Septic shock
Introduction
Septic shock is a life-threatening condition that happens when your blood pressure drops to a dangerously low level.
The fall in blood pressure is a reaction to a serious infection that develops in the blood. This causes a response from the body known as sepsis. If sepsis is not treated, it will lead to septic shock.
Symptoms of septic shock include cold skin and an increased heartbeat.
If you have septic shock, you will usually be admitted to an intensive care unit (ICU) so that your body’s functions and organs can be supported while the infection is treated. Read more about treating septic shock.
Sepsis
Sepsis occurs when an infection spreads through the blood, causing symptoms to develop throughout the whole body.
The term sepsis is sometimes used to refer to blood poisoning (septicaemia). This is not entirely accurate because sepsis is not just limited to the blood but affects the whole body, including the organs. Sepsis is usually caused by a bacterial infection, but it can sometimes be caused by viral or fungal infections.
The effects of sepsis
Sepsis can affect many of the vital processes of the body including:
- blood pressure
- breathing
- organ function
Sepsis can result in septic shock if it is not treated immediately.
Survival rate
Septic shock is very serious and the death rate is high. Over half of all people with septic shock will die from it.
If you have septic shock, your chance of survival will depend on:
- the cause of infection
- the number of organs that have failed
- how soon treatment is started
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Symptoms
If a serious bacterial infection develops in your blood, your body's immune system will react, causing symptoms throughout your body. This is known as sepsis.
If sepsis is not treated, septic shock may occur. This will cause your blood pressure to fall dramatically. The drop in blood pressure will affect the oxygen supply to major organs, including:
- heart
- brain
- kidneys
- liver
- intestines
The symptoms of sepsis
Most people with sepsis will have a high temperature (fever) of 38C (100.4F) or above. In some cases, you may have a low body temperature (hypothermia).
As well as a change in temperature, the initial symptoms of sepsis include:
- feeling weak
- chills that cause shaking
- a rapid heart rate
- rapid breathing
There may be other symptoms, depending on the type of infection you have and where in your body it started. Read more about the causes of septic shock.
As sepsis develops, you may feel restless, confused or lacking in energy. Other symptoms include:
- warm, flushed skin
- a very rapid heart rate
- a very rapid breathing rate
- urinating less and in smaller quantities than usual
- decreased blood pressure, particularly when standing
Severe sepsis
In the latter stages of sepsis, the symptoms become particularly severe. They include:
- a fall in body temperature below 36C (96.8F)
- severe shortness of breath
- skin that is cool and blotchy
- skin may turn blue due to reduced blood flow
- confusion or anxiety
- weakness
- unconsciousness
The reduced flow of blood may cause the tissue of vital organs, such as the liver or intestines, to die.
Septic shock
If the symptoms of sepsis are not treated or controlled effectively, it will lead to septic shock.
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Causes
Septic shock is a type of severe sepsis. This is caused by an infection. Your body responds to the infection with widespread inflammation, which causes the symptoms of sepsis.
Bacterial infection
Sepsis is often caused by a bacterial infection. Fungi, such as candida, and viruses can also sometimes lead to sepsis, although this is rare.
Bacterial infections that cause sepsis often develop while a person is in hospital. Infections that most commonly cause sepsis originate in the:
- lungs - infections affecting your lungs (lower respiratory tract infections), such as pneumonia or bronchitis, may be the cause of septic shock in a quarter of people
- urinary tract (the tubes that carry urine from the kidneys to the outside of the body) - urinary tract infections may be the cause of septic shock in a quarter of people.
- digestive system
- reproductive system
How the infection develops
Bacterial infections occur if harmful bacteria enter the blood through a cut in the skin. Infections can also develop in your body’s organs.
If you are healthy, your immune system (the body's natural defence system) will kill any bacteria that get into your blood. However, if your immune system is lowered or not working properly, it may become overloaded and unable to fight off infection.
If your immune system fails in this way, the bacteria in your blood will multiply, releasing poisonous chemicals (toxins) into your bloodstream. If this happens, the symptoms of sepsis may develop.
The toxins produced by bacteria can severely damage the body’s cells. They attack the walls of the small blood vessels, causing them to leak fluid from the blood into the surrounding tissues. This is called acute circulatory failure or shock. It significantly lowers your blood pressure.
The fall in blood pressure means the heart cannot supply the body’s vital organs with oxygen-rich blood. Without an oxygen-rich blood supply, the brain, heart, kidneys and liver cannot function properly.
The fall in blood pressure, which does not respond to treatment with fluids, is what distinguishes septic shock from severe sepsis.
Other conditions caused by sepsis
As well as septic shock, sepsis can also lead to several other serious, life-threatening health conditions, which may then lead to septic shock. These include:
- the lungs not being able to provide oxygen to the rest of the body (acute respiratory distress syndrome)
- proteins that control blood clotting becoming abnormally active (disseminated intravascular coagulation)
- a severe infection of the bloodstream called meningococcemia
- adrenal gland failure due to bleeding into the adrenal gland as a result of severe infection (Waterhouse-Friderichsen syndrome) - the adrenal glands are located above the kidneys, inside the back of the abdominal wall
People who are at risk
People who are particularly at risk of developing sepsis and septic shock include:
- newborn babies
- elderly people
- pregnant women
- people with long-term health conditions
- people with lowered immune systems, such as people with HIV or AIDS or people receiving chemotherapy
These groups are most at risk because their immune systems are weaker. This reduces their ability to fight serious infections, increasing the risk of sepsis.
Risk factors
Health conditions that increase the risk of sepsis and septic shock include:
- diabetes
- cirrhosis of the liver
- HIV or AIDS
- long-term kidney failure
- conditions that affect your heart and lungs
- some types of cancer in the bone marrow and white blood cells (leukaemia)
Other potential risk factors for sepsis and septic shock are:
- using medical devices that are inserted into the body, such as catheters, which may introduce bacteria to the body
- having an artificial joint or heart valve fitted
- major surgery, such as bowel surgery, which increases the risk of bacteria entering the body
- major injuries, such as burns covering a large part of your body
- being in hospital for a long time
- injecting recreational drugs, as syringes that are not sterile can introduce bacteria to your bloodstream
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Diagnosis
Septic shock is a type of severe sepsis and is treated as a medical emergency.
Sepsis may be suspected if you have an infection and you suddenly develop symptoms such as a very high or very low temperature, and a rapid heart rate or breathing rate. Read more about the symptoms of septic shock.
Several different tests can be used to diagnose the infection that causes sepsis.
Blood tests
To confirm a suspected diagnosis of sepsis, blood tests will be used to look for:
- bacteria in the bloodstream
- a reduced level of oxygen
- an abnormal number of infection-fighting white blood cells
- an abnormally high level of waste products
- a low amount of blood clotting cells (platelets)
Other tests
As well as blood tests, samples of other substances may be sent to a laboratory to be tested for bacteria. Examples include:
- urine
- phlegm from the lungs
- tissue samples from wounds
- the fluid that surrounds your brain and spinal cord, which can be taken during a lumbar puncture
This will help identify the infection that is causing sepsis.
If you have a catheter (a tube that allows urine to pass out of your body) and it may be the source of the bacterial infection, it may be removed. The tip can be cut off and tested for bacteria.
Monitoring your condition
If you have sepsis, you will be admitted to hospital immediately so that your blood pressure and vital organs can be monitored.
A number of tests may be done to check how well your vital organs, such as your heart and lungs, are working. You may have an electrocardiogram (ECG) to record your heart rhythm and determine whether there is a sufficient flow of blood to your heart.
During an ECG, electrodes are put on your arms, legs and chest. The electrodes are connected to a machine that records the electrical signals of each heartbeat. An abnormal ECG reading could suggest the muscles of your heart are not receiving enough blood.
Severe sepsis and septic shock
Severe sepsis is when your body’s response to infection has started to interfere with the function of vital organs, such as your heart, kidneys, lungs or liver.
Septic shock is when severe sepsis causes your blood pressure to drop to a dangerously low level.
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Treatment
Sepsis and septic shock are medical emergencies and must be treated immediately.
If you have sepsis, it's likely that you will be admitted to an intensive care unit (ICU) for urgent treatment and to carefully monitor your progress. You may be connected to various tubes and machines that measure:
- your blood pressure
- how much urine you produce
- how much oxygen is in your blood
Oxygen therapy
To help you breathe more easily, you will be given oxygen through one of the following:
- a face mask
- a tube inserted into your nose
- an endotracheal tube (ETT) that is inserted into your mouth
If you have severe shortness of breath, a mechanical ventilator may be used.
Increasing blood flow
If you have septic shock, you will probably be given fluids directly into a vein. This will help increase your blood pressure by increasing the amount of fluid in your blood.
To increase the blood flow to your vital organs, such as your brain, liver, kidneys and heart, you may be prescribed:
- inotropic medicines
- vasopressors
Inotropic medicines
Inotropic medicines (inotropes), such as dobutamine, stimulate your heart. They increase the strength of your heartbeat, which helps get oxygen-rich blood to your tissues and organs where it is needed.
Vasopressors
Vasopressors include:
- dopamine
- epinephrine
- norepinephrine
These medicines will cause your blood vessels to narrow, increasing your blood pressure and the flow of blood around your body. This will allow your vital organs to start functioning properly.
Antibiotics
Antibiotics are often used to treat sepsis and septic shock as these are usually caused by a bacterial infection.
The type of antibiotic that will be effective in treating the infection will depend on the type of bacterial infection and where in the body the infection started.
To increase your chances of survival, you may be started on antibiotics before the results of these tests are known. Initially, two or three types of antibiotics may be used. Once the results are known and the bacteria responsible for the infection have been identified, the most effective type of antibiotic can be used.
Drotrecogin alfa (activated)
If you have severe sepsis or septic shock, you may be prescribed a type of medicine called drotrecogin alfa (activated).
Drotrecogin alfa (activated) is an artificially produced human protein that can help prevent inflammation and blood clotting, reducing the risk of death.
Drotrecogin alfa (activated) will only be used if:
- two or more of your major organs are failing
- the medicine can be started within 24 hours of your organs failing
- it is being prescribed and supervised by a specialist with experience of treating people with sepsis in intensive care
Surgery
In severe cases of sepsis or septic shock, the large decrease in blood pressure and blood flow can cause organ tissue to die. If this happens, surgery may be required to remove the dead tissue.
You may also need surgery to remove the cause of your infection, for example:
- draining a collection of pus (an abscess)
- removing infected tissue
- removing a medical device, such as a heart valve
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Complications
If severe sepsis and septic shock are not treated quickly enough, or if treatment does not bring the condition under control, complications can occur such as:
- lungs not being able to take in enough oxygen (respiratory failure)
- the heart not being able to pump enough blood around the body (heart failure)
- other organ failure
These are serious health conditions that will need to be treated urgently. In over half of all cases, septic shock is fatal because of complications such as these.
Factors that can increase your risk of septic shock being fatal include:
- being elderly
- having another health condition
- having a weak immune system, for example because you have HIV
- being infected with bacteria that are resistant to antibiotics
- your organs starting to fail
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