Abstract
This study was designed to obtain normative data for FRC, dynamic (CLd) and specific lung compliance (CLs) during the first years of life. Thirteen boys and 9 girls free of respiratory disease were studied. Age, height, weight and ventilatory rate respectively ranged from 2 – 52 months, 55 – 96 cm, 4.9 – 16 Kg and 22 – 55/min. Studies were performed during chloral hydrate induced sleep. Infants breathed through a mouth piece or a face mask. FRC was determined by the closed circuit helium dilution technique using a 2.2 1 water sealed spirograph. Added dead space was subtracted from the measured volume and values were converted to BTPS. Measurement of tidal flow and volume through a heated pneumotachograph and of esophageal pressure with an air filled balloon catheter allowed for calculation of CLd as Δ V/ Δ P at zero flow. FRC, CLd and CLs respectively ranged from 110 – 430 ml, 8.1 – 34.7 ml/cm H2O and .051 – .110 ml/cm H2O/ml FRC. FRC and CLd were significantly correlated with height, age, weight and ventilatory rate while CLs was not. CLd was also significantly correlate with FRC. Multiple linear regression analysis showed that: 1– the only significant predictive variable for FRC was height: FRC = 6.2 × height – 200 (r=.83); 2– CLd was best predicted from FRC and age: CLd = .05 × FRC + .24 × age + 2.24 (r=.84); 3– CLs (.073 ± .004*) was independent of growth parameters. CLs would thus appear useful for evaluation of lung elastic properties in infancy. *(Mean ± SEM)
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