PREDISPOSING FACTORS PRACTICAL MEASURES FOR CAUSING HEAT RELATED DISORDERS PREVENTION 1.FEVER. 1.ACCLIMATIZATION. 2.VOMITING , DIARRHEA. 2.ADEQUATE WATER INTAKE. 3.OBESITY. 3.ADEQUATE SALT INTAKE. 4.ALCOHOLISM. 4.LIGHT LOOSE COTTON CLOTHING 5.DEFECTIVE SWEATING. 5.AIR CONDITIONING. 6.OVER EXERTION IN HOT HUMID CONDITIONS. 6.EARLY TREATMENT. EFFECTS OF HEAT ON HUMAN BODY. EYES : Exposure to UV radiation leads to premature formation of cataracts. Reflected light is particularly  rich in harmful short wavelength ultraviolet radiation. Using a spurious sunglass is more harmful than  not using any glasses, as these glasses cause a shading effect but do not cut the UV. The shading effect cause the pupil to dilate and present a larger aperture for the UV to enter the eyeball.   SKIN : It is mostly the shorter wave length UV radiation ( 290 - 320 nm ) that cause damage.  The skin could be damaged acutely as a Sun Burn or chronic damage in the form of premature aging of the skin, dyspigmentation, solar keratosis and skin cancer.  Preventive measures include : Gradual exposure of the skin to sunlight over a few days, this gives time for the body to produce melanin, the protective pigment in the skin. Wearing fullsleeves shirts and wide brimmed hats.Using a sun barrier cream.These are either zinc oxide creams offering a phsical barrier on account of it's opaque nature, or they contain 5 - 10 % para amino benzoic acid ( or its derivatives ) which offer chemical protection against the UV radiations. The efficiency of a sun screen cream is its sun protection factor SPF, this should be a minimum of 15. SPF of 15 means that if it would take 10 minutes of sun exposure to burn your skin, using a cream of SPF 15 would take 150 minutes of sun exposure to burn your skin. The above preventive measures are especially important in fair skinned people.  Prickly heat is a condition when the sweat glands get blocked in the prickle cell layer of the epidermis so the sweat escapes into the epidermis and causes irritation. Scratching causes secondary infection.  Moving to a cooler environment, reducing sweating by avoiding alcohol and spicy foods helps. The blocked ducts become patent in a week or two.Local application of calamine lotion is helpful.   SYSTEMIC EFFECTS : In cool climate the body looses heat by radiation and convection but when the environment temperature approaches 37 C, evaporation of sweat becomes the most important mechanism of loosing temperature. In humid conditions even this mechanism is jeopardized thus making it difficult for the body to loose heat. When the body cannot loose heat it leads to heat disorders.  Heat disorders can take three forms; heat syncope, heat exhaustion and heat stroke depending on the  environment, predisposing factors and the measures taken to prevent them. Heat Syncope : generally in warm atmosphere with poor air circulation in an improperly dressed person. Sudden onset preceded by weakness, vertigo or headache. Patient collapses appears ashen, temperature is normal, skin is cold and clammy. Lay the patient in recumbent position, and move to a cool place. Recovery should be rapid. Heat Exhaustion : generally in extreme heat or due to extra effort in hot weather when the patient has not taken enough fluids and salt to compensate the loss by sweating. The patient has giddiness, nausea, muscle cramps, headache, and may become delirious .The skin is cold and clammy. ( Cool Moist  -  Man ). Move the patient immediately to cool environment, Use fans to help cool him and give cold drinks with added salt 10 gms/L. Seek medical attention, untreated, can progress to heat stroke. Heat Hyperpyrexia (Heat Stroke ) : is a syndrome due to overheating of the body core. Especially in Unacclamatised people and generally in hot humid weather. Unsuitable clothing and poor ventilation increase the risk. This disorder affects the central nervous system and is associated with cessation of sweating. The onset is dramatic, when body temperature reaches 41 to 42 C patient becomes disoriented and looses consciousness rapidly, there are no warning signs though the patient may have noticed that his perspiration has stopped. On examination a burning skin is found. ( Hot Dry Man ) Reduce the temperature as quickly as possible. In the field move the patient to shade, remove clothing  the skin is kept wet and fanned vigorously ( spray the patient or loosely wrap the patient in cool wet sheet and fan vigorously. ) Ideally water should be 15C. Use of iced water or immersion in cold water causes vasoconstriction and thus hinders heat loss. Use of ice may also cause shivering producing heat. Cooling is to be stopped when rectal temperature reaches 39 C. Airway should be maintained and oxygen administered. Seek prompt medical attention. By: Dr Shaikh M K