Differential diagnostic values of functional residual capacity plethysmograph for infant bronchial foreign body and bronchiolitis

Objective To investigate the lung function data from infants of bronchial foreign body and bronchiolitis, and to explore the diagnostic values of functional residual capacity plethysmograph(FRCp) in the two diseases. Methods During January 2016 to January 2018, forty-six infants diagnosed with bronchial foreign body were selected as subjects.As well as 50 children diagnosed with bronchiolitis were selected as control group.All of the children had completed tidal breath pulmonary function test, lung compliance measurements using interrupter technique and plethysmographic measurements of FRCp.The differential diagnostic values of FRCp for the two diseases were analyzed with the receiver operating characteristic curve. Results In the bronchial foreign body group, respiratory rate(RR) was 31±7 times per minute, VT/kg was 7.7±1.5ml/kg, TPTEF/TE was 24.3(9.4%, VPEF/VE was 26.1%±7.6%, Ti/Te was 0.66±0.10, and FRCp was 280.6(208.4~396.1)ml.In bronchial foreign body infants, FRCp was obviously higher than that in control group(P<0.01), RR was higher than that in control group(P<0.05). There were no significant differences found in other indicators between the two groups.The optimal cut-off value of FRCp was 202.95 ml for the differentiation between the two groups, with a sensitivity of 85% and a specificity of 54%. Conclusion Most bronchial foreign body infants have obstructive ventilation dysfunction with elevated FRCp.FRCp in bronchial foreign body infants were obviously higher than that in bronchiolitis infants.Measurements of FRCp may be useful in the differential diagnosis of infant bronchial foreign body and bronchiolitis. Key words: Bronchial foreign body; Bronchiolitis; Functional residual capacity; Lung function