title: Impact of ventilation strategies during chest compression. An experimental study with clinical observations.
abstract: The optimal ventilation strategy during cardiopulmonary resuscitation (CPR) is unknown. Chest compression (CC) generates circulation, while during decompression, thoracic recoil generates negative pressure and venous return. Continuous flow insufflation of oxygen (CFI) allows noninterrupted CC and generates positive airway pressure (Paw). The main objective of this study was to assess the effects of positive Paw compared with the current recommended ventilation strategy on intrathoracic pressure (P(IT)) variations, ventilation, and lung volume. In a mechanical model, allowing compression of the thorax below an equilibrium volume mimicking functional residual capacity (FRC), CC alone or with manual bag ventilation were compared with two levels of Paw with CFI. Lung volume change below FRC at the end of decompression and P(IT), as well as estimated alveolar ventilation, were measured during the bench study. Recordings were obtained in five cardiac arrest patients to confirm the bench findings. Lung volume was continuously below FRC, and as a consequence P(IT) remained negative during decompression in all situations, including with positive Paw. Compared with manual bag or CC alone, CFI with positive Paw limited the fall in lung volume and resulted in larger positive and negative P(IT) variations. Positive Paw with CFI significantly augmented ventilation induced by CC. Recordings in patients confirmed a major loss of lung volume below FRC during CPR, even with positive Paw. Compared with manual bag ventilation, positive Paw associated with CFI limits the loss in lung volume, enhances CC-induced positive P(IT), maintains negative P(IT) during decompression, and generates more alveolar ventilation.
authors.affiliation: University Hospital of Geneva, Intensive Care Unit, Geneva, Switzerland; Intensive Care Unit, Hospital Israelita Albert Einstein, São Paulo, Brazil; Intensive Care Unit, Hospital Alemão Oswaldo Cruz, São Paulo, Brazil; rlcordioli@gmail.com ricardolc@einstein.br.
authors.forename: Ricardo L
authors.initials: RL
authors.lastname: Cordioli
authors.affiliation: University Hospital of Geneva, Intensive Care Unit, Geneva, Switzerland; Laboratoire Rayonnement-Matière et Instrumentation, Département de Physique, Université Hassan 1er, Settat, Morocco; Institut Supérieur des Sciences de la Santé, Université Hassan 1er, Settat, Morocco;
authors.forename: Aissam
authors.initials: A
authors.lastname: Lyazidi
authors.affiliation: Department of Anesthesia and Intensive Care Unit, Rouen, France;
authors.forename: Nathalie
authors.initials: N
authors.lastname: Rey
authors.affiliation: University Hospital of Geneva, Intensive Care Unit, Geneva, Switzerland;
authors.forename: Jean-Max
authors.initials: JM
authors.lastname: Granier
authors.affiliation: Emergency and Intensive Care Department, General Hospital of Annecy, Annecy, France;
authors.forename: Dominique
authors.initials: D
authors.lastname: Savary
authors.affiliation: Keenan Research Centre, St Michael's Hospital, Toronto, Ontario, Canada; Interdepartmental Division of Critical Care Medicine, University of Toronto, Toronto, Ontario, Canada; INSERM UMR 955, Creteil, France.
authors.forename: Laurent
authors.initials: L
authors.lastname: Brochard
authors.affiliation: Emergency and Intensive Care Department, General Hospital of Annecy, Annecy, France; INSERM UMR 955, Creteil, France.
authors.forename: Jean-Christophe M
authors.initials: JC
authors.lastname: Richard
mesh_terms: D016887:Cardiopulmonary Resuscitation / Q000379:methods; D003664:Decompression / Q000379:methods; D006323:Heart Arrest / Q000503:physiopathology; D006801:Humans; D007327:Insufflation / Q000379:methods; D007385:Intermittent Positive-Pressure Ventilation / Q000379:methods*; D008168:Lung / Q000502:physiology; D008954:Models, Biological; D011312:Pressure; D012119:Respiration; D012121:Respiration, Artificial / Q000379:methods; D013909:Thorax / Q000502:physiology*; D013990:Tidal Volume / Q000502:physiology*; D014691:Ventilation / Q000379:methods
keywords: cardiopulmonary resuscitation; chest compression; continuous flow insufflation; lung volume; ventilation