Respitrace Corporation

National Research Development Corporation

Frank D Stott

Marvin A Sackner

Herman L Watson

A method and apparatus are shown for monitoring respiration volumes by continuously measuring, while the patient breathes, variations in the patient's chest cross sectional area, or preferably, variations in both chest and abdomen areas. Each area is measured by measuring the inductance of an extensible electrical conductor closely looped around the body, by connecting the loop as the inductance in a variable frequency LC oscillator followed by a frequency-to-voltage converter and a voltage display. Calibration is made by measuring the area variations for a few breaths while directly measuring corresponding volumes of breath, preferably while the patient assumes at least two body positions, for example sitting and supine. The method and apparatus may also be used to monitor changes in area of any non-magnetic object.

Method and apparatus for monitoring respiration

Blood pressure measurement apparatus comprises means for variably occluding a body zone by progressive application of external pressure between levels respectively above systolic and below diastolic, means for detecting variations in blood volume in said zone during variable occlusion thereof, and means responsive to the occluding and detecting means to indicate as systolic and diastolic pressures the values of said external pressure respectively when the maximum and minimum detected volume levels are each about half way between zero and the maximum level following the last minimum which does not depart significantly from zero. The blood volume variations are preferably determined by reference to light transmission through the zone, suitably infrared, but other measures are suitable as determined by strain gauge, proton magnetic resonance or microwave absorbtion.

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Oxford, United Kingdom

Frank D Stott