Computerized simultaneous determination of natural age groups for 32 baroreflex arc function parameters and of the corresponding normal ranges for use in the diagnosis of cardiovascular autonomic neuropathy.

The diagnosis of diabetic cardiovascular autonomic neuropathy (DCVAN) is based on evaluation of baroreflex arc function (BRAF) by measuring R-R variability at rest and the R-R response to exercises such as the Valsalva manoeuvre, deep breathing, standing up, etc. Using an original computerized technique, we have studied 178 normal subjects (79 males and 99 females uniformly distributed between the ages of 16 and 88 years) so as to determine ages defining natural divisions into 'old' and 'young' groups as regards the values of various BRAF parameters, and simultaneously to determine the natural ranges for each age group so defined. For most of the 32 parameters considered the dividing ages obtained lay between 43 and 55 years. No dividing age could be determined for the response of arterial pressure to the Valsalva manoeuvre or standing up, nor for the mean heart rate while resting in a recumbent position, and in these cases normal ranges were determined for the age range of the whole sample. The effects of aging were not the same for all parameters. Thus instantaneous heart rate variability while sitting at rest and the response to deep breathing (maximum heart rate minus minimum heart rate) both decreased considerably with age, whereas the responses to the Valsalva manoeuvre (PV10) and to standing up (maximum heart rate/minimum heart rate) diminished less markedly. In conclusion, we consider that the reported results accurately establish the normal ranges of the BRAF parameters considered, whose reliability for individual diagnosis of DCVAN is thereby increased.