- A state of negative fluid balance; strictly defined as free water deficiency
- The two types of dehydration:
- Water loss
- Salt and water loss (combination of dehydration and hypovolemia)
- Responsible for 10% of all pediatric hospitalizations in the United States
- Gastroenteritis, one of its leading causes, accounts to 13/1,000 children <5 years of age annually in the United States.
- More than half a million hospital admissions annually in the United States for dehydration
- Of hospitalized older persons, 8% are dehydrated (1).
- Worldwide, ~3 to 5 billion cases of acute gastroenteritis occur each year in children <5 years of age, resulting in nearly 2 million deaths.
Etiology and Pathophysiology
- Negative fluid balance occurs when ongoing fluid losses exceed fluid intake.
- Fluid losses can be insensible (sweat, respiration), obligate (urine, stool), or abnormal (diarrhea, vomiting, osmotic diuresis in diabetic ketoacidosis).
- Negative fluid balance can lead to severe intravascular volume depletion (hypovolemia) and end-organ damage from inadequate perfusion.
- The elderly are at increased risk as kidney function, urine concentration, thirst sensation, aldosterone secretion, release of vasopressin, and renin activity are all significantly lowered with age.
- Decreased intake
- Increased output: vomiting, diarrheal illnesses, sweating, frequent urination
- “Third spacing” of fluids: effusions, ascites, capillary leaks from burns, or sepsis
Some causes of dehydration have a genetic component (diabetes), whereas others do not (gastroenteritis).
- Children <5 years of age at highest risk
- Decreased cognition
- Lack of access to water such as in critically sick intubated patients
- Increased exertion in high temperature
- Patient/parent education on early signs of dehydration
- Universal precautions (including hand hygiene)
Systematically assessing risk factors helps with early prevention and management of dehydration in the elderly, especially those in long-term care facilities.
|General condition: infants||Thirsty, alert, restless||Lethargic/drowsy||Limp, cold, cyanotic extremities, may be comatose|
|General condition: older children||Thirsty, alert, restless||Alert, postural dizziness||Apprehensive, cold, cyanotic extremities, muscle cramps|
|Quality of radial pulse||Normal||Thready/weak||Feeble or impalpable|
|Quality of respiration||Normal||Deep||Deep and rapid/tachypnea|
|BP||Normal||Normal to low||Low (shock)|
|Skin turgor||Normal skin turgor||Reduced skin turgor, cool skin||Skin tenting, cool, mottled, acrocyanotic skin|
|Mucous membranes||Moist||Dry||Very dry|
|Urine output||Normal||Reduced||None passed in many hours|
|Anterior fontanelle||Normal||Sunken||Markedly sunken|
Commonly Associated Conditions
- Hypovolemic shock
- Renal failure
- Heat illness
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