Hypovolemia | |
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Other names | Oligemia, hypovolaemia, oligaemia, hypovolæmia, volume depletion |
A diagram showing the formation of interstitial fluid from the bloodstream | |
Specialty | Emergency medicine |
Symptoms | Headache, fatigue, nausea, profuse sweating, dizziness |
Complications | Hypovolemic shock |
Differential diagnosis | Dehydration |
Hypovolemia, also known as volume depletion or volume contraction, is a state of abnormally low extracellular fluid in the body.[1] This may be due to either a loss of both salt and water or a decrease in blood volume.[2][3] Hypovolemia refers to the loss of extracellular fluid and should not be confused with dehydration.[4]
Hypovolemia is caused by a variety of events, but these can be simplified into two categories: those that are associated with kidney function and those that are not.[5] The signs and symptoms of hypovolemia worsen as the amount of fluid lost increases.[6] Immediately or shortly after mild fluid loss (from blood donation, diarrhea, vomiting, bleeding from trauma, etc.), one may experience headache, fatigue, weakness, dizziness, or thirst. Untreated hypovolemia or excessive and rapid losses of volume may lead to hypovolemic shock.[7] Signs and symptoms of hypovolemic shock include increased heart rate, low blood pressure, pale or cold skin, and altered mental status. When these signs are seen, immediate action should be taken to restore the lost volume.
The term hypovolemia refers collectively to two distinct disorders: (1) volume depletion, which describes the loss of sodium from the extracellular space (i.e., intravascular and interstitial fluid) that occurs during gastrointestinal hemorrhage, vomiting, diarrhea, and diuresis; and (2) dehydration, which refers to the loss of intracellular water (and total body water) that ultimately causes cellular desiccation and elevates the plasma sodium concentration and osmolality.