Method and apparatus for measuring blood pressure by the oscillometric technique

A method for measuring blood pressure, comprising:

• a) placing a blood pressure cuff around the limb of a subject, inflating it, and monitoring the pressure within said cuff as said cuff is slowly deflated;
• b) collecting Time, Cuff pressure and Pressure pulse amplitude data during this deflation time;
• c) representing said Time, Cuff pressure and Pressure pulse amplitude data in a pressure versus time waveform;
• d) from this pressure versus time waveform, deriving an oscillating component due to blood pressure pulses;
• e) representing said oscillating component by an oscillometric envelope;
• f) obtaining a value for the peak amplitude Amax of said oscillometric envelope;
• g) determining a cuff pressure CP which corresponds in time with Amax, this pressure representing the mean arterial pressure (MAP) of the subject;
• h) calculating a PIPSBP value from said MAP pressure;
• i) performing the calculation Asbp=Amax*PIPSBP to determine a systolic amplitude value Asbp along said oscillometric envelope;
• j) determining the cuff pressure C which corresponds in time to Asbp;
• and
• k) displaying cuff pressure C, this value representing the systolic blood pressure (SBP) of the subject.

A system for measuring blood pressure by the oscillometric technique, said system comprising:

• a) a microprocessor;
• b) a program memory accessible by said microprocessor;
• c) a first software program component stored within said program memory for operating said microprocessor;
• d) a data memory connected to said microprocessor for storing data from said microprocessor;
• e) a blood pressure measurement subsystem acting under the control of said first software program component, said subsystem acquiring once per sample period, and providing to said microprocessor, an instantaneous pressure value representing the blood pressure within a blood pressure cuff placed on a subject;
• f) a second software program component stored within said program memory for extracting, from said instantaneous pressure value, data relating to time T, cuff pressure C and a pulse amplitude A, said time, pressure and amplitude data stored by said microprocessor into said data memory;
• g) a systolic blood pressure determiner comprising a third software program component for determining MAP from said time, pressure and amplitude data, for determining PIPs from said MAP, and for determining SBP and DBP values from said PIPs;
• and
• h) a user interface allowing a user to provide input to said system and to receive output from said system.

A method for determining a blood pressure of a subject, the method comprising:

• a) using an oscillometric technique to obtain oscillometric data;
• b) estimating mean arterial pressure (MAP), or estimating systolic blood pressure (SBP) from said oscillometric data;
• c) determining PIPSBP, PIPDBP, or both PIPSBP, and PIPDBP values as functions of estimated MAP or estimated SBP;
• and
• d) using said PIPSBP and/or PIPDBP values in an oscillometric technique to determine SBP and/or DBP.

A method for measuring blood pressure, comprising the steps of:

• a) applying a blood pressure cuff around a limb of a subject, inflating said cuff to occlude the flow of blood in that limb, and then deflating the cuff while collecting Cuff Pressure Data;
• b) extracting Pulse Amplitudes from said Cuff Pressure Data, the Pulse Amplitudes comprising the oscillating component due to the blood pressure pulse;
• c) representing the sequence of said Pulse Amplitudes by an envelope;
• d) obtaining a peak value of said envelope, Amax;
• e) determining a cuff pressure which corresponds in time with Amax, this pressure being an estimate of the mean arterial pressure (MAP) of the subject;
• f) determining the PIPSBP, PIPDBP, or both PIPSBP and PIPDBP values from said MAP pressure;
• and
• g) determining the systolic blood pressure according to said PIPSBP, or the diastolic pressure according to said PIPDBP.

An apparatus for measuring blood pressure, said apparatus comprising:

• a) a microprocessor;
• b) a program memory accessible by said microprocessor;
• c) a first software program component stored within said program memory;
• d) a data memory connected to said microprocessor;
• e) a blood pressure measurement subsystem acting under the control of said first software program component, said subsystem periodically acquiring, and providing to said microprocessor, instantaneous pressure values representing the pressure within a blood pressure cuff placed on a subject, and storing said values from said microprocessor in said data memory;
• f) a second software program component stored within said program memory for extracting, from plurality of said instantaneous pressure values, data relating to pulse amplitudes A and their corresponding cuff pressures C, said A and C data stored by said microprocessor into said data memory;
• g) a third software program component stored within said program memory for determining the MAP from said A and C data;
• h) a fourth software program component stored within said program memory for determining the PIPs based on said MAP;
• and
• i) a fifth software program component stored within said program memory for determining the SBP and DBP based on said PIPs and said A and C data.

An apparatus for measuring blood pressure, said apparatus comprising:

• a) means for collecting TAC data from a subject;
• b) means for determining MAP of said subject from said TAC data;
• c) means for determining PIPSBP, and optionally PIPDBP, as a function of said MAP;
• and
• d) means for computing SBP, and optionally DBP, from said PIPSBP and said PIPDBP values, respectively.

A method for measuring blood pressure, comprising the steps of:

• a) applying a blood pressure cuff around a limb of a subject, inflating said cuff to occlude the flow of blood in that limb, and then deflating the cuff while collecting Cuff Pressure Data;
• b) extracting from said Cuff Pressure Data the Pulse Amplitudes, which are the oscillating component due to the blood pressure pulse;
• c) representing the sequence of said discrete Pulse Amplitudes by an oscillometric envelope;
• d) obtaining a reference point on said envelope;
• e) computing PIPSBP and, optionally, PIPDBP values from said reference point;
• and
• f) determining a reference time point corresponding to PIPSBP and, optionally, PIPDBP;
• and
• g) determining a cuff pressure value corresponding to said reference time point.