References:
- Saunders Comprehensive Review for the NCLEX-RN Examination, 9th Edition, ISBN 978-032-37-9530-2, by Linda Anne Silvestri, Angela E. Silvestri, and Jessica Grimm (Ch. 8, pp. 88-105)
“Dehydration” occurs when fluid intake does not meet the fluid needs of the body. The treatment goal is to restore fluid volume, replace electrolytes as needed, and eliminate the cause of the imbalance.
Depending on the type of fluid and/or electrolyte loss, fluid volume deficits can be classified as:
| Type | Description | Result |
|---|---|---|
| Isotonic Dehydration; “Hypovolemia” | Fluids and electrolytes are lost equally. The most common form. Caused by inadequate intake, fluid shifting, and excessive loss of isotonic body fluids. | Decreased circulating blood volume and inadequate tissue perfusion. |
| Hypertonic Dehydration | Fluid loss is greater than electrolyte loss. Electrolyte concentration in extracellular spaces increases, which draws fluid from intracellular spaces. Caused by conditions that increase fluid loss, e.g. excessive perspiration, hyperventilation, ketoacidosis, prolonged fevers, diarrhea, early-stage kidney disease, and diabetes insipidus. | Cellular dehydration and shrinkage as intracellular fluids move into the plasma and interstitial fluid spaces. |
| Hypotonic Dehydration | Electrolyte loss is greater than fluid loss. Electrolyte concentration in intracellular spaces increases, which draws fluid into intracellular spaces. Caused by chronic illness, excessive hypotonic fluid replacement, kidney disease, and chronic malnutrition. | Cellular swelling occurs as plasma and interstitial fluid enters the cells. |
Assessment
- Cardiovascular:
- Thready, increased pulse rate; diminished peripheral pulses
- Decreased blood pressure and orthostatic hypotension
- Flat neck and hand veins in dependent positions
- Decreased central venous pressure
- Dysrhythmias
- Respiratory:
- Increased rate and depth of respirations
- Dyspnea
- Neuromuscular:
- Decreased CNS activity (lethargy to coma)
- Skeletal muscle weakness
- Fever (depending on amount of loss)
- Renal: decreased urine output
- Integumentary
- Dry skin with poor turgor (tenting)
- Dry mouth
- Gastrointestinal:
- Decreased motility and bowel sounds
- Constipation
- Decreased body weight
- Thirst
- Laboratory Findings: increased serum osmolality (concentration), hematocrit, BUN, sodium, and specific gravity
Intervention
Prevent further fluid loss. Return (increase) fluid compartment volumes to normal ranges. Oral rehydration therapy is used if possible, but IV fluid replacement if dehydration is severe. Monitor the patient’s intake and output.
- IV solutions used for different types of dehydration varies. Generally, use isotonic solutions for isotonic dehydration, hypertonic solutions for hypotonic dehydration, and vice versa.
- If possible, treat etiology using medications such as antidiarrheals, antimicrobials, antiemetics, and antipyretics to correct the cause and treat symptoms.
- Be prepared to administer medications to treat electrolyte imbalance, if present.