title: Incidence and prediction of inadequate preoxygenation before induction of anaesthesia.
abstract: BACKGROUND
  Preoxygenation aims to obtain an expired oxygen fraction (FEO2)≥90%. Little is known about the incidence and predictors of inadequate preoxygenation in the clinical setting.
  
  
  METHODS
  Over a 12-month period, 1050 consecutive preoperative patients were prospectively included. Preoxygenation was performed for 3minutes with a facial mask using a machine circuit and 12-L/min oxygen flow. Inadequate preoxygenation was defined as an FEO2<90%. A logistic regression was performed to identify incidence and independent predictors.
  
  
  RESULTS
  The patient characteristics were: age 51±20years, 47% male, BMI of 26±5kg/m(2), and ASA score (median [extremes]) of 2 [1-4]. Inadequate preoxygenation was observed in 589 patients (56%). The effective FiO2 delivered was lower in the patients with inadequate preoxygenation than in those with adequate preoxygenation, 95±3% vs. 98±2%, P<0.001. The difference between the FiO2 and the FEO2 was higher (12±6% vs. 6±3%, P<0.0001) in patients with inadequate preoxygenation compared with those with adequate preoxygenation. The independent risk factors for inadequate preoxygenation were: firstly, bearded male (odds ratio [OR] of 9.1 [2.7-31.4] P<0.001); secondly, beardless male (OR 2.4 [1.6-3.4] P<0.001), thirdly, ASA score of 4 (OR 9.1 [2.6-31.2] P<0.015); fourthly, ASA score of 2-3 (OR 2.4 [1.6-3.4] P<0.015); fifthly, lack of teeth (OR 2.4 [1.2-4.5] P<0.006), and lastly age>55 years (OR 1.8 [1.2-2.7] P<0.005).
  
  
  CONCLUSIONS
  Inadequate preoxygenation, defined as an FEO2 <90% despite 3-min tidal volume breathing, was a common occurrence. The predictive factors share an overlap with those previously identified for difficult mask ventilation.
authors.affiliation: EA 3409, department of anaesthesiology and critical care medicine, Avicenne university hospital, Paris-13 university, AP-HP, 125, route de Stalingrad, 93009 Bobigny, France. Electronic address: christophe.baillard@avc.aphp.fr.
authors.forename: C
authors.initials: C
authors.lastname: Baillard
authors.affiliation: EA 3409, department of anaesthesiology and critical care medicine, Avicenne university hospital, Paris-13 university, AP-HP, 125, route de Stalingrad, 93009 Bobigny, France.
authors.forename: F
authors.initials: F
authors.lastname: Depret
authors.affiliation: Clinical research unit, Avicenne university hospital, Paris-13 university, AP-HP, 125, route de Stalingrad, 93009 Bobigny, France.
authors.forename: V
authors.initials: V
authors.lastname: Levy
authors.affiliation: Clinical research unit, Avicenne university hospital, Paris-13 university, AP-HP, 125, route de Stalingrad, 93009 Bobigny, France.
authors.forename: M
authors.initials: M
authors.lastname: Boubaya
authors.affiliation: EA 3409, department of anaesthesiology and critical care medicine, Avicenne university hospital, Paris-13 university, AP-HP, 125, route de Stalingrad, 93009 Bobigny, France.
authors.forename: S
authors.initials: S
authors.lastname: Beloucif
mesh_terms: D000293:Adolescent; D000328:Adult; D000368:Aged; D000369:Aged, 80 and over; D000758:Anesthesia / Q000379:methods*; D005260:Female; D006801:Humans; D000860:Hypoxia / Q000175:diagnosis / Q000209:etiology; D015994:Incidence; D007431:Intraoperative Complications / Q000175:diagnosis / Q000209:etiology; D008297:Male; D019300:Medical Errors / Q000706:statistics & numerical data; D008875:Middle Aged; D010100:Oxygen / Q000008:administration & dosage*; D056888:Patient Positioning; D012121:Respiration, Artificial; D055815:Young Adult
chemical_list: D010100:Oxygen
keywords: Airway; Anesthésie générale; General anesthesia; Preoxygenation; Préoxygénation; Voies aériennes