What Is Distributive Shock?

Overview

Distributive shock, also referred to as vasodilatory shock, is a life-threatening condition where the blood vessels relax and loosen, resulting in an inadequate amount of oxygen in tissues and organs. If not treated quickly and adequately, this condition is associated with a high death rate. 

Similar to when you go to the optician and they “dilate” your eyes, vasodilation is a term that describes your blood vessels widening, becoming flaccid. This severely drops blood pressure and prevents adequate flow throughout the body. This can result in fluid leaking into the surrounding tissue and organ failure.

Distributive shock is one of the four classifications of shock and is the most common type. Shock is an overarching term for circulatory failure and is associated with a high sickness and death rate. The four types of shock are distributive, cardiogenic, hypovolemic, and obstructive.¹ 

Types of distributive shock

There are three types of distributive shock that are categorised based on the cause of vasodilation.

• Septic shock is due to a bacterial infection that results in sepsis, the body’s extreme response to an infection. The Sepsis Alliance reports that one third of those who develop sepsis die. They also report that the chance of sepsis developing into severe sepsis and septic shock rises by 4%-9% every hour left untreated.
• Anaphylactic shock occurs in response to an allergic reaction. This one is most commonly known as it is common for people with severe allergies. In the United States, it has been reported that 1.6%-5.1% of the population has experienced anaphylaxis. However, the fatality rate is reported to be 0.3%.
• Neurogenic shock is a result of a spinal cord injury. It has been reported that the incidence of neurogenic shock from a spinal cord injury ranges from 19%-31%.²

Causes of distributive shock

The causes of distributive shock are dependent on the type. Septic and neurogenic shock come secondary to their initial cause. Septic shock follows sepsis if left untreated long enough and neurogenic shock follows a trauma that initially damages the spinal cord. 

Listed below are the main causes of each type of distributive shock as well as some non-specific causes.

Anaphylactic shock:

• Severe allergic reaction
• Asthma

Septic shock:

• Bacterial infection
• Parasites
• Viral infection, but this is rare

Neurogenic shock:

• Trauma with the cervical (neck) spinal cord such as a car accident or fall

Other non-specific causes of distributive shock:

• Adrenal insufficiency - seen in patients who take chronic steroids and suddenly stop taking the medication
• Capillary leak syndrome - due to low blood albumin
• Drug overdose and toxicity - some drugs can cause vasodilation if taken in too high amounts or incorrectly

Signs and symptoms of distributive shock

A characteristic trait of all types of distributive shock is dangerously low blood pressure, referred to as hypotension. Hypotension can cause disruption of important organs such as the heart, lungs, and kidneys from inadequate blood flow and oxygen levels. Other symptoms can be dependent on the type of shock.

Symptoms of septic shock include:³

• Abnormally high heart rate
• Disorientation
• Fast breathing
• Weakness
• Shortness of breath
• Chills
• Low body temperature

Symptoms of anaphylactic shock include:

• Lightheadedness
• Trouble breathing
• Wheezing
• Hives
• Fainting
• Swelling of facial features

Symptoms of neurogenic shock include:

• Abnormally slow heart rate (bradycardia)
• Unable to regulate body temperature
• Disorientation

Management and treatment for distributive shock

The treatment of distributive shock is dependent on the type. Overall, most patients can benefit from intravenous (IV) fluids given over an extended period to raise their blood pressure. The goal of treating distributive shock is to have adequate tissue perfusion (blood flow).

In the case of septic shock, the first course of treatment is the administration of norepinephrine. This drug will help to narrow the blood vessels without harming the heart. You may also be prescribed medications to fight the initial infection that caused the sepsis.³

In the case of anaphylactic shock, the first course of treatment is the administration of epinephrine. Similar to norepinephrine, this drug helps narrow the blood vessels without harming the heart but also helps support breathing.

Other treatments can include:

• Antihistamines
• Steroids
• Fluids
• Albuterol

In the case of neurogenic shock, the first course of treatment is to stabilise the neck and spinal cord to prevent further injury. This type of shock is due to an injury, unlike the others. Fluids will be given and medication to treat the slow heart rate may be administered. 

If the patient is unresponsive to the fluids and vasopressors, this could be attributed to adrenal insufficiency. In this case, a steroid treatment such as hydrocortisone can be administered.

Diagnosis

Distributive shock is often diagnosed in the emergency department of the hospital, as symptoms can come on and worsen rapidly. The evaluation begins by evaluating the airway, breathing, and blood pressure. The doctor may conduct tests to look at the heart and lungs, and to look at the state of the organs and rule out other similarly-presenting conditions. Once ruled out, the doctor can conduct an ultrasound to look at the heart, lungs, and abdomen.

Your doctor will also ask you or someone accompanying you if you have any severe allergies or what kind of medication you are taking. This can help quickly identify potential triggers of your symptoms.

FAQs

How can I prevent distributive shock?

To prevent distributive shock, it is important to be aware of your surroundings. Make sure to maintain proper hygiene to avoid bacterial or viral infections to prevent sepsis. Make note of your allergies and take proper precautions if you know that you are severely allergic to something. If possible, it would be beneficial to carry around an adrenaline injector for fast action should you accidentally come in contact with your allergen. To prevent neurogenic shock, it is important to not put yourself in dangerous situations, or take proper precautions when you do.  

How common is distributive shock?

Distributive shock is the most common type of shock. Septic shock is the most common distributive shock seen in emergency rooms. It was reported that those admitted to the hospital with severe sepsis have a mortality rate higher than 50%.

Who is at risk of distributive shock?

Distributive shock is a fairly common condition. Those with severe allergies are at high risk of anaphylactic shock if they are not careful about preventing contact with their allergen. 

Summary

Distributive shock is a condition where blood vessels expand and leak fluid into the surrounding tissues in response to a trigger. It is the most common type of shock. 

Within this condition, there are three subcategories dependent on the cause: septic, anaphylactic, and neurogenic shock. Septic shock is due to a bacterial infection and is what follows sepsis. Anaphylactic shock, one of the more commonly known types of distributive shock, is in response to a severe allergic reaction. Neurogenic shock is from an injury to the spinal cord, such as from a car accident or fall. All have the characteristic of low blood pressure, which leads to further organ damage. 

Initial general treatment for all types includes IV fluids to increase blood pressure and oxygen administration. Other treatments include the administration of medication that can help constrict the blood vessels and regulate the heart rate. It is important to be aware of potential triggers that could develop into shock and always visit the doctor if you believe you are experiencing any severe symptoms.