Apparatus and method for noninvasive blood pressure measurement

A method of determining a patient's blood pressure comprising the steps of:

• storing reference features representative of blood pressure from a population of reference patients;
• periodically obtaining calibration blood pressure values from the patient, said calibration blood pressure values representing the patient's absolute blood pressure;
• noninvasively obtaining blood pressure pulses from the patient;
• processing said blood pressure pulses to obtain processed features representative of said blood pressure pulses;
• comparing said processed features with said reference features to provide comparison signals representative of the comparison of said processed features with said reference features;
• and
• scaling said comparison signals with respect to said calibration blood pressure values and said blood pressure pulses to provide the patient's true blood pressure.

A monitor for measuring a waveform representing a patient's physiological function, said monitor comprising:

• memory means for storing reference features representative of reference waveforms from a population of reference patients, said reference waveforms being representative of the reference patients' physiological function;
• means for periodically obtaining a calibration waveform from the patient representative of the patient's physiological function;
• means for obtaining a waveform representative of the patient's physiological function;
• processing means for processing said obtained waveform to obtain processed features;
• comparing means for comparing said processed features with said reference features to provide a comparison signal;
• and
• means responsive to said calibration waveform and said obtained waveform for scaling the comparison signal to provide a signal representative of the patient's physiological function.

A method of monitoring a patient's physiological function, comprising the steps of:

• storing reference features representative of reference waveforms from a population of reference patients, said reference waveforms being representative of the reference patients' physiological function;
• periodically obtaining a calibration waveform from the patient, said calibration waveform being representative of the patient's physiological function;
• obtaining a waveform representative of the patient's physiological function;
• processing said obtained waveform to obtain processed features;
• comparing said processed features with said reference features to provide a comparison signal;
• and
• scaling the comparison signal with respect to the calibration waveform and the obtained waveform to provide a signal representative of the patient's physiological function.