Shock (circulatory)

Shock
Shock
	US Navy EMT trainees and firemen using IV fluid replacement in treating a trauma training mannequin to prevent hypovolemic shock.
Specialty	Critical care medicine
Symptoms	Initial: Weakness, fast heart rate, fast breathing, sweating, anxiety, increased thirst; Later: Confusion, unconsciousness, cardiac arrest
Types	Low volume, cardiogenic, obstructive, distributive
Causes	Low volume: Severe bleeding, vomiting, diarrhea, dehydration, or pancreatitis; Cardiogenic: severe heart attack (especially of the left or right ventricles), severe heart failure, cardiac contusion; Obstructive: Cardiac tamponade, tension pneumothorax; Distributive: Sepsis, spinal cord injury, certain overdoses
Diagnostic method	Based on symptoms, physical exam, laboratory tests
Treatment	Based on the underlying cause
Medication	Intravenous fluid, vasopressors
Prognosis	Risk of death 20 to 50%
Frequency	1.2 million per year (US)

Shock is the state of insufficient blood flow to the tissues of the body as a result of problems with the circulatory system.^[1]^[2] Initial symptoms of shock may include weakness, fast heart rate, fast breathing, sweating, anxiety, and increased thirst.^[1] This may be followed by confusion, unconsciousness, or cardiac arrest, as complications worsen.^[1]

Shock is divided into four main types based on the underlying cause: hypovolemic, cardiogenic, obstructive, and distributive shock.^[2] Hypovolemic shock, also known as low volume shock, may be from bleeding, diarrhea, or vomiting.^[1] Cardiogenic shock may be due to a heart attack or cardiac contusion.^[1] Obstructive shock may be due to cardiac tamponade or a tension pneumothorax.^[1] Distributive shock may be due to sepsis, anaphylaxis, injury to the upper spinal cord, or certain overdoses.^[1]^[4]

The diagnosis is generally based on a combination of symptoms, physical examination, and laboratory tests.^[2] A decreased pulse pressure (systolic blood pressure minus diastolic blood pressure) or a fast heart rate raises concerns.^[1] The heart rate divided by systolic blood pressure, known as the shock index (SI), of greater than 0.8 supports the diagnosis more than low blood pressure or a fast heart rate in isolation.^[5]^[6]

Treatment of shock is based on the likely underlying cause.^[2] An open airway and sufficient breathing should be established.^[2] Any ongoing bleeding should be stopped, which may require surgery or embolization.^[2] Intravenous fluid, such as Ringer's lactate or packed red blood cells, is often given.^[2] Efforts to maintain a normal body temperature are also important.^[2] Vasopressors may be useful in certain cases.^[2] Shock is both common and has a high risk of death.^[3] In the United States about 1.2 million people present to the emergency room each year with shock and their risk of death is between 20 and 50%.^[3]

^ ^a ^b ^c ^d ^e ^f ^g ^h ⁱ ^j ^k ^l ^m ⁿ International Trauma Life Support for Emergency Care Providers (8 ed.). Pearson Education Limited. 2018. pp. 172–73. ISBN 978-1292-17084-8.
^ ^a ^b ^c ^d ^e ^f ^g ^h ⁱ ^j ^k ^l ^m ATLS – Advanced Trauma Life Support – Student Course Manual (10 ed.). American College of Surgeons. 2018. pp. 43–52, 135. ISBN 978-78-0-9968267.
^ ^a ^b ^c ^d Tabas, Jeffrey; Reynolds, Teri (2010). High Risk Emergencies, An Issue of Emergency Medicine Clinics (E-book). Elsevier Health Sciences. p. 58. ISBN 978-1455700257.
^ Smith, N; Lopez, RA; Silberman, M (January 2019). "Distributive Shock". StatPearls (Internet). PMID 29261964.
^ Olaussen A, Blackburn T, Mitra B, Fitzgerald M (June 2014). "Review article: shock index for prediction of critical bleeding post-trauma: a systematic review". Emergency Medicine Australasia. 26 (3): 223–28. doi:10.1111/1742-6723.12232. PMID 24712642. S2CID 19881753.
^ Guyton, Arthur; Hall, John (2006). "Chapter 24: Circulatory Shock and Physiology of Its Treatment". In Gruliow, Rebecca (ed.). Textbook of Medical Physiology (11th ed.). Philadelphia, Pennsylvania: Elsevier Inc. pp. 278–88. ISBN 978-0-7216-0240-0.

[ITLSPg172-1] ^ ^a ^b ^c ^d ^e ^f ^g ^h ⁱ ^j ^k ^l ^m ⁿ International Trauma Life Support for Emergency Care Providers (8 ed.). Pearson Education Limited. 2018. pp. 172–73. ISBN 978-1292-17084-8.

[ATLS2018-2] ^ ^a ^b ^c ^d ^e ^f ^g ^h ⁱ ^j ^k ^l ^m ATLS – Advanced Trauma Life Support – Student Course Manual (10 ed.). American College of Surgeons. 2018. pp. 43–52, 135. ISBN 978-78-0-9968267.

[Tab2010-3] Tabas, Jeffrey; Reynolds, Teri (2010). High Risk Emergencies, An Issue of Emergency Medicine Clinics (E-book). Elsevier Health Sciences. p. 58. ISBN 978-1455700257.

[Stat2019Dis-4] Smith, N; Lopez, RA; Silberman, M (January 2019). "Distributive Shock". StatPearls (Internet). PMID 29261964.

[Olaussen-5] Olaussen A, Blackburn T, Mitra B, Fitzgerald M (June 2014). "Review article: shock index for prediction of critical bleeding post-trauma: a systematic review". Emergency Medicine Australasia. 26 (3): 223–28. doi:10.1111/1742-6723.12232. PMID 24712642. S2CID 19881753.

[Guyton-6] Guyton, Arthur; Hall, John (2006). "Chapter 24: Circulatory Shock and Physiology of Its Treatment". In Gruliow, Rebecca (ed.). Textbook of Medical Physiology (11th ed.). Philadelphia, Pennsylvania: Elsevier Inc. pp. 278–88. ISBN 978-0-7216-0240-0.

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