Heat syncope is

fainting Syncope , commonly known as fainting or passing out, is a loss of consciousness and muscle strength characterized by a fast onset, short duration, and spontaneous recovery. It is caused by a decrease in blood flow to the brain, typically from ...

or dizziness as a result of overheating ('' syncope'' is the medical term for fainting). It is a type of

heat illness Heat illness is a spectrum of disorders due to increased body temperature. It can be caused by either environmental conditions or by exertion. It includes minor conditions such as heat cramps, heat syncope, and heat exhaustion as well as the ...

. The basic symptom of heat syncope is fainting, with or without

mental confusion In psychology, confusion is the quality or emotional state of being bewildered or unclear. The term "acute mental confusion"

. Heat syncope is caused by peripheral vessel dilation, resulting in diminished blood flow to the brain and

dehydration In physiology, dehydration is a lack of total body water that disrupts metabolic processes. It occurs when free water loss exceeds intake, often resulting from excessive sweating, health conditions, or inadequate consumption of water. Mild deh ...

Signs and symptoms

Symptoms of heat syncope may include faintness, dizziness, headache, increased pulse, restlessness, nausea, vomiting, pale/clammy skin, and brief loss of consciousness.

Causes

Heat syncope occurs in a warm environment when

blood pressure Blood pressure (BP) is the pressure of Circulatory system, circulating blood against the walls of blood vessels. Most of this pressure results from the heart pumping blood through the circulatory system. When used without qualification, the term ...

is lowered as the body dilates (widens)

arterioles An arteriole is a small-diameter blood vessel in the microcirculation that extends and branches out from an artery and leads to capillaries. Arterioles have muscular walls (usually only one to two layers of smooth muscle cells) and are the pr ...

(small

blood vessel Blood vessels are the tubular structures of a circulatory system that transport blood throughout many Animal, animals’ bodies. Blood vessels transport blood cells, nutrients, and oxygen to most of the Tissue (biology), tissues of a Body (bi ...

s) in the skin to radiate heat. This condition occurs within five days of

acclimatization Acclimatization or acclimatisation ( also called acclimation or acclimatation) is the process in which an individual organism adjusts to a change in its environment (such as a change in altitude, temperature, humidity, photoperiod, or pH), ...

to higher temperatures, before the

blood volume Blood volume (volemia) is the volume of blood ( blood cells and plasma) in the circulatory system of any individual. Humans A typical adult has a blood volume of approximately 5 liters, with females and males having approximately the same blood p ...

expands.Heat Acclimatization
(doc file cannot be opened) The result is less blood to the brain, causing light-headedness and

when a person stands up quickly or stands for a long period of time. Those who perform strenuous work outside in warm climates are at particular risk.

Diagnosis

The diagnosis of heat syncope is done during a physical examination. During the physical exam the practitioner will test the blood pressure of the patient, and the pulse. If the patient is experiencing heat syncope the blood pressure will be low, and the pulse will be elevated. Observation of excess sweating will also be a key sign. Finally, the practitioner will ask questions figuring out the history of the patient's symptoms. If the patient developed symptoms while engaging in physical activity and high temperatures it will then be a true case of heat syncope.

Prevention

Physical activity in extremely hot weather should be avoided. If a person starts to experience over heating, and symptoms of heat syncope, they should move or be moved to a shaded or cool area. It is also recommended to avoid alcoholic beverages in hot weather, because they cause dehydration which may worsen symptoms. Finally, drinking plenty of water with

electrolyte An electrolyte is a substance that conducts electricity through the movement of ions, but not through the movement of electrons. This includes most soluble Salt (chemistry), salts, acids, and Base (chemistry), bases, dissolved in a polar solven ...

s is imperative when engaging in physical activity in hot weather.

Treatment

The basic treatment for heat syncope is like that for other types of fainting: the patient is positioned in a seating or

supine position The supine position () means lying horizontally, with the face and torso facing up, as opposed to the prone position, which is face down. When used in surgical procedures, it grants access to the peritoneal, thoracic, and pericardium, pericardial ...

with legs raised. Water containing salt, or another drink containing electrolytes, is administered slowly, and the patient is moved to a cooler area, such as the shade. The affected person should rest and recover, because heat syncope can lead to

heat stroke Heat stroke or heatstroke, also known as sun-stroke, is a severe heat illness that results in a body temperature greater than , along with red skin, headache, dizziness, and confusion. Sweating is generally present in exertional heatstro ...

heat exhaustion Heat exhaustion is a heat-related illness characterized by the body's inability to effectively cool itself, typically occurring in high ambient temperatures or during intense physical exertion. In heat exhaustion, core body temperature ranges from ...

References

External links

{{Disorders of consciousness Medical emergencies Effects of external causes