title: A lung recruitment maneuver immediately before rescue surfactant therapy does not affect the lung mechanical response in immature lambs with respiratory distress syndrome.
abstract: BACKGROUND
  In animals with acquired surfactant-deficiency, a recruitment maneuver by increased tidal volumes enhances the effect of exogenous surfactant. In contrast, in the preterm lamb model, hyperinflation early after birth impairs the effect of surfactant prophylaxis. Here we examined whether a lung recruitment maneuver just before surfactant would affect the response to rescue treatment in immature lambs with established respiratory distress syndrome (RDS).
  
  
  METHODS
  Five pairs of preterm twin lambs with gestational age 127 days were delivered by cesarean section and supported by pressure-limited mechanical ventilation for 4 h. At 30 min of age, when all the lambs were in severe respiratory failure, they were treated with porcine surfactant, 200 mg x kg-1. One lamb in each pair was subjected to a lung recruitment maneuver consisting of five sustained inflations of 20 ml x kg-1 just before surfactant instillation.
  
  
  RESULTS
  At 10 min after surfactant treatment, all the lambs showed a large improvement in oxygenation and an increase in inspiratory capacity and static compliance. Except for a transiently better oxygenation after surfactant therapy in the recruitment group (P < 0.05), there was no significant between-group differences in gas exchange or lung mechanics at any time point during the study. There was no difference in post mortem intrapulmonary air volume or alveolar expansion in histologic lung sections between groups.
  
  
  CONCLUSIONS
  This small study does not show any positive or negative effect of a lung recruitment maneuver on the response to rescue surfactant therapy in immature animals with RDS.
authors.affiliation: Department of Anesthesiology, University Hospital MAS, Malmö, Sweden. jonas.ingimarsson@skane.se
authors.forename: J
authors.initials: J
authors.lastname: Ingimarsson
authors.forename: L J
authors.initials: LJ
authors.lastname: Björklund
authors.forename: T
authors.initials: T
authors.lastname: Curstedt
authors.forename: A
authors.initials: A
authors.lastname: Larsson
authors.forename: B
authors.initials: B
authors.lastname: Robertson
authors.forename: O
authors.initials: O
authors.lastname: Werner
mesh_terms: D000818:Animals; D000831:Animals, Newborn; D002245:Carbon Dioxide / Q000097:blood; D006801:Humans; D007231:Infant, Newborn; D011659:Pulmonary Gas Exchange; D011663:Pulmonary Surfactants / Q000627:therapeutic use*; D012127:Respiratory Distress Syndrome, Newborn / Q000503:physiopathology / Q000628:therapy*; D015656:Respiratory Mechanics / Q000502:physiology*; D012756:Sheep
chemical_list: D011663:Pulmonary Surfactants; D002245:Carbon Dioxide