Efforts to reduce measurement variation and observer error in blood pressure measurements have met some success in research and institutional environments. However, these efforts, which include the random-zero sphygmomanometer, the zero muddler, and automated sphygmomanometers, have generally not been suitable in professional and office-based clinical applications where most blood pressure measurements are still taken. The objective of this proposal is to determine the feasibility of developing an improved sphygmomanometer which is affordable and technically acceptable to the medical professional, and which can significantly reduce observer bias, measurement variability, and systematic error. The proposed device would employ digital technology to enhance human blood pressure judgement (rather than replace it as automated electronic devices do), and to allow decision points to be "latched" or momentarily frozen to avoid errors associated with reading a moving scale. The principal areas of investigation will be 1) the design of appropriate circuitry to meet requisite size, performance, and cost constraints, 2) the development of a "latching" function to freeze decision points, 3) the development of back extrapolation algorithm (if necessary) to eliminate systematic error, and 4) extensive testing of prototype units in real and simulated clinical sites.