Method of Calibrating a Blood Pressure Measurement Device
Systems, methods, and devices of the various embodiments enable calibration of continuous non-interfering blood pressure measurement devices. The measured quantity may be related to an arterial lumen or arterial cross sectional area. The arterial cross-sectional area may be related to transmural pressure, and thus the measured quantity may be related to transmural pressure by applying the first relationship to the second relationship. Sensor outputs may be obtained at a number of different heights, while the blood pressure measurement device is attached to the limb of a patient. The obtained sensor outputs may be used to determine a set of unknown parameters associated with the relationship of the transmural pressure to the sensor output. Upon determination of the parameters, the relationship of the transmural pressure to the sensor output may be used to obtain blood pressure measurements.
1 . A method for calibrating a blood pressure measurement device, comprising:
determining, by an elevation sensor, an elevation of the blood pressure measurement device;
determining, by an arterial measurement sensor, distension of an artery;
determining, by a processor of the blood pressure measurement device, a pulse shape;
determining, by the processor, whether a change in distension of an artery and elevation of a measurement device occurred between two observation times;
determining, by the processor, whether a change in pulse rate has occurred between the two observation times in response to determining that a change in distension of an artery and elevation of a measurement device occurred between two observation times;
storing, in a memory, the pulse shape, distension, and elevation in response to determining that the pulse rate is constant;
determining, by the processor, a coefficient fitting an exponentially decaying function representing an exponential decay of a portion of a diastolic phase to diastolic parts of measured pulses; and
determining, by the processor, a calibration of the arterial measurement sensor based at least in part on the exponentially decaying function and an incremental variation between the two observation times.
2 . The method of claim 1 , wherein determining, by the processor, a calibration of the arterial measurement sensor based at least in part on the exponentially decaying function and an incremental variation between the two observation times comprises determining an initial calibration of the arterial measurement sensor.
3 . The method of claim 2 , wherein determining, by the processor, a calibration of the arterial measurement sensor based at least in part on the exponentially decaying function and an incremental variation between the two observation times is performed prior to each measurement session.
4 . The method of claim 1 , wherein determining distension of an artery comprises measurement one or more of bioimpedance, impedance plethysmography, photoplethsmography, ultrasound, and surface pressure sensing.
5 . A blood pressure measurement device comprising:
a non-interfering arterial measurement sensor configured to measure a first change in distension of an artery at a measurement location on a limb of a subject without interference to an arterial pressure at the measurement location during a series of pulses; and
a processor in communication with the non-interfering arterial measurement sensor, wherein the processor is configured with processor executable instructions to perform operations to:
determine an elevation of the blood pressure measurement device;
determine distension of an artery;
determine a pulse shape;
determine whether a change in distension of an artery and elevation of a measurement device occurred between two observation times;
determine whether a change in pulse rate has occurred between the two observation times in response to determining that a change in distension of an artery and elevation of a measurement device occurred between two observation times;
store the pulse shape, distension, and elevation in response to determining that the pulse rate is constant;
determine a coefficient fitting an exponentially decaying function representing an exponential decay of a portion of a diastolic phase to diastolic parts of measured pulses; and
determine a calibration of the arterial measurement sensor based at least in part on the exponentially decaying function and an incremental variation between the two observation times.
6 . The blood pressure measurement device of claim 5 , wherein determine a calibration of the arterial measurement sensor based at least in part on the exponentially decaying function and an incremental variation between the two observation times comprises determining an initial calibration of the arterial measurement sensor.
7 . The blood pressure measurement device of claim 6 , wherein determine a calibration of the arterial measurement sensor based at least in part on the exponentially decaying function and an incremental variation between the two observation times is performed prior to each measurement session.
8 . The blood pressure measurement device of claim 5 , wherein distension of the artery is measured by one or more of bioimpedance, impedance plethysmography, photoplethsmography, ultrasound, and surface pressure sensing.
9 . A non-transitory processor-readable storage medium having stored thereon processor-executable instructions to cause a processor to perform operations comprising:
determining an elevation of the blood pressure measurement device;
determining distension of an artery by an arterial measurement sensor;
determining a pulse shape;
determining whether a change in distension of an artery and elevation of a measurement device occurred between two observation times;
determining whether a change in pulse rate has occurred between the two observation times in response to determining that a change in distension of an artery and elevation of a measurement device occurred between two observation times;
storing the pulse shape, distension, and elevation in response to determining that the pulse rate is constant;
determining a coefficient fitting an exponentially decaying function representing an exponential decay of a portion of a diastolic phase to diastolic parts of measured pulses; and
determining a calibration of the arterial measurement sensor based at least in part on the exponentially decaying function and an incremental variation between the two observation times.
10 . The non-transitory processor-readable storage medium of claim 9 , wherein the stored processor readable instructions are configured to cause a processor to perform operations such that determining a calibration of the arterial measurement sensor based at least in part on the exponentially decaying function and an incremental variation between the two observation times comprises determining an initial calibration of the arterial measurement sensor.
11 . The non-transitory processor-readable storage medium of claim 10 , wherein the stored processor readable instructions are configured to cause a processor to perform operations such that determining a calibration of the arterial measurement sensor based at least in part on the exponentially decaying function and an incremental variation between the two observation times is performed prior to each measurement session.
12 . The non-transitory processor-readable storage medium of claim 9 , wherein the stored processor readable instructions are configured to cause a processor to perform operations such that distension of the artery is measured by one or more of bioimpedance, impedance plethysmography, photoplethsmography, ultrasound, and surface pressure sensing.