title: Functional residual capacity (FRC) and lung clearance index (LCI) in mechanically ventilated infants: application in the newborn with congenital diaphragmatic hernia (CDH).
abstract: BACKGROUND
  Functional residual capacity (FRC) and lung clearance index (LCI) are sensitive parameters for early detection of airway disease in infancy. The closed helium dilution method has been applied to assess lung volume and ventilation inhomogeneity (VI) in spontaneously breathing infants.
  
  
  OBJECTIVE
  The aims of this study were as follows: (1) to assess applicability of the helium gas dilution technique in mechanically ventilated infants with high-risk congenital diaphragmatic hernia (CDH) and to evaluate changes in breathing patterns, lung volume, and VI during the first days of life before and after surgery, and (2) to analyze the possible correlation between changes in lung volume, cerebral hemodynamics, and oxygenation before and after surgical correction of CDH through near-infrared spectroscopy (NIRS) monitoring.
  
  
  METHODS
  Lung function tests were performed by multibreath washout traces with an ultrasonic flowmeter and helium gas dilution technique. For all babies, three acceptable FRC and LCI measurements were collected for each test (mean and SD of three measurements were calculated) before surgery (T0), 24 h after surgery (T1) during mechanical ventilation, and within 24 h after extubation in spontaneous breathing (T2). Cerebral and splanchnic hemodynamics were continuously monitored by NIRS during mechanical ventilation to evaluate relationships between changes in lung volume and capillary-venous oxyhemoglobin saturation in tissues. Fraction of inspired oxygen delivered was adjusted to keep oxygen saturation between 90% and 95%.
  
  
  RESULTS
  Thirteen CDH infants were studied; median GA = 38 weeks (range 35-41) and median BW = 3000 g (range 1850-3670). FRC and LCI significantly improved after extubation when compared with pre-surgical values. No differences were found in tidal volume (Vt) and NIRS monitoring before and after surgery and after extubation. Neither LCI nor FRC was correlated with NIRS values.
  
  
  CONCLUSIONS
  Helium gas dilution technique is an applicable and reliable technique to measure lung volumes and ventilation inhomogeneity also in ventilated infants. NIRS is a non-invasive technique to monitor tissue oxygenation during surgery and mechanical ventilation. In CDH newborns these preliminary data show an improvement in both FRC and LCI after extubation.
authors.affiliation: Department of Medical and Surgical Neonatology, Bambino Gesù Children's Hospital, IRCCS, Rome, Italy. francesca.landolfo@opbg.net
authors.forename: Francesca
authors.initials: F
authors.lastname: Landolfo
authors.forename: Ferdinando
authors.initials: F
authors.lastname: Savignoni
authors.forename: Irma
authors.initials: I
authors.lastname: Capolupo
authors.forename: Claudia
authors.initials: C
authors.lastname: Columbo
authors.forename: Flaminia
authors.initials: F
authors.lastname: Calzolari
authors.forename: Paola
authors.initials: P
authors.lastname: Giliberti
authors.forename: Natalia
authors.initials: N
authors.lastname: Chukhlantseva
authors.forename: Pietro
authors.initials: P
authors.lastname: Bagolan
authors.forename: Andrea
authors.initials: A
authors.lastname: Dotta
mesh_terms: D005260:Female; D005652:Functional Residual Capacity; D006548:Hernia, Diaphragmatic / Q000503:physiopathology; D065630:Hernias, Diaphragmatic, Congenital; D006801:Humans; D007231:Infant, Newborn; D008168:Lung / Q000503:physiopathology*; D008297:Male; D011446:Prospective Studies; D012121:Respiration, Artificial
keywords: Application in newborn; Congenital diaphragmatic hernia (CDH); Functional residual capacity (FRC); Lung clearance index (LCI); Mechanically ventilated infants