Erythema ab igne (EAI), also known as hot water bottle rash, is a skin condition caused by long-term exposure to heat (infrared radiation). Prolonged thermal radiation exposure to the skin can lead to the development of reticulated erythema, hyperpigmentation, scaling, and telangiectasias in the affected area. Some people may complain of mild itchiness and a burning sensation, but often, unless a change in pigmentation is seen, it can go unnoticed. Causes
Different types of heat sources can cause this condition such as:

Repeated application of hot water bottles, heating blankets, or heat pads to treat chronic pain—e.g., chronic back pain. Repeated exposure to heated car seats, space heaters, or fireplaces. Repeated or prolonged exposure to a heater is a common cause of this condition in elderly individuals. Occupational hazards of silversmiths and jewelers (face exposed to heat), bakers, and chefs (arms, face)
Resting a laptop computer on the thigh (laptop computer-induced erythema ab igne). In a 2012 review, Riahi and Cohen describe the characteristics of laptop computer-induced erythema ab igne. Temperatures between 43 and 47 °C can cause this skin condition; modern laptops can generate temperatures in this range. Indeed, laptops with powerful processors can reach temperatures of 50 °C and be associated with burns. Positioning the laptop on the thighs can allow for direct exposure to the heating elements of the laptop, which include the central processing unit (CPU) and the graphics processing unit (GPU). At least 15 cases have been reported by 2012 with the condition usually affecting the left anterior thigh.
When used as an adjunctive therapy, the edema reducing properties of HBO, along with down regulation of inflammatory cytokines may contribute to the improvement in vision. Prevention of vision loss requires that certain conditions be met: the treatment be started before irreversible damage has occurred (over 24 hours), the occlusion must not also occur at the ophthalmic artery, and treatment must continue until the inner layers of the retina are again oxygenated by the retinal arteries. References


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