PERINATAL LUNG-FUNCTION MEASUREMENTS AND PREDICTION OF RESPIRATORY-PROBLEMS IN INFANCY

The aim of this study was to determine which lung function test employ ed in the perinatal period gave the results most significantly associa ted with respiratory problems in infancy. The ratio of the proportion of time to reach peak tidal expiratory flow to total expiratory time ( t(PTEF):t(E)), thoracic gas volume (TGV) and airway resistance (R-aw) (from which specific conductance (SG(aw)) was calculated) measurements were examined from 85 infants born at or near term. The infants were followed until at least one year of age and described as symptomatic i f they wheezed for at least 24 hours. Twenty-three infants were sympto matic in the first year. The symptomatic group, compared to the asympt omatic, had a higher median FRC (p < 0.01) and R-aw (p < 0.001); their median SG(aw) was lower (p < 0.001). It was possible to obtain t(PTEF ):t(E) results from only 61 infants; the median t(PTEF):t(E) did not d iffer significantly between symptomatic and asymptomatic infants. Logi stic regression analysis demonstrated a high R-aw and FRC, but not a l ow t(PTEF):t(E), independently related to positive symptom status. A h igh R-aw (>26 cmH(2)O (1 s(-1))(-1)) was the most sensitive (83%) pred ictor of subsequent respiratory problems, but all the tests examined h ad low positive predictive values.