Spectroscopic burn injury evaluation apparatus and method

#This invention relates generally to the evaluation of burn injuries and, more particularly, to apparatus, and related methods, that evaluate a burn injury using ultraviolet or visible light fluorescence spectroscopy and infrared absorption spectroscopy of skin tissue at the site of the burn injury.

#As shown in FIG. 1, the skin 2 is composed of a thin outer layer 4 (the epidermis) and a thicker inner layer 6 (the dermis). Beneath the dermis is subcutaneous tissue 8, which contains mostly fat, and eventually the muscle fascia 10 and muscle 12. The epidermis forms a tough, waterproof protective coating having tough dead cells on its outside surface that are continually worn away and having living cells on its inner most parts that replace the worn away dead cells. The dermis is living tissue that includes blood vessels 14, nerves 16, sweat glands 18, and hair follicles 20.

#Heating of the skin 2, however brief, can cause damage to the cells of its living tissue. Such damage typically is referred to as a burn. Generally, burns can be categorized into degrees that indicate the depth of the burn injury. First degree burns cause reddening of the skin and affect only the epidermis 4. Such burns heal quickly, but the damaged skin may peel away after a day or two. A "sunburn" is an example of a first degree burn. A second degree burn damages the skin more deeply, extending into the dermis 6 and usually causes blisters. However, some of the dermis is left to recover. A third degree burn destroys the full thickness of the dermis and, if the burn is very deep, muscles 12 and bones may be exposed.

#FIG. 1 is a perspective view of a cross-section of human skin.

#FIG. 2 is a block diagram of a burn evaluation apparatus embodying the present invention.

#FIG. 3 is a graph prospectively representing the intensity of fluorescence verses wavelength for normal skin induced to fluoresce by laser light having a wavelength of about 405 nanometers.

#As shown in the exemplary drawings, the present invention is embodied in a burn evaluation apparatus 30, and related method, that allows a surgeon to make a quick evaluation of the extent and depth of a burn injury to the skin. More specifically, the burn classification apparatus employs induced ultraviolet or blue light fluorescence spectroscopy and infrared (IR) reflectance spectroscopy to monitor the condition of the structural and metabolic compounds in the injured skin allowing evaluation of the potential viability of the skin at the burn site. The apparatus helps prevent the unnecessary removal of viable skin that will heal spontaneously within a few weeks, thereby reducing the amount of skin that must be surgically grafted.

#With reference now to FIG. 2, the apparatus 30 of the present invention is shown to include a plurality of light sources 32-42, a sensor 44, and a processor 46. In addition, optical fiber bundles 48-54 assist in directing excitation light from the light sources to the burn site on the skin 2 and return light from burn site to the sensor 44.

#The plurality of light sources 32-42 consist of six-diode lasers, each producing excitation light at a predetermined wavelength. The first light source 32 emits narrow-band excitation light having a wavelength of approximately 405 nanometers produced by frequency doubling light from a diode laser having a wavelength of approximately 810 nanometers. The second light source 34 emits narrow-band excitation light having a wavelength of about 452 nanometers produced by frequency doubling light from a diode laser having a wavelength of about 904 nanometers. The wavelengths of the excitation light from the first and second light sources are chosen to induce a fluorescence response in the skin's metabolic and structural compounds, discussed in more detail below. The third, fourth, and fifth light sources 36-40 emit near-infrared (NIR) light at the wavelengths of 775 nanometers, 810 nanometer, and 904 nanometers, respectively, which are useful in detecting content of and state of hemoglobin in the skin. The sixth light source emits infrared light having a wavelength of approximately 980 nanometers that is used to evaluate the skin's tissue water content.