Document Detail

Effects of prone position and positive end-expiratory pressure on lung perfusion and ventilation.
MedLine Citation:
PMID:  18596639     Owner:  NLM     Status:  MEDLINE    
OBJECTIVES: Prone positioning is frequently used during acute respiratory distress syndrome. However, mechanisms by which it improves oxygenation are poorly understood, as well as its interaction with positive end-expiratory pressure. This study was conducted to decipher the respective effects of positive end-expiratory pressure and posture during lung injury on regional lung ventilation, perfusion and recruitment assessed by positron emission tomography. DESIGN: Experimental study. SETTING: Research laboratory of a university hospital. SUBJECTS: Six female piglets. INTERVENTIONS: After oleic acid-induced lung injury, all animals were studied in supine and prone position at both positive end-expiratory pressure 0 and positive end-expiratory pressure 10 cm H2O. MEASUREMENTS AND MAIN RESULTS: In each experimental condition, regional lung perfusion and ventilation were assessed with positron emission tomograph using intravenous 15O-labeled water and inhaled nitrogen-13. Nonaerated lung weight was assessed with positron emission tomograph, and alveolar recruitment was defined as the difference of nonaerated lung weight between conditions. Positive end-expiratory pressure was associated with significant alveolar recruitment (130 +/- 85 and 65 +/- 29 g of lung in supine and prone position, respectively [p < 0.05 vs. 0]), whereas recruitment induced by posture was not statistically significant (77 +/- 97 g with positive end-expiratory pressure 0 and 13 +/- 19 g with positive end-expiratory pressure 10 [p > 0.05 vs. 0]). Regardless the posture, positive end-expiratory pressure redistributed both perfusion and ventilation toward dependent regions. Recruitment by positive end-expiratory pressure was restricted to dorsal regions in supine position, but extended diffusely along the ventral-to-dorsal dimension in prone position. Prone position was associated with recruitment in dorsal regions with concomitant derecruitment in ventral regions, magnitude of this being reduced by positive end-expiratory pressure. Prone position redistributed ventilation toward dorsal and ventral regions at positive end-expiratory pressure 0 and positive end-expiratory pressure, respectively. Finally, prone position redistributed perfusion toward ventral regions, to an extent amplified by positive end-expiratory pressure. CONCLUSIONS: Positive end-expiratory pressure and posture act synergistically by redistributing lung regional perfusion toward ventral regions, but have antagonistic effects on regional ventilation.
Jean-Christophe Richard; Fabienne Bregeon; Nicolas Costes; Didier L E Bars; Christian Tourvieille; Franck Lavenne; Marc Janier; Gaël Bourdin; Gérard Gimenez; Claude Guerin
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Publication Detail:
Type:  Journal Article; Research Support, Non-U.S. Gov't    
Journal Detail:
Title:  Critical care medicine     Volume:  36     ISSN:  1530-0293     ISO Abbreviation:  Crit. Care Med.     Publication Date:  2008 Aug 
Date Detail:
Created Date:  2008-07-31     Completed Date:  2008-08-25     Revised Date:  -    
Medline Journal Info:
Nlm Unique ID:  0355501     Medline TA:  Crit Care Med     Country:  United States    
Other Details:
Languages:  eng     Pagination:  2373-80     Citation Subset:  AIM; IM    
Hospices civils de Lyon, Service de Réanimation Médicale et d'Assistance Respiratoire, Hôpital de la Croix Rousse, Lyon, France.
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MeSH Terms
Blood Gas Analysis
Disease Models, Animal*
Positive-Pressure Respiration*
Positron-Emission Tomography
Prone Position
Pulmonary Circulation
Respiratory Distress Syndrome, Adult / therapy*
Comment In:
Crit Care Med. 2008 Aug;36(8):2469-71   [PMID:  18664808 ]

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