Fluid Volume Deficit: causes, assessment, intervention

 Fluid Volume Deficit 

Description 

• Dehydration occurs when the fluid intake of the body is not sufficient to meet the fluid needs of the body. 
• The goal of treatment is to restore fluid volume, replace electrolytes as needed,  and eliminate the cause of the volume deficit. 

Type of fluid volume deficits

• Isotonic dehydration 
• Water and dissolved electrolytes are lost in equal proportions. 
• Known as hypovolemia, isotonic dehydration is the most common type of dehydration. 
• Isotonic dehydration results in decreased circulating blood volume and inadequate tissue perfusion. 
• Hypertonic dehydration
• Water loss exceeds electrolyte loss. 
• The clinical problems that occur result from alteration in the concentrations of specific plasma electrolytes. 
• Fluid moves from the intracellular compartment into the plasma and interstitial fluid space, causing cellular dehydration and shrinkage. 
• Hypotonic dehydration 
• Electrolyte loss exceeds water loss.
• The clinical problems that occur result from fluid shifts between compartments, causing a decrease in plasma volume. 
• Fluid moves from the plasma and interstitial fluid space into the cells,  causing a plasma volume deficit and causing the cells to swell.

Causes of fluid volume deficits 

• Isotonic dehydration 
• Inadequate intake of fluids and solutes
• Fluid shifts between compartment 
• Excessive losses of isotonic body fluids. 
• Hypertonic dehydration - conditions that increase fluid loss, such as excessive perspiration, hyperventilation, ketoacidosis, prolonged fever, diarrhoea, early-stage renal failure, and diabetes insipidus.
• Hypotonic dehydration 
• Chronic illness
• Excessive fluid replacement (hypotonic )
• Renal failure 
• Chronic malnutrition 

ASSESSMENT 

Cardiovascular 

• Thready, increased pulse rate
• Decreased blood pressure and orthostatic (postural) hypotension
• Flat neck and hand veins independent position 
• Diminished peripheral pulses

Respiratory - Increased rate and depth of respiration 

Neuromuscular 

• Decreased central nervous system activity from lethargy to coma
• Fever

Renal

• Decreased urinary output
• Increased urinary specific gravity 

Integumentary

• Dry skin
• Poor turgor, tenting present 
• Dry mouth

Gastrointestinal 

• Decreased motility and diminished bowel sounds 
• Constipation 
• Thirst
• Decreased body weight 

Hypotonic dehydration: skeletal muscle weakness 

Hypertonic dehydration 

• Hyperactive deep tendon reflexes 
• Pitting oedema 

Laboratory findings 

• Increased serum osmolality
• Increased hematocrit 
• Increased blood urea nitrogen 
• Increased serum sodium level 

Nursing intervention 

• Monitor cardiovascular, respiratory,  neuromuscular, renal, integumentary and gastrointestinal status.
• Prevent further fluid losses and increase fluid compartment volumes to normal ranges.
• Provide oral rehydration therapy if possible and intravenous (IV) fluid replacement if the dehydration is severe, monitor intake and output.
• Generally, isotonic dehydration is treated with isotonic fluid solutions, hypertonic dehydration with hypotonic fluid solutions, and hypotonic dehydration with hypertonic fluid solutions 
• Administer medication as prescribed such as antidiarrheal, antimicrobial, antiemetic, and antipyretic medication, to correct the cause and treat any symptoms. 
• Administer oxygen as prescribed. 
• Monitor electrolyte values and prepare to administer medication to treat an imbalance, if present