Baroreflex sensitivity analysis: spontaneous methodology vs. Valsalva’s maneuver

Huan Yang, Jason R. Carter Clin Auton Res. 2013 Jun;23(3):133-9. doi: 10.1007/s10286-013-0195-9. Epub 2013 May 16. Baroreflex is an important mechanism that helps to maintain blood pressure. We know that dysfunction of the arterial baroreflex has been associated with hypertension. The baroreflex sensitivity (BRS) is an index of autonomic baroreflex control sympathetic outflow or heart rate. In order to determine sympathetic (sBRS) you to estimate responses in muscle sympathetic nerve activity to changes in diastolic arterial pressure (DAP). In order to determine cardiovagal BRS (cBRS) is estimated by response in heart rate to changes in systolic arterial pressure (SAP). There are two non-pharmacological methods that can be used to determine BRS in humans. Those methods are spontaneous assessments using weighted regression analyses to examine changes in MSNA (sBRS) or heart rate (cBRS) as they relate to resting oscillation in DAP or SAP and also the valsalva maneuver (VM). Since no one so far has compared the two assessments in order to determine if they are reliable within an individual for sBRS and cBRS. They hypothesized that spontaneous BRS assessed via spontaneous methods would be positively correlated to VM BRS. 26 young subjects age around 22 were used. They all had to meet a certain criteria. They recorded blood pressure using a sphygmomanometer while the subjects were engaged in the VM. They also recorded measured the peroneal nerve activity in the right leg. They found that the spontaneous blood pressure oscillations were positively correlated with the VM sBRS. However spontaneous cBRS was not correlated te VM cBRS. These data suggest that methods using to evaluate sBRS are reliable. -MD