title: CPAP of 4 cm H(2)O Has no short-term benefit at term in infants with BPD.
abstract: BACKGROUND
  Lung development and function is compromised at term in infants with bronchopulmonary dysplasia (BPD), characterized by reduced functional residual capacity (FRC) and impaired gas-mixing efficiency in distal airways.
  
  
  OBJECTIVE
  To determine whether continuous positive airway pressure (CPAP) improves FRC, ventilation, distal airway function, and gas exchange in spontaneously breathing infants with BPD.
  
  
  METHODS
  Twenty-one infants with BPD (median birth weight 0.72 kg (range 0.50-1.27) and median gestational age 26 weeks (range 23-28)) were studied before and after CPAP of 4 cm H(2)O was applied by a facemask system. A multiple-breath nitrogen washout method was used to assess FRC, ventilation, and gas-mixing efficiency. Moment analysis and lung clearance index was calculated from the nitrogen-decay curve for assessment of gas-mixing efficiency. Transcutaneous (Tc) PO(2)/PCO(2) was monitored during stable infant conditions before each washout test.
  
  
  RESULTS
  When CPAP was raised from 0 to 4 cm H(2)O, FRC increased significantly together with a significant increase in moment ratios (M(1)/M(0) and M(2)/M(0)). Tc PO(2) decreased significantly and the breathing pattern changed, with significantly reduced respiratory rate, minute ventilation, and alveolar ventilation. There was also an increase in tidal volume and dead space.
  
  
  CONCLUSIONS
  CPAP of 4 cm H(2)O applied with a facemask at term to infants with BPD did not improve ventilation, gas-mixing efficiency in distal airways, or oxygenation despite an increase in FRC. We speculate that instead of promoting recruitment of unventilated lung volumes, increasing the end-expiratory pressure in infants with BPD may lead to an overexpansion of already ventilated parts of the lung, causing further compromise of lung function.
authors.affiliation: Department of Paediatrics, Queen Silvia Children's Hospital, Sahlgrenska Academy at the University of Gothenburg, Gothenburg, Sweden.
authors.forename: Kenneth L
authors.initials: KL
authors.lastname: Sandberg
authors.forename: Ola
authors.initials: O
authors.lastname: Hjalmarson
mesh_terms: D001784:Blood Gas Analysis; D001997:Bronchopulmonary Dysplasia / Q000209:etiology / Q000503:physiopathology / Q000628:therapy*; D045422:Continuous Positive Airway Pressure; D005260:Female; D005652:Functional Residual Capacity; D005865:Gestational Age; D006801:Humans; D052577:Infant, Extremely Low Birth Weight; D062071:Infant, Extremely Premature; D007231:Infant, Newborn; D008168:Lung / Q000378:metabolism / Q000503:physiopathology; D008297:Male; D016896:Treatment Outcome