title: The effect of two levels of pressure support ventilation on tidal volume delivery and minute ventilation in preterm infants.
abstract: OBJECTIVE
  To study the effect of different levels of pressure support ventilation (PSV) on respiratory parameters in preterm infants during the weaning phase of mechanical ventilation.
  
  
  METHODS
  In this quasi-experimental crossover study, a total of 19 154 breaths were analysed from 10 ventilated infants of <32 weeks' gestation. Breath-to-breath data on minute ventilation, tidal volume, respiratory rate, peak inspiratory pressure and mean airway pressure were collected during three study epochs: synchronised intermittent mandatory ventilation (SIMV) alone, SIMV with partial PSV (PS(min)), and SIMV with full PSV (PS(max)). PS(min) was set to provide an exhaled tidal volume (V(Te)) between 2.5-4 ml/kg and PS(max) 5-8 ml/kg V(Te). Statistical analyses were performed using analysis of variance (ANOVA) for repeated measures.
  
  
  RESULTS
  The addition of full PSV (PS(max)) was associated with a significant increase in total minute ventilation as compared with SIMV alone (392 ml/kg/min vs 270 ml/kg/min, respectively; p<0.05). This difference in minute ventilation was still present when PS(min) was used (332 ml/kg/min as compared with 270 ml/kg/min in SIMV; p<0.05). There was also a concomitant decrease in the respiratory rate with both PS(max) (59 breaths per minute) and PS(min) (65 breaths per minute) compared with SIMV alone (72 breaths per min) (p<0.05).
  
  
  CONCLUSIONS
  Pressure support ventilation increases total minute ventilation and stabilises breathing in proportion to the level of pressure support used. This may be advantageous and provide a useful ventilation strategy for use during weaning stages of mechanical ventilation in preterm infants.
authors.affiliation: University Hospital of North Tees, Stockton-on-Tees, UK.
authors.forename: S
authors.initials: S
authors.lastname: Gupta
authors.forename: S K
authors.initials: SK
authors.lastname: Sinha
authors.forename: S M
authors.initials: SM
authors.lastname: Donn
mesh_terms: D018592:Cross-Over Studies; D004739:England; D005260:Female; D006801:Humans; D007231:Infant, Newborn; D007234:Infant, Premature; D007235:Infant, Premature, Diseases / Q000628:therapy*; D015931:Intensive Care, Neonatal; D007385:Intermittent Positive-Pressure Ventilation; D008297:Male; D012119:Respiration; D012131:Respiratory Insufficiency / Q000628:therapy*; D013990:Tidal Volume / Q000502:physiology; D015300:Ventilator Weaning