Parameters for assessing vibration-induced cardiovascular responses in awake dogs.

The vibration parameters for assessing the response of the cardiovascular system to whole-body vibration were studied. Six awake, chronically instrumented canines were restrained with their spines vertical, and exposed to GZ sinusoidal vibration of 2-12 HZ for a constant peak acceleration amplitude of +-1.0 G. Vibration exposures of 30 s with intervening recovery periods of 2 min were employed. The following variables were measured: mean heart rate (MHR), stroke volume (SV), mean aortic flow (MAF), mean aortic pressure (MAP), the peak net force transmitted to the canine/body weight (PNF/BW), and the vibration platform frequency (ft), displacement, and acceleration. The percentage change from control (no vibration) of MAF varied linearly with PNF/BW for all cases. MAF also varied linearly with the log MHR/ft for the number of dogs which primarily changed MHR during the vibration exposures. The response of MAP was minimal in all cases, indicating a decrease in total peripheral resistance with increasing PHF.