title: Effects of manual hyperinflation in preterm newborns under mechanical ventilation.
abstract: OBJECTIVE
  To assess the effects of manual hyperinflation, performed with a manual resuscitator with and without the positive end-expiratory pressure valve, on the respiratory function of preterm newborns under mechanical ventilation.
  
  
  METHODS
  Cross-sectional study of hemodynamically stable preterm newborns with gestational age of less than 32 weeks, under mechanical ventilation and dependent on it at 28 days of life. Manual hyperinflation was applied randomly, alternating the use or not of the positive end-expiratory pressure valve, followed by tracheal aspiration for ending the maneuver. For nominal data, the two-tailed Wilcoxon test was applied at the 5% significance level and 80% power.
  
  
  RESULTS
  Twenty-eight preterm newborns, with an average birth weight of 1,005.71 ± 372.16g, an average gestational age of 28.90 ± 1.79 weeks, an average corrected age of 33.26 ± 1.78 weeks, and an average mechanical ventilation time of 29.5 (15 - 53) days, were studied. Increases in inspiratory and expiratory volumes occurred between time-points A5 (before the maneuver) and C1 (immediately after tracheal aspiration) in both the maneuver with the valve (p = 0.001 and p = 0.009) and without the valve (p = 0.026 and p = 0.001), respectively. There was also an increase in expiratory resistance between time-points A5 and C1 (p = 0.044).
  
  
  CONCLUSIONS
  Lung volumes increased when performing the maneuver with and without the valve, with a significant difference in the first minute after aspiration. There was a significant difference in expiratory resistance between the time-points A5 (before the maneuver) and C1 (immediately after tracheal aspiration) in the first minute after aspiration within each maneuver.
authors.affiliation: Instituto da Criança, Hospital das Clínicas, Faculdade de Medicina, Universidade de São Paulo, São Paulo, SP, Brazil.
authors.forename: Camila Chaves
authors.initials: CC
authors.lastname: Viana
authors.affiliation: Instituto da Criança, Hospital das Clínicas, Faculdade de Medicina, Universidade de São Paulo, São Paulo, SP, Brazil.
authors.forename: Carla Marques
authors.initials: CM
authors.lastname: Nicolau
authors.affiliation: Instituto da Criança, Hospital das Clínicas, Faculdade de Medicina, Universidade de São Paulo, São Paulo, SP, Brazil.
authors.forename: Regina Celia Turola Passos
authors.initials: RC
authors.lastname: Juliani
authors.affiliation: Departamento de Pediatria, Hospital das Clínicas, Faculdade de Medicina, Universidade de São Paulo, São Paulo, SP, Brazil.
authors.forename: Werther Brunow de
authors.initials: WB
authors.lastname: Carvalho
authors.affiliation: Instituto da Criança, Hospital das Clínicas, Faculdade de Medicina, Universidade de São Paulo, São Paulo, SP, Brazil.
authors.forename: Vera Lucia Jornada
authors.initials: VL
authors.lastname: Krebs
mesh_terms: D003430:Cross-Sectional Studies; D005260:Female; D006801:Humans; D007231:Infant, Newborn; D007234:Infant, Premature; D008168:Lung / Q000378:metabolism*; D008176:Lung Volume Measurements; D008297:Male; D011175:Positive-Pressure Respiration / Q000379:methods*; D011446:Prospective Studies; D012121:Respiration, Artificial / Q000379:methods*; D012138:Respiratory Therapy / Q000379:methods*; D018709:Statistics, Nonparametric; D013997:Time Factors