Value of tidal lung function in differentiating central and small intrathoracic airway obstructive lesions / 中华实用儿科临床杂志

ABSTRACT

Objective:To explore the value of tidal lung function in distinguishing central and small intrathoracic airway obstructive lesions.Methods:A total of 124 infants with intrathoracic obstructive diseases, including bronchiolitis obliterans (BO), bronchiolitis, airway foreign body, and airway stenosis, were confirmed in Children′s Hospital of Chongqing Medical University from April 2014 to June 2019 and selected as subjects, and 111 normal infants were enrolled as healthy control group.According to the location of lesions, these subjects suffering from intrathoracic obstructive diseases were divided into small airway lesion group(BO, bronchiolitis) and central airway lesion group(airway foreign body, airway stenosis). Lung function was assessed by plethysmography.Results:As for the ratio of time to reach peak tidal expiratory flow to total expiratory time (TPTEF/TE) and the ratio of volume to reach peak tidal expiratory flow to total expiratory volume (VPTEF/VE), all disease groups were lower than that in healthy control group TEF/TE BO 13.2(10.3, 16.3)%, bronchiolitis 15.9 (13.2, 19.7)%, airway foreign body 24.5 (16.7, 30.7)%, airway stenosis 20.7 (16.1, 29.3)%, healthy control group 30.2(25.6, 36.5)%; VPTEF/VE BO 18.2(17.8, 22.3)%, bronchiolitis 20.3(17.0, 21.6)%, airway foreign body 26.0(20.5, 30.7)%, airway stenosis 22.9(20.2, 29.1)%, healthy control group 31.5(28.1, 37.0)%]( P<0.05) and the lesion in the small airway lesion group was significantly lower than that in central airway lesion group.Compared with the healthy control group, the functional residual capacity (FRC)was higher in each disease group[BO (501.6±166.5) mL, bronchiolitis (334.6±149.6) mL, airway foreign body (392.2±130.1) mL, airway stenosis (350.1±127.9) mL, healthy control group (191.6±73.8) mL]( P<0.05). The ratio of peak expiratory flow to tidal expiratory flow at 25% remaining expiration(PF/TEF 25) was obviously higher in small airway lesion group than that in central airway lesion and healthy control group [BO 232.7(183.2, 261.2)%, bronchiolitis 186.4 (153.3, 247.7)%, airway foreign body 143.1(126.8, 168.9)%, airway stenosis 140.3(122.9, 186.0)%, healthy control group 132.3 (123.1, 147.8)%] ( P<0.05), while no significant differences were found between central airway lesion group and healthy control group ( P>0.05). There were no significant differences in effective airway resistance among all groups ( P>0.05). The tidal breathing flow volume (TBFV) curve shape of small airway lesion group showed the depression of expiratory phase to the transverse axis, while the slope of descending branch of expiratory phase had no significant increase in central airway lesion group. Conclusions:Combined with the increase in PF/TEF 25, the decrease in TPTEF/TE and VPTEF/VE is the characteristic of small airway obstruction.PF/TEF 25 is a sensitive index reflecting small airway obstruction.Combined with the value of lung function parameters, the shape of TBFV is helpful to distinguish central and small airway obstructive lesions.