Hypovolemia

Hypovolemia is a condition of decreased intravascular volume that may be caused by acute blood loss or dehydration. It is primarily a clinical diagnosis. In acute blood loss, hematocrit will be normal until there is time for fluid equilibration, which dilutes the intravascular compartment. Symptoms and signs vary according to the cause of hypovolemia.

Causes

Start with an obvious example: Someone's arm gets ripped off and blood is pouring from the shoulder stump. That person is losing blood and will soon become hypovolemic because his body won't be able to produce enough blood to make up for what he's losing.

Obvious causes of hypovolemia are :

• Internal bleeding and dehydration.
• Traumatic accidents.
• Chronic illnesses
• Ruptured ectopic pregnancies
• Low fluid intake.
• Extensive vomiting.
• Severe diarrhea

It's a common causes of dehydration.

Symptoms

• Symptoms of disorders that lead to hypovolemia (e.g., bleeding, vomiting, diarrhea, fever)
• Generalized weakness
• Dizziness (may be exaggerated by standing)

Signs

• Dry mucous membranes
• Poor skin turgor
• Tachycardia (may be blunted by beta-blockers)
• Orthostatic vital signs/tilt test; the sensitivity and specificity of orthostatic vital signs are poor. Patients who report feeling dizzy with position change should be considered to have orthostatic hypotension even if their vital signs do not meet the classic criteria. Specificity is high if pulse change > 30; unnecessary to test in the presence of symptoms or tachycardia.
• End-organ hypoperfusion (e.g., low urinary output, abnormal mental status, chest pain)
• Decreased jugular venous pressure

Treatment

The treatment of patients with hypovolemic shock often begins at an accident scene. The prehospital care team should work to prevent further injury, transport the patient to the hospital as rapidly as possible. Direct pressure should be applied to external bleeding vessels to prevent further blood loss.

Obtain professional medical care immediately. Limited measures to help include:

• Don't give fluids by mouth.
• Treat the allergic reaction.
• Have the victim lie flat with the feet elevated about 12 inches to increase circulation. But if the victim suffers from a head, neck, back or leg injury, leave the victim in the position in which they were found unless doing so poses other immediate danger.
• Keep the victim comfortable and warm.
• Treat the patient promptly.

Hospital treatment focuses on replacing blood and fluid volume. Treatment may include determination of the cause of blood loss and control of bleeding to prevent recurrence of hypovolemic shock.