Clinical usefulness of the diffusing capacity of the lung for carbon monoxide (DLco) in the identification of humidifier disinfectant-associated lung injury in children

Abstract

Background: Humidifier disinfectant-associated lung injury (HDLI) is classified as an interstitial lung disease due to pulmonary fibrosis, which may be characterized by decreased DLco levels. Then, DLco can be a possible clinical marker of HDLI. However, there is no published information on DLco levels in HDLI children compared with controls. The purpose of this study was to establish a reference equation for DLco in healthy Korean children and to evaluate the levels of DLco in a national cohort of HDLI survivors and to compare those data to controls Methods: DLco were performed in a nationwide cohort of HDLI survivors aged from 5 to 12 years. To investigate the reference value of DLco in controls, we recruited age- and sex-matched outpatients who had no exposure history of HD and underlying respiratory disease. Results: The study population consisted of 67 HDLI survivors and 216 controls, respectively. Height is the most significant factor to influence the log-transformed DLco (LnDLco) in both sexes (boys, R2=0.724; girls, R2=0.734, respectively). Multiple regression equations were obtained for LnDLco using variables including age, height, and weight in both sexes (boy, R2=0.736; girl, R2=0.755, respectively). To compare HDLI survivors with controls, HDLI children have lower DLco than control groups. In particular, the mean difference is significantly higher in boys taller than 130cm (130–139cm, 12.6 vs. 9.5, P=0.055; 140–149cm, 16.4 vs. 12.8, P<0.001; 150cm≤, 20.3 vs. 16.2, P=0.050. respectively). Conclusion: The DLco value increases with increased height, but the rate of increase in HDLI children is less than that of the control groups. DLco may be considered a useful pulmonary function test for HDLI survivor in children for the diagnosis and follow-up of HDLI.