title: Reversal of dependent lung collapse predicts response to lung recruitment in children with early acute lung injury.
abstract: OBJECTIVE
  To describe the resolution of regional atelectasis and the development of regional lung overdistension during a lung-recruitment protocol in children with acute lung injury.
  
  
  METHODS
  Prospective interventional trial.
  
  
  METHODS
  Pediatric intensive care unit.
  
  
  METHODS
  Ten children with early (<72 hrs) acute lung injury.
  
  
  METHODS
  Sustained inflation maneuver (positive airway pressure of 40 cm H2O for 40 secs), followed by a stepwise recruitment maneuver (escalating plateau pressures by 5 cm H2O every 15 mins) until physiologic lung recruitment, defined by PaO2 + PaCO2 ≥400 mm Hg, was achieved. Regional lung volumes and mechanics were measured using electrical impedance tomography.
  
  
  RESULTS
  Patients that responded to the stepwise lung-recruitment maneuver had atelectasis in 54% of the dependent lung regions, while nonresponders had atelectasis in 10% of the dependent lung regions (p = .032). In the pressure step preceding physiologic lung recruitment, a significant reversal of atelectasis occurred in 17% of the dependent lung regions (p = .016). Stepwise recruitment overdistended 8% of the dependent lung regions in responders, but 58% of the same regions in nonresponders (p < .001). Lung compliance in dependent lung regions increased in responders, while compliance in nonresponders did not improve. In contrast to the stepwise recruitment maneuver, the sustained inflation did not produce significant changes in atelectasis or oxygenation: atelectasis was only reversed in 12% of the lung (p = .122), and there was only a modest improvement in oxygenation (27 ± 14 mm Hg, p = .088).
  
  
  CONCLUSIONS
  Reversal of atelectasis in the most dependent lung region preceded improvements in gas exchange during a stepwise lung-recruitment strategy. Lung recruitment of dependent lung areas was accompanied by considerable overdistension of nondependent lung regions. Larger amounts of atelectasis in dependent lung areas were associated with a positive response to a stepwise lung-recruitment maneuver.
authors.affiliation: From the Division of Critical Care Medicine, Children's Hospital Boston, Harvard Medical School, Boston, MA, USA. gerhard.wolf@childrens.harvard.edu
authors.forename: Gerhard K
authors.initials: GK
authors.lastname: Wolf
authors.forename: Camille
authors.initials: C
authors.lastname: Gómez-Laberge
authors.forename: John N
authors.initials: JN
authors.lastname: Kheir
authors.forename: David
authors.initials: D
authors.lastname: Zurakowski
authors.forename: Brian K
authors.initials: BK
authors.lastname: Walsh
authors.forename: Andy
authors.initials: A
authors.lastname: Adler
authors.forename: John H
authors.initials: JH
authors.lastname: Arnold
mesh_terms: D055371:Acute Lung Injury / Q000503:physiopathology / Q000628:therapy*; D000293:Adolescent; D002245:Carbon Dioxide / Q000097:blood; D002648:Child; D002675:Child, Preschool; D017097:Electric Impedance; D005260:Female; D006801:Humans; D008170:Lung Compliance; D008176:Lung Volume Measurements; D008297:Male; D010100:Oxygen / Q000097:blood; D011175:Positive-Pressure Respiration; D011446:Prospective Studies; D001261:Pulmonary Atelectasis / Q000503:physiopathology / Q000628:therapy*; D014054:Tomography
chemical_list: D002245:Carbon Dioxide; D010100:Oxygen