A cardiac monitor generates infrared light which is directed at the skin of an individual to be monitored. The light reflected from the skin is detected and automatically controlled. The pulsatile flow of blood in the underlying vascular network modulates the reflected light which is detected by a photo sensitive sensor which generates a signal indicative of the modulations. The modulated signal is coupled to a pulse detector which filters our spurious signals and generates one pulse for each systole in a cardiac cycle. The systolic pulse is coupled to a pulse interval to heartbeat rate converter which converts the interval between each succeeding systolic pulse into a signal which is preferably continuously and visually displayed to provide a continuous monitor of the heartbeat rate of the monitored individual.
A portable medical apparatus for use in diagnosing, testing and/or treating simultaneously various types of body disorders, including neurological or muscular abnormalities, by non-invasive and painless procedure comprising essentially an amplifier interconnected with a sensor, a meter, a threshold control, an electronic driver, a transducer and a power supply in the form of a low-voltage battery, stimulates living tissue by electromagnetic energy produced thereby for transmission thereof to the afflicted portion of patient's body.
A pulsed IR reflectance plethysmograph for heart rate measurement and display in a digital watch or as a medical instrument using, for example, a pulsed LED light emitting diode for transmitting light pulses and a photodiode for receiving light pulses reflected from a finger. The LED and photodiode are mounted in a small sensor on the watch or medical instrument. The photodiode is connected directly to a signal conditioning circuit which rapidly removes unwanted asynchronous ambient background light signals such as from sunlight, by means of a switched ambient light subtractor circuit which performs the subtraction without requiring amplification or conversion of the detector signal photocurrent to another electrical parameter. The signal current after cancellation of the ambient background signal is sampled in an integrate and hold circuit to provide a heart systolic pressure wave. The synchronous steady state IR pulse carrier envelope signal is cancelled by a perfect second-order feedback loop via an integrating amplifier and a switched transconductance element that operates with fast response, even under conditions of large overloads that occur at the sensor. Pulses of the heart systolic pressure wave are then detected to determine the pulse rate which is displayed. When only the presence of an unmodulated IR light carrier is to be detected, as in an IR light beam detector, an ambient light subtractor in accordance with the invention is provided in an unswitched configuration that removes ambient light with a minimum number of components over an extremely wide dynamic range.
Disclosed is an optical measurement apparatus for a living body to provide a means for measuring blood flow activity within a short time inside the body, even if the test subject cannot distinguish between the active task period and the rest period. An optical measurement apparatus for a living body comprises a light irradiating section, and a light detecting section for detecting light transmitting through or reflected from the interior of the body. The concentration of carbon dioxide gas taken into the body is controlled by the respiration of the test subject and the resulting change in output from the light detecting section is then evaluated.
A pulse rate monitor for use while exercising. A clothespin type finger clip remote from the counting and display unit grips the user's finger in a predictable, mechanically stable manner. A light emitting diode, strobed to reduce battery drain, transmits infrared radiation through the finger, and electronic circuitry monitors the modulation of radiation caused by changes in capillaries with each heart beat. The circuitry includes an active load for the phototransistor, which, by means of bandpass filtered feedback, enhances heart beat signal and reduces sensitivity to ambient light, noise, and variations in phototransistor characteristics.
High speed selective imaging of blood vessels is accomplished by subjecting an area of interest to a plurality of short repetition time NMR pulse sequences during each high velocity period and low velocity period of a heart beat cycle for several or more heart beats. The imaging data from each NMR pulse sequence is collected and weighted according to whether it corresponds to a high velocity period or a low blood velocity period. The weighted imaging data corresponding to high blood velocity periods is then subtracted from weighted imaging data corresponding to low blood velocity periods and the resulting data used to form an image which depicts only the blood vessels of interest. Also, an imaging data processing apparatus is disclosed which operates in real time so as to permit an operator to optimize diagnostic performance.
