LUNG-FUNCTION IS AWAKE HEALTHY INFANTS - THE 1ST 5 DAYS OF LIFE

Our main aim was to determine an appropriate time for lung function me asurements in infants, prior to environmental influences upon their re spiratory tract.Tidal flow-volume loops, respiratory system compliance (Crs) and resistance (Rrs) (single breath passive occlusion technique ) were measured in 24 healthy, awake infants, at one hour and on the f ollowing four days of life to investigate variability and reproducibil ity over time. Possible differences in lung function were sought betwe en the 12 vaginally-delivered and 12 Caesarean section-delivered infan ts. Tidal volumes increased each day, but significantly so only from D ay 0 to Day 1. The expiratory flow-time ratios (time to reach peak exp iratory flow to total expiratory time (T(me)/T(e)) and tidal expirator y flow at 75% to peak flow (TEF25/PTEF)) and expiratory flow-volume ra tio (volume to reach peak expiratory flow to total expiratory volume ( V(me)/V(e)) were significantly smaller on Day 1 than Day 0, but did no t change significantly thereafter. Crs and Rrs were lower on Day 0 tha n later. Intra-individual variation remained stable for tidal flow-vol ume parameters throughout the study, but was significantly higher duri ng Day 0 and Day 1 for Crs and Rrs. There were no significant differen ces related to mode of delivery of the infant. We conclude that, for e pidemiological purposes, tidal lung function parameters may be measure d from Day 2 to Day 4, and that they are not influenced by mode of del ivery of the infant.