Last Thursday Patently Apple posted a continuation report titled "Apple Files Major Updates to Two of their Blood Pressure inventions for Apple Watch." Today the U.S. Patent and Trademark Office officially granted Apple a major patent regarding a future Apple Watch feature that could monitor the blood pressure of a user.
More specifically, embodiments may determine and apply one or more correction factors for calculating or adjusting a measured blood pressure to provide for a more accurate blood pressure measurement. This may be particularly beneficial with blood pressure measurement devices that may be worn by a user that non-invasively measure and monitor blood pressure of a user.
A person's blood pressure is a continuously changing vital parameter. As a result, blood pressure measurements during intermittent visits to a physician may be insufficient to detect some forms of hypertension. For example, hypertension can occur in a pattern that evades detection during a visit to the physician's office (in-office measurements).
Common hypertension patterns include white coat hypertension (elevated only during a limited morning period of time), borderline hypertension (fluctuating above and below definitional levels over time), nocturnal hypertension (elevated only during sleeping hours), isolated systolic hypertension (elevated systolic pressure with non-elevated diastolic pressure), and isolated diastolic hypertension (elevated diastolic pressure with non-elevated systolic pressure).
To detect such hypertension patterns, it may be beneficial to perform additional blood pressure measurements over time to obtain a more complete view of a person's blood pressure pattern and features. Although continuous measurement of blood pressure can be achieved by invasive means, for example, via an intra-arterial pressure sensing catheter, non-invasive blood pressure measurement approaches may be more preferable.
In general, blood pressure measurements from relatively large and bulky oscillimetry cuffs (e.g., 5 cm or more in width) have minimal error in the blood pressure measurement. While such blood pressure measurement devices may be adequate for special cases, more convenient blood pressure monitoring may be desirable. More convenient blood pressure monitoring may increase the adoption of non-clinical measurements and monitoring of blood pressure by common consumers, thereby decreasing risks associated with delayed detection of hypertension.
Apple's invention provides non-invasive devices and methods for determining an pressure of blood within a cardiovascular system of a user. It may be desirable to reduce a bulkiness of current blood pressure measurement devices to make blood pressure measurements more convenient. While reducing the bulkiness of current blood pressure measurement devices may be desirable, doing so may come with additional challenges.
Apple's patent FIG. 1 below presents an exemplary method flowchart according to some embodiments of the present invention; FIG. 2 illustrates a method of applanation tonometry that may be used with embodiments of the methods and devices.
Apple's patent FIG. 3 above FIG. 3 illustrates an exemplary cross-section of a wrist which may include: palmaris longus tendon 110, median nerve 112, flexor dig. sublimis 114, ulnar artery 116, ulnar nerve 117, flexor carp. uln. 118, flex. dig. profundus 120, ext. carp. uln. 122, distal radio-unlar artic. 124, ext. dig. quinti prop. 126, ext. dig. commun. 128, ext. indicis. prop. 130, ext. poll. long. 132, ext. carp. rad. brev. 134, ext. carp. rad. long. 136, ext poll brev. 138, abd. poll. long. 140, radial artery 142, flex. carp. rad. 144, and flex. poll. long. 146. As mentioned above, the radial artery 142 is generally targeted in arterial applanation tonometry given its position adjacent the radial bone (radius).
Apple's patent FIG. 4 below illustrates an exemplary device #10a that may measure blood pressure using applanation tonometry; FIG. 5 illustrates another exemplary device #10b that may measure blood pressure using oscillometry; FIG. 11 illustrates an exemplary device 1100 for detecting a band configuration/estimating a wrist circumference, and/or estimating a target artery depth.
Apple's patent FIG. 12 above illustrates an Apple Watch that includes an ultrasound transducer #1210 coupled with a band #1202. The ultrasound transducer may be configured to direct ultrasound energy toward the target artery #1201. The ultrasound transducer may be further configured to receive reflected ultrasound energy from the target artery to determine a depth of the target artery.
Apple's patent FIG. 14 above FIG. 14 illustrates an exemplary device for estimating target artery depth. The band may support an actuator #1406 proximate the target artery #1407. One or more sensors #1408 may be provided that are configured to measure a parameter associated with an actuation amount of the actuator to determine a distance.
Apple further notes that band #1404 may include an actuator may be a fluid bladder in some embodiments. While illustrated as a fluid bladder, it should be understood that actuator may be a linear actuator in other embodiments.
The pressure sensor may detect (e.g., with a change in pressure) an initial contact with a contact end #1412 of the actuator to the skin. Thereafter, after the actuator has been actuated to be urged against the wrist of the user by a distance D, the pressure sensor may measure a mean arterial pressure. In at least some embodiments, the distance actuated D when the device #1400 measures a mean arterial pressure may be associated with the target artery depth.
This estimated target artery depth may then be used to calculate a correction factor for application to the measured blood pressure to provide an adjusted blood pressure measurement.
Review Apple's granted patent 10,849,555 for finer details.