Hypovolemic shock is due to a critical loss in the effective circulating blood volume with systemic hypoperfusion. If left untreated, hypovolemic shock can lead to ischemic injury of vital organs, leading to multi-system organ failure and death. The first step in management is to rule out other forms of shock, which will dictate treatment. Hypovolemic shock may be due to loss in total body fluids versus bleeding. When the etiology of hypovolemic shock has been determined, blood or fluid loss replacement should be carried out as soon as possible to minimize tissue ischemia.

Classes of Hemorrhage

In hypovolemic shock caused by hemorrhage, blood volume loss is categorized into 4 classes:

Class I hemorrhage:

• blood volume loss up to 15%, with
• minimal tachycardia,
• no change in blood pressure or respiratory rate. (This indicates a threshold of compensatory reserve.)

Class II hemorrhage:

• 15-20% blood volume loss with
• tachycardia (100-120),
• tachypnea (respirations 20-24),
• decreased pulse-pressure (Systolic – Diastolic, e.g., 100 – 70 = pulse-pressure of 30),
• cool + clammy skin, and
• delayed capillary refill.

Class III hemorrhage:

• 30-40% blood volume loss, with
• significant drop in BP and mental status,
• tachycardia (>120, thready),
• tachypnea,
• oliguria.

Class IV hemorrhage:

• 40% of blood volume loss with
• pulse-pressure <25 mmHg,
• marked tachycardia.

RISK FACTORS

Hypovolemic shock usually occurs as a result of either an illness, injury, or other medical condition. As a result, doctors may find it hard to predetermine specific risk factors. Any risk factors would be the risk of getting a condition that can cause the shock, such as the risk of being severely injured in a car crash or having an aneurysm rupture.

When a person is dehydrated, they lose a significant amount of water volume. People who are dehydrated can become hypovolemic if they are also losing salt, which can lead to a loss in blood volume.

For this reason, people who are dehydrated, or at risk of becoming dehydrated, should continue to drink fluids, especially if their illness is causing them to experience vomiting or diarrhea. These can lead to further loss of fluids

SIGNS AND SYMPTOMS

Early:

1. lassitude
2. fatigue
3. thirst
4. muscle cramps
5. dizziness
6. hypotension, first seen as orthostatic (from sitting to standing)

Later:

1. rapid, shallow breathing (tachypnea due to metabolic acidosis)
2. tachycardia
3. abdominal pain from mesenteric ischemia
4. chest pain from coronary ischemia
5. lethargy and confusion–from cerebral vascular ischemia
6. hypotension in all positions (not just orthostatic)

At first, your diastolic (bottom or second number) blood pressure increases. As you keep losing blood or fluids, your systolic (top or first number) blood pressure comes down.

medications

You may receive these medicines for hypovolemic shock:

• Epinephrine (Adrenalin®).
• Norepinephrine (Levophed®).
• Dopamine.
• Dobutamine (Inotrex®).

complications

Hypovolemic shock can lead to complications such as:

• Infection (if you were injured)
• Damage to your kidneys and other organs
• Death