Effects of oxygen on autonomic nervous system dysfunction in patients withchronic obstructive pulmonary disease

Chronic hypoxaemia can play a pathological role in abnormalities of the aut onomic nervous system (ANS). In patients with chronic obstructive pulmonary disease (COPD), chronic hypoxaemia is associated with increased mortality and only long-term oxygen therapy is able to improve their survival. Normox aemic COPD patients have been shown to suffer from abnormalities in ANS fun ction. The aims of this study were to evaluate ANS function in COPD patient s with chronic hypercapnic respiratory insufficiency and to test whether ox ygen supplementation could reverse any ANS dysfunction, Eleven stable COPD patients with chronic hypercapnic respiratory insufficie ncy underwent evaluation of ANS by analysis of variability in cardiac frequ ency at rest and during both vagal (controlled breathing) and sympathetic ( tilting) stimuli breathing with and without oxygen supplementation. Thirtee n male, healthy, nonsmoking volunteers served as controls. Evaluation of ANS in CORD patients during hypoxic conditions showed alterat ions both at rest and in response to vagal and sympathetic stimuli. Oxygen supply reversed hypoxaemia without significant changes in arterial carbon d ioxide tension and, therefore, ANS alterations were corrected during sympat hetic stimulus only. Breathing room air and oxygen, the resting low-frequen cy (LF) powers were 45+/-15 and 148+/-55 ms(2).Hz(-1), respectively, and co ntrolled breathing LF were 107+/-41 and 141+/-113 ms(2).Hz(-1), respectivel y. In stable patients with chronic obstructive pulmonary disease with chronic respiratory insufficiency, hypoxaemia is associated with derangements in th e autonomic nervous system which mag be partially reversed by oxygen admini stration.