title: Effects of different flow patterns and end-inspiratory pause on oxygenation and ventilation in newborn piglets: an experimental study.
abstract: BACKGROUND
  Historically, the elective ventilatory flow pattern for neonates has been decelerating flow (DF). Decelerating flow waveform has been suggested to improve gas exchange in the neonate when compared with square flow (SF) waveform by improving the ventilation perfusion. However, the superiority of DF compared with SF has not yet been demonstrated during ventilation in small infants. The aim of this study was to compare SF vs. DF, with or without end-inspiratory pause (EIP), in terms of oxygenation and ventilation in an experimental model of newborn piglets.
  
  
  METHODS
  The lungs of 12 newborn Landrace/LargeWhite crossbred piglets were ventilated with SF, DF, SF-EIP and DF-EIP. Tidal volume (VT), inspiratory to expiratory ratio (I/E), respiratory rate (RR), and FiO2 were keep constant during the study. In order to assure an open lung during the study while preventing alveolar collapse, a positive end-expiratory pressure (PEEP) of 6 cmH2O was applied after a single recruitment maneuver. Gas exchange, lung mechanics and hemodynamics were measured.
  
  
  RESULTS
  The inspiratory flow waveform had no effect on arterial oxygenation pressure (PaO2) (276 vs. 278 mmHg, p = 0.77), alveolar dead space to alveolar tidal volume (VDalv/VTalv) (0.21 vs. 0.19 ml, p = 0.33), mean airway pressure (Pawm) (13.1 vs. 14.0 cmH2O, p = 0.69) and compliance (Crs) (3.5 vs. 3.5 ml cmH2O(-1), p = 0.73) when comparing SF and DF. A short EIP (10%) did not produce changes in the results.
  
  
  CONCLUSIONS
  The present study showed that there are no differences between SF, DF, SF-EIP and DF-EIP in oxygenation, ventilation, lung mechanics, or hemodynamics in this experimental model of newborn piglets with healthy lungs.
authors.affiliation: Anesthesiology and Critical Care Department, Hospital Clínico Universitario of Valencia, Av. Blasco Ibañez, 17, CP: 46010 Valencia, Spain.
authors.forename: Carlos
authors.initials: C
authors.lastname: Ferrando
authors.affiliation: Anesthesiology and Critical Care Department, Hospital Clínico Universitario of Valencia, Av. Blasco Ibañez, 17, CP: 46010 Valencia, Spain.
authors.forename: Marisa
authors.initials: M
authors.lastname: García
authors.affiliation: Anesthesiology and Critical Care Department, Hospital Clínico Universitario of Valencia, Av. Blasco Ibañez, 17, CP: 46010 Valencia, Spain.
authors.forename: Andrea
authors.initials: A
authors.lastname: Gutierrez
authors.affiliation: Anesthesiology and Critical Care Department, Hospital Clínico Universitario of Valencia, Av. Blasco Ibañez, 17, CP: 46010 Valencia, Spain.
authors.forename: Jose A
authors.initials: JA
authors.lastname: Carbonell
authors.affiliation: Anesthesiology and Critical Care Department, Hospital Clínico Universitario of Valencia, Av. Blasco Ibañez, 17, CP: 46010 Valencia, Spain.
authors.forename: Gerardo
authors.initials: G
authors.lastname: Aguilar
authors.affiliation: Anesthesiology and Critical Care Department, Hospital Clínico Universitario of Valencia, Av. Blasco Ibañez, 17, CP: 46010 Valencia, Spain.
authors.forename: Marina
authors.initials: M
authors.lastname: Soro
authors.affiliation: Anesthesiology and Critical Care Department, Hospital Clínico Universitario of Valencia, Av. Blasco Ibañez, 17, CP: 46010 Valencia, Spain.
authors.forename: Francisco J
authors.initials: FJ
authors.lastname: Belda
mesh_terms: D000758:Anesthesia; D000818:Animals; D000831:Animals, Newborn / Q000502:physiology*; D005260:Female; D006439:Hemodynamics / Q000502:physiology; D008991:Monitoring, Physiologic; D010102:Oxygen Inhalation Therapy / Q000379:methods*; D012121:Respiration, Artificial / Q000379:methods*; D015656:Respiratory Mechanics / Q000502:physiology; D013552:Swine; D016896:Treatment Outcome
keywords: Flow waveform; Mechanical Ventilation; Oxygenation; Pediatrics; Ventilation