What is shock?

Shock is a medical emergency that occurs when there is not enough blood flowing to vital organs, such as the brain and the heart.

When someone goes into shock, their organs may stop working properly. Mechanical support, intravenous fluids and/or drug therapy may be needed to restore function while the cause of their shock is treated.

Shock is a life-threatening condition that can have severe effects on the whole body.

What does the cardiovascular system do?

The cardiovascular system is the body’s system for moving vital nutrients, gases and hormones around. The cardiovascular system is made up of the heart, lungs and blood vessels all working together.

More about the cardiovascular system

What causes shock?

Many different things can cause shock. They can be grouped by type.

  • Hypovolaemic shock – Shock caused by a large loss of blood or body fluids, such as from a serious accident, major surgery, a burn or a medical condition that causes severe vomiting and diarrhoea.
  • Cardiogenic shock – Shock due to heart muscle damage, which can happen during a heart attack or when the heart muscle has a severe infection.
  • Septic shock – Shock caused by severe bacterial infection.
  • Anaphylactic shock – Shock caused by a severe allergic reaction.
  • Neurogenic or spinal shock – Shock caused by damage to the nervous system (brain or spinal cord).

How is shock treated?

The treatment of the particular type of shock will be focused on correcting the primary problem and treating the effects of the shock on the other body systems. In broad terms this means the following.

  • For hypovolaemic shock the patient will be given fluids to replace those lost as well as stopping the cause of the fluid loss. For example if the patient is bleeding they may require surgery to stop the cause of the bleeding.
  • For cardiogenic shock the patient will be given medications to support the heart. Some patients may require the insertion of an intra-aortic balloon pump (IABP).
  • In septic shock patients require antibiotics urgently. Additionally if the cause of the sepsis is an abscess, surgery may be required to drain the collection. A small number of patients may experience severe breathing problems and require intubation.
  • For anaphylactic shock removal of the allergen and adrenaline are urgently required.
  • Neurogenic or spinal shock is special in that direct treatment may not be possible. The patient will be closely monitored to ensure the level of shock is stabilising and other body systems are not adversely affected.

What happens in intensive care?

  • Monitoring of the heart rate, blood pressure, oxygen saturation and temperature. This will be seen on a bedside monitor.
  • An arterial line may be inserted to monitor blood pressure and to take blood samples.
  • Medication and intravenous fluids may be given via an intravenous cannula or a central venous catheter.
  • If a patient is unconscious, or cannot breathe or swallow properly, an endotracheal tube will be inserted and they will be mechanically ventilated. Some patients who need to be ventilated for more than a week or two will have a tracheostomy tube inserted. The ventilated patient will require suctioning to remove secretions from the lungs and airways.
  • If a patient is unable to eat, nutrition will be given via a nasogastric tube. This is a tube that is placed in the nose and goes down the throat into the stomach. Fluid can also be removed from the stomach via the nasogastric tube.
  • Insertion of an indwelling catheter to drain and measure urine output.
  • Chest x-rays and other tests, such as blood tests, CT scan, magnetic resonance imaging (MRI), echocardiogram, electrocardiogram (ECG) and urine tests.
  • Sequential compression devices may be put on the legs to prevent deep vein thrombosis.
  • An air mattress may be used to prevent pressure areas developing.

Publication details

Version 1.1. First published 2015. Next review 2023.


The information on this page is general in nature and cannot reflect individual patient variation. It reflects Australian intensive care practice, which may differ from that in other countries. It is intended as a supplement to the more specific information provided by the doctors and nurses caring for your loved one. ICNSW attests to the accuracy of the information contained here but takes no responsibility for how it may apply to an individual patient. Please refer to the full disclaimer.