Background: Common tests for evaluating gas exchange impairment have different strengths and weaknesses. Alveolar-to-arterial oxygen pressure difference (AaDO 2 ) at peak exercise is a sensitive indicator but it cannot be measured repeatedly. Diffusing capacity of the lung for carbon monoxide (DLco) is measured at rest and may be too insensitive to predict the effects of exercise on gas exchange impairment.Oxygen desaturation during a 6-minute walk test (∆SpO 2 -6MWT) can be measured repeatedly, but its value in sarcoidosis is unknown. Here, we evaluated the ability of ∆SpO 2 -6MWT and DLco to predict gas exchange impairment during exercise in sarcoidosis.Methods: This retrospective study of 130 subjects with sarcoidosis investigated the relationship between DLco, ∆SpO 2 -6MWT, and peak AaDO 2 using correlation tests, inter-test reliability analyses, and predictive values. For the analyses of inter-test reliability and predictive values, DLco, peak AaDO 2 , and ∆SpO 2 -6MWT were considered as binary variables (normal/abnormal) according to previously defined thresholds.Results: Correlation coefficients between DLco, ∆SpO 2 -6MWT, and peak AaDO 2 were intermediate (0.53-0.67, P<0.0003) and Kappa coefficients were low (0.21-0.42, P=0.0003-0.02). DLco predicted (I) increased peak AaDO 2 with a positive predictive value (PPV) of 66% and a negative predictive value (NPV) of 78% and (II) increased ∆SpO 2 -6MWT with a PPV at 36% and an NPV at 88%. Normal DLco was a good predictor of the absence of severe desaturation during the 6MWT (94% NPV) and at peak exercise during cardiopulmonary exercise test (CPET) (100% NPV). ∆SpO 2 -6MWT predicted peak AaDO 2 increase with a PPV of 74% and an NPV of 60%. Conclusions:In a large population of sarcoidosis patients, neither ∆SpO 2 -6MWT nor DLco was a good predictor of increased peak AaDO 2 . In contrast, normal DLco was a good predictor of the absence of severe desaturation during the 6MWT and at peak exercise during CPET.

Background Recent studies report very low adherence of practitioners to ATS/IDSA recommendations for the treatment of nontuberculous mycobacteria pulmonary disease (NTM-PD), as well as a great variability of practices. Type of management could impact prognosis. Methods To evaluate management and prognosis of patients with NTM-PD cases with respect to ATS recommendations, we conducted a multicenter retrospective cohort study (18 sentinel sites distributed throughout France), over a period of six years. We collected clinical, radiological, microbiological characteristics, management and outcome of the patients (especially death or not). Results 477 patients with NTM-PD were included. Respiratory comorbidities were found in 68% of cases, tuberculosis sequelae in 31.4% of patients, and immunosuppression in 16.8% of cases. The three most common NTM species were Mycobacterium avium complex (60%), M. xenopi (20%) and M. kansasii (5.7%). Smear-positive was found in one third of NTM-PD. Nodulobronchiectatic forms were observed in 54.3% of cases, and cavitary forms in 19.1% of patients. Sixty-three percent of patients were treated, 72.4% of patients with smear-positive samples, and 57.5% of patients with smear-negative samples. Treatment was in adequacy with ATS guidelines in 73.5%. The 2-year mortality was 14.4%. In the Cox regression, treatment (HR = 0.51), age (HR = 1.02), and M. abscessus (3.19) appeared as the 3 significant independent prognostic factors. Conclusion These findings highlight the adequacy between French practices and the ATS/IDSA guidelines. Treatment was associated with a better survival.

A 20-year-old male student, nonsmoker with no medical history or drug consumption, consulted for asthenia without any other symptoms. A chest x-ray was performed, revealing an opacity on the left upper lobe. He was treated with macrolides, but a new x-ray showed no improvement. A chest computed tomography (CT) scan showed a left hilar bilobar mass (Figs. 1A, B), a 4 cm left upper mass, and a 4 cm retrohilar mass. He was referred for a pulmonology consultation. He had no other symptoms and was not receiving any treatment.