title: Onset of mechanical ventilation is associated with rapid activation of circulating phagocytes in preterm infants.
abstract: OBJECTIVE
  In preterm infants with respiratory distress syndrome (RDS), circulating neutrophils are activated. Kinetics and effects of surfactant therapy on this activation are unknown. Therefore, we studied activation of circulating neutrophils and monocytes in newborn preterm infants with and without RDS.
  
  
  METHODS
  Preterm infants with RDS who were mechanically ventilated and received surfactant ("ventilated infants": n = 38; mean gestational age +/- SD: 28.3 +/- 2.2 weeks; mean birth weight +/- SD: 1086 +/- 353 g) and preterm infants who received nasal continuous positive airway pressure (n = 8) or no ventilatory support (n = 17) ("control infants": mean gestational age +/- SD: 32.1 +/- 1.2 weeks; mean birth weight +/- SD: 1787 +/- 457 g) were recruited. Blood samples were taken from ventilated infants at birth, before surfactant treatment, at 1 and 2 hours after surfactant, and at 12 to 24 hours of age. Blood samples were taken from control infants at birth, at 2 to 6 hours, and at 12 to 24 hours of age. Phagocyte CD11b expression was analyzed by flow cytometry.
  
  
  RESULTS
  In ventilated infants, phagocyte CD11b expression increased from birth to the first postnatal samples. It increased further by 12 to 24 hours of age. Control infants with or without nasal continuous positive airway pressure showed no significant increase after birth. At 12 to 24 hours of age, phagocyte CD11b expression was higher in ventilated infants than in control infants. In ventilated infants, neutrophil CD11b expression at 1 and 2 hours after surfactant correlated positively with gestational age.
  
  
  CONCLUSIONS
  In preterm infants with RDS, significant activation of circulating phagocytes occurs within 1 to 3 hours of the onset of mechanical ventilation, independent of surfactant administration, which indicates that mechanical ventilation may be the inducer of this systemic inflammatory response.
authors.affiliation: Hospital for Children and Adolescents, Helsinki, Finland. riikka.s.turunen@helsinki.fi
authors.forename: Riikka
authors.initials: R
authors.lastname: Turunen
authors.forename: Irmeli
authors.initials: I
authors.lastname: Nupponen
authors.forename: Sanna
authors.initials: S
authors.lastname: Siitonen
authors.forename: Heikki
authors.initials: H
authors.lastname: Repo
authors.forename: Sture
authors.initials: S
authors.lastname: Andersson
mesh_terms: D039481:CD11b Antigen / Q000032:analysis; D045422:Continuous Positive Airway Pressure; D006801:Humans; D007231:Infant, Newborn; D007234:Infant, Premature; D009000:Monocytes / Q000276:immunology; D009504:Neutrophils / Q000276:immunology; D010586:Phagocytes / Q000276:immunology / Q000502:physiology*; D011663:Pulmonary Surfactants / Q000627:therapeutic use*; D012127:Respiratory Distress Syndrome, Newborn / Q000503:physiopathology* / Q000628:therapy
chemical_list: D039481:CD11b Antigen; D011663:Pulmonary Surfactants