Patent ID: 7155273

Claim:
An apparatus for detecting the presence of a non-blanchable erythema symptomatic of a pressure sore in human tissue, said apparatus comprising; a. a housing, b. an optically transmissive window located in a wall of said housing, said window having an outer surface pressable against human tissue and thereby cause said tissue to blanch, c. a light source located within said housing inwardly of said window, said light source being energizable to emit light outwards through said window to the exterior of said housing, d. a first, leading photodetector having a field of view through said window which includes a first region spaced from said light source in a first direction, e. a second, trailing photodetector having a field of view through said window which includes a second region spaced apart in a second direction from said light source, f. signal processing means having input terminals connected to said leading and trailing photodetectors and at least a first output terminal which outputs a signal indicative of which photodetector output signal is larger, said signal processing means including a first differential amplifier having a first input terminal connected to an output terminal of said leading photodetector, and a second input terminal connected to an output terminal of said trailing photodetector, and a second differential amplifier having a first input terminal connected to an output terminal of said trailing photodetector, and a second input terminal connected to an output terminal of said leading photodetector, g. indicator means connected to said signal processor means and providing a first type perceptible indicator response to a first-type output signal from said signal processing means, and a second-type perceptible indicator response to a second-type output signal from said signal processing means, said indicator means including a first annunciator which provides a first-type perceptible signal if said output signal from said leading photodetector exceeds by a first pre-determined threshold value an output signal from said trailing photodetector, and a second-type perceptible signal if said output signal from said trailing photodetector exceeds by a second pre-determined threshold value an output signal from said leading photodetector, and h. a first, NO-GO test/calibration template, said first template having thereon a first, leading colored test pattern positionable against said window underneath said leading photodetector, and a second, trailing colored test pattern simultaneously positionable underneath said trailing photodetector, said first colored test pattern having hue and saturation levels corresponding to that of a non-blanchable, erythema, and said second colored test pattern having hue and saturation levels corresponding to that of healthy tissue, said first and second test patterns being sufficiently different in hue and saturation levels to cause said first annunciator to output said first-type perceptible signal.