Dehydration (Volume & Electrolyte Depletion)

• • Water deficit without solute deficit

  • Rare in surgical patients

  • Water deficit can be estimated from serum Na concentration

  • Water deficit: ((140 - serum Na) * total body water))/140

Epidemiology

• • Occurs in patients unable to regulate water intake

  • Insensible water loss from fever

  • Tube feedings with inadequate water content

  • Diabetes insipidus

Symptoms and Signs

• • Concentrated urine

  • CNS depression

  • Lethargy

  • Coma

  • Muscle rigidity

  • Tremors

  • Spasticity

  • Seizures

Laboratory Findings

• • Hypernatremia

  • Low urine Na despite hypernatremia

• • Water deficit usually accompanied by solute (Na+) deficit

• • Physical exam

  • Serial serum Na

• • Replacement of enough water to return serum Na concentration to normal

  • Treat patient with D5W unless hypotension has developed in which case hypotonic saline should be used

Treatment Monitoring

• • Serum Na

Prognosis

• • Excellent

Prevention

• • Adequate water intake

References