Blood Pressure Control: A Comparison of Feedback and Instructions Using Pulse Wave Velocity Measurements

Abstract

ABSTRACT A comparison was made between blood pressure changes with exteroceptive feedback and simple instructions. Twenty subjects were instructed either to raise or lower pressure for four sessions, while a further 20 were allowed to view an analogue visual display of mean arterial pressure. Pressure changes were continuously monitored with the pulse wave velocity method. When changes were analyzed from the initial baseline, both groups showed divergence between Increase and Decrease over trials, but feedback enhanced control in Increase only. On assessment from the running baseline, feedback control was superior in both direction conditions. This difference may In due to interaction between running baseline changes and experimental conditions. Control by feedback groups deteriorated when feedback was withdrawn. Modifications were accompanied by alterations in heart rate, respiratory activity and movement, although the association was of a gross nature only, being more prominent in increase conditions.