Hot weather and Cardiac Diseases Prof. Dr. Berkten Berkalp Created: 2016-03-30 11:50:08
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Hot weather and Cardiac Diseases

Our body requires a particular temperature range in order to survive. Our body temperature should be constant at 36.6 C in order to normally maintain our bodily functions. Several body temperature regulating mechanisms are activated depending on variation at temperature of outer environment, and thus, change of body temperature is avoided. Sweating and vaporization of sweat ensures heat loss of body.

Hot weather and Cardiac Diseases

Dilatation of subcutaneous blood vessels accelerates cutaneous blood circulation and thus, body temperature is decreased. Those conditions lead to reduction of blood pressure and increased of pulse rate. At cold weather, subcutaneous blood vessels contract resulting with decrease in heat loss of body; chill is felt at end points of our body such as hands and feet. Load on heart increases since blood is pumped to subcutaneous vessels in order to regulate body temperature and heart works faster. Such changes are not well for coronary artery diseases; they lead to tiredness of heart and decrease in blood supply to heart muscle resulting with chest pain suffered by patients. Pulse decreasing drugs, which are used in some patients with cardiac disease, have negative influences on cooling system of body and patients may more severely feel atmospheric temperature.

Atmospheric temperature and the feeling air temperature are different. Feeling temperature is influenced by external humidity. When humidity rate increases, feeling temperature also increases. Higher humidity rate decreases vaporization of sweat resulting with higher feeling temperature. Therefore, increase in air temperature is more severely felt at seashore.

The mild discomfort caused by higher air temperature is referred as heat exhaustion. It is secondary to sweating as well as dehydration and salt loss. Fatigue, headache and dizziness occur. Muscle cramps can be felt in arms, legs and on abdomen. They usually occur in subjects with heavy duty or working out at high temperature. In the event of heat exhaustion, patient should be carried to a cool place or under shade; subject should be undressed and made rest until complaints disappear. Patient can also be made take shower with cold water. Patient should be ingested plenty of water. Alcohol, caffeine- or glucose-containing drinks, which may lead to dehydration, should be avoided. Patient should be transported to hospital if complaints persist over 1 hour.

Heat stroke is a serious condition, body temperature elevates above 39 C and skin is dry, hot and red. There is pulsating headache. Pulse rate is high; nausea, dizziness and impairment of consciousness occur. Vomiting and involuntary movements can be seen. Patient should be transported to a cool place; body cooling techniques such as ice or damped cloth application and patient should be immediately referred to hospital.

Who are negatively influenced by hot weather?

Elderly subjects and children aged below 4 years,

Subjects with chronic renal failure or undergoing dialysis,

Obese subjects, pregnant, subjects working at outdoor conditions (agriculture and construction workers), subjects working an hot and humid places such as bakery, kitchen and dry cleaning and subjects working out in open air,

Drugs aggravating thermaesthesia have negative influences on body temperature regulation system and they decrease threshold of resistance to hot weather (psychiatric drugs, anti-anxietic agents, some drugs used for Parkinson’s disease).

Inadequate fluid intake, alcohol consumption,

Subjects with coronary artery diseases, subjects with history of stent placement , cardiac valve replacement and taking blood thinners, subjects with heart failure, hypertensive subjects, diabetic subjects,

For patients with heart failure and renal disease, the necessity to limit daily fluid intake may lead to problems at extremely hot weather since increased loss cannot be compensated. Patients with heart failure may not pump volume of blood required to cool body. Drugs used for treating heart failure may also have negative influences on mechanisms ensuring adaptation to hot weather.

Sweating is a body reaction against hot weather and resulting reduction in blood pressure and increased pulse rate may be hazardous. Extreme fluid loss in patients with coronary heart disease may increase viscosity of blood. Formation of blood clots on stenotic parts of coronary arteries may induce heart attack.

* Diuretics ensure excretion of water and salt via urine. If fluid or salt loss via sweating occurs at hot weather, dehydration occurs and blood becomes more viscose. Blood urea level elevates and excretion of other drugs may be influenced.

* Heart rate reduces in subjects receiving beta-blockers; heart rate may not increase adequately to cool body.

* In case of anti-hypertensive drug use, degree of decrease in blood pressure increases secondary to hot weather and complaints occur such as fatigue, easily getting tired and dizziness when subject stands up.

General measures

Particular activities such as jogging and exercise should be avoided at hot weather; early morning or late afternoon should be preferred for such activities. One should avoid staying in parked vehicles since environmental temperature inside the vehicle may reach extreme values.

Plenty of water should be ingested and alcohol and caffeine- and glucose-containing drinks should be avoided. Subjects who need to work at hot weather should drink minimum 2 glasses of water per hour. Tea and coffee increase fluid loss based on diuretic effect. Alcoholic drinks should be consumed at low volumes and at night hours. Easily digested foods should be consumed in short intervals. Consumption of foods rich in protein and fat should be decreased.

One should stay at air-conditioned and cool place. If there is no air-conditioner, hands and face should be often washed and one should often take cool shower. Light-weight, air-permeable (cotton), light colored and loose garments should be preferred and light-color hat and sunglasses should be used. Sun lotion with protection factor should be applied to body exposing to sun light.

Treatment and drug doses of patients with heart diseases should be under supervision of doctor and they should follow necessary adjustments and advices.

Do you know that?

Seventy five (75) percent of body is comprised of water. Eight five (85) percent of brain, 90 percent of blood, 75 percent of muscles, 82 percent of kidneys and 22 percent of bones are comprised of water. Water balance of body ensures smooth operation of metabolism and normal blood viscosity. Daily water consumption should be minimum 2 liters.

We heavily sweat at hot weather; however, we are not required to intake more salt. Salt loss via sweating is not really much event at very hot weather.

Salt consumption should be cared not only by elder subjects but it should be taken into account by all subjects at any age group. Excess salt consumption may elevate blood pressure.

Salt content of foods may not be concluded by tasting them. If one heavily consumes salt, he/she may have insensitive taste buds. Salt content of foods should be reviewed.

World Health Organization recommends that daily salt intake is limited to 1 tea spoon (5-6 g).

This post has been written by Prof. Dr. Berkten Berkalp and viewed 16921 times.