Introduction[edit | edit source]
Shock is a life-threatening manifestation of circulatory failure. Circulatory shock leads to cellular and tissue hypoxia resulting in cellular death and dysfunction of vital organs. Effects of shock are reversible in the early stages and a delay in diagnosis and/or timely initiation of treatment can lead to irreversible changes including multiorgan failure and death.
Image 1: A graphical illustration of circulatory shock.
Etiology[edit | edit source]
Shock is characterized by decreased oxygen delivery and/or increased oxygen consumption or inadequate oxygen utilization leading to cellular and tissue hypoxia. It is a life-threatening condition of circulatory failure and most commonly manifested as hypotension (systolic blood pressure less than 90 mm Hg or MAP less than 65 mmHg). Shock is the final manifestation of a complex list of etiologies and could be fatal without timely management.
Some of the different types of medical shock include:
- Hypovolaemic – meaning not enough blood volume. Causes include bleeding, which could be internal eg ruptured artery or organ, external eg a deep wound or dehydration. Chronic vomiting, diarrhoea, dehydration or severe burns can also reduce blood volume and cause a dangerous drop in blood pressure
- Cardiogenic – caused when the heart cannot effectively pump blood around the body. eg heart attack, heart disease (egcardiomyopathy) or valve disorders may prevent a person’s heart from functioning properly
- Neurogenic – injury to a person’s spine may damage the nerves that control the diameter of blood vessels. The blood vessels below the spinal injury relax and expand and cause a drop in blood pressure
- Septic – an infection makes the blood vessels dilate, which drops blood pressure. eg E. coli infection may trigger septic shock
- Anaphylactic – a severe allergic reaction causes blood vessels to dilate, which results in low blood pressure
- Burn Shock
- Obstructive – blood flow is stopped. Obstructive shock can be caused by cardiac tamponade, which is an abnormal build-up of fluid in the pericardium that compresses the heart and stops it from beating properly, or pulmonary embolism.
- Endocrine – in a critically ill person, a severe hormonal disorder eg hypothyroidism may stop the heart from functioning properly and lead to a life-threatening drop in blood pressure.
Epidemiology[edit | edit source]
Distributive shock is the most common type of shock, followed by hypovolemic and cardiogenic shock. Obstructive shock is relatively less common. The most common type of distributive shock is septic shock and has a mortality rate between 40 to 50%.
Pathophysiology[edit | edit source]
Hypoxia at the cellular level causes a series of physiologic and biochemical changes, resulting in acidosis and a decrease in regional blood flow, which further worsens the tissue hypoxia.
Generally, shock has the following three stages:
- Pre-shock or compensated shock: Characterized by compensatory mechanisms to counter the decrease in tissue perfusion, including tachycardia, peripheral vasoconstriction, and changes in systemic blood pressure
- Shock - During this stage, most of the classic signs and symptoms of shock appear due to early organ dysfunction, resulting from the progression of the pre-shock stage as the compensatory mechanisms become insufficient.
- End-organ dysfunction - This is the final stage, leading to irreversible organ dysfunction, multiorgan failure, and death
Signs and Symptoms[edit | edit source]
Depending on the cause, symptoms and signs of shock may include:
- A rapid weak, thready pulse due to decreased blood flow combined with tachycardia
- Cool, clammy skin due to vasoconstriction
- Rapid and shallow breathing due to sympathetic nervous system stimulation and acidosis
- Hypothermia due to decreased perfusion and evaporation of sweat
- Thirst and dry mouth, due to fluid depletion
- Cold and mottled skin , especially extremities, due to insufficient perfusion of the skin.
Treatment[edit | edit source]
The initial approach to management is the stabilization of the airway and breathing with oxygen and oral mechanical ventilation when needed. Specific treatment depends on the type of shock, but could include:
- Hypovolaemic shock – stopping the bleeding and boosting the person’s blood volume with intravenous fluids (fluids given directly into the person’s bloodstream through a tube and needle). In severe cases, the person may need a blood transfusion. Internal or external wounds may need surgery
- Cardiogenic shock – boosting blood volume with intravenous fluids. Medications to constrict (narrow) the blood vessels will improve the heart’s ability to pump. Some people may need heart surgery
- Neurogenic shock – giving intravenous fluids and medications, including corticosteroids
- Septic shock – giving antibiotics for the infection. The person may need supportive hospital care, for example, mechanical ventilation to help them breathe
- Anaphylactic shock – the person may need medications such as antihistamines, adrenaline or corticosteroids
- Obstructive shock – removing the obstruction, for example, surgery or clot-dissolving medication to remove a blood clot in the pulmonary artery
- Endocrine shock – administering medications to correct the hormonal imbalance, for example, thyroid medication to treat hypothyroidism.
Physiotherapy[edit | edit source]
Medical shock is a life-threatening emergency. Effective first aid and prompt medical attention can save a person’s life. Be aware of the first aid management which includes:
- Lay the Person Down, if Possible: Elevate the person's feet about 12 inches unless head, neck, or back is injured or you suspect broken hip or leg bones; Do not raise the person's head; Turn the person on side if they are vomiting or bleeding from the mouth.
- Begin CPR, if Necessary: If the person is not breathing or breathing seems dangerously weak, or a child, start CPR for children, for an adult, start adult CPR; Continue CPR until help arrives or the person wakes up.
- Treat Obvious Injuries
- Keep Person Warm and Comfortable: Loosen restrictive clothing; Cover with a coat or blanket; Keep the person still. Do not move the person unless there is danger; Reassure the person; Do not give anything to eat or drink.
- Follow Up: At the hospital, the person will be given oxygen and intravenous fluids; Blood test, urine tests, heart test and xrays and/or CT scans may be done; Other treatment will depend on the cause of shock.
Prognosis[edit | edit source]
Generally, hypovolaemic, neurogenic and anaphylactic shock respond well to treatment. But in about half of all cases of cardiogenic and septic shock, the person will die.
- Sepsis and septic shock, in general, are associated with long-term morbidity and mortality, with many of the survivors requiring placement into long-term acute care facilities or post-acute care centers.
- Septic shock has a mortality rate between 40% and 50%.
- Cardiogenic shock has a mortality rate ranging from 50% to 75%, an improvement over prior mortality rates.
- Hypovolemic and obstructive shock generally have much lower mortality and respond better to timely treatment.
References[edit | edit source]
- Haseer Koya H, Paul M. Shock. [Updated 2021 Jul 26]. In: StatPearls [Internet]. Treasure Island (FL): StatPearls Publishing; 2021 Jan. Available:https://www.ncbi.nlm.nih.gov/books/NBK531492/ (accessed 9.9.2021)
- Better health Shock Available:https://www.betterhealth.vic.gov.au/health/conditionsandtreatments/shock#types-of-shock (accessed 9.9.2021)
- Taha M, Elbaih A. Pathophysiology and management of different types of shock. Narayana Med J. 2017;6:14-39.Available: https://www.researchgate.net/publication/317577007_Pathophysiology_and_management_of_different_types_of_shock (accessed 9.9.2021)
- Webmd Shock treatment Available: https://www.webmd.com/first-aid/shock-treatment (accessed 9.9.2021)