Desaturation-Distance Ratio During Submaximal and Maximal Exercise Tests and Its Association With Lung Function Parameters in Patients With Lymphangioleiomyomatosis.

Douglas Silva Queiroz,Alexandre Franco Amaral,Bruno Guedes Baldi,Henrique Takachi Moriya,Celso R F Carvalho,Carlos Roberto Ribeiro Carvalho,Martina Rodrigues Oliveira,Cibele Cristine Berto Marques Da Silva

doi:10.3389/fmed.2021.659416

Abstract

Background: The desaturation–distance ratio (DDR), the ratio of the desaturation area to the distance walked, is a promising, reliable, and simple physiologic tool for functional evaluation in subjects with interstitial lung diseases. Lymphangioleiomyomatosis (LAM) is a rare neoplastic condition frequently associated with exercise impairment. However, DDR has rarely been evaluated in patients with LAM.Objectives: To assess DDR during maximal and submaximal exercises and evaluate whether DDR can be predicted using lung function parameters.Methods: A cross-sectional study was conducted in a cohort of women with LAM. The 6-min walking test (6MWT) and the incremental shuttle walking test (ISWT) were performed, and DDR was obtained from both tests. The functional parameters were assessed at rest using spirometry and body plethysmography. The pulmonary function variables predictive of DDR were also assessed.Results: Forty patients were included in this study. The mean age was 46 ± 10 years. Airway obstruction, reduced DLCO, and air trapping were found in 60, 57, and 15% of patients, respectively. The distance walked and the DDR for the 6MWT and ISWT were, respectively, 517 ± 65 and 443 ± 127 m; and 6.6 (3.8–10.9) and 8.3 (6.2–12.7). FEV1 (airway obstruction) and reduced DLCO and RV/TLC (air trapping) were independent variables predictive of DDR during exercises field tests [DDR6MWT = 18.66–(0.06 × FEV1%pred)–(0.10 × DLCO%pred) + (1.54 × air trapping), = 0.43] and maximal [DDRISWT = 18.84–(0.09 × FEV1%pred)–(0.05 × DLCO%pred) + (3.10 × air trapping), = 0.33].Conclusion: Our results demonstrated that DDR is a useful tool for functional evaluation during maximal and submaximal exercises in patients with LAM, and it can be predicted using airway obstruction, reduced DLCO, and air trapping.

Highlights

Lymphangioleiomyomatosis (LAM) is a rare neoplastic cystic lung disease that affects, mainly women, ∼5 persons per million [1]
Our results demonstrated that desaturation–distance ratio (DDR) is a useful tool for functional evaluation during maximal and submaximal exercises in patients with LAM, and it can be predicted using airway obstruction, reduced DLCO, and air trapping
Our results demonstrated that DDR obtained during the submaximal (6MWT) and maximal (ISWT) exercise tests were associated with the severity of pulmonary impairment, air trapping, and reduced DLCO in patients with LAM

Summary

Introduction

Lymphangioleiomyomatosis (LAM) is a rare neoplastic cystic lung disease that affects, mainly women, ∼5 persons per million [1]. It is characterized by the proliferation of abnormal smooth muscle-like LAM cells, resulting in vascular and airway obstruction and cyst formation [2]. Functional impairment in subjects with LAM is frequently associated with exercise limitation [6, 7] that seems multifactorial, including ventilatory and gas exchange abnormalities, cardiovascular dysfunction, and muscle fatigue [7,8,9]. The desaturation–distance ratio (DDR), the ratio of the desaturation area to the distance walked, is a promising, reliable, and simple physiologic tool for functional evaluation in subjects with interstitial lung diseases. Lymphangioleiomyomatosis (LAM) is a rare neoplastic condition frequently associated with exercise impairment. DDR has rarely been evaluated in patients with LAM

Objectives

Methods

Results