Hypovolemic Shock

Rapid administration of an isotonic crystalloid solution such as a normal saline or lactated Ringer solution is the gold standard for treating hypovolemic shock. A fluid bolus within the first hour of onset offers the best chances of recovery. Fluid administration prevents hypotension and refractory shock. Hypovolemic shock may cause acid-base imbalances and metabolic disorders.

There are two types of hypovolemic shock: nonhemorrhagic and hemorrhagic.

Nonhemorrhagic Hypovolemic Shock

Dehydration is a loss of water and electrolytes that causes an increase or decrease of solutes in the blood. Nonhemorrhagic fluid loss can be due to gastrointestinal losses, renal losses, or capillary leaks. 

The clinical signs and symptoms determine the severity. Severity guides the patient’s treatment. The percentage of fluid loss can be estimated by assessing the patient’s general appearance, presence or absence of tears, the moisture of the mucous membranes, skin elasticity, respiratory rate and depth, heart rate, blood pressure, capillary refill time, urine output, and mental status.

The Severity of Dehydration Based on Clinical Signs and Symptoms

The Severity of Dehydration Based on Clinical Signs and Symptoms

A 5% volume loss represents a loss of about 50 mL/kg and is clinically significant. Therefore, correcting with only a 20 mL/kg IV bolus of crystalloid solution is likely inadequate. After restoring perfusion, the team must restore the rest of the fluid deficit over the next 24 to 48 hours.

Hemorrhagic Hypovolemic Shock

In hemorrhagic hypovolemic shock, the patient’s volume losses are estimated based on clinical findings. Blood loss can be mild, moderate, or severe. An acute blood loss of more than 30% (more than 25 mL/kg) is classified as moderate to severe.

Systemic Responses to Blood Loss

Systemic Responses to Blood Loss

Hemorrhagic blood loss requires a rapid infusion of isotonic crystalloid of 20 mL/kg. It may be necessary to give up to 3 boluses to replace a 25% blood volume loss (3 mL of crystalloid solution is required to replace 1 mL of blood loss). 

For hemorrhagic shock following trauma, the provider should consider administering blood products instead of crystalloid IV fluids. Transfusion with RBCs should be delivered in 10 mL/kg boluses and whole blood at 20 mL/kg. Warming the blood before transfusion prevents adverse reactions.

The clinician should request the following ancillary tests: 

• Complete blood count 
• Blood-typing and cross-matching
• Arterial blood gases
• Electrolyte panel
• Glucose
• Ionized calcium 
• Serum or plasma lactate concentration
• Imaging modalities to locate the source of bleeding

Medical Treatment for Hypovolemic Hemorrhagic Shock

Typically, vasoactive agents will not be administered for the management of hypovolemic shock. Vasoactive agents such as epinephrine are reserved for children that deteriorate even after the initial therapies are given or if the child presents with signs and symptoms of cardiopulmonary failure or impending cardiac arrest.

Acid-Base Balance

Tachypnea is a result of compensatory respiratory alkalosis caused by hypovolemic shock early in its course. The resulting alkalosis is not enough to correct the acidosis produced in hypovolemic shock. 

If left to progress, acidosis worsens as the child fatigues from the increased respiratory effort. These signs are indicative of poor management of hemorrhagic shock. Sodium bicarbonate should only be considered for gastrointestinal and renal losses.