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BackgroundSulfur mustard (SM) exposure causes acute and chronic respiratory diseases. The extent of small airway dysfunction (SAD) in individuals exposed to SM is unclear. This study evaluated and compared SAD in SM-exposed and SM-unexposed participants using noninvasive lung function tests assessing small airway function.MethodsThis retrospective cohort study involved SM-exposed (n = 15, mean age: 53 ± 8 years) and SM-unexposed (n = 15, mean age: 53 ± 7 years) Kurdish-Swedish individuals in Sweden. Small airway resistance and reactance were assessed using impulse oscillometry (IOS). Nitrogen (N2) multiple breath washout (MBW) was employed to assess lung ventilation heterogeneity. The gas-exchanging capacity of the lungs was assessed using the diffusing capacity of the lungs for the carbon monoxide (DLCO) test. Lung function outcomes were reported as absolute values and z-scores. Group comparisons were performed using the Mann–Whitney U test.ResultsNo statistically significant differences in age, height, or body mass index were observed between the two groups. IOS showed significantly increased small airway resistance, while N2MBW exhibited significantly increased global and acinar ventilation heterogeneity in SM-exposed individuals compared to that in unexposed individuals. SAD was identified in 14 of 15 SM-exposed individuals, defined as at least one abnormal IOS difference between resistance at 5 and 20 Hz (R5-R20) and/or area of reactance (AX) or N2MBW lung’s acinar zone (Sacin), and DLCO adjusted to the alveolar volume (DLCO/VA) outcome. Of these 14 individuals, only 5 demonstrated concordant findings across the IOS and N2MBW tests.ConclusionExposure to SM was positively associated with long-term impairment of respiratory tract function in the small airways in the majority of the previously SM-exposed individuals in the present study. Furthermore, both IOS and N2MBW should be employed to detect SAD in SM-exposed survivors as they provide complementary information. Identifying and characterizing the remaining pathology of the small airways in survivors of SM exposure is a first step toward improved treatment and follow-up.

Background Respiratory functional sequelae in COVID-19 patients admitted to the intensive care unit for invasive ventilation are sparsely reported. The aim of this study was to investigate the radiological lung appearance, lung function and their association at 6 months after hospital discharge. It was hypothesized that the degree of pathological morphology on CT scans would correlate with lung function at the time of follow-up. Methods and findings In this single-centre prospective observational study, 86 from 154 patients admitted to ICU due to COVID-19 between March 2020 and May 2021 were followed up at 6 months post discharge with computed tomography (CT) of the chest and pulmonary function tests (PFTs). The PFT results were expressed as z-scores calculated as the difference between the measured and predicted values divided by the standard deviation obtained from a reference population. Correlations were evaluated by Spearman’s rho including the 95% confidence interval. Pathological changes on CT were found in 78/85 participants with fibrous parenchymal bands being the most prevalent finding (91%) followed by traction bronchiectasis (64%) and ground glass opacities (41%). Sixty-five participants performed PFTs, and a restrictive pattern was the most prevalent abnormality (34%). Diffusing capacity of the lung for carbon monoxide (DLCO) was reduced in 66% of participants. The CT severity score weakly correlated with forced vital capacity (FVC) z-score (0.295, p = 0.006), DLCO z-score (-0.231, p = 0.032) and alveolar volume (VA) z-score (0.253, p = 0.019). Conclusions Most patients showed persistent radiological abnormalities on CT and reduced lung volumes, impaired diffusion capacity and patterns of restrictive lung function at 6 months post discharge from the ICU. The correlations between abnormalities on CT and lung function tests were weak. Further, studies with a long-term follow-up of lung function in this group of patients are needed.

BackgroundRespiratory functional sequelae in COVID-19 patients admitted to the intensive care unit for invasive ventilation are sparsely reported. The aim of this study was to investigate the radiological lung appearance, lung function and their association at 6 months after hospital discharge. It was hypothesized that the degree of pathological morphology on CT scans would correlate with lung function at the time of follow-up.Methods and findingsIn this single-centre prospective observational study, 86 from 154 patients admitted to ICU due to COVID-19 between March 2020 and May 2021 were followed up at 6 months post discharge with computed tomography (CT) of the chest and pulmonary function tests (PFTs). The PFT results were expressed as z-scores calculated as the difference between the measured and predicted values divided by the standard deviation obtained from a reference population. Correlations were evaluated by Spearman's rho including the 95% confidence interval. Pathological changes on CT were found in 78/85 participants with fibrous parenchymal bands being the most prevalent finding (91%) followed by traction bronchiectasis (64%) and ground glass opacities (41%). Sixty-five participants performed PFTs, and a restrictive pattern was the most prevalent abnormality (34%). Diffusing capacity of the lung for carbon monoxide (DLCO) was reduced in 66% of participants. The CT severity score weakly correlated with forced vital capacity (FVC) z-score (0.295, p = 0.006), DLCO z-score (-0.231, p = 0.032) and alveolar volume (VA) z-score (0.253, p = 0.019).ConclusionsMost patients showed persistent radiological abnormalities on CT and reduced lung volumes, impaired diffusion capacity and patterns of restrictive lung function at 6 months post discharge from the ICU. The correlations between abnormalities on CT and lung function tests were weak. Further, studies with a long-term follow-up of lung function in this group of patients are needed.

Abstract We have previously shown that functional residual capacity (FRC) and lung clearance index were significantly greater in sleeping healthy infants when measured by N2 (nitrogen) washout using 100% O2 (oxygen) versus 4% SF6 (sulfur hexafluoride) washout using air. Following 100% O2 exposure, tidal volumes decreased by over 30%, while end‐expiratory lung volume (EELV, i.e., FRC) rose markedly based on ultrasonic flow meter assessments. In the present study to investigate the mechanism behind the observed changes, N2 MBW was performed in 10 separate healthy full‐term spontaneously sleeping infants, mean (range) 26 (18–31) weeks, with simultaneous EELV monitoring (respiratory inductance plethysmography, RIP) and oxygen uptake (V´O2) assessment during prephase air breathing, during N2 washout by exposure to 100% O2, and subsequently during air breathing. While flow meter signals suggested a rise in ELLV by mean (SD) 26 (9) ml over the washout period, RIP signals demonstrated no EELV change. V'O2/FRC ratio during air breathing was mean (SD) 0.43 (0.08)/min, approximately seven times higher than that calculated from adult data. We propose that our previously reported flow meter‐based overestimation of EELV was in fact a physiological artifact caused by rapid and marked movement of O2 across the alveolar capillary membrane into the blood and tissue during 100% O2 exposure, without concomitant transfer of N2 to the same degree in the opposite direction. This may be driven by the high observed O2 consumption and resulting cardiac output encountered in infancy. Furthermore, the low resting lung volume in infancy may make this error in lung volume determination by N2 washout relatively large.