title: Prone positioning unloads the right ventricle in severe ARDS.
abstract: BACKGROUND
  Despite airway pressure limitation, acute cor pulmonale persists in a minority of ARDS patients. Insufficient airway pressure limitation, hypercapnia, or both may be responsible. Because prone positioning (PP) has been shown to be a safe way to reduce airway pressure and to improve alveolar ventilation, we decided to assess its effect on right ventricular (RV) pressure overload in ARDS patients.
  
  
  METHODS
  Between January 1998 and December 2006, we studied 42 ARDS patients treated by PP to correct severe oxygenation impairment (Pao2/fraction of inspired oxygen ratio, <100 mm Hg). RV function was evaluated by bedside transesophageal echocardiography, before and after 18 h of prone-position ventilation. RV enlargement was measured by RV/left ventricular (LV) end-diastolic area ratio in the long axis. Septal dyskinesia was quantified by measuring short-axis systolic eccentricity of the LV.
  
  
  RESULTS
  Before PP, 21 patients (50%) had acute cor pulmonale, defined by RV enlargement associated with septal dyskinesia (group 1), whereas 21 patients had a normal RV (group 2). PP was accompanied by a significant decrease in airway pressure and Paco2. In group 1, this produced a significant decrease in mean (+/-SD) RV enlargement (from 0.91+/-0.22 to 0.61+/-0.21) after 18 h of PP (p=0.000) and a significant reduction in mean septal dyskinesia (from 1.5+/-0.2 to 1.1+/-0.1) after 18 h of PP (p=0.000).
  
  
  CONCLUSIONS
  In the most severe forms of ARDS, PP was an efficient means of controlling RV pressure overload.
authors.affiliation: Medical Intensive Care Unit, University Hospital Ambroise Paré, 9 Avenue Charles de Gaulle, 92104, Boulogne Cedex, France.
authors.forename: Antoine
authors.initials: A
authors.lastname: Vieillard-Baron
authors.forename: Cyril
authors.initials: C
authors.lastname: Charron
authors.forename: Vincent
authors.initials: V
authors.lastname: Caille
authors.forename: Guillaume
authors.initials: G
authors.lastname: Belliard
authors.forename: Bernard
authors.initials: B
authors.lastname: Page
authors.forename: François
authors.initials: F
authors.lastname: Jardin
mesh_terms: D018806:APACHE; D016009:Chi-Square Distribution; D017548:Echocardiography, Transesophageal; D005260:Female; D006801:Humans; D008297:Male; D008875:Middle Aged; D016684:Prone Position / Q000502:physiology*; D011660:Pulmonary Heart Disease / Q000000981:diagnostic imaging / Q000503:physiopathology*; D012121:Respiration, Artificial; D012128:Respiratory Distress Syndrome / Q000503:physiopathology* / Q000628:therapy; D018709:Statistics, Nonparametric; D018497:Ventricular Dysfunction, Right / Q000000981:diagnostic imaging / Q000503:physiopathology*