title: Optimizing bag-valve-mask ventilation with a new mouth-to-bag resuscitator.
abstract: When ventilating an unintubated patient with a self-inflating bag, high peak inspiratory flow rates may result in high peak airway pressure with subsequent stomach inflation; this may occur frequently when rescuers without daily experience in bag-valve-mask ventilation need to perform advanced airway management. The purpose of this study was to assess the effects of a newly developed self-inflating bag (mouth-to-bag resuscitator; Ambu, Glostrup, Denmark) that limits peak inspiratory flow. A bench model simulating a patient with an unintubated airway was used, consisting of a face mask, manikin head, training lung (lung compliance, 100 ml/0.098 kPa (100 ml/cm H(2)O)); airway resistance, 0.39 kPa/l per second (4 cm H(2)O/l/s), oesophagus (LESP, 1.96 kPa (20 cm H(2)O)) and simulated stomach. Twenty nurses were randomised to ventilate the manikin for 1 min (respiratory rate: 12 per minute) with either a standard self-inflating bag or the mouth-to-bag resuscitator, which requires the rescuer to blow up a single-use balloon inside the self-inflating bag, which in turns displaces air towards the patient. When supplemental oxygen is added, ventilation with up to 100% oxygen may be obtained, since expired air is only used as the driving gas. The mouth-to-bag resuscitator therefore allows two instead of one hand sealing the mask on the patient's face. The volunteers were blinded to the experimental design of the model until completion of the experimental protocol. The mouth-to-bag resuscitator versus standard self-inflating bag resulted in significantly (P<0.05) higher mean+/-S.D. mask tidal volumes (1048+/-161 vs. 785+/-174 ml) and lung tidal volumes (911+/-148 vs. 678+/-157 ml), longer inspiratory times (1.7+/-0.4 vs. 1.4+/-0.4 s), but significantly lower peak inspiratory flow rates (50+/-9 vs. 62+/-13 l/min) and mask leakage (10+/-4 vs. 15+/-9%); peak inspiratory pressure (17+/-2 vs. 17+/-2 cm H(2)O) and stomach tidal volumes (16+/-30 vs. 18+/-35 ml) were comparable. In conclusion, employing the mouth-to-bag resuscitator during simulated ventilation of an unintubated patient in respiratory arrest significantly decreased inspiratory flow rate and improved lung tidal volumes, while decreasing mask leakage.
authors.affiliation: Department of Anesthesiology and Critical Care Medicine, Leopold-Franzens-University, Anichstrasse 35, Innsbruck A6020, Austria. horst.wagner-berger@uibk.ac.at
authors.forename: Horst G
authors.initials: HG
authors.lastname: Wagner-Berger
authors.forename: Volker
authors.initials: V
authors.lastname: Wenzel
authors.forename: Angelika
authors.initials: A
authors.lastname: Stallinger
authors.forename: Wolfgang G
authors.initials: WG
authors.lastname: Voelckel
authors.forename: Klaus
authors.initials: K
authors.lastname: Rheinberger
authors.forename: Sven
authors.initials: S
authors.lastname: Augenstein
authors.forename: Holger
authors.initials: H
authors.lastname: Herff
authors.forename: Ahamed H
authors.initials: AH
authors.lastname: Idris
authors.forename: Volker
authors.initials: V
authors.lastname: Dörges
authors.forename: Karl H
authors.initials: KH
authors.lastname: Lindner
authors.forename: Christoph
authors.initials: C
authors.lastname: Hörmann
mesh_terms: D016887:Cardiopulmonary Resuscitation / Q000193:education* / Q000379:methods*; D004506:Education, Nursing; D005260:Female; D006801:Humans; D007442:Intubation, Intratracheal / Q000379:methods; D017214:Laryngeal Masks; D008168:Lung / Q000502:physiology; D008297:Male; D008348:Manikins; D011336:Probability; D011361:Professional Competence; D012123:Pulmonary Ventilation; D012121:Respiration, Artificial / Q000379:methods; D013270:Stomach / Q000502:physiology; D013990:Tidal Volume