US 11,918,324 B2
Electrical coupling of pulse transit time (PTT) measurement system to heart for blood pressure measurement
Thomas J. Sullivan, Cupertino, CA (US); Wren Nancy Dougherty, San Francisco, CA (US); Richard C. Kimoto, Cupertino, CA (US); Erno Klaassen, Cupertino, CA (US); Ravi K. Narasimhan, Sunnyvale, CA (US); Stephen J. Waydo, Cupertino, CA (US); Todd K. Whitehurst, Cupertino, CA (US); Derek Park-Shing Young, Cupertino, CA (US); Santiago Quijano, Cupertino, CA (US); and Zijing Zeng, Cupertino, CA (US)
Assigned to Apple Inc., Cupertino, CA (US)
Filed by Apple Inc., Cupertino, CA (US)
Filed on Aug. 11, 2020, as Appl. No. 16/990,650.
Application 16/990,650 is a continuation of application No. 15/681,024, filed on Aug. 18, 2017, granted, now 10,779,738.
Application 15/681,024 is a continuation of application No. 15/507,401, abandoned, previously published as PCT/US2015/048849, filed on Sep. 8, 2015.
Claims priority of provisional application 62/047,486, filed on Sep. 8, 2014.
Prior Publication US 2020/0367767 A1, Nov. 26, 2020
This patent is subject to a terminal disclaimer.
Int. Cl. A61B 5/021 (2006.01); A61B 5/00 (2006.01); A61B 5/024 (2006.01); A61B 5/053 (2021.01); A61B 5/1455 (2006.01); A61B 5/282 (2021.01)
CPC A61B 5/02125 (2013.01) [A61B 5/14551 (2013.01); A61B 5/282 (2021.01); A61B 5/681 (2013.01); A61B 5/6824 (2013.01); A61B 5/02416 (2013.01); A61B 5/053 (2013.01)] 20 Claims
OG exemplary drawing
 
1. A method of determining one or more blood pressure values of a subject, the method comprising:
propagating an alternating drive current through the subject between a first drive current electrode and a second drive current electrode, wherein the second drive current electrode is externally located on a wrist-worn device worn on a wrist of the subject and engaged with the subject so that a portion of the alternating drive current travels through a thorax of the subject, and wherein the first drive current electrode is non-invasively engaged with the subject's skin at the wrist;
sensing voltage levels of the subject resulting from the alternating drive current via a first sense electrode and a second sense electrode, wherein the second sense electrode is externally located on the wrist-worn device and engaged with the subject so as to sense a voltage level induced by the alternating drive current, and wherein the first sense electrode is non-invasively engaged with the subject's skin at the wrist;
processing the voltage levels to detect when a volume of blood is ejected from the left ventricle;
processing output from a pulse arrival sensor coupled to the wrist-worn device to detect when a blood pressure pulse generated by ejection of the volume of blood from the left ventricle arrives at the wrist;
calculating a pulse transit time (PTT) for transit of the blood pressure pulse from the left ventricle to the wrist; and
determining one or more blood pressure values for the subject based on the PTT.