What Is Shock?

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Shock is a medical emergency that occurs when the tissues in your body can't get enough blood, oxygen, and nutrients. Loss of consciousness may be the first noticeable effect and shock can worsen rapidly, potentially causing permanent organ damage or death. There are several types of shock, as well as several causes, including traumatic blood loss and sudden heart failure. Emergency medical professionals can identify shock very quickly, and the condition requires urgent treatment.

Types of Shock

There are four types of shock:

  • Hypovolemic
  • Distributive
  • Cardiogenic
  • Obstructive

It's also possible to have a combination of these. For example, septic shock is an infection that results in dehydration (hypovolemic) and blood vessel dilation (distributive). Trauma to the chest often results in a tension pneumothorax (obstructive) and severe bleeding (hypovolemic).

Hypovolemic

Hypovolemic shock develops when there is a deficient amount of fluid and blood flowing in the blood vessels.

This type of shock is usually characterized by a rapid, weak pulse and low blood pressure. Sometimes, hypovolemic shock is associated with pale, cold skin.

Distributive

Distributive shock usually occurs when blood vessels dilate (widen). Neurogenic shock, sepsis, and anaphylaxis can produce this physical reaction.

Distributive shock is characterized by low blood pressure, and possibly redness or swelling of the limbs or any part of the body.

Cardiogenic

Cardiogenic shock can develop when the heart cannot pump as it should. A heart attack is a sudden event in which heart muscles cannot function. Heart failure, a chronic process, makes it difficult for the heart to pump and predisposes one to shock of any type.

The result of cardiogenic shock is that the body doesn't get the blood that it needs. Your medical team can identify cardiogenic shock by assessing your heart rhythm, pulse, blood pressure, and oxygen levels (such as with a pulse oximeter).

Obstructive

Obstructive shock occurs when the flow of blood is blocked. Certain types of trauma or medical emergencies can physically prevent blood from flowing in the heart and/or blood vessels.

This type of shock is more difficult to diagnose, often involving imaging tests (such as a chest X-ray) or interventional diagnostic tests.

Shock Symptoms

There are a number of signs and symptoms of shock, some of which depend on the cause and the stage of shock.

Some of them may seem to be contradictory. For example, shock can make a person's heart race, producing a rapid pulse, or it can make heart rate and pulse slow down.

Shock is a true medical emergency. If you have any concern that you or someone else is could be experiencing shock, call 911 immediately.

Common symptoms of shock include:

  • Trouble breathing
  • Weak pulse
  • Rapid heart rate, which can later slow down
  • Confusion
  • Loss of consciousness
  • Collapsing
  • Pale, clammy, and/or sweaty skin
  • Cold hands or body

Associated Symptoms

Shock can be accompanied by other signs and symptoms as well. These are not part of the body's shock reaction, but they give your medical team a clue as to the cause, which can help direct the treatment plan.

  • Fever can occur with sepsis, a severe blood infection
  • Skin redness, rash, and swelling are signs of an anaphylactic (allergic) reaction
  • Pupil dilation (unusually large pupils) is a sign of brain damage
  • Cough can accompany lung failure

Causes

Shock occurs when there is severely diminished blood flow (hypoperfusion) to the body's tissues and organs. It is caused by major medical events.

Shock can begin suddenly, such as immediately after a serious injury involving rapid blood loss or with an acute cardiac episode. It can also develop gradually, such as with a chronic illness that prevents blood from traveling through the body as it should.

Situations that cause shock include:

  • Sepsis
  • Dehydration: Lack of body fluid
  • Hemorrhage: Bleeding within the body or blood loss from the body
  • Anaphylaxis: A major, possibly fatal, allergic reaction
  • Neurogenic problems: Difficulty controlling blood pressure and pulse due to brain and/or spine damage
  • Heart attack: A sudden disruption in the heart function and heartbeat
  • Pericardial tamponade: Physical pressure around the heart muscle
  • Pneumothorax: A collapsed lung

During major physical stress, such as that caused by sepsis, neurological damage, and anaphylaxis, the body cannot maintain normal control over blood pressure and pulse. This is described as hemodynamic instability, and it interferes with blood flow to the tissues.

Being severely dehydrated or having an infection or heart failure can make you more prone to shock. That said, shock can affect anyone at any age.

Diagnosis

Shock is diagnosed based on a person's symptoms and vital signs. Paramedics can quickly assess heart rate by checking someone's pulse and can assess blood pressure based on the intensity of the pulse and a blood pressure reading. Paramedics also assess breathing rate.

If the body is able to maintain normal blood pressure as a shock is developing, it is described as compensated shock. Compensated shock rapidly worsens if untreated. As blood pressure begins to fall, the situation is defined as uncompensated shock. Uncompensated shock can be fatal.

Once you are stabilized, your medical team will determine which type of shock you have.

Treatment

Shock must be treated urgently. Your medical team will likely start treatment in the ambulance if you are being transported to the hospital. If you develop shock while already in the hospital, treatment will be initiated right away.

Treatment strategies used during shock include:

  • Intravenous (IV fluids)
  • Maintaining optimal body temperature (warming with a blanket or using medication to lower a fever)
  • Medications to raise blood pressure or slow pulse if necessary
  • Nasal oxygen
  • Support for breathing

You may not need all of these treatments right away, but your medical team will closely monitor you so they can start them if and when needed.

Treating the Underlying Cause

The cause of shock must also be treated medically or surgically. For example:

  • You may need antibiotics to manage an infection.
  • Surgical repair of a wound may be necessary.
  • A blood transfusion may be needed to replace blood lost during extensive bleeding.
  • If you have fluid compressing your lungs, you may need to have thoracentesis—an interventional procedure that removes fluid from around the lungs.

The outcome after an episode of shock can vary. Recovery can take months and generally involves rehabilitation.

A Word From Verywell

Shock is a major medical event. After recovering from the life-threatening stage, you may have residual effects, such as fatigue, muscle weakness, or weight loss. Keep your doctors abreast of what you are experiencing and stick with any continued therapies recommended for the best chance at recovery.

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