Dehydration

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Original Editors - Jordan Dellamano & Daniel McCoy  from Bellarmine University's Pathophysiology of Complex Patient Problems project.

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Definition/Description

Dehydration occurs when you lose more fluid than you take in, and your body doesn't have enough water and other fluids to carry out its normal functions. Young children, older adults, the ill and chronically ill are especially susceptible.

Dehydration symptoms generally become noticeable after 2% of one's normal water volume has been lost.

You can usually reverse mild to moderate dehydration by drinking more fluids, but severe dehydration needs immediate medical treatment.  

There are three main types of dehydration: hypotonic (primarily a loss of electrolytes), hypertonic (primarily loss of water), and isotonic (equal loss of water and electrolytes).  The most commonly seen in humans is isotonic.

Prevalence

Dehydration is most commonly found in the elderly, infants, people with fever, athletes, people living in high altitudes, and the chronically ill.  Children are most affected in the first two years of their life and 2.2 million will die in this year. 

Characteristics/Clinical Presentation 

Mild Dehydration	Moderate Dehydration	Severe Dehydration
flushed face extreme thirst dry, warm skin cannot pass urine, or dark and yellow dizziness made worse in standing weakness cramping in arms and legs crying with few or no tears sleepy or irritable unwell headaches dry mout, dry tongue; with thick saliva	low BP fainting severe muscle contractions in arms, legs, stomach, and back convulsions bloated stomach heart failure sunken fontanelle (soft spot on infant's head) sunken dry eyes skin loses firmness and looks wrinkled lack of elasticity of skin rapid and deep breathing fast, weak pulse	effects are more pronounced hypovolaemic shock death may occur

• At about 5% to 6% water loss, one may become groggy or sleepy, experience headaches or nausea, and may feel parasthesias.
• With 10% to 15% fluid loss, muscles may become spastic, skin may shrivel and wrinkle, vision may dim, urination will be greatly reduced and may become painful, and delirium may begin.
• Losses of greater than 15% are usually fatal.

Associated Co-morbidities

Physiological factors

Aged >85.

Female,

Reduced total body water.

Reduced body weight.

Altered renal function.

Reduced sensation of thirst.

Altered taste sensation and reduced appetite.

Functional factors

Reduced mobility.

Communication difficulties.

Reduced oral intake <l,500ml/day.

Poor manual dexterity.

Self-neglect,

Somnolence,

Fear of incontinence.

Fear of nocturia.

Environmental factors

Hospitalisation,

Insufficient caregivers/understaffing.

Untrained carers.

Hot weather.

Overheated environment.

Isolation,

Disease-related factors

Alzheimer's disease.

Increased fluid loss, for example, diarrhoea,

vomiting, fever, polyuria, wounds.

Reduced fluid intake, for example, anorexia,

dysphagia, depression, dementia, confusion,

Latrogenic factors

Laxatives, diuretics, lithium.

Dietary or fluid restrictions,

Polypharmacy: more than four medications.

Nil by mouth, for example, fasting for procedures

Medications

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Diagnostic Tests/Lab Tests/Lab Values

A Primary Care Physician can often diagnose dehydration based off of a person's physical signs and symptoms such as skin tugor, color of urine, and sunken eyes.

To help confirm a diagnosis of dehydration and to what degree, a blood test and urinalysis may be performed.

Blood test: can check levels of electrolytes like sodium and potassium, and how well one's kidneys are working.

Urinalysis: can show whether a person is dehydrated and to what degree.

Etiology/Causes

External/stress-related causes:

• Prolonged physical activity without consuming adequate water, especially in a hot environment
  
• Prolonged exposure to dry air
  
• Survival situations, especially desert survival conditions
  
• Blood loss or hypotension due to physical trauma
  
• Diarrhea
  
• Hyperthermia
  
• Shock
  
• Vomiting
  
  

Infectious Diseases:

• Cholera
• Gastroenteritis
• Shigellosis
• Yellow fever
  
  

Malnutrition:

• Electrolyte imbalance

1. Hypernatremia
2. Hyponatremia

• Excessive alcohol consumption
• Fasting
• Patient refusal of nutrition and hydration

Other:

• Severe hyperglycemia, as seen in Diabetes Mellitus

Systemic Involvement

Dehydration can cause serious systemic involvement, especially severe dehydration. Some problems that may occur include: heat injury, cerebral edema, seizures, hypovolemic shock, kidney failure, coma and death.

Heat injury: Heat injury occurs most often in individuals who exercise vigorously and sweat excessively. Severity of heat injury ranges from mild heat cramps to heat exhaustion to a more life-threatening heat stroke.

Cerebral edema: This condition, also called swelling of the brain, occurs when one is trying to rehydrate. Cerebral edema occurs when one's body tries to pull too much water back into its cells causing them to swell and rupture.

Seizures: Seizures occur when one's electrolytes are out of balance and send mixed signals between cells. This can lead to involuntary muscle contractions and loss of consciousness.

Hypovolemic shock: This is one of the more serious conditions that can come from dehydration. This may happen when a low blood volume causes the person's blood pressure to drop along with a drop in the amount of oxygen in the body.

Kidney failure: This potentially life-threatening problem happens when a person's kidneys are no longer able to remove excess fluids and waste from the body.

Coma and death: If severe dehydration isn't treated quickly, it can be fatal.

Medical Management (current best evidence)

The treatment of dehydration is best corrected with replenishment of necessary water and electrolytes. For minor dehydration, consumption of a sports drink, like Gatorade or Powerade, will be sufficient in rehydrating the body. For more severe cases, one needs medical attention in which fluids are administered through an IV.

Physical Therapy Management (current best evidence)

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Alternative/Holistic Management (current best evidence)

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Differential Diagnosis

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Case Reports/ Case Studies

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Resources

Dehydration: best practice in the care home

Dehydration Fact Sheet

Dehydration and the Flu

Dehydration in the Elderly

Recent Related Research (from Pubmed)

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References

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