Reduced intraindividual variability of repeated cardiovascular reflex tests: An additional marker of autonomic neuropathy in insulin-dependent (type I) diabetes mellitus?

Abstract

The particular questions asked in our study were: 1. does the individual reproducibility of the cardiovascular reflex tests differ between healthy controls and patients suffering from type I diabetes mellitus and 2. if there is a difference, do the different cardiovascular reflexes vary in this regard? Nine healthy controls (4 women, 5 men, age 31 +/- 2.1 years) and 11 type I diabetics (4 women, 7 men, age 30.9 +/- 5.6 years, duration of diabetes 3.23 years) underwent the following tests 6 times in a 12-h period (07:00 to 19:00): variation of heart rate during deep breathing (E/I ratio), variation of heart rate during lying and standing (tachycardia/bradycardia or 30/15 ratio), Valsalva maneuver (Valsalva ratio), response of diastolic blood pressure to sustained hand grip, and response of systolic blood pressure to posture. The test results did not indicate a diurnal fluctuation nor were they systematically influenced by antecedent insulin injections or meals, either in diabetic patients or in healthy controls. The 11 diabetics had significantly lower intraindividual variations of E/I and Valsalva ratios than the controls (p less than 0.05, p less than 0.001, respectively). In the diabetics with parasympathetic failure the intraindividual variabilities of all cardiovascular reflex responses were lower than those of the patients with an intact autonomic nervous system as well as those of the control subjects. On the contrary, in the diabetic patients without autonomic neuropathy, only the intraindividual variability of the Valsalva maneuver was significantly attenuated (p less than 0.025), compared with the healthy volunteers. To conclude, the more pathological the single test result, the greater is its reproducibility and its clinical significance.

Cardiovascular autonomic reflex tests:normal responses and age‐related reference values

“…However, recently the value of this method during exercise has been questioned, because the indirect method underestimates especially the intra-arterial diastolic pressure (Kaijser, 1987). Additionally, in the present study, in accordance with previous studies (Comi et al, 1986;Kronert et al, 1986), the repeatability of blood pressure responses was very poor. 0.10, lower 80% tolerance limit (lowest normal value); 0-025, lower 95% tolerance limit (lowest borderline).…”

“…The coefficients of variation of max/min and IIHR were 10 and 14%, thus showing satisfactory repeatability. Previous studies have concluded that the repeatability of madmin is good (Ewing et al, 1978;O'Brien et al, 1986a;Comi et al, 1986;Kronert et al, 1986).…”

Self-Monitoring of Cardiac Autonomic Function at Home is Feasible

“…Adding to this complexity, there is evidence that the reproducibility of the cardiovascular reflex tests are higher in diabetes patients than in healthy controls due to a well-described reduction in HRV in the diabetes population. [26][27][28] Further studies in the diabetes population are therefore necessary to investigate whether or not it is of clinical relevance to perform self-monitoring of CAN.…”