence of awareness during bolus induction can be modeled as dose dependent. However, when combining a short-acting induction drug and a delayed-onset neuromuscular blocker, the continuous infusion of the hypnotic drug may prevent awareness during induction.
authors.affiliation: Klinik für Anästhesiologie, F.A. Universität Erlangen-Nurnberg, Erlangen, Germany. UM.St_Pierre@01019freenet.de
authors.forename: M
authors.initials: M
authors.lastname: St Pierre
authors.forename: B
authors.initials: B
authors.lastname: Landsleitner
authors.forename: H
authors.initials: H
authors.lastname: Schwilden
authors.forename: J
authors.initials: J
authors.lastname: Schuettler
mesh_terms: D000328:Adult; D000368:Aged; D000369:Aged, 80 and over; D000771:Anesthesia, Intravenous; D018685:Anesthetics, Inhalation / Q000008:administration & dosage; D018686:Anesthetics, Intravenous / Q000008:administration & dosage*; D001279:Atracurium / Q000008:administration & dosage / Q000031:analogs & derivatives*; D001364:Awareness / Q000187:drug effects; D015331:Cohort Studies; D004305:Dose-Response Relationship, Drug; D017558:Elective Surgical Procedures; D005045:Etomidate / Q000008:administration & dosage*; D005260:Female; D005283:Fentanyl / Q000008:administration & dosage*; D005542:Forearm / Q000294:innervation; D006801:Humans; D006993:Hypnotics and Sedatives / Q000008:administration & dosage; D007442:Intubation, Intratracheal; D007530:Isoflurane / Q000008:administration & dosage; D007828:Laryngoscopy; D008297:Male; D008875:Middle Aged; D019148:Neuromuscular Blockade; D009466:Neuromuscular Blocking Agents / Q000008:administration & dosage*; D009469:Neuromuscular Junction / Q000187:drug effects; D011446:Prospective Studies; D013997:Time Factors
chemical_list: D018685:Anesthetics, Inhalation; D018686:Anesthetics, Intravenous; D006993:Hypnotics and Sedatives; D009466:Neuromuscular Blocking Agents; D001279:Atracurium; D007530:Isoflurane; C101584:cisatracurium; D005283:Fentanyl; D005045:Etomidate