Biofeedback Training of Blood Pressure: A Comparison of Three Feedback Techniques.

Three biofeedback procedures were compared for their effectiveness in training subjects to modify systolic blood pressure (BP). Three groups of 6 normotensives received three training sessions using one of three types of systolic BP feedback: 1) proportional feedback at 75-sec intervals, 2) relatively continuous proportional feedback, or 3) a form of continuous binary feedback. Three subjects also completed a fourth, no-feedback, session. Each session consisted of 5 training cycles, during which the subject was first instructed to "lower" BP and then "don't lower" BP. This design permitted demonstration of subjects' ability to control BP, rather than just lowering it. Systolic and diastolic Bps were recorded, as were heart rate, respiration rate and respiration volume. The continuous binary feedback technique was most successful in producing systolic BP control, apparently due to the short feedback latency and maximal information available to subjects. Diastolic BP often increased within sessions even when systolic BP decreased. No consistent covariation between BP and other physiological responses was observed, although at times these responses varied systematically with instruction. Continued systolic BP control at diminished levels was demonstrated by subjects who completed a fourth, no-feedback, session. [ABSTRACT FROM AUTHOR]