Cardiopulmonary exercise testing variables as predictors of long-term outcome in thoracic sarcoidosis

A.J Lopes,M.R.M Mainenti,F.S Guimarães,S.L.S Menezes,C.M Dias,J.F Oliveira

doi:10.1590/s0100-879x2012007500018

Abstract

Cardiopulmonary exercise testing (CPET) plays an important role in the assessment of functional capacity in patients with interstitial lung disease. The aim of this study was to identify CPET measures that might be helpful in predicting the vital capacity and diffusion capacity outcomes of patients with thoracic sarcoidosis. A longitudinal study was conducted on 42 nonsmoking patients with thoracic sarcoidosis (median age = 46.5 years, 22 females). At the first evaluation, spirometry, the measurement of single-breath carbon monoxide diffusing capacity (DLCOsb) and CPET were performed. Five years later, the patients underwent a second evaluation consisting of spirometry and DLCOsb measurement. After 5 years, forced vital capacity (FVC)% and DLCOsb% had decreased significantly [95.5 (82-105) vs 87.5 (58-103) and 93.5 (79-103) vs 84.5 (44-102), respectively; P < 0.0001 for both]. In CPET, the peak oxygen uptake, maximum respiratory rate, breathing reserve, alveolar-arterial oxygen pressure gradient at peak exercise (P(A-a)O2), and Δ SpO2 values showed a strong correlation with the relative differences for FVC% and DLCOsb% (P < 0.0001 for all). P(A-a)O2 ≥22 mmHg and breathing reserve ≤40% were identified as significant independent variables for the decline in pulmonary function. Patients with thoracic sarcoidosis showed a significant reduction in FVC% and DLCOsb% after 5 years of follow-up. These data show that the outcome measures of CPET are predictors of the decline of pulmonary function.

Highlights

Sarcoidosis is a multisystem granulomatous disease of unknown origin that occurs in mediastinal and pulmonary sites in 90% of cases
The most common parameters that indicate functional impairment are forced vital capacity (FVC) and single-breath diffusion of carbon monoxide across the lung (DLCOsb); these measures are often combined with radiological assessment
Cardiopulmonary exercise testing (CPET) provides an accurate assessment of functional capacity in patients with interstitial lung disease, allowing the clinician to grade the severity of the disease

Summary

Introduction

Sarcoidosis is a multisystem granulomatous disease of unknown origin that occurs in mediastinal and pulmonary sites in 90% of cases. Parenchymal abnormalities often resolve spontaneously, but progress toward pulmonary fibrosis in 20-25% of cases [1]. Clinicians frequently find it difficult to manage patients with thoracic sarcoidosis due to the significant variability in disease manifestation and multiple, non-specific symptoms. Pulmonary function tests (PFTs) are important for measuring initial lung impairment and providing a baseline to assess improvement or deterioration of lung disease. The most common parameters that indicate functional impairment are forced vital capacity (FVC) and single-breath diffusion of carbon monoxide across the lung (DLCOsb); these measures are often combined with radiological assessment. Cardiopulmonary exercise testing (CPET) provides an accurate assessment of functional capacity in patients with interstitial lung disease, allowing the clinician to grade the severity of the disease. Many sarcoidosis patients experience significant symptoms only with exertion and remain asymptomatic at rest [3,4]

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