Shock – a medical emergency

What is shock?

From a medical point of view – as opposed to the psychological sense – shock is not an exceptional psychological state, but an acute circulatory disorder: vital tissues are no longer receiving an adequate blood supply, leading to a lack of oxygen. As a result, the person affected loses consciousness and is at risk of organ failure. Shock occurs when blood pressure drops so low that the body’s cells are not supplied with enough blood and therefore do not receive enough oxygen. Consequently, cells in the brain, kidneys, liver and heart no longer function normally. If blood flow is not restored quickly enough, these cells suffer irreversible damage and die. The fatal consequence is that, if the cells are too severely damaged, the affected organ may fail. This also means that the person concerned may die. People suffering from circulatory shock must be taken immediately to an A&E department and receive intensive care.

There are various types of shock:

Hypovolaemic shock (divided into four sub-types):

• haemorrhagic shock resulting from acute bleeding without significant tissue damage
• traumatic haemorrhagic shock resulting from acute bleeding with tissue damage
• hypovolaemic shock in the strict sense, resulting from a critical reduction in circulating plasma volume without acute bleeding
• traumatic hypovolaemic shock resulting from a critical decrease in circulating plasma volume without acute bleeding, caused by tissue damage and the release of mediators

Distributive shock (divided into three subgroups):

• anaphylactic or allergic shock resulting from a severe allergic reaction
• neurogenic shock resulting from severe injuries or acute diseases of the brain and spinal cord
• septic shock resulting from blood poisoning

Cardiogenic shock

Obstructive shock

The four main types of shock can be broadly categorised according to the organ systems primarily affected:

• Blood and fluid compartments
• Vascular system
• Heart
• Circulatory system

This also explains why the different types of shock have different causes and each require a specific treatment.

What are the causes?

The triggers of shock are varied. It is important to take the different types of shock into account.

Hypovolaemic shock is caused by extreme fluid loss. As a result, there is insufficient blood volume in the blood vessels. Typical causes of this type of shock include severe extensive burns, blunt trauma and multiple trauma.

Distributive shock is caused by uncontrolled vasodilation and the associated sharp drop in blood pressure. Typical triggers for anaphylactic shock include allergic reactions to medicines, insect stings or food. Typical causes of neurogenic shock include severe injuries or acute conditions affecting the brain and spinal cord. These can lead to the failure of the nervous system’s blood pressure regulation and an extreme drop in blood pressure. A typical trigger for septic shock is blood poisoning, in which blood pressure regulation fails, thereby triggering symptoms of shock.

Cardiogenic shock is caused by heart failure. Typical causes include coronary heart disease, heart attack and chronic heart failure, which can lead to a failure of the heart’s pumping capacity.

Obstructive shock is caused by an acute blockage of a major blood vessel. As a result, blood circulation can no longer be maintained. Typical causes of this type of shock include pulmonary embolism, pericardial tamponade (where the heart is compressed and can therefore no longer pump sufficient blood) and tension pneumothorax (air accumulates between the chest wall and the lung, increasing the pressure in the chest cavity; this reduces the volume of blood returning to the heart).

What are the signs of shock? 

Shock can manifest itself in a variety of ways. Typical symptoms include, amongst others:

• A drop in blood pressure
• Heart rate: increased heart rate (tachycardia) except in neurogenic shock, where the heart rate is significantly slowed (bradycardia)
• Skin: pale, clammy skin in hypovolaemic and cardiogenic shock; flushed, hot skin in septic shock; pale, warm, dry skin in neurogenic shock; redness, hyperthermia, itching, possibly swelling in anaphylactic shock.
• Barely palpable pulse
• rapid breathing, subjective difficulty breathing
• Restlessness, nervousness, anxiety, tremors
• Altered consciousness, such as apathy
• Loss of consciousness

Shock – what should you do?

If you suspect that someone is in shock, you must call an ambulance immediately and administer first aid:

• Speak to and touch the person affected (check their consciousness by speaking to them clearly and gently shaking their shoulders)
• If they are conscious, lay them down, raise their legs and cover them so that blood can flow from their raised legs to the brain and organs.
• It is essential to avoid agitation and distress (shield the person if necessary)
• If the person is unconscious but breathing normally, shout for help to alert bystanders to the emergency.
• Place the person in the recovery position
• Cover the person
• Reassure, look after, comfort and monitor them until the ambulance arrives, and keep checking their consciousness and breathing
• If the person is unconscious and not breathing normally, perform cardiopulmonary resuscitation

When the emergency team arrives, it is important to inform them, if relevant, whether the person has eaten anything in particular shortly beforehand, whether they have been stung by an insect, or whether they have a heart condition. It is also important to provide information about any accidents, recent surgery or infections. All of this provides the doctor with valuable clues for diagnosing and treating the person affected.

How is shock diagnosed?

The diagnosis is based primarily on evidence of organ damage identified during the medical examination. Those affected may, for example:

• be less aware of their surroundings
• no longer produce urine
• have blue-tinged fingers or toes
• have a racing heart, breathe rapidly or sweat profusely

Specific tests that may be used include:

• Blood test (lactate concentration): This measures the amount of waste products from cellular activity in the blood; if the lactate level is elevated, this suggests that the organs are not receiving enough oxygen and blood and that the person may be in a state of shock.
• Blood tests that indicate a high or low number of white blood cells, bacteria or other microorganisms in the blood: these can help determine whether the person has an infection that could cause septic shock. A high creatinine level, for example, may indicate that the kidneys are damaged, and high concentrations of troponin (a cardiac biomarker) may suggest that the heart is damaged.
• Other tests, depending on the likely cause of the shock: for example, blood cultures and cultures of other bodily fluids if a severe infection is suspected.
• Electrocardiography and other imaging techniques: these are used to visualise the heart if the patient shows symptoms of a heart problem.

How is shock treated?

The first steps in treating shock are to stop any bleeding, administer oxygen, intravenous fluids and/or blood transfusions, and sometimes administer medication to raise blood pressure.

However, these measures are sometimes insufficient to counteract the effects of shock – for example, in cases of severe bleeding and persistent fluid loss, a severe heart attack, or when the shock is caused by a factor unrelated to blood volume.

In such cases, other measures are employed, depending on the cause of the shock. If, for example, the shock is due to the heart’s reduced pumping capacity, the heart’s function must be restored. If the cause is a heart attack, percutaneous transluminal coronary angioplasty (PTCA) or coronary artery bypass surgery may be used. Surgery may also be necessary if the cause is a damaged heart valve or a tear in the heart wall. If cardiac tamponade (excess fluid compressing the heart) is present, this can be drained using a needle or through surgery.

If the cause of the shock is an infection, this is treated with antibiotics and the source of the infection is eliminated. If the shock was caused by bleeding, it may be necessary to stop the bleeding surgically. If the shock is anaphylactic, a corticosteroid may be administered.

Prognosis following shock

If left untreated, shock can be fatal. With appropriate treatment, the prognosis depends on the following factors:

• Cause of the shock
• other medical conditions from which the patient suffers
• Presence and severity of organ failure
• Time elapsed before treatment began
• Type of treatment provided If multi-organ failure is present, there is a high risk of dying from the consequences of shock, and the risk of mortality increases with the number of organs affected. Even if the shock is the result of a severe heart attack or if septic shock is present, it is unfortunately likely that the person will die, particularly in the case of older people.