Massachusetts Institute of Technology

Phillip Shaltis

Haruhiko Harry Asada

Devin B McCombie

Andrew Tomas Reisner

Reginald C Hutchinson

An apparatus and methods for performing a circulatory measurement on an extremity, such as a hand, of a subject. The circulatory measurement results in the derivation of an output circulatory metric that may encompass blood pressure or various other circulatory metrics. An indicator of an input circulatory metric at a locus on the extremity is measured, such as a pulse transit time, and calibrated to account for the hydrostatic component of blood pressure arising due to vertical displacement of the extremity with respect to the heart.

Wearable pulse wave velocity blood pressure sensor and methods of calibration thereof

Methods and apparatus for measuring arterial blood pressure at an extremity of a subject. Arterial blood pressure is derived from a circulatory measurement performed on an extremity of a subject and the circulatory measurement is normalized to account for the instantaneous vertical displacement of the extremity. The vertical displacement of the extremity relative to the heart of the subject is obtained using the angular orientation of the subject's extremity. An improved photoplethysmograph can discriminate light traversing the extremity from ambient light on the basis of differential response. The apparatus may have a conducting polymer actuator for applying pressure to the extremity of the subject. A pulsatile waveform from the photoplethysmographic signal may be obtained at a plurality of externally applied pressures to calibrate the photoplethysmograph.

Wearable blood pressure sensor and method of calibration

A method and an apparatus for distinguishing concentrations of blood constituents among distinct vascular components in situ. The method has steps of inducing periodic vibration, characterized by a frequency, in a limb of a person in such as manner as to selectively excite a resonant response in a specified blood vessel of the person, an artery or a vein, illuminating the limb of the person with a light source, and synchronously detecting a plethysmographic signal for discriminating response attributable to the specified blood vessel.

Vibratory venous and arterial oximetry sensor

A ring plethysmograph having a pressure adjustment for locally pressurizing one side of a finger thereby biasing the pressure on an artery wall so that the plethysmograph is optimally sensitive without interfering with blood flow. An auxiliary photodetector, possibly with a second light source, is disposed on the low-pressure side of the finger for two purposes: providing a noise reference for canceling noise on the plethysmograph signal, and also for providing a separate motion signal for monitoring the activity level of a patient.

Growing community of inventors

Attleboro Falls, MA, United States of America

Phillip Shaltis