Heat stroke is a common condition especially during the summer months and when a heatwave strikes. Every year it accounts for over 300 deaths in the United States. Almost half of all these deaths occurred in people older than 65 years who are more prone to heat-related illnesses, as are babies. Without spotting the early signs of a heat illness and intervening to cool down the body, it will eventually result in a heat stroke with serious and even deadly consequences.
How To Spot A Heat Stroke
A heat stroke is preceded by heat cramps and heat exhaustion, two other types of heat-related illnesses. All three are caused by the same factors – overexposure to a heat source with insufficient internal and external cooling. The elderly and small children, particularly babies, are most prone because of the natural temperature regulatory mechanisms are often not as effective as in older children, adolescents and younger adults.
Normally the hypothalamus of the brain regulates body temperature. When the inner body temperature rises, the hypothalamus is able to detect it and trigger cooling mechanisms. This includes increasing perspiration, widening superficial blood vessels for greater blood flow to the surface and compelling a person to seek a cooler environment. However, in older people and babies, as well as in people with certain disease and medication these thermoregulatory mechanisms may be impaired.
Read more on heat illness.
From Cramps to Death
Ideally a heat illness should be spotted the earliest stage, namely heat cramps. Intervention that is instituted as soon as possible will prevent heat exhaustion and a heat stroke. As the name suggests, muscle cramps are the main symptom. Heat cramps can be mild initially and if a person is undertaking strenuous physical activity at the time, these symptoms can be missed entirely.
The signs and symptoms of the next stage known as heat exhaustion is difficult to miss. There is profuse perspiration along with fatigue, nausea and dizziness. People who have other underlying diseases, particularly acute infections, may mistaken these symptoms for the infection itself. Sleeping off the symptoms as a means to prevent the onset of heat exhaustion may not be sufficient unless a room is cooled and there is adequate rehydration.
Heat stroke is the most severe form of heat illnesses. It is a result of the body’s internal temperature rising about 41.1ºC (106ºF). At this temperature, various biochemical processes in the body are disrupted to a point where homeostasis cannot be maintained. Once again depending on how rapidly treatment is forthcoming, a heat stroke may subside or lead to complications like death.
Do I have a heat stroke?
Every person should be cautious about the possibility of a heat stroke or even milder heat illness when in a hot environment. If in doubt whether a heat-related illness has arisen, rest in a cool room and increase fluid consumption, preferably in the form of oral rehydrating solutions. It is better to prevent a heat illness before it arises. Some of the signs and symptoms of heat stroke overlap with dehydration, which commonly arises with heat illnesses.
Read more on how to prevent a heat stroke.
Sweaty to No Sweating
Initially a person will sweat profusely as the body attempts to cool itself down as much as possible. Perspiration is one the main ways that the body regulates its temperature. Evaporation of sweat from the skin surface has a cooling effect. However, as the heat illness progresses and dehydration sets in this sweating subsides. By the point of a heat stroke, the skin will feel hot to touch but it is usually dry.
Flushing of the skin is a result of the body attempting to cool itself down. Tiny blood vessels in the skin dilate (widen) so that heat from deeper in the body can be passed out into the environment with the assistance of perspiration. As the temperature within the body builds up the flushing intensifies and a there may be extreme redness. This is further exacerbated by sunburn in the event of intense sun exposure which also contributes to skin redness.
High Body Temperature
It may seem obvious that the body temperature will be raised, specifically the inner core temperature. However, this may not always be evident in the early stages of heat illness. The reason is that the body’s cooling mechanisms are still managing to keep the core temperature within a normal range but this eventually fails. The body temperature then rises to dangerous levels by the time a heat stroke sets in.
Reduced Urine Output
As the body loses fluid and electrolytes, the kidney tries to preseve remaining water and salts. It does this by reducing urine output. A person may urinate less often even with drinking fluids. Eventually there may be a total cessation of urine excretion (anuria). This can also be a sign of kidney damage which may arise with severe dehydration and an abnormally high body temperature.
Dry Mouth, Throat and Eyes
Dryness of the mucous membranes, particularly of the mouth, throat and eyes, is another sign of heat illness. This includes the lips. It is a result of dehydration but does indicate that the loss of fluid is not being matched by the intake of fluid. Saliva, tear and mucus production is therefore reduced. However, with severe heat illness this dryness is severely pronounced.
Alterations in mental state occur for a number of different reasons. It can vary from confusion, irritability and agitation to slurred speech, delirium and even seizures. A coma is also possible when a heat stroke develops and remains untreated for a period of time. It is not uncommon for some of these symptoms to be confused with a fever or even alcohol intoxication in some cases.
Rapid Heart Rate and Breathing
With fluid and electrolyte loss, the blood volume also decreases. The heart has to work faster to distribute blood throughout the body and breathing also increases to oxygenate blood faster. This is evident as a rapid heart rate and rapid breathing rate. Furthermore the body is under strain from the disruptions of various biochemical processes as a result of the elevation of the inner body temperature.
Other Signs and Symptoms
- Nausea and sometimes vomiting
- Muscle cramps
- Difficulty sleeping
- Loss of appetite
- Constipation and sometimes diarrhea