Calibrating for Blood Pressure Using Height Difference

One or more machine-readable storage devices storing instructions that are executable by one or more processing devices to perform operations comprising:

• obtaining a first pulse transit time (PTT) measurement for a subject, wherein the PTT represents a time taken by a pulse pressure wave traveling to the wrist of the subject, and wherein the first PTT is measured when the wrist of the subject is at a first height;
• obtaining a second PTT measurement for the subject, wherein the second PTT is measured when the wrist of the subject is at a second height;
• computing a hydrostatic difference in blood pressure as a function of the difference between the first height and the second height;
• and
• computing a calibration metric as a function of (i) the hydrostatic difference in blood pressure, and (ii) the difference between the first PTT and the second PTT.

A system comprising:

• memory;
• and
• one or more processing devices configured to perform operations comprising:
• obtaining a first pulse transit time (PTT) measurement for a subject, wherein the PTT represents a time taken by a pulse pressure wave traveling to the wrist of the subject, and wherein the first PTT is measured when the wrist of the subject is at a first height;
• obtaining a second PTT measurement for the subject, wherein the second PTT is measured when the wrist of the subject is at a second height;
• computing a hydrostatic difference in blood pressure as a function of the difference between the first height and the second height;
• and
• computing a calibration metric as a function of (i) the hydrostatic difference in blood pressure, and (ii) the difference between the first PTT and the second PTT.