title: A two-handed jaw-thrust technique is superior to the one-handed "EC-clamp" technique for mask ventilation in the apneic unconscious person.
abstract: BACKGROUND
  Mask ventilation is considered a "basic" skill for airway management. A one-handed "EC-clamp" technique is most often used after induction of anesthesia with a two-handed jaw-thrust technique reserved for difficult cases. Our aim was to directly compare both techniques with the primary outcome of air exchange in the lungs.
  
  
  METHODS
  Forty-two elective surgical patients were mask-ventilated after induction of anesthesia by using a one-handed "EC-clamp" technique and a two-handed jaw-thrust technique during pressure-control ventilation in randomized, crossover fashion. When unresponsive to a jaw thrust, expired tidal volumes were recorded from the expiratory limb of the anesthesia machine each for five consecutive breaths. Inadequate mask ventilation and dead-space ventilation were defined as an average tidal volume less than 4 ml/kg predicted body weight or less than 150 ml/breath, respectively. Differences in minute ventilation and tidal volume between techniques were assessed with the use of a mixed-effects model.
  
  
  RESULTS
  Patients were (mean ± SD) 56 ± 18 yr old with a body mass index of 30 ± 7.1 kg/m. Minute ventilation was 6.32 ± 3.24 l/min with one hand and 7.95 ± 2.70 l/min with two hands. The tidal volume was 6.80 ± 3.10 ml/kg predicted body weight with one hand and 8.60 ± 2.31 ml/kg predicted body weight with two hands. Improvement with two hands was independent of the order used. Inadequate or dead-space ventilation occurred more frequently during use of the one-handed compared with the two-handed technique (14 vs. 5%; P = 0.013).
  
  
  CONCLUSIONS
  A two-handed jaw-thrust mask technique improves upper airway patency as measured by greater tidal volumes during pressure-controlled ventilation than a one-handed "EC-clamp" technique in the unconscious apneic person.
authors.affiliation: Pulmonary, Allergy and Critical Care, University of Wisconsin School of Medicine and Public Health, Madison, Wisconsin, USA. joffea@uw.edu
authors.forename: Aaron M
authors.initials: AM
authors.lastname: Joffe
authors.forename: Scott
authors.initials: S
authors.lastname: Hetzel
authors.forename: Elaine C
authors.initials: EC
authors.lastname: Liew
mesh_terms: D000293:Adolescent; D000328:Adult; D000368:Aged; D001049:Apnea / Q000150:complications*; D002983:Clinical Competence; D018592:Cross-Over Studies; D004311:Double-Blind Method; D005260:Female; D006801:Humans; D007430:Intraoperative Care; D007568:Jaw / Q000502:physiology*; D017214:Laryngeal Masks; D008297:Male; D008875:Middle Aged; D012121:Respiration, Artificial / Q000379:methods*; D012129:Respiratory Function Tests; D012307:Risk Factors; D013990:Tidal Volume; D014474:Unconsciousness; D055815:Young Adult