Lung function measurement by using baby body plethysmography in newborns with pneumonia

Abstract

Objective To access the changes of lung function of newborns with pneumonia and to investigate the feasibility of measuring lung function in the body plethysmograph for diagnosing and treating respiratory diseases. Methods There were 117 infants, 1 day after being diagnosed with mild or moderate pneumonia, aged 4-28 days, involved in the study, those who needed oxygen cure, mechanical ventilation, or had complications from pneumonia were ruled out.Pulmonary function tests (PFTs) were performed in the baby body plethysmography to access tidal breathing, plethysmographic functional residual capacity (FRCP), and effective airway resistance (Reff). The other 126 contemporaneous healthy children took the same test for comparison.According to their ages, infants were grouped into 4-7 d, 8-14 d, 15-21 d and 22-28 d. Results Of the 117 infants with pneumonia, 79 (67.5% equivalently) had abnormal lung function.Compared with the controls, infants with pneumonia had significantly higher values of peak tidal expiratory flow [(59.4±16.6) mL/s vs(52.9±16.6 ) mL/s], expiratory flow at 75% tidal volume [(57.4±16.7)mL/s vs(49.5±16.7) mL/s], special effective airway resistance (0.48 kPa·s vs 0.27 kPa·s), Reff [6.96 kPa·s/L vs 4.82 kPa·s/L ] and Reff per kilogram [1.99 kPa·s/(L·kg)vs 1.44 kPa·s/(L·kg)], but lower values of time to peak tidal expiratory flow as a percentage of total expiratory time [(26.5±10.0)% vs(36.8±9.9)%], volume to peak tidal expiratory flow as a percentage of total expiratory volume[(27.9±7.3)% vs(35.6±8.4)% ]and expiratory flow at 25% tidal volume [(36.3±11.7) mL/s vs(40.1±12.4) mL/s]. There were no significant differences in the values of respiratory rate, FRCP and FRCP/kg between the pneumonia children and the healthy control children.Compared with the infants aged≤14 days, there were more significant differences in relative parameters of lung function between the pneumonia group and the healthy control group for infants aged 15-28 days. Conclusions Newborns with pneumonia had a high ratio of abnormal lung function, which went up to 67.5%, and had apparent obstruction of small airways.Neonates with pneumonia aged 15-28 days had more apparent lesion of lung function.Measuring lung function by means of plethysmography among newborns is feasible and it can detect abnormal lung function sensitively. Key words: Body plethysmography; Pulmonary function; Pneumonia; Neonate