Abstract: An automated sphygmomanometer which models the oscillometric envelope as two lines through the points defined by pressure and amplitude which are determined during the oscillometric blood pressure determination. One of the lines is the best fit through the points on the low pressure (diastolic) side of the oscillometric envelope, while the other line is the best fit through the points on the high pressure (systolic) side of the oscillometric envelope. The dividing point for the low and high pressure sides is chosen as the point where the best fit line through the points on one side and the best fit line through the points on the other side have the greatest amplitude at the point of intersection. The result is a linear approximation of the oscillometric envelope by two lines forming a triangle with the baseline. A second pass is preferably performed to improve the linear approximation by eliminating points with oscillation amplitudes that are outside of the area of interest.

Abstract: A cuff for a blood pressure meter includes material that does not stretch and in which the length of the surface in contact with the finger does not vary when the cuff is filled with compressed air, regardless of the diameter of the finger. Because the internal pressure in the cuff closely approximates the blood pressure of the finger, the device is accurate. Compressed air is pumped into chambers formed by a basic structure and containment walls. Folded portions which are provided on the containment walls cause surfaces of the containment walls which contact the object to be measured to remain parallel to protruding bodies located on the basic structure as they are displaced by inflation of the chambers.