Longitudinal Measures Of Lung Function In Preterm Infants Of Different Gestational Age And Infants With Bronchopulmonary Dysplasia By Ultrasonic Flow Meter

Objective: To investigate dynamic changes of lung function inpreterm infants born at different gestational age without respiratorycomplications, and to investigate lung function characteristics of preterminfants with and infants with bronchopulmonary dysplasia (BPD), assessingthe influence of lung functional development for them.Methods: Thirty-four healthy full-term infants,30late preterminfants，25non-BPD preterm infants born less than34gestational weekswere studied on the7th,14th,28th day after birth，and at a matched postmenstrual age of37weeks to41weeks during quiet natural sleep，also22BPD preterm infant were studied when mean corrected gestational age was38weeks. Lung function parameters measured were functional residualcapacity (FRC/Kg) and ventilation inhomogeneity by multiple breathwashout measurements using an ultrasonic flow meter, as well as tidalbreathing parameters.Results: Lung function of the three group improved with the increase of days. The flow-volume loop was not typical oval, the more smaller thegestational age at birth the more obviously; at the correct gestational age37-41weeks, lung function parameters of the late neonatal was close to thelevel of full-term infants, and children less than34weeks premature failureto achieve catch-up growth in lung function; Compared to healthy terminfants, preterm infants with BPD and preterm infants without BPD havelower FRC/kg(16.45±3.03，18.61±1.84，20.67±2.24，F=14.59，P<0.001),increased ventilation inhomogeneity, expressed as LCI(7.92±1.05，7.18±0.70，6.56±0.75， F=17.99, P<0.001), higher respiratoryrates(50.91±3.57，47.00±6.04，39.21±5.39F=38.55, P<0.001) and lowerratios of time to peak expiratory flow and expiratory time (TPTEF/TE)(23.41±3.90，26.64±4.12，30.82±4.27，F=22.38,P<0.001). The BPD infantsdiffered from preterm infants without BPD in the same variables (allP<0.05).During the corrected gestational age from37-41weeks, an earlierpeak expiratory flow and concave expiratory limbs of the TBFVL were seenof the BPD infants and the preterm infants who were born less than34weeksgestational age, the change of the flow-volume loop was much obviously inthe BPD group.Conclusion: Overall, in infants who did and did not develop BPD,lung function improved throughout the neonatal period. at the samepostmenstrual age during37-48weeks, BPD and non-BPD preterm have asignificant reduced FRC, impairment of gas mixing efficiency and small airway obstruction, the BPD group is more evidence.