A planimetric technique for measuring deformation of the carotid sinus region.

This paper describes a planimetric technique for measuring the volume of the carotid sinus region from still photographs taken during pressure and volume forcings. The method consists of first digitizing the curves defining the boundary of the carotid sinus and then calculating its volume by assuming that the carotid sinus region is made up of a finite number of circular "pancake" slices. Plots of the calculated volume (Vc) vs. applied pressure forcings (P) were compared with plots of injected volume (Vi) vs. recorded pressure to assess the sensitivity of the method used to calculate volume changes from still photographs. The plots of Vc vs. P were remarkably similar to the plots of Vi vs. recorded pressure, and a plot of Vc vs. Vi was linear, suggesting that this method provides a good estimate of volume changes. Application of this method can yield useful data on mechanisms of the baroreceptor process.