TY - JOUR T1 - Sarcoidosis patient: Do we need to perform plethysmography when spirometry and DLCO were done? JF - European Respiratory Journal JO - Eur Respir J VL - 38 IS - Suppl 55 SP - p3608 AU - Piotr Boros AU - Magdalena Martusewicz-Boros AU - Philip Quanjer AU - Paul Enright AU - Stefan Wesolowski Y1 - 2011/09/01 UR - http://erj.ersjournals.com/content/38/Suppl_55/p3608.abstract N2 - Introduction: Plethysmographic measurement of total lung capacity (TLCbox) is the gold standard for measuring lung volumes. Gas dilution methods are considered less accurate in patients with substantial airway obstruction and take more time. DLCOsb is usually done in patients suspected of having an interstitial lung disease (ILD) and the test includes measurement of alveolar volume (VA).Aim of study: To compare TLCbox with TLCVA in a large group of sarcoidosis patients in different stages of the disease.Methods: Data from 830 consecutive sarcoidosis patients (223 in stage I, 486 in stage II, and 121 in stage III). All tests met 2005 ATS/ERS PFT technique and quality guidelines. TLCVA was calculated as the sum of VA and dead space.Results: TLCbox was larger than TLCVA by a mean of 0.18 L (95%CI: 0.15; 0.20) and 2.8% (95%CI: 2.3; 3.3). TLC was normal (above the 5th percentile) in 772 patients (93%) by TLCbox and in 762 cases (92%) by TLCVA. Sensitivity of the TLCVA for a low TLCbox was 83% and specificity 97%, so NPV was 99% and PPV 71%. The AUC by ROC analysis was 0.90. Airway obstruction was present in only 12% of the patients, but their TLCVA was significantly lower than their TLCbox when compared to those without airway obstruction (0.39 L ±0.39 vs. 0.15 L ±0.39). In this subgroup, the sensitivity of TLCVA was only 50% and specificity 96%, so NPV was 98% but PPV only 33%. The differences of TLCbox and TLCVA were correlated with FEV1/FVC ratio.Conclusions: A normal TLCVA rules out a low TLCbox with a high degree of certainty in patients with sarcoidosis, but a low TLCVA does not confirm a low TLCbox in patients with airway obstruction. ER -