Abstract: In a system for measuring blood pressure and the like based on a sensed quantity representing the sum of pressure applied by a pressure cuff and a fluctuating component representative of the pulsatile pressure within the blood vessel method and apparatus for indicating blood pressure only if that pressure determined in a first preferred manner correlates substantially with a pressure determined in a secondary, different manner. More specifically, the sensed quantity is analyzed in a manner preferred for determining diastolic pressure and a manner preferred for determining systolic pressure, and the diastolic and systolic pressures or pressure ranges established by analyzing the sensed quantity in a secondary manner or manners. Examples of preferred and secondary techniques for diastolic and systolic pressure determinations are discussed.

Abstract: An improved method and apparatus for determining blood pressure in a system employing a variable pressure cuff and having means for sensing a quantity comprising the sum of applied cuff pressure and a component representative of pulsatile pressure in a blood vessel, a particular time derivative of at least the fluctuating component of the quantity is obtained and utilized for determining blood pressure. More specifically, the particular time derivative comprises the second (or greater) derivative and it is analyzed to determine at what applied pressure it first and last crosses a negative threshold value, those pressures then being indicated as diastolic and systolic pressure depending on whether applied pressure is increased or decreased. The threshold value may be dynamically determined.