Abstract
This prospective study analyzed the involvement of the autonomic nervous system in pulmonary and cardiac function by evaluating cardiovascular reflex and its correlation with pulmonary function abnormalities of type 2 diabetic patients. Diabetic patients (N = 17) and healthy subjects (N = 17) were evaluated by 1) pulmonary function tests including spirometry, He-dilution method, N2 washout test, and specific airway conductance (SGaw) determined by plethysmography before and after aerosol administration of atropine sulfate, and 2) autonomic cardiovascular activity by the passive tilting test and the magnitude of respiratory sinus arrhythmia (RSA). Basal heart rate was higher in the diabetic group (87.8 +/- 11.2 bpm; mean +/- SD) than in the control group (72.9 +/- 7.8 bpm, P<0.05). The increase of heart rate at 5 s of tilting was 11.8 +/- 6.5 bpm in diabetic patients and 17.6 +/- 6.2 bpm in the control group (P<0.05). Systemic arterial pressure and RSA analysis did not reveal significant differences between groups. Diabetes intragroup analysis revealed two behaviors: 10 patients with close to normal findings and 7 with significant abnormalities in terms of RSA, with the latter subgroup presenting one or more abnormalities in other tests and clear evidence of cardiovascular autonomic dysfunction. End-expiratory flows were significantly lower in diabetic patients than in the control group (P<0.05). Pulmonary function tests before and after atropine administration demonstrated comparable responses by both groups. Type 2 diabetic patients have cardiac autonomic dysfunction that is not associated with bronchomotor tone alterations, probably reflecting a less severe impairment than that of type 1 diabetes mellitus. Yet, a reduction of end-expiratory flow was detected.
Highlights
Several respiratory alterations have been reported in association with diabetes mellitus, mainly insulin-dependent diabetes, including alveolar epithelial and capillary basal membrane thickening [1], reduction of diffusion capacity [2,3], centrilobular emphysema [4], lung connective tissue changes [5], respiratory muscle dysfunction [6], and chest wall abnormalities [7]
The autonomic neuropathy of diabetic patients may influence the control of breathing and this might explain the sudden deaths occurring in patients with severe disease [12]
There were no differences in anthropometric parameters between the diabetic and control groups
Summary
Several respiratory alterations have been reported in association with diabetes mellitus, mainly insulin-dependent diabetes, including alveolar epithelial and capillary basal membrane thickening [1], reduction of diffusion capacity [2,3], centrilobular emphysema [4], lung connective tissue changes [5], respiratory muscle dysfunction [6], and chest wall abnormalities [7]. The relevance of these findings in the clinical evaluation of this disease has not been well established [8,9]. There is increasing evidence that the autonomic control of airway smooth muscle may be altered in type 1 diabetes [13]
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Schedule a callMore From: Brazilian journal of medical and biological research = Revista brasileira de pesquisas medicas e biologicas
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