[Changes in pulmonary function in infants and young children with Mycoplasma pneumoniae pneumonia].

Objective: To study the changes in pulmonary function in infants and young children with Mycoplasma pneumoniae pneumonia (MPP).

Methods: A total of 196 hospitalized children (at age of 0-36 months) who were diagnosed with MPP from January 2014 to June 2018 were enrolled as study subjects. A total of 208 children (at age of 0-36 months) with pneumonia not caused by Mycoplasma pneumoniae infection during the same period of time were enrolled as controls (non-MPP group). A retrospective analysis was performed for their clinical data. The two groups were compared in the pulmonary function on the next day after admission and on the day of discharge. The children with MPP were followed up to observe pulmonary function at weeks 2 and 4 after discharge.

Results: Compared with the non-MPP group, the MPP group had significant reductions in the ratio of time to peak tidal expiratory flow to total expiratory time (TPTEF/TE), ratio of volume to peak tidal expiratory flow to total expiratory volume (VPTEF/VE), inspiratory-to-expiratory time ratio, and tidal expiratory flow at 25% remaining expiration on the next day after admission and on the day of discharge (P<0.05). In addition there were significant increases in the ratio of peak tidal expiratory flow to tidal expiratory flow at 25% remaining expiration, respiratory rate, effective airway resistance, and plethysmographic functional residual capacity per kilogram (P<0.05). Compared with the normal reference values of pulmonary function parameters, both groups had reductions in VPTEF/VE and TPTEF/TE on the next day after admission; on the day of discharge, the MPP group still had reductions in VPTEF/VE and TPTEF/TE, while the non-MPP group had normal values. The MPP group had increases in VPTEF/VE and TPTEF/TE from the day of discharge to weeks 2 and 4 after discharge (P<0.05), but TPTEF/TE still did not reach the normal value at week 4 after discharge.

Conclusions: Airway obstruction is observed in infants and young children with acute MPP or non-MPP, and the children with MPP have a higher severity of airway obstruction and a longer time for improvement, with a certain degree of airway limitation in the recovery stage.