title: Unexpected effect of recruitment procedure on lung volume measured by respiratory inductive plethysmography (RIP) during high frequency oscillatory ventilation (HFOV) in preterm neonates with respiratory distress syndrome (RDS).
abstract: BACKGROUND
  In clinical practice, one of the major problems in optimizing recruitment or lung volume during HFOV in preterm infants is the inability to accurately measure direct changes in lung volume at bedside.
  
  
  OBJECTIVE
  To evaluate changes in lung volume during the recruitment phase of elective HFOV in preterm infants with RDS using respiratory inductive plethysmography.
  
  
  METHODS
  The preliminary results of an observational prospective study were reported. Newborns with GA ≤ 27 weeks requiring elective HFOV for a diagnosis of RDS were studied within the first 6 hours of life using RIP technology, before surfactant instillation. HFOV was performed with Draeger Babylog 8000 plus ventilator with "optimum lung volume strategy "(continuous distending pressure (CDP) increased step-by-step until FiO(2) ≤ 0.25 was reached). Data on ventilator settings, gas exchange and RIP volume were collected and analyzed. The analysis package used in this study visualizes measured data from the Bicore-II device (CareFusion), Pulse Oximeter Masimo, AX300 FiO(2) monitor device and TCM4 shuttle (TCM4, Radiometer, Copenaghen, Denmark).
  
  
  RESULTS
  Four preterm infants (two females) with mean ± SD gestational age of 26.5 ± 1.0 weeks and mean ± SD birth weight of 978 ± 188 grams were studied. Relative FRC slightly increased during the first steps of the recruitment phase, while deeply decreased at higher CDP values (≥ 15 cm H(2)O). Notwithstanding FiO(2) decreased until 0.25 in all the newborns except one.
  
  
  CONCLUSIONS
  Because RIP cannot differentiate between changes in lung fluid or intrathoracic gas, we hypothesized that as CDP increases and total lung capacity is approached, pulmonary vascular resistance increases as a consequence of the compression of intra-alveolar vessels. This increases right ventricular afterload which, combined with re-establishment of right-to left shunting, results in decreased pulmonary blood flow and then decreased lung volume. Caution should then be used when using high CDP values during the recruitment procedure.
authors: Department of Pediatrics, Division of Neonatology, Pol. A. Gemelli-Università Cattolica S. Cuore, Rome, Italy. givento@tin.it
authors: Giovanni
authors: G
authors: Vento
authors: Milena
authors: M
authors: Tana
authors: Chiara
authors: C
authors: Tirone
authors: Claudia
authors: C
authors: Aurilia
authors: Alessandra
authors: A
authors: Lio
authors: Sarah
authors: S
authors: Perelli
authors: Cinzia
authors: C
authors: Ricci
authors: Costantino
authors: C
authors: Romagnoli
mesh_terms: D000005:Abdomen / Q000033:anatomy & histology / Q000502:physiology; D005260:Female; D005865:Gestational Age; D006612:High-Frequency Ventilation / Q000379:methods*; D006801:Humans; D007231:Infant, Newborn; D007234:Infant, Premature / Q000502:physiology; D008168:Lung / Q000033:anatomy & histology* / Q000254:growth & development; D008176:Lung Volume Measurements / Q000379:methods; D008297:Male; D018579:Patient Selection; D010991:Plethysmography / Q000379:methods; D012127:Respiratory Distress Syndrome, Newborn / Q000628:therapy*; D035423:Thoracic Cavity / Q000033:anatomy & histology / Q000502:physiology