title: Breathing intolerance index in healthy infants.
abstract: BACKGROUND
  The breathing intolerance index (BITI) is used to justify ventilator use in adult patients with pulmonary or chest wall disease. BITI in ventilated patients is mostly ≥0.15. The mean BITI of healthy adults in the upright sitting position and the supine position is 0.050 ± 0.009 and 0.057 ± 0.016, respectively. The aim of this study was to establish a normal BITI in infants.
  
  
  METHODS
  Thirty healthy infants were examined in the supine position. BITI was defined as BITI = (Ti/Ttot) × (TV/VC), where Ti is inspiratory time, Ttot is total breath cycle duration, TV is tidal volume, and VC is vital capacity. TV and Ti/Ttot were obtained from tidal breathing at rest and VC was obtained spirometrically. BITI was calculated using customized software.
  
  
  RESULTS
  The mean ± SD BITI of 30 healthy infants in the supine position was 0.120 ± 0.013. The BITI of infants was significantly higher than that of adults.
  
  
  CONCLUSIONS
  BITI was measured in healthy infants. Further evaluation is needed to determine the significance and usefulness of BITI.
authors.affiliation: Division of Neonatal Intensive Care, Tokyo Women's Medical University Medical Center East, Tokyo, Japan.
authors.forename: Hisaya
authors.initials: H
authors.lastname: Hasegawa
authors.forename: Nobuhide
authors.initials: N
authors.lastname: Henmi
authors.forename: Shio
authors.initials: S
authors.lastname: Tsuruta
authors.forename: Yoshitaka
authors.initials: Y
authors.lastname: Miyoshi
authors.forename: Yousuke
authors.initials: Y
authors.lastname: Yamada
authors.forename: Junichi
authors.initials: J
authors.lastname: Muto
authors.forename: Masanori
authors.initials: M
authors.lastname: Wasa
mesh_terms: D003964:Diaphragm / Q000502:physiology*; D005260:Female; D006801:Humans; D007231:Infant, Newborn; D008297:Male; D012016:Reference Values; D012119:Respiration; D012129:Respiratory Function Tests
keywords: breathing intolerance index; infant; pulmonary function