Abstract
This study was carried out to make a definite diagnosis for diabetic autonomic neuropathy.The baroreflex activated by a Valsalva manoeuvre (VM) is an excellent gauge of autonomic function.The VM is a convenient way to measure accurately the time relationships between blood pressure and heart rate response, Such latency measurements consist of5elements:1) tachycardia latency (TL), 2) bradycardia latency (BL), 3) blood pressure latency (BpL), 4) overshoot latency (OvL), and5) Valsalva ratio (VR).R-Rdb is measured as the difference between the maximum and minimum heart rates during deep breathing.A significant prolongation of BL was observed in patients with diabetic neuropathy as compared to the control group.This may indicate that BL is a good parameter of parasympathetic impariment.On the contrary, the Valsalva ratio (VR), which is believed to be valuable for assessingautonomic function, showed no statistically significant difference between the diabetic group and the control group, nor did latencies correlate significantly with R-Rdb.Our observation leads us to suggest that abnormality of the VM-induced baroreflex in the diabetic group is characterized by an absence of overshoot and/or bradycardia in phase 4.In addition, slow return of blood pressure to baseline and prolongation of the latency values are associated with abnormal baroreflex.A significant delay of TL in the overshoot (-) group was observed as compared to the overshoot (+) group.This delay of TL may be a good indicator of diabetic symapathetic failure.These changes, such as absent baroreflex and/or prolonged latencies, may show a definite discriminating criteria in autonomic dysfunction in diabetes mellitus.
