Effects of oxygen supplementation in autonomic nervous system function during exercise in patients with idiopathic pulmonary fibrosis and exertional desaturation

Abstract

Introduction: Patients with idiopathic pulmonary fibrosis (IPF) have reduced exercise capacity and often present exertional dyspnea and desaturation. The role of autonomic nervous system (ANS) as a pathogenetic contributor to this dysfunction has not been evaluated. Objective: To evaluate whether improvement of arterial oxygen saturation (SpO 2 ) via oxygen supplementation results to ANS function improvement, during steady state submaximal exercise. Methods: This is a secondary analysis of a single-blind, randomized, placebocontrolled, cross-over trial, including 12 IPF patients, with isolated exertional desaturation. Following a maximal cardiopulmonary test, participants underwent two submaximal steady state tests during which they received either supplementary oxygen or medical air. Continuous beat-to-beat blood pressure measurements were recorded (Finapres Medical Systems, Amsterdam, The Netherlands). Autonomic function was assessed non-invasively by heart rate variability (HRV); root mean square of successive differences (RMSSD) and standard-deviation-Poincare-plot (SD1) were used as indices of parasympathetic output. Entropy and detrended fluctuation analysis (DFA) were also used. Results: During rest, oxygen supplementation did not significantly alter RMSSD and SD1. During exercise, subjects presented no significant alterations compared with baseline, in most HRV indices examined. There was no improvement of this behavior with O 2 -supplementation. Approximate-entropy increased during exercise, with no differences between protocols. Conclusions: IPF patients presented an inadequate adaptive response of their ANS to exercise and recovery. Although oxygen supplementation significantly prolonged exercise duration and prevented the substantial exertional desaturation, the blunted vagal response to steady-state exercise in these patients was not improved, suggesting that acute oxygen supplementation does not sufficiently improve ANS dysfunction in these patients.

Análisis de la regulación autonómica vía la causalidad de Granger de los sistemas cardiovascular y respiratorio en la fibrosis pulmonar idiopática

“…La prueba 6MWT es un marcador de la capacidad de ejercicio funcional utilizada cada vez más en las evaluaciones clínicas iniciales y longitudinales de los pacientes con FPI (Swigris et al, 2009). En el trabajo realizado por Boutou et al se estudió el efecto del oxígeno exclusivamente en pacientes con FPI, dentro de sus hallazgos principales se encontró que en reposo éste no altera la actividad parasimpática (representada por el RMSSD y el SD1), mientras que en ejercicio no encontraron diferencias de los índices con respecto a la etapa basal; concluyeron que este tipo de pacientes presenta una inadecuada respuesta adaptativa de su SNA al ejercicio y recuperación, y la administración del oxígeno no mejora dicha disfunción (Boutou et al, 2021).…”