Another point noted after researching this area was there is variation in the operation of heater coolers. Although heater cooler units all serve the purpose of heating and cooling the blood, how they circulate the water can be different. It is important to point out that some heater coolers draw water into the unit rather than pump water outward. This action would result in lower water pressures in the heat exchanger and a higher likelihood of blood to water leak as opposed to water to blood leaks. This mode of water circulation could aid in the detection of a leak resulting from the visibility of blood in the circulating water lines. It would also spare the patient from the deleterious effects of unsterile contaminated water entering the bloodstream. The Hemotherm CSZ (Cincinnati, OH) pumps water outward. Our institution now uses a heat cooler system that circulates water by drawing water in rather than pumping it outward (Sorin T-3, Mirandola, Italy).
Although device failure is infrequent, the procedure for reporting of the incident is very important. In this case, the failure was documented first with risk management at the hospital as a patient near miss. Next the suspected device failure was reported to Health Canada, Ottawa, Ontario, Canada. The device was then secured and sent to Health Canada for further testing. At their investigations, laboratory testing confirmed communication between the water and blood compartments. After concluding the investigation of the device, Health Canada then decides if this warrants any further course of action at the industry level such as recalls or investigation of manufacturing methods.
Radiation. Like water flowing downhill, heat naturally moves from warm areas to cooler ones. As long as the air around you is cooler than your body, you radiate heat to the air. But this transfer stops when the air temperature approaches body temperature.
Radiation requires rerouting blood flow so more of it goes to the skin. This makes the heart beat faster and pump harder. On a hot day, it may circulate two to four times as much blood each minute as it does on a cool day.
Hot, humid weather can be especially hard for people with heart failure, or those on the verge of it. The extra work for the heart, compounded by the loss of sodium and potassium and the internal flood of stress hormones, can push some people into trouble. The combination of increased blood flow to the skin and dehydration may drop blood pressure enough to cause dizziness or falls.
Heat-related trouble ranges from irritating problems such as prickly heat (also known as heat rash) to heat exhaustion and the potentially deadly heat stroke. It can be hard to tell where heat exhaustion ends and heat stroke begins. Both can be mistaken for a summer "flu," at least at first. Be on the lookout for:
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Rhabdomyolysis (rhabdo) is a medical condition associated with heat stress and prolonged physical exertion. Rhabdo causes the rapid breakdown, rupture, and death of muscle. When muscle tissue dies, electrolytes and large proteins are released into the bloodstream. This can cause irregular heart rhythms, seizures, and damage to the kidneys.
Heat syncope is a fainting (syncope) episode or dizziness that usually occurs when standing for too long or suddenly standing up after sitting or lying. Factors that may contribute to heat syncope include dehydration and lack of acclimatization.
If you experience these symptoms, seek medical attention right away. Heat stroke is not the same as a stroke. Stroke happens when a blood vessel to the brain either bursts or is blocked by a clot, causing a decrease in oxygen flow to the brain.
This intricate apparatus balances heat production with heat loss, keeping the body at a temperature just right for optimal function. This balancing act is directed automatically and seamlessly by the hypothalamus, a small portion of the brain that serves as the command center for numerous bodily functions, including the coordination of the autonomic nervous system.
But unlike a thermostat, which simply turns the heat or air conditioning on or off until a desired temperature is reached, the hypothalamus must regulate and fine-tune a complex set of temperature-control activities. It not only helps to balance body fluids and maintain salt concentrations, it also controls the release of chemicals and hormones related to temperature.
The middle layer of the skin, or dermis, stores most of the body's water. When heat activates sweat glands, these glands bring that water, along with the body's salt, to the surface of the skin as sweat. Once on the surface, the water evaporates. Water evaporating from the skin cools the body, keeping its temperature in a healthy range.
In a related function, blood vessels react to the introduction of outside organisms, such as bacteria, and to internal hormone and chemical changes by expanding and contracting. These actions move blood and heat closer to or farther from the skin, thus releasing or conserving warmth.
On most days, the hypothalamus reacts to increases in outdoor temperature by sending messages to the blood vessels, telling them to dilate. This sends warm blood, fluids and salts to the skin, setting off the process of evaporation.
"Problems occur when a person is in the heat for a long time or in such extremes of heat or humidity that the evaporation process fails," says Edward Ward, MD, director of the emergency department at RUSH University Medical Center.
An ounce of prevention: Because heatstroke is so serious, Ward strongly advises focusing on prevention. This is especially true for people age 65 and older, who are at higher risk for heat illness simply because the regulating mechanism becomes less effective with time.
Additionally, cardiovascular and neurological conditions increase a person's risk for heatstroke, as do medications that interfere with the body's ability to sweat properly, such as antipsychotics and antispasmodics.
"If you're worried or think you're having problems because of the heat, try to contact your primary care doctor," Ward says. "But if it's a real crisis, go to the emergency room. We'd much rather see you sooner than later."
The female body has a regular monthly cycle of hormonal ups and downs. During menopause and the years prior to it, this cycle becomes erratic and extreme, with large fluctuations in estrogen levels. The fluctuations of this hormone lead to a complex chain of events that affects the function of the hypothalamus and triggers changes in the blood vessels that increase blood flow.
How to tell if you're having a hot flash: The rise in temperature involved in hot flashes is not severe. During a hot flash, the blood rushing to the vessels nearest the skin may raise skin temperature by five to seven degrees, but core body temperature will not usually rise above a normal 98.6 degrees.
Specifically, these chemicals cause blood vessels to narrow and pull heat into the innermost part of the body. The result is a fever. Fever not only signals that a foreign invader has entered the body; it's also a sign that the body's immune system is working to combat that invader.
As we age, our ability to adequately respond to summer heat can become a serious problem. Older people are at significant increased risk of heat-related illnesses, known collectively as hyperthermia, during the summer months. Hyperthermia can include heat stroke, heat edema (swelling in your ankles and feet when you get hot), heat syncope (sudden dizziness after exercising in the heat), heat cramps, and heat exhaustion.
Older people, particularly those at special risk, should stay indoors on particularly hot and humid days, especially when there is an air pollution alert in effect. To stay cool, drink plenty of fluids and wear light-colored, loose-fitting clothes in natural fabrics. People without fans or air conditioners should keep their homes as cool as possible or go someplace cool. Senior centers, religious groups, and social service organizations in many communities provide cooling centers when the temperatures rise. Or visit public air conditioned places such as shopping malls, movie theaters, or libraries.
Heat stroke is a severe form of hyperthermia that occurs when the body is overwhelmed by heat and unable to control its temperature. Someone with a body temperature above 104 degrees Fahrenheit is likely suffering from heat stroke. Symptoms include fainting; a change in behavior (confusion, combativeness, staggering, possible delirium or coma); dry, flushed skin and a strong, rapid pulse; and lack of sweating. Seek immediate medical attention for a person with any of these symptoms, especially an older adult.
If you are having a hard time paying for home cooling and heating costs, there are some resources that might help. Contact the National Energy Assistance Referral service, your local Area Agency on Aging, senior center, or social service agency.
Heat waves sweeping across much of the nation have led to more emergency room visits. From New York to Oregon, doctors say the long stretch of scorching temperatures is taking its toll. As NPR's Allison Aubrey reports, heat-related illnesses can sneak up on people faster than they expect, especially if they take certain kinds of medications.
ALLISON AUBREY, BYLINE: If you live in Texas, you're no stranger to the heat. But Roy McFadden, who lives in Katy, a suburb of Houston, says he didn't realize just how hot it was getting last weekend.
AUBREY: After that, he went to play softball with his daughter. They were out for a few hours as the temperature climbed to 99 degrees and the heat index hit 105. He started to feel very dizzy and lightheaded. 041b061a72