Personal hand-held monitor to produce a theoretical curve based on PPG signals at diastole and systole, measured pressure data at diastole and systole, and times of diastole and systole

1. A personal hand-held monitor (PHHM) configured to derive one or more measurements of a parameter related to health of a subject from data collected by the PHHM, the PHHM comprising:

a signal acquisition device (SAD) which includes an optical sensor and a pressure sensor, wherein the optical sensor is a photoplethysmography (PPG) sensor; and

a processor;

wherein the processor of the PHHM is configured to analyse measured optical data and measured pressure data which are obtainable from applying the SAD to a body part or applying a body part to the SAD;

wherein:

the processor is further configured to derive timing data indicating a time of systole (TS) and a time of diastole (TD) during application of the SAD to the body part or the application of the body part to the SAD; and

the processor is configured to produce a theoretical curve from which each beat of a heart is characterised based on:

the photoplethysmography signal at diastole (PPD) and photoplethysmography signal at systole (PPS), where PPD and PPS are the measured PPG sensor signals at TD and TS, respectively,

the measured pressure data at diastole (PD) and the measured pressure data at systole (PS), where PD and PS are the measured pressure sensor signals at TD and TS respectively, and

TD and TS;

wherein the processor of the PHHM is configured to calculate, for each beat, deltaPPG, deltaP and q, wherein:

deltaPPG=PPS−PPD;

deltaP=the measured pressure data at systole minus the measured pressure data at diastole; and

q is an estimate of a pressure at systole minus a pressure at diastole from scaling deltaPPG; and

wherein the processor of the PHHM is configured to transform PS and PD into PM and L,

wherein:

PM=(PS+PD)/2; and

L=PS−PD.

2. The PHHM of claim 1 , wherein the processor of the PHHM is configured to enhance accuracy of L by combining PS−PD with q.

3. The PHHM of claim 2 , wherein the processor of the PHHM is configured to accept data in any order by interpolating the measured pressure data, the measured optical data, and/or the timing data, or parameters derived from the measured pressure data, the measured optical data and/or the timing data, onto a regular grid.

4. The PHHM of claim 3 , wherein the processor is configured to employ a non-parametric regression algorithm for the interpolating and, optionally, a Loess regression.

5. The PHHM of claim 4 , wherein the processor of the PHHM is configured to map the measured pressure data, the measured optical data and/or the timing data or parameters derived from the measured pressure data, the measured optical data and/or the timing data against PM and to interpolate an order of 200 points over a range of measured pressures.

6. The PHHM of claim 1 , wherein the parameter is the subject's blood pressure and the processor of the PHHM is configured to conduct a further analysis to extract an estimate of systolic blood pressure (SBP) and diastolic blood pressure (DBP) from the measured pressure data, the measured optical data and/or the timing data, or from processed data as processed from the measured pressure data, the measured optical data and/or the timing data by the processor.

7. The PHHM of claim 6 , wherein the processor of the PHHM is configured to conduct at least two analyses of the measured pressure data, the measured optical data and/or the timing data independently and to combine them to find the most accurate estimate of SBP and DBP.

8. The PHHM of claim 7 , wherein each analysis involves fitting data to the theoretical curve.

9. The PHHM of claim 1 , wherein each beat of the heart is further characterised by TD and a high frequency component of the measured optical signal in a region before TD (ACD).

10. The PHHM of claim 1 , wherein each beat of the heart is further characterised by one or more of:

a measure of a curvature of a plot of the measured optical signal in a region before TD (SHAPED); and

a measure of a curvature of a plot of the measured optical signal in a region after TS (SHAPES).

11. The PHHM of claim 8 , where precision of the fitting is calculated by comparison with an anticipated curve.