Cardiovascular autonomic neuropathy in chronic obstructive pulmonary disease.
BACKGROUND
While autonomic neuropathy has been reported in chronically hypoxaemic patients of chronic obstructive pulmonary disease (COPD), whether it also occurs in patients with milder disease and in those without chronic hypoxaemia has not been explored.


METHODS
Lung function measurements including spirometry and transfer factor for carbon monoxide, mean pulmonary artery pressure estimation by color-doppler echocardiography and arterial blood gas analysis were carried out in 56 patients with COPD and 11 age-matched controls. Autonomic function was assessed by tests of cardiovascular reflexes and expressed as valsalva ratio, 30:15 ratio, IE difference and the blood pressure response to postural change.


RESULTS
Among patients, majority of the test responses were in the abnormal or borderline range compared to more than 90% of test responses in the normal or borderline range among normals. Almost 50% of patients had definite neuropathy as compared to none in normals. Although, the autonomic neuropathy tended to be observed more often in patients with moderate and severe COPD, it was also found in a fair proportion of patients with mild COPD. Similarly, while it was more prevalent in patients with hypoxaemia, it was also found to occur in those without hypoxaemia. The responses to tests of autonomic function had weak relationships with FEV1% predicted and PaO2.


CONCLUSIONS
Cardiovascular autonomic neuropathy is common in COPD and is found even in early stages of the disease.
Chhabra
S K
SK
Department of Cardiorespiratory Physiology, Clinical Research Centre, Vallabhbhai Patel Chest Institute, University of Delhi, Delhi 110 007, India. skchhabra@mailcity.com
De
Sajal
S
D000328:Adult; D000368:Aged; D001342:Autonomic Nervous System Diseases / Q000209:etiology* / Q000503:physiopathology; D002245:Carbon Dioxide / Q000097:blood; D002319:Cardiovascular System / Q000294:innervation*; D005541:Forced Expiratory Volume; D006339:Heart Rate; D006801:Humans; D007024:Hypotension, Orthostatic / Q000209:etiology; D008297:Male; D008875:Middle Aged; D010100:Oxygen / Q000097:blood; D010313:Partial Pressure; D011446:Prospective Studies; D029424:Pulmonary Disease, Chronic Obstructive / Q000150:complications* / Q000503:physiopathology; D012720:Severity of Illness Index; D014636:Valsalva Maneuver
D002245:Carbon Dioxide; D010100:Oxygen