The project will be pursued in our respiratory, autonomic nervous system physiology
laboratory (Respiratory, autonomic nervous system physiology laboratory, Department of
Pneumology and Intensive Care Medicine, RWTH Aachen University Hospital; Head of
Department: Professor Michael Dreher).
Overactivity of the sympathetic nerve activity (SNA) axis is a known phenomenon in
patients with systolic heart failure (HF) and has recently been described in patients
with primary lung disease as seen in chronic obstructive pulmonary disease (COPD).
Thus, insights into the nature of and factors involved in increased SNA in COPD are
urgently needed.
Potentially obstructive sleep apnea (OSA) with not only repetitive obstructions but also
additional hypoxia and poor sleep quality additively increase SNA in COPD. In addition,
inspiratory muscle dysfunction (if adequately measured by magnetic diaphragm stimulation
studies and comprehensive diaphragm ultrasound) with related hypercapnia, pulmonary
hypertension (PH) and systemic inflammation all likely also impact on SNA in COPD.
However, systematic analyses on this clinically relevant topic are currently lacking.
Thus, using a comprehensive, multimodal approach and state-of-the-art technology, this
research project is designed to determine the extent and nature of increased SNA in COPD
(AIM 1) and evaluate the underlying mechanisms (AIM 2). The project will address the
following hypotheses:
In COPD, concomitant OSA with poor sleep is independently associated with increased
SNA,.
PH, inspiratory muscle dysfunction and systemic inflammation describe a COPD
phenotype characterised by increased SNA, manifesting differently.
To test these hypotheses COPD patients without an established cardiovascular disease will
be enrolled and the extent, nature and mechanism of SNA increase compared with healthy
controls matched in a 3:1 ratio for age, sex and body mass index (BMI).
Invasive assessment of muscle SNA to the point of single unit recordings with analysis of
single postganglionic sympathetic firing, and hence SNA drive to the peripheral
vasculature, is the gold standard for quantification of SNA in humans but is only
available in a few centres worldwide because it is costly, time consuming and requires a
high level of training.
A small substudy will investigate the short term acute treatment effects of non-invasive
ventilation and oxygen supplementation on SNA in patients with COPD.
