Shock

Shock is a life-threatening medical emergency that occurs when your body doesn’t have enough blood flowing through it to keep your organs working properly. Without quick treatment, shock can lead to permanent organ damage or death.

Table of contents

• What is shock?
• Recognizing the symptoms
• Different types of shock
• What causes shock?
• First aid and immediate response
• Medical treatment
• Outlook and recovery

What is shock?

Shock is a critical condition that happens when your body is not getting enough blood flow. This lack of blood flow means your cells and organs do not receive enough oxygen and nutrients to function properly.^[1] Many organs can be damaged as a result, and shock requires immediate treatment because it can get worse very rapidly.^[1]

When you experience shock, you don’t have enough blood circulating through your system to keep organs and tissues functioning properly. A drop in blood pressure reduces the flow of oxygen and nutrients to vital organs such as your brain, heart and lungs.^[6] Without oxygen, your body’s systems start shutting down. If they don’t get their oxygen supply back quickly enough, the affected cells will start dying.^[7]

Effects of shock are reversible in the early stages. However, a delay in diagnosis or timely treatment can lead to irreversible changes including multiorgan failure (when several organs stop working at once) and death.^[3] As many as 1 in 5 people in shock will die from it.^[1]

Recognizing the symptoms

If you go into shock, you may experience one or more of the following symptoms. The presentation can vary, with some people having only minimal symptoms such as confusion and weakness.^[2]

Common symptoms include:

• Rapid, weak, or absent pulse
• Irregular heartbeat or rapid heartbeat
• Rapid, shallow breathing or difficulty breathing
• Pale, cool, or clammy skin
• A gray or bluish tinge to lips or fingernails
• Dizziness, lightheadedness, or fainting
• Confusion or changes in mental status or behavior, such as anxiousness or agitation
• Dilated pupils or lackluster eyes
• Profuse sweating or moist skin
• Chest pain
• Nausea or vomiting
• Thirst and dry mouth
• Low or no urine output
• Weakness or fatigue
• Being unconscious or unresponsive

A person in shock has extremely low blood pressure. Depending on the specific cause and type of shock, symptoms will vary.^[1] While the general signs for all types of shock are low blood pressure, decreased urine output, and confusion, these may not always be present.^[4]

Different types of shock

There are mainly four broad categories of shock: distributive, hypovolemic, cardiogenic, and obstructive.^[3] Each type is based on what has affected the flow of blood through your body.^[2]

Hypovolemic shock

Hypovolemic shock (also known as low volume shock) happens when you don’t have enough liquid blood volume to keep it circulating. This can result from severe blood loss, which could be internal (such as a ruptured artery or organ) or external (such as a deep wound).^[6] It may also be caused by heavy bleeding, dehydration, chronic vomiting, diarrhea, or severe burns.^[1]

Cardiogenic shock

Cardiogenic shock occurs when your heart isn’t pumping blood effectively. This can happen when something interferes with your heart’s pumping action or disrupts blood flow through your heart.^[7] Various conditions including heart attack, heart disease (such as cardiomyopathy), valve disorders, or cardiac contusion may prevent your heart from functioning properly.^[6]

Distributive shock

Distributive shock is characterized by peripheral vasodilatation (widening of blood vessels). Normally, your body automatically adjusts blood vessel width to manage blood pressure, but distributive shock means your circulatory system can’t do that properly.^[7]

Types of distributive shock include:

• Septic shock: A subset of sepsis with severe circulatory, cellular, and metabolic abnormalities resulting in tissue hypoperfusion (insufficient blood flow to tissues). It is manifested as hypotension (low blood pressure) which requires vasopressor therapy and elevated lactate levels.^[3]
• Anaphylactic shock: Caused by severe allergic reaction^[1]
• Neurogenic shock: Injury to the spine may damage the nerves that control the diameter (width) of blood vessels. The blood vessels below the spinal injury relax and expand (dilate) and cause a drop in blood pressure.^[6]

Obstructive shock

Obstructive shock occurs when blood can’t get where it needs to go. This means something is blocking circulation, such as something pressing on your heart directly or on nearby blood vessels.^[7] Conditions that can cause obstructive shock include pneumothorax (collapsed lung), blood collecting in the space between the chest wall and lung, or cardiac tamponade (when blood or fluids fill the space around the heart).^[2]

What causes shock?

Shock can be caused by any condition that reduces blood flow through your body. The wide range of causes contributes to each of the different categories of shock.^[3]

Common causes include:

• Heart problems such as heart attack or heart failure
• Low blood volume from heavy bleeding or dehydration
• Changes in blood vessels from infection or severe allergic reactions
• Certain medicines that significantly reduce heart function or blood pressure
• Slow heart rates and changes in blood vessel tone from spinal injuries
• Severe burns
• Severe infection (sepsis)
• Poisoning
• Trauma or heatstroke
• Collapsed lung (pneumothorax)

Shock is often associated with heavy external or internal bleeding from a serious injury. Toxic shock syndrome is an example of shock caused by an infection.^[1]

First aid and immediate response

Shock is a life-threatening medical emergency. If you suspect that you or someone you’re with is going into shock, call 911 (or your local emergency services number) immediately.^[7] Do not wait for milder symptoms to worsen before calling for emergency medical help.^[1]

Steps to take while waiting for help

After calling 911 or your local emergency number, take the following steps right away:^[5]

Check safety and breathing:

• Make sure you and the person are out of danger
• Check the person’s airway, breathing, and circulation
• If necessary, begin rescue breathing and CPR
• Even if the person is able to breathe on their own, continue to check rate of breathing at least every 5 minutes until help arrives^[1]
• Begin CPR if the person shows no signs of life, such as not breathing, coughing or moving^[5]

Position the person correctly:

• Lay the person down and elevate the legs and feet about 12 inches (30 centimeters), unless you think this may cause pain or further injury
• Do not elevate their head
• If raising the legs will cause pain or potential harm, leave the person lying flat^[1]
• Do not move the person if they might have a head, neck, back or spine injury (unless not moving them would put them in more danger). Also, avoid moving them if they have any visibly broken bones^[7]

Provide comfort and care:

• Keep the person still
• Give appropriate first aid for any wounds, injuries, or illnesses
• Keep the person warm and comfortable
• Loosen tight clothing
• If needed, cover the person with a blanket to prevent chilling^[5]

If the person vomits or drools:

• Turn the person or their head to one side to prevent choking if you do not suspect an injury to the spine
• If a spinal injury is suspected, “log roll” the person instead. To do this, keep the person’s head, neck, and back in line, and roll the body and head as a unit^[1]

What NOT to do

In case of shock:^[1]

• Do not give the person anything by mouth, including anything to eat or drink
• Do not move the person with a known or suspected spinal injury
• Do not wait for milder shock symptoms to worsen before calling for emergency medical help
• Do not move the person unless it’s needed^[5]

Medical treatment

At the hospital, the person will be given oxygen and intravenous fluids. Blood tests, urine tests, heart tests, and x-rays or CT scans may be performed. Other treatment will depend on the cause of shock.^[12]

The goal of shock treatment is to stabilize a person as much as possible and restore blood flow and oxygen to the organs.^[7] Treatment is based on the underlying cause and may include:

• Intravenous fluids to restore blood volume
• Vasopressors (medications that help tighten blood vessels and raise blood pressure)^[4]
• Medications to treat the specific cause (such as antibiotics for septic shock)
• Blood transfusions if needed
• Mechanical support for the heart or breathing
• Surgery if necessary to stop bleeding or repair damage

Outlook and recovery

Shock keeps organs from getting enough blood or oxygen. If shock is not treated, it can lead to permanent organ damage or even death.^[5] The risk of death can be 20 to 50 percent.^[4]

The outlook depends on several factors, including the type and cause of shock, how quickly treatment is started, and the person’s overall health. Effects of shock are reversible in the early stages, which is why immediate medical attention is critical.^[3]

Many things affect the severity and effect of shock on a person, such as their health, age, gender and personality, where on their body they are injured, and the environment.^[6]