title: Measurement of lung volume and ventilation distribution with an ultrasonic flow meter in healthy infants.
abstract: Small airway disease in infants is characterised by abnormal lung volume and uneven ventilation distribution. An inert tracer gas washin/washout technique using a pulsed ultrasonic flow meter is presented to measure functional residual capacity (FRC) and ventilation distribution in spontaneously breathing and unsedated infants. With a pulsed ultrasound sent through the main stream of the flow meter, flow, volume and MM of the breathing gas can be calculated. Sulphur hexafluoride was used as a tracer gas. In a mechanical lung model (volume range 53-188 mL) and in 12 healthy infants (aged 38.3+/-9.2 days; mean+/-SD) accuracy and reproducibility of the technique was assessed. Indices of ventilation distribution such as alveolar-based mean dilution number (AMDN) and pulmonary clearance delay (PCD) were calculated. Mean error of volume measurement in the lung model was 0.58% (coefficient of variance (CV) 1.3%). FRC was in the low predicted range for normal infants (18.0+/-2.0 mL x kg(-1)) and highly reproducible (5.5+/-1.7% intra-subject CV). AMDN was 1.63+/-0.15 and PCD was 52.9+/-11.1%. Measurement of functional residual capacity and ventilation distribution using a sulphur hexafluoride washin/washout and an ultrasonic flow meter proved to be highly accurate and reproducible in a lung model and in healthy, spontaneously breathing and unsedated infants.
authors.affiliation: Dept of Paediatrics, Children's Hospital University of Bern, Switzerland. andreas.schibler@insel.ch
authors.forename: A
authors.initials: A
authors.lastname: Schibler
authors.forename: G L
authors.initials: GL
authors.lastname: Hall
authors.forename: F
authors.initials: F
authors.lastname: Businger
authors.forename: B
authors.initials: B
authors.lastname: Reinmann
authors.forename: J H
authors.initials: JH
authors.lastname: Wildhaber
authors.forename: M
authors.initials: M
authors.lastname: Cernelc
authors.forename: U
authors.initials: U
authors.lastname: Frey
mesh_terms: D005260:Female; D005652:Functional Residual Capacity; D006801:Humans; D007231:Infant, Newborn; D008176:Lung Volume Measurements / Q000379:methods*; D008297:Male; D008953:Models, Anatomic; D011336:Probability; D011659:Pulmonary Gas Exchange / Q000502:physiology; D012016:Reference Values; D015656:Respiratory Mechanics / Q000502:physiology*; D012143:Respiratory Physiological Phenomena; D012494:Sampling Studies; D012680:Sensitivity and Specificity; D014465:Ultrasonics; D014691:Ventilation