Dehydration

Description

• Dehydration is a deficiency in total body water (1).
• The two types of dehydration:
  • Water loss
  • Salt and water loss (combination of dehydration and hypovolemia)

Epidemiology

Dehydration is associated with increased mortality and morbidity and is prevalent in the health-care setting and in the community (1); responsible for 10% of all pediatric hospitalizations United States (2)

Incidence
In the United States, admission rate for dehydration and related diagnosis has remained stable at approximately 130 per 100,000 for the general population. Two observational studies in Europe have shown that 37–46% of patients aged >65 years presented to major hospitals with dehydration (1).

Prevalence
Several retrospective studies have sought to evaluate the prevalence of dehydration occurring after hospital admission, with current estimates of 2–3.5% of patients meeting dehydration criteria (1).

Etiology and Pathophysiology

• Body water can be lost through the skin, lungs, kidneys, and gastrointestinal tract.
• Negative fluid balance occurs when ongoing fluid losses exceed fluid intake.
• Fluid losses can be insensible (sweat, respiration), obligate (urine, stool), or abdominal (diarrhea, vomiting, osmotic diuresis in diabetic ketoacidosis).
• Negative fluid balance can lead to hypovolemia (severe intravascular volume depletion) and end-organ damage from inadequate perfusion.
• “Third spacing” of fluids can occur in patients with effusions, ascites, capillary leaks (e.g., burns), or sepsis.

Geriatric Considerations
The elderly are at increased risk as kidney function, urine concentration, thirst sensation, aldosterone secretion, release of vasopressin, and renin activity all significantly decline with age.

Genetics
Some cases of dehydration have a genetic component (diabetes), whereas others do not (gastroenteritis).

Risk Factors

• Children <5 years of age at highest risk (2)
• Elderly
• Acute or chronic illness
• Decreased cognition or mental status
• Lack of access to water
• Increased exertion in high temperature
• Taking certain medications (e.g., diuretics)

General Prevention

• Patient and/or parent education on early signs of dehydration
• Provide preferred beverages (especially in illness).
• Universal precautions (including hand hygiene)

Commonly Associated Conditions

• Hyponatremia
• Hypernatremia
• Hypokalemia
• Hyperglycemia
• Hypovolemic shock
• Renal failure
• Rhabdomyolysis
• Heat illness