Medical Director Message July 2024

Dr. Jeffrey Luk

Dr Luk is the EMS Medical Director for departments under UH Cleveland Medical Center

July 15, 2024

Heat edema is a type of minor heat illness. It consists of peripheral edema of an unknown cause, generally located in the ankle and wrist, and occurs in the first few days of heat exposure. It is usually self-limited and does not require any intervention other than elevation of the extremities.

Another type of minor heat illness is heat tetany. It presents as spasms in the hands and feet and is secondary to breathing fast, resulting in a decrease in carbon dioxide and ionized serum calcium. It is often seen in conjunction with other heat syndromes or causes of hyperventilation since it may be an attempt to compensate for exercise-induced lactic acidosis. It should resolve with reversal of the hyperventilation.

Heat syncope is a brief loss of muscle tone in the body with or without loss of consciousness. Vital signs are typically normal by the time of examination. It occurs early in exposure to a new heat stress and is often preceded by dehydration or the presence of drugs that affect the normal mechanisms to compensate for heat. The etiology is usually mild dehydration in combination with the rerouting of blood into the extremities for cooling. Treatment includes rest, rehydration with electrolyte-containing fluids, and gradual return to activity.

Heat rash is common in acclimatization, in tropical areas, and in those with tight clothes. It is an intensely itchy, red, slight raised, or fluid-filled rash. It is caused by the plugging, dilation, and rupture of sweat glands followed by skin maceration from sweating. Therapy is to keep the skin cool and dry, avoid powders to prevent further plugging, avoid tight clothing, and antihistamines for itching as needed.

Heat cramps are painful intermittent spasms in the hands, arms, legs, and abdominal muscles. The patient may feel dizzy or faint. Vitals are stable. The skin is moist and warm. The patient’s body temperature is normal or slightly increased. Treatment includes removing the patient from the heat by placing in a cool, shaded area or air conditioning. You can treat the patient with oral fluid and electrolyte replacement; if the patient cannot take oral fluid, then IV fluid with normal saline is appropriate.

Heat exhaustion is the most common heat illness in the prehospital setting. Common presenting symptoms are normal or slightly elevated temperature, cool and clammy skin, heavy sweating, tachycardia, tachypnea, and hypotension. The patient may report a headache, anxiety, and numbness/tingling in extremities, but the patient should NOT have any evidence of mental status changes. Most patients present with a combined picture of salt and water depletion. Treat the patient by removing them from the heat and place in a cool shaded environment or air conditioning. Place the patient in a shock position as necessary. Rehydration with IV fluids may require up to 4L of more. Without termination of the heat stressor and immediate treatment, symptoms may progress to frank heat stroke.

Be safe and have a great summer,

Jeffrey Luk, MD

July 8, 2024

Heat illness is defined as the inability of your body to cope with heat stress. It is very prevalent, so we must understand how our bodies regulate temperature and what happens when it is overwhelmed. If heat illness is unrecognized and untreated, it can seriously harm the body. For example, heat stroke in athletes is second only to head and C-spine injuries as a cause of death. However, not all forms of heat-related illness require emergency treatment. Risk factors for heat illness include the following: 

Heat illness is usually a combination of multiple processes: 

The body adapts to heat through multiple mechanisms: 

Heat dissipates through multiple mechanisms. In the first phase, heat radiates from small blood vessels in the skin. Increased heat loss occurs as the circulatory system adjusts blood flow from the core to the outside parts of the body (i.e., extremities). Blood flow is decreased to the intestines and the heart rate increases. In the second phase, active heat loss occurs by sweating and the evaporation of sweat. Sweat glands are stimulated by the sympathetic nervous system, which increases losses via evaporation.  

In acclimatization, the body adapts to repeated heat stress over 10 to 60 days. Although this process will protect against heat illness, as the temperature one feels when the skin is wet and is exposed to moving air approaches 86°F, even young, well-acclimated individuals are susceptible to vigorous or prolonged physical activity.

Be safe and have a great summer,

Jeffrey Luk, MD