Dehydration

Dehydration 1 - DEFINITION Dehydration is loss of water and important blood salts like potassium (K+) and sodium (Na+). Dehydration means that the body does not have enough fluids to function at an optimal level. Dehydration can be caused by : 1. 2. 3.

fluid loss (through vomiting, diarrhea, excessive urination or excessive sweating), inadequate intake, or a combination of both.

Dehydration is classified as mild, moderate, or severe based on the percentage of body weight lost during the acute illness: Depending on age, • Mild dehydration -- a loss of 3-5% of body weight • Moderate dehydration -- a loss of 6-9% of body weight • Severe dehydration -- a loss of more than 10-15% of body weight. This is a lifethreatening emergency! Vital organs like the kidneys, brain, and heart can’t function without a certain minimum of water and salt. In underdeveloped countries, dehydration from diseases like cholera and dysentery kills millions every year (usually infants and children).

2 - SYMPTOMS • • • •

excessive loss of fluid through vomiting, urinating, stools or sweating poor intake of fluids, "can't keep anything down" decreased or absent urine output (oliguria or anuria) with severe dehydration -- lethargic or comatose

Below are some additional warning signs : Mild Thirst Dry lips Slightly dry mouth membranes

Signs of Dehydration Moderate Very dry mouth membranes Sunken eyes Skin doesn’t bounce back quickly when lightly pinched and released.

Severe All signs of moderate dehydration Rapid, weak pulse (more than 100 at rest). Cold hands and feet Rapid breathing Blue lips Confusion, lethargy, difficult to arouse

2.1 - PHYSICAL EXAMINATION A physical examination may also show signs of: • low blood pressure(hypotension) • rapid heart rate(tachycardia) • blood chemistries (to check electrolytes, especially sodium, potassium, and bicarbonate levels) • urine specific gravity (a high specific gravity indicates significant dehydration) • BUN (blood urea nitrogen -- may be elevated with dehydration)

• creatinine (creatinine -- may be elevated with dehydration) • Complete Blood Count (CBC) to look for signs of concentrated blood (hemoconcentration) • Other tests may be done to determine the specific cause of the dehydration (for example, a blood sugar to check for diabetes). 3 - TREATMENT When dehydration is recognized and treated promptly, the outcome is generally good. 3.1 - Mild dehydration : Drinking fluids is often sufficient for mild dehydration Mild dehydration is safe to self-treat at all ages, as long as it doesn’t worsen. To treat dehydration, you must first address the cause: fever, Vomiting, Diarrhea, and Heat Exhaustion are the most common reasons for dehydration. While you’re treating the underlying problem, begin small amounts of oral re-hydrating solution (ORS). Commercial ORS replaces important blood salts and water in balanced amounts designed especially for dehydration in sick people They are formulated to allow your intestines to absorb maximum amounts of water along with small amounts of salts. Don’t confuse ORS with sports drinks designed for concentrated energy and salt replacement in healthy, highperformance athletes. These drinks can actually aggravate vomiting and diarrhea and are so concentrated they can limit intestinal water absorption. Once signs of dehydration have disappeared, ORS is no longer necessary, but a clear liquid diet might still be useful if vomiting or diarrhea persists. 3.2 - Moderate dehydration In teenagers and adults with, careful home treatment can be safe, but phone contact with a physician is advisable. 3.3 - Severe dehydration : If you’re severely dehydrated, you must get to a hospital right away. Intravenous fluids and hospitalization may be necessary for moderate to severe dehydration. The health care provider must also determine and, if possible, treat the cause of the dehydration.

4 - Complications Untreated severe dehydration may result in seizures, permanent brain damage, or death. Severe dehydration decreases blood volume and causes the blood to clot more readily. A renal vein thrombosis may occur. When the blood clot in the renal vein is moving into in the heart or the lungs, it can cause serious complications as a pulmonary embolism. Death can be a consequence if it is not cured in time. Most cases of renal vein thrombosis resolve without any permanent damage.

5 - PREVENTION The real key to preventing dehydration is to stay ahead of the game. Drink a minimum of two liters of water or juice each day. By very hot weather, this quantity can reach 5 liters. The drinks

should be spaced out over the course of the day rather than consumed in a short period of time. Again, avoid caffeinated beverages.

6 – OTHER EXAMPLES OF DEHYDRATION 6.1 - Dehydration and Divers When a person is dehydrated, there is a reduced volume of blood in the body. Less volume means less blood flow to the tissues. This in turn affects the body's ability to wash out waste, such as nitrogen. The result is that a diver surfaces without having off-gassed as efficiently as he would have if he had been well hydrated. The increased nitrogen remaining in the body translates into a higher risk of DCS. Blood flow to certain tissues is further compromised during dehydration by the body's own means of compensating for a low blood volume. To guarantee an adequate supply of blood to vital organs like the brain and kidneys, the body signals blood vessels supplying other parts, like skin and muscles, to clamp down, restricting flow even more. In addition to the increased risk of DCS, dehydration can adversely affect divers in other ways. Since there is a reduced volume of blood circulating through the body, the heart has to work harder and pump faster in order to meet the body's demand. This leads to decreased endurance and increased fatigue, which diminishes diving performance. Clearly, it's important to be aware of those factors that can lead to dehydration. When we are above water, the greatest force upon our bodies is gravity. When we are sitting or standing, the force of gravity causes blood to collect or pool in the legs. When we enter the water, the most significant force acting upon the body is the atmospheric pressure of the water, which serves to force the pooled blood out of the legs and into the body's general circulation. Another response of the body upon entering the water is to clamp down the blood vessels to the skin in order to minimize heat loss. This also serves to push more blood to the center of the body. Your body perceives this increased blood flow as a volume overload, and signals the kidneys to make more urine to correct it. The result is that all too familiar urge. It is important to mention that the increase in circulating blood does not offset the effects of dehydration. There is still less blood flowing through your body than there would be if you were well hydrated.

6.1 - Dehydration and Travellers (by Russell Eaton) www.airtravelsurvival.com Avoiding Blood Clots When You Travel Many travel experts say that DVT (Deep Vein Thrombosis) is not specifically linked to flying and can occur anywhere people are immobile for lengthy periods. This is indeed an argument often used by the airline industry, and is a myth that is even held by many doctors. As explained in my book 'Air Travel Survival' (www.airtravelsurvival.com) there is a wide-held misconception that a long journey on a bus, car or train is no different to a long journey on a plane if the seating is equally cramped. This is not so. In the context of blood clots, air travel is fundamentally different to any other kind of travel because of dehydration. Air travel dehydration (i.e. insufficient water in the body) is caused by not drinking sufficient water during the journey, by drinking alcohol, tea and coffee instead of water, and by super-dry cabin air. So unlike a bus, car or train journey, when you travel by air you are much more likely to suffer dehydration, and this in turn increases the danger of blood clots. This is so for four reasons:

1) - BLOOD THICKENING. Dehydration makes the blood thicker and heavier from lack of water, and therefore more likely to settle in the legs instead of circulating freely around the body. The thicker blood allows a blood clot to form and grow more quickly. 2) - VEIN CONSTRICTION. Dehydration dries the skin and constricts the surface veins. This slows down the blood circulation, also making your blood thicker, thus increasing the likelihood of a blood clot. RESOURCES: "Vascular Diseases of Acute Onset: Renal Vein Thrombosis." In The Merck Manual of Diagnosis and Therapy. 16th ed. Ed. Robert Berkow. Rahway, NJ: Merck Research Laboratories, 1992. CAUTION : The information provided herein should not be used during any medical emergency or for the diagnosis or treatment of any medical condition. A licensed physician should be consulted for diagnosis and treatment of any and all medical conditions.