Assessment of Baroreflex Using Cross-Correlation Function in Diabetic Autonomic Neuropathy

Baroreflex is a rapid response system in human body for dealing with the changes in blood pressure. Systolic arterial blood pressure (SABP) and mean heart rate (MHR) were analyzed by cross-correlation function (CCF) in diabetics with autonomic neuropathy to evaluate baroreflex. 60 diabetics were separated into 3 groups by different severity of autonomic neuropathy (AN). The control group was 10 age-matched healthy subjects. SABP and MHR were acquired during both supine and head-up tilt positions. Average max CCF value of healthy subjects was significantly higher (p<0.05) than those in diabetic groups. It indicated that the correlation of SABP and MHR in diabetics was lower and it might reveal SABP and MHR in diabetics cannot be controlled as well as that in healthy subjects by the function of baroreflex. Besides, max CCF index values (phase difference) in diabetics were significantly lower (p<0.05) than that in healthy subjects. Lower phase difference in diabetics revealed the change of SABP almost caused the change of MHR simultaneously. It might indicate baroreflex cannot buffer the change of blood pressure and heart rate. Standard deviation of max CCF value in healthy subjects was significantly lower (p<0.05) than that in diabetic with severe autonomic neuropathy. It revealed variation of SABP and MHR was higher in diabetic with severe AN. It could indicate the fluctuations of blood pressure and heart rate were higher with less functioning of baroreflex. According to the results, diabetic autonomic neuropathy exerted an influence on baroreflex in diabetics. Therefore, blood pressure and heart rate cannot be maintained by the function of baroreflex. It might cause blood flow decreasing or increasing in the blood vessels and bring kinds of health complications. In conclusion, cross-correlation function can be useful to assess baroreflex and severity of diabetic autonomic neuropathy.