[Comparative evaluation of diabetic cardiac autonomic neuropathy by spectrum analysis and Ewing's tests]

62 diabetic patients of both sex (age: 46 +/- 16 yr, BMI: 26.1 +/- 4 kg/m2, casual blood pressure: 134 +/- 17/81 +/- 11 mmHg, mean age of diabetes: 11 +/- 9 yr) without cardiovascular medications were recruited. Autonomic involvement was based on the results from a battery of five cardiovascular tests as suggested by Ewing. The result of each test and a scoring system was considered. All patients underwent power spectral analysis (PSA) of digital blood pressure (BP) and RR intervals recorded in the recumbent position and after tilting with a Finapres monitor. The percentage of total power (0.025-0.4 Hz) computed in the low-frequency band (0.070-0.139 Hz) computed in the low-frequency band (0.070-0.139 Hz) was chosen as a sympathetic index (sigma Ind). Results of tests were correlated with sigma Ind.

24 patients (39%) have an autonomic involvement. The most affected tests are: the Valsalva maneuver (VAL): 16% RR response from lying to standing (LS): 25%, sustained handgrip (SHG): 30%, postural hypotension (PH); 57%, deep breathing (DB): 87%. Correlations coefficients of cardiovascular tests and sigma Ind are: VAL/sigma Ind (SBP tilt): r = 0.277, p = 0.029; Val/sigma Ind (DBP tilt): r = 0.318, p = 0.012; VAL/sigma Ind (RR tilt): ns. PH/Ind sigma (SBP tilt): r = 0.391, p = 0.0017; PH/sigma Ind (DBP tilt): r = -0.296, p = 0.019; PH/sigma Ind (RR tilt): r = -0.308, p = 0.015, DB/sigma Ind (SBP tilt): r = 0.417, p = 0.0007; DB/sigma Ind (DBP tilt): r = 0.361, p = 0.0039; DB/sigma Ind (RR tilt): ns. Results of LS and SHG show no correlation with Ind sigma. Correlations between global autonomic score (GAS) and sigma Ind during tilting have the following values: GAS/sigma Ind (SBP tilt): r = -0486, p = 0.0001; GAS/sigma Ind (DBP tilt): r = -0.385, p = 0.002; GAS/sigma Ind (RR tilt): r = -0.411, p = 0.0009.

The so-called sympathetic index computed from PSA are well correlated with autonomic tests. They allow an early detection of sympathetic involvement in diabetics patients. These results are to consider while managing these subjects.