The first series of patent applications relating to an Apple Watch doubling as a blood pressure device surfaced in November. One was titled "Blood Pressure Monitoring using a multi-function wrist-worn device. The Apple Watch was highlighted during the WWDC 2018 keynote. Apple's CEO highlighted how Apple Watch 3 was used to call for help in an emergency that saved a life. You could watch that segment of the keynote that begins at the 1:05:37 mark.

Today the US Patent & Trademark Office published a new patent application from Apple that builds on Apple's invention that could bring a custom Apple Watch band to market that is designed to take a user's blood pressure.

Apple notes that "A low-profile blood pressure measurement system and methods of use are disclosed. The system includes an expandable member that has a multi-compartment structure and/or is mounted on a rigid surface or structure. The system may be incorporated into a portable electronic device, or may be configured for use with, or to otherwise communicate with a portable multi-function device."

Apple's Patent Background

High blood pressure or hypertension is common medical condition, yet it often goes undetected or untreated. According to the Centers for Disease Control, 1 in 3 adult Americans have hypertension, and only about half of those diagnosed with the disease are under adequate blood pressure control.

The actual measurement of blood pressure can vary with a number of factors, including recent activity, body position at the time of measurement, ingested substances such as alcohol and caffeine, and current stress levels. Even the presence of a patient at a doctor's office can transiently increase blood pressure, a phenomenon known as "white coat hypertension".

To obtain a more reliable and/or accurate assessment of a patient's blood pressure, a patient may be asked to periodically check and record their blood pressure at home, or to even wear an ambulatory blood pressure monitoring (ABPM) device for a period of time, typically a single 24-hour period. The ABPM device is often programmed or configured to inflate at intervals, e.g. every 15-20 minutes during the day, and every 20-30 minutes at night).

Blood pressure measurements may be performed in number of ways. In the ausculatory method, a pressure cuff is placed around the arm and is inflated sufficiently to occlude the brachial artery. The pressure is then decreased gradually and a stethoscope is used to detect Korotkoff sounds. The Korotkoff sounds are the result of turbulent flow through a partially occluded artery, and the pressures corresponding to the onset and cessation of the Korotkoff sounds are the systolic and diastolic blood pressures, respectively.

In the oscillometric method (also see: korotkoff Sounds vs. Oscillometric BP measurement), the onset and cessation of pulsatile pressure changes sensed in the cuff to determine the systolic and diastolic blood pressure.

In the applanation tonometry method, a pressure sensor is placed against an artery to slightly flatten the artery against the underlying anatomical structures, so the pressure waveform can be directly measured. The central venous pressure and the systolic and diastolic pressures can then be determined from the waveform.

Apple's invention covers a low-profile blood pressure measurement system and methods of use are disclosed. The system includes an expandable member that has a multi-compartment structure and/or is mounted on a rigid surface or structure. The system may be incorporated into a portable electronic device, or may be configured for use with, or to otherwise communicate with a portable multi-function device.

In one embodiment, a blood pressure measurement system is provided where the system comprises a pressure sensor, an expandable member or structure comprising a plurality of expandable cells, wherein the plurality of expandable cells comprises at least three expandable cells or at least two repeating expandable cells, and an expansion actuator configured to selectively expand the expandable member. The expandable member may be an inflatable structure, and the expandable cells may be inflatable cells and the expansion actuator may be an air pump. The expandable member may comprise a length, a width and a vertical dimension, and wherein the length is orthogonal to the width and the height and the width is orthogonal to the vertical dimension, and wherein the length is greater than equal to the width, and the width is greater than or equal to the vertical dimension.

The system may also further comprise a frame member, the frame member comprising a rigid base, and wherein the expandable member is attached to the rigid base. The frame member may optionally further comprise a first side wall, a second side wall, and a cavity therebetween, wherein the expandable member is at least partially located in the cavity. In some instances, the expandable member may be configured to expand out of the cavity when in the expanded state.

In some other embodiments, the inflatable structure may comprise a first expandable cell, a second expandable cell, and a third expandable cell therebetween, wherein the expansion actuator is configured to inflate the first and second expandable cells to a greater pressure than the third expandable cell. The first expandable cell is a first expandable edge cell and the second expandable cell is a second expandable edge cell. The expandable member may further comprise a sensing cell overlying the plurality of elongate structures.

Apple's patent FIGS. 1A and 1B below are posterior and anterior views of an exemplary blood pressure measurement system worn on the wrist.

Apple's patent FIG. 3A presented above is a block diagram illustrating an exemplary controller configuration of a system.

Apple's patent FIGS. 12A and 12B presented above are schematic cross-section and perspective views of an exemplary expandable member comprising multiple expandable cells in a stacked and bi-sectioned configuration; FIG. 17A is a schematic perspective view of an expandable member comprising a lower plurality of expandable cells and an upper plurality of expandable cells with different orientation than the lower plurality. FIG. 17B depicts the overall orientation of the expandable member in FIG. 17A with respect to the band of the blood pressure measurement system.

FIGS. 4A and 4B are perspective schematic views of an expandable member in a flat and circumferential configuration; FIG. 5 is a perspective schematic view an exemplary system with an expandable member and a housing that supports a display; FIG. 19 is a perspective schematic view of an exemplary system with an expandable member located on a frame member.

In some examples of the blood pressure measurement device, the device may further comprise a support member to facilitate the application of force by the expandable member. In FIG. 19, for example, the device #1900 comprises an expandable member #1902 that is mounted on an inner surface #1904 of a support member #1906. The support member may comprise rigid or semi-rigid materials, including but not limited polyethylene terephthalate (PET), high density polyethylene (HDPE), polyvinyl chloride (PVC), polypropylene (PP) and polystyrene, or a metal, for example.

The support member 1906 may comprise a single structure or may comprise a plurality of linked or articulated structures, similar to a metal watchband, for example.

Apple's patent application 20180153418 was filed back in Q4 2017. Considering that this is a patent application, the timing of such a product to market is unknown at this time.

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