The Quick and Dirty Guide to Shock

Any time a patient dies, shock is involved. Shock is the loss of sufficient circulation to support the vital organs. The foundation of all types of shock is hypotension, which results in hypoxia. This hypotension can result from the failure of any part of the circulatory system, and the resulting failure can be categorized in different ways depending on its severity.

The Types of Shock

The circulatory system is nothing more than a complex loop of fluid moved by a pump. Shock can result if the pump, the tubing, or the fluid is damaged or lost. Each type of shock has various causes.

Failure of the pump (heart) is known as Cardiogenic Shock. There are many ways that the heart can fail, but the most common and highly tested presentation is congestive heart failure (CHF). CHF is a chronic decrease in the heart's output due to damage to the muscle cells. Patients in cardiogenic shock will have cool, clammy, pale skin and swelling in their lower extremities. If their condition is severe, they may have low oxygen saturation.

Failure of the tubing (blood vessels) takes three primary forms:

• Anaphylactic Shock occurs when an allergen causes a massive allergic response. White blood cells release a massive amount of chemical messengers that make blood vessels vasodilate and leak fluid into the tissues inappropriately. These patients will have hot, red skin, potentially with a rash, tachycardia, and may have swelling of the face and lips. They may experience difficulty breathing and/or airway compromise from this swelling.
• Neurogenic Shock occurs when a spinal injury high in the neck cuts off the body from the sympathetic nervous system, preventing the blood vessels from vasoconstricting and the heart from increasing its rate. These patients will be bradycardic or have a normal heart rate despite being hypotensive. Physical paralysis of the legs and arms is almost always present.
• Septic Shock is the most common cause of “container failure.” Microbes in the bloodstream stimulate an aggressive immune response. If they are present in large numbers, this can result in leakage of the blood vessels and vasodilation in a reaction similar to anaphylaxis. These patients will have hot, red skin and tachycardia and usually have chills, fever, and diaphoresis symptoms.

Loss of fluid (blood) is a cause of shock known as Hypovolemic Shock. Blood can be lost in many ways, with trauma or chronic/acute bleeding into the intestines being the most common causes in the EMS setting. These patients generally have cool, pale, clammy skin and are tachycardic. They often have a history of bleeding or a recent traumatic injury.

Obstructive Shock occurs when there is a physical obstruction to blood flow within the circulatory system, impairing the heart’s ability to pump effectively. Common causes include:

• Tension Pneumothorax: Air trapped in the pleural space compresses the lungs and heart, reducing venous return to the heart and leading to hypotension and hypoxia. Signs include tracheal deviation, absent lung sounds on the affected side, and jugular venous distension.
• Cardiac Tamponade: Fluid accumulates in the pericardial sac, compressing the heart and impairing its ability to pump blood. Symptoms include muffled heart sounds, hypotension, and jugular venous distension (Beck’s triad).
• Pulmonary Embolism: A blood clot blocks a pulmonary artery, obstructing blood flow to the lungs and increasing the workload on the right ventricle. Symptoms include sudden onset dyspnea, chest pain, and signs of right-sided heart failure.

Summary of Signs and Symptoms

The Categories of Shock

Shock of any type can be placed into one of three categories based on the signs and symptoms the patient is experiencing:

1. Compensated Shock: Dysfunction of the heart, blood vessels, or blood volume can be covered up by one of the other systems. The heart increases the rate at which it pumps blood, and the blood vessels can vasoconstrict to increase pressure reaching the organs. Signs include elevated heart rate, systolic blood pressure over 90, and normal mental status. Some patients may feel palpitations, shortness of breath, fatigue, or other nonspecific symptoms.

2. Decompensated Shock: Other systems can no longer completely cover for the malfunctioning system. Hypotension is the key sign, along with organ dysfunction, indicated by altered mental status, confusion, sweating, chills, vision changes, and extreme fatigue.

3. Irreversible Shock: Death is imminent. The patient is usually unconscious, with severe hypotension and potentially decreasing heart rate.

The Treatment of Shock

The treatment of all types/categories of shock focuses on the ABCs.

• Airway: Usually compromised later during shock, requiring positive pressure ventilation and airway adjuncts.
• Breathing: Neurogenic shock can compromise breathing early due to paralysis of respiratory muscles.
• The treatment of compromised circulation is central in shock. The majority of patients in shock require IV fluids to slow or prevent them from progressing to decompensated or irreversible shock. Septic shock and hypovolemic shock always require IV fluids. Neurogenic and anaphylactic shock sometimes require them, and patients in cardiogenic shock should never be given IV fluids. 

Anaphylactic and neurogenic shock have special treatments available; anaphylaxis is managed with epinephrine, an “Epi-Pen” is a 0.3mg dose of 1mg/ml epinephrine and is the most common EMS treatment for anaphylaxis, these patients may require repeat doses of epinephrine if they continue to decompensate. Neurogenic shock is also managed with epinephrine in addition to IV fluids if hypotension is present.