Personal health data collection
The present invention provides a PHHM for the measurement of a subject's BP and, optionally, one or more other vital signs, comprising a housing located on a PHHCD or a hand-held component of a computing system; a blood flow occlusion means located in the housing such that, when the housing is located on the PHHCD or the hand-held component, an open surface of the blood flow occlusion means is available to be pressed against a body part of the subject or to have a body part of the subject pressed against it; a pressure sensor adapted to provide an electrical signal indicative of the pressure applied to or by the open surface; a means for detecting the flow of blood in the body part of the subject when pressure is applied to or by the open surface; and means for receiving electrical signals from the pressure sensor and the blood flow detecting means and for transmitting electrical signals indicative of the pressure and blood flow to the processor of the PHHCD or the computing system, wherein the processor of the PHHCD or computing system is adapted to process signals acquired by the pressure sensor and the blood flow detecting means to provide at least a measurement of the BP of a subject, the processor is further adapted to carry out a process to measure a DBP value and a SBP value, the DBP and the SBP values are estimated in such a way that the difference between the measured optical signals and those that would be generated by the estimation of the DBP and SBP values is minimized or the DBP and the SBP values are estimated in such a way that the difference between the measured incremental pressure signals and those that would be generated by the estimation of the DBP and SBP values is minimized. The present invention also provides alternative PHHMs and SADs for use in such PHMS.
1. A system, comprising:
a processor; and
a signal acquisition device (SAD), the SAD comprising:
a blood flow occlusion device having an open surface available to be pressed against a body part of the subject or to have a body part of the subject pressed against it;
a pressure sensor adapted to provide an electrical signal indicative of the pressure applied to or by the open surface;
an optical blood flow detecting device configured to detect the flow of blood in the body part of the subject when pressure is applied to or by the open surface; and
a device configured to: receive electrical signals from the pressure sensor and the optical blood flow detecting device and to transmit electrical signals indicative of the pressure and blood flow to the processor,
wherein the processor is configured to provide at least a measurement of the diastolic blood pressure (DBP) and systolic blood pressure (SBP) of the subject using a non-linear parametric function that predicts optical signals, and wherein the subject's DBP and SBP values are estimated by:
using the parametric functions to generate predicted optical signals from one or more candidate DBP and SBP values;
comparing the predicted optical signals to the measured optical signals; and
adjusting the candidate DBP and SBP values to find the candidate DBP and SBP values that minimize the difference between the predicted optical signals and the measured optical signals, and using those candidate DBP and SBP values as the estimate of the subject's DBP and SBP values.
2. The system of claim 1 , wherein the processor is adapted to measure the gradient of the absolute optical signal at systole as a function of the measured external pressure and to use the said slope in order to estimate the error due to a misplaced body part.
3. The system of claim 1 , wherein the processor is adapted to measure the relative amplitude of red and infrared optical signals as a function of the pressure measured by the pressure sensor and to use said ratio to estimate the error due to a misplaced body part.
4. The system of claim 1 , wherein the processor is adapted to derive from the measured pressure and optical signals estimates of the degree to which the body part is misplaced.
5. The system of claim 4 , wherein the processor is adapted to use estimates of the degree to which the body part is misplaced to estimate and correct for the error in the estimated SBP and/or DBP due to the misplacing of the body part.
6. The system of claim 4 , wherein the error in the measured SBP is used to estimate and correct for the error in the measured DBP or vice versa.
7. The system of claim 1 , wherein the processor is adapted to use said gradient to determine if the body part is so misplaced as to render resulting estimates of SBP and DBP unreliable and to warn the user by way of audible and/or visual signals.
8. The system of claim 1 , wherein the PHHM is further adapted to generate a correction factor based on the relative locations of the body part of the subject and the blood flow occlusion device, wherein said correction factor is used to increase the accuracy of estimation of the value of BP.
9. The system of claim 1 , wherein a genetic algorithm is adapted to carry out the generating and comparing, and to do so repetitively for a fixed number of repetitions.
10. The system of claim 9 , wherein the genetic algorithm is adapted to carry out generating and comparing repetitively until a desired minimized different is achieved.
11. The system of claim 1 , wherein the non-linear parametric function predicts optical signals from a decay law of optical intensity.
12. A method for estimating a subject's DBP and SBP, comprising:
receiving electrical signals indicative of the subject's pressure and blood flow;
providing at least a measurement of the diastolic blood pressure (DBP) and systolic blood pressure (SBP) of the subject using a non-linear parametric function that predicts optical signals from a decay law of optical intensity, wherein the subject's DBP and SBP values are estimated by:
using the parametric functions to generate predicted optical signals from one or more candidate DBP and SBP values;
comparing the predicted optical signals to the measured optical signals; and
adjusting the candidate DBP and SBP values to find the candidate DBP and SBP values that minimize the different between the predicted optical signals and the measured optical signals, and using those candidate DBP and SBP values as the estimate of the subject's DBP and SBP values.