Response to recruitment maneuver influences net alveolar fluid clearance in acute respiratory distress syndrome.
BACKGROUND
Alveolar fluid clearance is impaired in the majority of patients with acute respiratory distress syndrome (ARDS). Experimental studies have shown that a reduction of tidal volume increases alveolar fluid clearance. This study was aimed at assessing the impact of the response to a recruitment maneuver (RM) on net alveolar fluid clearance.


METHODS
In 15 patients with ARDS, pulmonary edema fluid and plasma protein concentrations were measured before and after an RM, consisting of a positive end-expiratory pressure maintained 10 cm H2O above the lower inflection point of the pressure-volume curve during 15 min. Cardiorespiratory parameters were measured at baseline (before RM) and 1 and 4 h later. RM-induced lung recruitment was measured using the pressure-volume curve method. Net alveolar fluid clearance was measured by measuring changes in bronchoalveolar protein concentrations before and after RM.


RESULTS
In responders, defined as patients showing an RM-induced increase in arterial oxygen tension of 20% of baseline value or greater, net alveolar fluid clearance (19 +/- 13%/h) and significant alveolar recruitment (113 +/- 101 ml) were observed. In nonresponders, neither net alveolar fluid clearance (-24 +/- 11%/h) nor alveolar recruitment was measured. Responders and nonresponders differed only in terms of lung morphology: Responders had a diffuse loss of aeration, whereas nonresponders had a focal loss of aeration, predominating in the lower lobes.


CONCLUSIONS
In the absence of alveolar recruitment and improvement in arterial oxygenation, RM decreases the rate of alveolar fluid clearance, suggesting that lung overinflation may be associated with epithelial dysfunction.
Constantin
Jean-Michel
JM
Surgical Intensive Care Unit, Department of Anesthesiology, Hôtel-Dieu Hospital, University Hospital of Clermont-Ferrand, INSERM U384, Clermont-Ferrand, France. jmconstantin@chu-clermontferrand.fr
Cayot-Constantin
Sophie
S
Roszyk
Laurence
L
Futier
Emmanuel
E
Sapin
Vincent
V
Dastugue
Bernard
B
Bazin
Jean-Etienne
JE
Rouby
Jean-Jacques
JJ
D000328:Adult; D000368:Aged; D001798:Blood Proteins / Q000032:analysis; D005260:Female; D006801:Humans; D008297:Male; D008875:Middle Aged; D010100:Oxygen / Q000097:blood; D011175:Positive-Pressure Respiration; D011650:Pulmonary Alveoli / Q000378:metabolism*; D011654:Pulmonary Edema / Q000378:metabolism*; D012128:Respiratory Distress Syndrome / Q000503:physiopathology / Q000628:therapy*; D015656:Respiratory Mechanics; D013990:Tidal Volume / Q000502:physiology*
D001798:Blood Proteins; D010100:Oxygen