title: Effects of non-synchronised nasal intermittent positive pressure ventilation on spontaneous breathing in preterm infants.
abstract: BACKGROUND
  Nasal intermittent positive pressure ventilation (NIPPV) may be beneficial but the mechanisms of action are undetermined.
  
  
  OBJECTIVE
  To investigate the effects of non-synchronised NIPPV on spontaneous breathing in premature infants.
  
  
  METHODS
  10 infants receiving ventilator generated non-synchronised NIPPV were studied for 30 min. Delivered pressure was measured at the nose; respiration was recorded using respiratory inductance plethysmography. Oxygen saturation, carbon dioxide, heart rate, inspired oxygen and video images were recorded.
  
  
  RESULTS
  Median gestational age, birth weight, age and study weight were 25(+3) weeks, 797 g, 24 days and 1076 g. When the NIPPV pressure peak commenced during spontaneous inspiration the inspiratory time increased by 21% (p=0.002), relative tidal volume increased by 15% (p=0.01) and expiratory time was unchanged. When the NIPPV pressure peak commenced during spontaneous expiration the expiratory time increased by 13% (p=0.04). NIPPV pressures delivered during apnoea (range 8-28 cm H(2)O) produced chest inflation 5% of the time, resulting in small tidal volumes (26.7% of spontaneous breath size) but reduced oxygen desaturation. NIPPV pressure peaks occurred throughout spontaneous respiration proportional to the inspiratory: expiratory ratio.
  
  
  CONCLUSIONS
  NIPPV pressure peaks only resulted in a small increase in relative tidal volumes when delivered during spontaneous inspiration. During apnoea pressure peaks occasionally resulted in chest inflation, which ameliorated oxygen desaturations. Infants did not become entrained with the NIPPV pressure changes. Synchronising every rise in applied pressure with spontaneous inspiration may increase the effectiveness of NIPPV and warrants investigation.
authors.affiliation: Department of Newborn Research, The Royal Women's Hospital, Locked Bag 300, Parkville, VIC 3052, Australia. louise.owen@thewomens.org.au
authors.forename: L S
authors.initials: LS
authors.lastname: Owen
authors.forename: C J
authors.initials: CJ
authors.lastname: Morley
authors.forename: J A
authors.initials: JA
authors.lastname: Dawson
authors.forename: P G
authors.initials: PG
authors.lastname: Davis
mesh_terms: D001049:Apnea / Q000503:physiopathology / Q000628:therapy; D001724:Birth Weight; D005260:Female; D005865:Gestational Age; D006801:Humans; D007231:Infant, Newborn; D007234:Infant, Premature / Q000097:blood / Q000502:physiology*; D007235:Infant, Premature, Diseases / Q000503:physiopathology / Q000628:therapy*; D007385:Intermittent Positive-Pressure Ventilation / Q000379:methods*; D008297:Male; D010100:Oxygen / Q000097:blood; D010991:Plethysmography / Q000379:methods; D012119:Respiration; D013990:Tidal Volume / Q000502:physiology
chemical_list: D010100:Oxygen