Validation of blood pressure

Apparatus for processing an input signal including a desired component that varies slowly in value within an expected range but which may include undesired, spurious, sudden changes in amplitude extending outside said range, comprising

• means for providing a reference signal representing an average value of the input signal,
• means for deriving a difference signal representing the difference in amplitude between said input signal and said reference signal,
• means for deriving an average difference signal representing an average of the differences represented by said difference signal, and
• means for producing a first output signal when the value represented by said difference signal exceeds a given relationship to said average of the difference signals, and for producing a second output signal when the said difference signal is less than the given relationship to an average of the difference signals.

Apparatus for deriving from a signal that represents the variation of blood pressure with time values representing one of the systolic and diastolic blood pressures that are relatively free from the effects of noise, comprising

• means for deriving from a blood pressure signal desired peak values representing one of the systolic and diastolic blood pressure values for each heartbeat, which desired peak values may include undesired peaks of noise having amplitudes that may extend outside of the expected amplitude range of the desired peak value,
• means for deriving from the output of said means a reference value representing a long-term average of the desired and undesired peak values,
• means for deriving the value of the absolute difference between each peak value and said reference value,
• means for deriving an average of the values of absolute difference,
• means for producing a first output value when the value of the absolute difference of a peak value and said reference value exceeds a predetermined portion of said average of the values of absolute difference,
• means for producing a second output value when the value of the absolute difference of a peak value and said reference value is less than said predetermined portion of said average of the values of absolute difference, and
• means for deriving an average of the desired peak values that produce said second output value during a predetermined interval of time.