Autonomic nerve dysfunction in COPD as assessed by the acetylcholine sweat-spot test

Area of Science:

• Cardiovascular Autonomic Neuroscience
• Respiratory Medicine
• Neurology

Background:

• Hypoxic chronic obstructive pulmonary disease (COPD) patients exhibit subclinical parasympathetic autonomic neuropathy.
• Previous cardiovascular-respiratory tests may be biased by chest disease.
• The acetylcholine sweat-spot test offers an unbiased assessment of sympathetic nerve function.

Purpose of the Study:

• To evaluate sympathetic nerve function in hypoxemic COPD patients using the acetylcholine sweat-spot test.
• To determine the repeatability and sensitivity of the sweat-spot test in COPD.
• To correlate sweat-spot test results with disease severity and other autonomic function tests.

Main Methods:

• 35 hypoxemic COPD patients and 7 age-matched controls underwent intradermal acetylcholine injection.
• Sweat gland response was quantified on the foot's dorsum.
• Cardiovascular autonomic function, arterial blood gases, lung function, and smoking history were recorded.

Main Results:

• The acetylcholine sweat-spot test demonstrated high repeatability in COPD patients.
• Abnormal sweat-spot test results were found in 24 patients, with 8 borderline.
• Abnormal scores correlated significantly with worse FEV1, arterial blood gases, and parasympathetic cardiovascular tests.

Conclusions:

• Hypoxemic COPD patients present with both parasympathetic cardiovascular and peripheral sympathetic autonomic neuropathy.
• The acetylcholine sweat-spot test is a repeatable, sensitive, and easy-to-perform indicator of autonomic dysfunction in COPD.
• This test is valuable for assessing breathless individuals with COPD.