It's no secret that Apple has a great interest in the health applications of its technology: since the Apple Watch Series 4, the Apple Watch has been able to measure electrocardiograms and detect irregular heart rhythms.

And now a new patent discovered by AppleInsider shows how a future Apple Watch could measure blood pressure without wearing an inflatable cuff.

While there was no mention of a wrist-worn wearable, the Apple Watch seems like the most sensible destination: the patent, titled "Stretchable Blood Pressure Cuff," shows how an elastic band could hold an inflatable bladder to the body and describes a method of "compressing one or more blood vessels in an extremity to restrict and/or stop blood flow through the vessels." The resulting data may be "used to determine one or more physiological parameters of the user, such as the user's blood pressure."

It functions via a "bladder assembly configured to hold fluid in an internal chamber."

It sounds a little uncomfortable, but so does the use of a blood pressure cuff. The advantage is that no extra device is needed, and as the patent explains, "in some cases it may be desirable to wear the monitoring device for extended periods of time so that physiological measurements can be taken on a regular or continuous basis."

Notably, Apple is not the first company to introduce blood pressure monitoring, but this is the first such device to be found in a doctor's office. Samsung's Galaxy Watch 3 introduced the ability to measure this, but when I tested it, I was advised that it needs to be recalibrated with a regular blood pressure monitor once a month to maintain accuracy.

Wrist blood pressure monitors also exist, but not everyone is convinced that they are as accurate as arm cuffs. Sheldon G. Sheps, M.D., writes on the Mayo Clinic website, "To get an accurate reading when measuring blood pressure with a wrist monitor, the arm and wrist must be at heart level," as discovered by an AppleInsider comment. Still, blood pressure measured at the wrist is often higher and less accurate than that measured at the upper arm." This is because the arteries in the wrist are narrower and not as skin deep as those in the upper arm.

There is also the question of how Apple can make a strap that is both stretchy enough to compensate for a blood pressure bladder and discreet-looking at the same time. But as AppleInsider points out, the details of the patent don't seem a million miles away from the Leather Link band Apple Watch 7:

The patent is only a patent, and there is no guarantee that it will be commercialized. However, it is an interesting insight into Apple's possible solution to make the Apple Watch a kind of doctor's substitute to be worn on the wrist.