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Sunday, August 6, 2017

Dehydration

  Dehydration

Definition

— Dehydration occurs when you use or lose more fluid than you take in, and your body doesn't have enough water and other fluids to carry out its normal functions. If you don't replace lost fluids, you will get dehydrated.

— Common causes of dehydration include vigorous exercise, especially in hot weather; intense diarrhea; vomiting; fever or excessive sweating. Not drinking enough water during exercise or in hot weather even if you're not exercising also may cause dehydration. Anyone may become dehydrated, but young children, older adults and people with chronic illnesses are most at risk.
— You can usually reverse mild to moderate dehydration by drinking more fluids, but severe dehydration needs immediate medical treatment. The safest approach is preventing dehydration in the first place. Keep an eye on how much fluid you lose during hot weather, illness or exercise, and drink enough liquids to replace what you've lost.

Dehydration or volume depletion is classified as mild, moderate or severe based on how much body fluid is lost. When severe, dehydration is a life-threatening emergency




























Symptoms

Mild to moderate dehydration is likely to cause:
Dry, sticky mouth
Sleepiness or tiredness — children are likely to be less active than usual
Thirst
Decreased urine output
No wet diapers for three hours for infants
Few or no tears when crying
Dry skin
Headache
Constipation
Dizziness or lightheadedness
Severe dehydration, a medical emergency, can cause:
Extreme thirst
Extreme fussiness or sleepiness in infants and children; irritability and confusion in adults
Very dry mouth, skin and mucous membranes
Little or no urination — any urine that is produced will be darker than normal
Sunken eyes
Shriveled and dry skin that lacks elasticity and doesn't "bounce back" when pinched into a fold
In infants, sunken fontanels — the soft spots on the top of a baby's head
Low blood pressure
Rapid heartbeat
Rapid breathing
No tears when crying
Fever
In the most serious cases, delirium or unconsciousness

Causes

— Dehydration occurs when there isn't enough water to replace what's lost throughout the day. Your system literally dries out. Sometimes dehydration occurs for simple reasons: You don't drink enough because you're sick or busy, or because you lack access to safe drinking water when you're traveling, hiking or camping.

Other dehydration causes include:

Diarrhea, vomiting. Severe, acute diarrhea — that is, diarrhea that comes on suddenly and violently — can cause a tremendous loss of water and electrolytes in a short amount of time. If you have vomiting along with diarrhea, you lose even more fluids and minerals. Children and infants are especially at risk. Diarrhea may be caused by a bacterial or viral infection, food sensitivity, a reaction to medications or a bowel disorder.

— Fever. In general, the higher your fever, the more dehydrated you may become. If you have a fever in addition to diarrhea and vomiting, you lose even more fluids.

— Excessive sweating. You lose water when you sweat. If you do vigorous activity and don't replace fluids as you go along, you can become dehydrated. Hot, humid weather increases the amount you sweat and the amount of fluid you lose. But you can also become dehydrated in winter if you don't replace lost fluids. Preteens and teens who participate in sports may be especially susceptible, both because of their body weight, which is generally lower than that of adults, and because they may not be experienced enough to know the warning signs of dehydration.

— Increased urination. This may be due to undiagnosed or uncontrolled diabetes. Certain medications, such as diuretics and some blood pressure medications, also can lead to dehydration, generally because they cause you to urinate or perspire more than normal.

— Drinking fluids is usually sufficient for mild dehydration. It is better to have frequent, small amounts of fluid (using a teaspoon or syringe for an infant or child) rather than trying to force large amounts of fluid at one time. Drinking too much fluid at once can bring on more vomiting.

— Electrolyte solutions or freezer pops are especially effective. These are available at pharmacies. Sport drinks contain a lot of sugar and can cause or worsen diarrhea. In infants and children, avoid using water as the primary replacement fluid.

Causes of dehydration in children's

— In most cases, volume depletion in children is from fluid losses from vomiting or diarrhea.

— Vomiting may be caused by any of the following systems or processes:

— CNS (eg, infections, space-occupying lesions)

— GI (eg, gastroenteritis, obstruction, hepatitis, liver failure, appendicitis, peritonitis, intussusceptions, volvulus, pyloric stenosis, toxicity [ingestion, overdose, drug effects])

— Endocrine (eg, diabetic
ketoacidosis [DKA], congenital adrenal hypoplasia, Addisonian crisis)

— Renal (eg, infection, pyelonephritis, renal failure, renal tubular acidosis)

— Psychiatric (eg, psychogenic vomiting) - This is not seen in infants and is rare in children compared with adults.

Risk Factors

— Infants and children. Infants and children are especially vulnerable because of their relatively small body weights and high turnover of water and electrolytes. They're also the group most likely to experience diarrhea.

— Older adults. As you age, you become more susceptible to dehydration for several reasons: Your body's ability to conserve water is reduced, your thirst sense becomes less acute, and you're less able to respond to changes in temperature. What's more, older adults, especially people in nursing homes or living alone, tend to eat less than younger people do and sometimes may forget to eat or drink altogether. Disability or neglect also may prevent them from being well nourished. These problems are compounded by chronic illnesses such as diabetes, dementia, and by the use of certain medications.

— People with chronic illnesses. Having uncontrolled or untreated diabetes puts you at high risk of dehydration. But other chronic illnesses, such as kidney disease and heart failure, also make you more likely to become dehydrated. Even having a cold or sore throat makes you more susceptible to dehydration because you're less likely to feel like eating or drinking when you're sick. A fever increases dehydration even more.

— Endurance athletes. Anyone who exercises can become dehydrated, especially in hot, humid conditions or at high altitudes. But athletes who train for and participate in ultra marathons, triathlons, mountain climbing expeditions and cycling tournaments are at particularly high risk. That's because the longer you exercise, the more difficult it is to stay hydrated. During exercise, your body may lose more water than it can absorb. With every hour you exercise, your fluid debt increases. Dehydration is also cumulative over a period of days, which means you can become dehydrated with even a moderate exercise routine if you don't drink enough to replace what you lose on a daily basis.

— People living at high altitudes. Living, working and exercising at high altitudes (generally defined as above 8,200 feet, or about 2,500 meters) can cause a number of health problems. One is dehydration, which commonly occurs when your body tries to adjust to high elevations through increased urination and more rapid breathing — the faster you breathe to maintain adequate oxygen levels in your blood, the more water vapor you exhale.

— People working or exercising outside in hot, humid weather. When it's hot and humid, your risk of dehydration and heat illness increases. That's because when the air is humid, sweat can't evaporate and cool you as quickly as it normally does, and this can lead to an increased body temperature and the need for more fluids.

Pathophysiology

— Pediatric dehydration is frequently the result of gastroenteritis, characterized by vomiting and diarrhea. However, other causes of dehydration may include poor oral intake due to diseases such as stomatitis, insensible losses due to fever, or osmotic diuresis from uncontrolled diabetes mellitus.

— Volume depletion denotes lessening of the total intravascular plasma, whereas dehydration denotes loss of plasma-free water disproportionate to the loss of sodium. The distinction is important because volume depletion can exist with or without dehydration, and dehydration can exist with or without volume depletion

— In children with dehydration, the most common underlying problem actually is volume depletion, not dehydration. Intravascular sodium levels are within the reference range, indicating that excess free water is not being lost from plasma. Rather, the entire plasma pool is contracted with solutes (mostly sodium) and solvents (mostly water) lost in proportionate quantities. This is volume depletion without dehydration. The most common cause is excessive extrinsic loss of fluids.

— Pediatric patients, especially those younger than 4 years, tend to be more susceptible to volume depletion as a result of vomiting, diarrhea, or increases in insensible water losses. Significant fluid losses may occur rapidly. The turnover of fluids and solute in infants and young children can be as much as 3 times that of adults. This is because of the following:

— Higher metabolic rates

— Increased body surface area to mass index

— Higher body water contents (Water comprises approximately 70% of body weight in infants, 65% in children, and 60% in adults.)

Sodium considerations

Hyponatremia

 Volume depletion can be concurrent with hyponatremia. This is characterized by plasma volume contraction with free water excess. An example is a child with diarrhea who has been given tap water to replete diarrheal losses. Free water is replenished, but sodium and other solutes are not.

— In hyponatremic volume depletion, the person may appear more ill clinically than fluid losses indicate. The degree of volume depletion may be clinically overestimated. Serum sodium levels less than 120 mEq/L may result in seizures. If intravascular free water excess is not corrected during volume replenishment, the shift of free water to the intracellular fluid compartment may cause cerebral edema.

Hypernatremia

— In hypernatremic volume depletion, the patient may appear less ill clinically than fluid losses indicate. The degree of volume depletion may be underestimated. Usually, at least a 10% volume deficit exists with Hypernatremia volume depletion.

— As in hyponatremia, hypernatremic volume depletion may result in serious central nervous system (CNS) effects as a result of structural changes in central neurons. However, cerebral shrinkage occurs instead of cerebral edema. This may result in intracerebral hemorrhage, seizures, coma, and death. For this reason, volume restoration must be performed gradually over 24 hours or more. Gradual restoration prevents a rapid shift of fluid across the blood-brain barrier and into the intracellular fluid compartment.

Potassium Considerations

— Potassium shifts between intracellular and extracellular fluid compartments occur more slowly than free water shifts. Serum potassium level may not reflect intracellular potassium levels.

— Although a potassium deficit is present in all patients with volume depletion, it is not usually clinically significant. However, failure to correct for a potassium deficit during volume repletion may result in clinically significant hypokalemia. Potassium should not be added to replacement fluids until adequate urine output is obtained.
Acid and base problems
— Clinicians may observe derangements of acid-base balance with volume depletion. Some degree of metabolic acidosis is common, especially in infants.

— Mechanisms include bicarbonate loss in stool and ketone production. Hypovolemia causes decreased tissue perfusion and increased lactic acid production. Decreased renal perfusion causes decreased glomerular filtration rate, which, in turn, leads to decreased hydrogen (H+) ion excretion. These factors combine to produce a metabolic acidosis.

— In most patients, acidosis is mild and easily corrected with volume restoration (as increased renal perfusion permits excretion of excess H+ ions in the urine). Administration of glucose-containing fluids further decreases ketone production

Frequency

United States

Pediatric dehydration particularly that due to gastroenteritis is a common ED complaint. Approximately 200,000 hospitalizations and 300 deaths per year are attributed to gastroenteritis each year.

International

According to the Centers for Disease Control and Prevention (CDC), for children younger than 5 years, the annual incidence of diarrheal illness is approximately 1.5 billion, while deaths are estimated between 1.5 and 2.5 million. Though these numbers are staggering, they actually represent an improvement from the early 1980s, when the death rate was approximately 5 million per year.

Mortality/Morbidity

— Morbidity varies with the degree of volume depletion and the underlying cause.

— The severely volume-depleted infant or child is at risk for death from cardiovascular collapse.

— Hyponatremia resulting from replacement of free water alone may cause seizures.

— Improper management of volume repletion may cause iatrogenic morbidity or mortality.

Complication

Dehydration can lead to serious complications, including:

— Heat injury. If you don't drink enough fluids when you're exercising vigorously and perspiring heavily, you may end up with a heat injury, ranging in severity from mild heat cramps to heat exhaustion or potentially life-threatening heatstroke.

— Swelling of the brain (cerebral edema). Sometimes, when you're getting fluids again after being dehydrated, the body tries to pull too much water back into your cells. This can cause some cells to swell and rupture. The consequences are especially grave when brain cells are affected.

— Seizures. Electrolytes — such as potassium and sodium — help carry electrical signals from cell to cell. If your electrolytes are out of balance, the normal electrical messages can become mixed up, which can lead to involuntary muscle contractions and sometimes to a loss of consciousness.

— Low blood volume shock (hypovolemic shock). This is one of the most serious, and sometimes life-threatening, complications of dehydration. It occurs when low blood volume causes a drop in blood pressure and a drop in the amount of oxygen in your body.

— Kidney failure. This potentially life-threatening problem occurs when your kidneys are no longer able to remove excess fluids and waste from your blood.

— Coma and death. When not treated promptly and appropriately, severe dehydration can be fatal.

Test and Diagnosis

— Blood tests. Blood samples may be used to check for a number of factors, such as the levels of your electrolytes — especially sodium and potassium — and how well your kidneys are working.

— Urinalysis. Tests done on your urine can help show whether you're dehydrated and to what degree.

Treatment and Drug

The only effective treatment for dehydration is to replace lost fluids and lost electrolytes.

The best approach to dehydration treatment depends on age, the severity of dehydration and its cause.

Treating dehydration in sick children

— Use an oral rehydration solution. Unless your doctor advises otherwise, use an oral rehydration solution such as Pedialyte for infants and children who have diarrhea, vomiting or fever. These solutions contain water and salts in specific proportions to replenish both fluids and electrolytes. They're also designed for easier digestion. Oral rehydration products are readily available in most drugstores, and many pharmacies carry their own brands. Begin giving fluids early in the course of an illness instead of waiting until the situation becomes urgent.

— Be sure to give enough solution. Your doctor may suggest specific amounts, depending on your child's age and degree of dehydration, but a general rule of thumb is to keep giving liquids slowly until your child's urine becomes clear in color. When your child is vomiting, try giving small amounts of solution at frequent intervals — try a spoonful or so every few minutes, for instance. If your child can't keep this down, wait 30 to 60 minutes and try again. Room temperature fluids are best.

— Continue to breast-feed. Don't stop breast-feeding when your baby is sick, but offer your baby an oral rehydration solution in a bottle as well. If you give your baby formula, try switching to one that's lactose-free until diarrhea improves — lactose can be difficult to digest during diarrhea, making diarrhea worse. Never dilute formula more than the instructions advise. Your doctor may suggest substituting an oral rehydration solution for the formula for a short time.

— Avoid certain foods and drinks. The best liquid for a sick child is an oral rehydration solution — plain water doesn't provide essential electrolytes, and although sports drinks replenish electrolytes, they replace those lost through sweating, not through diarrhea or vomiting. Milk, caffeinated beverages, fruit juices or gelatins don't relieve dehydration and may make children's diarrhea symptoms worse.

— Treating dehydration in sick adults

— Most adults with mild to moderate dehydration from diarrhea, vomiting or fever can improve their condition by drinking more water or other liquids. Certain liquids, such as fruit juices, carbonated beverages or coffee, can make diarrhea worse.

Treating dehydration in athletes of all ages

— For exercise-related dehydration, cool water is your best bet. Sports drinks containing electrolytes and a carbohydrate solution also may be helpful. There's no need for salt tablets — too much salt can lead to hypernatremic dehydration, a condition in which your body not only is short of water but also carries an excess of sodium. Avoid drinking carbonated beverages, such as colas or other types of soda.

— Treating severe dehydration

— Children and adults who are severely dehydrated should be treated by emergency personnel arriving in an ambulance or in a hospital emergency room, where they can receive salts and fluids through a vein (intravenously) rather than by mouth. Intravenous hydration provides the body with water and essential nutrients much more quickly than oral solutions do — something that's essential in life-threatening situations.

Prevention

To prevent dehydration, drink plenty of fluids and eat foods high in water such as fruits and vegetables.

Letting thirst be your guide is an adequate daily guideline for most healthy people. Fluids can be

obtained not just from water but also from other beverages and foods. But, if you're exercising, don't

wait for thirst to keep up with your fluids.

— Under certain circumstances, you may need to take in more fluids than usual:

— Illness. Start giving extra water or an oral rehydration solution at the first signs of illness — don't wait until dehydration occurs. And although they might sound appealing, traditional "clear fluids" such as ginger ale or other sodas contain too much sugar and too little sodium to replenish lost electrolytes.

— Exercise. In general, it's best to start hydrating the day before strenuous exercise. Producing lots of clear, dilute urine is a good indication that you're well hydrated. Before exercising, drink 1 to 3 cups (0.24 to 0.70 liters) of water. During the activity, replenish fluids at regular intervals and continue drinking water or other fluids after you're finished.

— Keep in mind that drinking too much not only can cause bloating and discomfort but also may lead to a potentially fatal condition in which your blood sodium becomes too low (hyponatremia). This occurs when you drink more fluids than you lose through sweating.

— Environment. You need to drink additional water in hot or humid weather to help lower your body temperature and to replace what you lose through sweating. You may also need extra water in cold weather if you sweat while wearing insulated clothing. Heated, indoor air can cause your skin to lose moisture, increasing your daily fluid requirements. And altitudes greater than 8,200 feet (2,500 meters) also can affect how much water your body needs. If dehydration occurs when you're exercising in hot weather, get into a shady area, recline, and start drinking water or a sports drink. Young athletes should be encouraged to let their coaches know if they're having symptoms of dehydration.

Home Remedies for Dehydration


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