Heat syncope

Heat syncope Fainting that occurs in some people after standing for a long period of time. 

Heat Syncope. Heat exposure can cause postural hypotension leading to a syncopal or near-syncopal episode. Heat syncope is believed to result from intense sweating, which leads to dehydration, followed by peripheral vasodilatation. Initial management of the patient with heat syncope involves cooling and rehydration of the patient with oral rehydration solutions (such as commercially available sports drinks). 

Adverse health outcomes associated with high environmental temperatures include heatstroke, heat exhaustion, heat syncope, and heat cramps. Heatstroke (i.e., core body temperature greater than or equal to 105 °F/40.4 °C) is the most serious of these conditions and is characterized by rapid progression of lethargy, confusion, and unconsciousness it is often fatal despite... 

Heat Syncope Standing individuals not acclimatized to hot environments may faint. That results when the body redistributes blood to peripheral tissue and reduces the blood flow to the brain. The treatment for this condition... 

Undesirable heat strain results from a combination of factors - clothing, activity levels, age, health and fitness status. The body can pick up or lose heat from conduction (very little) convection (movement of air over the body) or radiation. It can also lose heat by evaporation of sweat however, it is not desirable for even a normal fit heaWy young man to sweat more than 1 litre/hour over 8 hours (women s tolerances have not been as well studied). Also, in conditions where heat retention is at the rate of 73 W for an hour, the body core temperature will rise approximately 1.2°C. A rise above this can lead to heat syncope (fainting) heat exhaustion anhidrosis (sweating stops) and heat stroke. Figures 8.5 and 8.6 show the full range of effects. 

Heat syncope, or heat collapse, is fainting caused by the reduction of cerebral blood flow and circulation. Often, the fainting is preceded by skin pallor, vision blurring, dizziness, and nausea. Mild dehydration contributes to heat syncope. 

Heat syncope fainting while standing erect and immobile in heat. 

Heat stroke Heat exhaustion Dehydration Heat syncope (fainting)... 

A review of symptoms will enable the medical officer to evaluate the ability of an individual to work in protective ensemble. Questions concerning shortness of breath or labored breathing on exertion, asthma, other respiratory symptoms, chest pain, high blood pressure, and heat intolerance will provide helpful information. Questions about allergic reactions to rubber products and cold-induced bronchospasm should be asked and a brief psychiatric history directed toward the individual s ability to be encapsulated in personal protective equipment should be taken. Questions about panic attacks, syncopal episodes, or hyperventilation will also offer valuable information. 

In cases where syncope occurs only under exceptional circumstances, management primarily entails education of the patient and their family regarding the nature of the disorder and the predisposing factors to be avoided (such as extreme heat, dehydration and drugs that may precipitate syncope, for example, alcohol and vasodilators). Patients should be instructed to lie down at the onset of any prodromal symptoms. 

AU of the above can be serious, but it is heat stroke—also called sun stroke— that is of particular concern. It should be treated as a medical emergency. Although heat stroke usually follows from syncope and exhaustion, it can occur without any previous signs. 

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