Shock
Basics
Description
Description
- Inadequate supply of blood and oxygen to meet the metabolic demands of the tissues
- Toxic metabolites are not removed
- If untreated, inevitable progression from inadequate perfusion to organ dysfunction and ultimately to death
- Major categories of shock:
- Hypovolemic shock:
- Decreased circulating blood volume
- Suspect hemorrhage if acute onset
- Severe dehydration if progressive onset and elevated hematocrit, BUN, and/or creatinine
- Obstructive (cardiogenic) shock:
- Decreased cardiac output and myocardial dysfunction leading to tissue hypoxia in the setting of adequate intravascular volume
- Venous congestion with increase in central venous pressure
- Compensatory increase in SVR
- May be caused by cardiac dysfunction or obstruction of inflow/outflow of blood to/from the heart
- Septic shock:
- An initial infectious insult overwhelms the immune system
- Biochemical messengers (cytokines, leukotrienes, histamines, prostaglandins) cause vessel dilatation
- Capillary endothelium become disrupted causing vascular leak
- Drop in SVR leads to inadequate tissue perfusion
- Secondarily, decreased cardiac output from “cardiac stun” results in cold septic shock
- Neurogenic shock:
- Spinal cord insults disrupt sympathetic stimulation to vessels
- Loss of sympathetic tone causes arteriodilating and vasodilatation
- Lesions proximal to T4 disrupt sympathetic, spares vagal innervation causing bradycardia
- Anaphylactic shock:
- An antigen stimulates the allergic reaction
- Mast cells degranulate
- Histamine releases, along with autocoids, stimulate an anaphylaxis cascade
- Vascular smooth muscle relaxes
- Capillary endothelium leaks
- Drop in SVR leads to inadequate tissue perfusion
- Pharmacologic agents may cause shock through smooth muscle dilation or myocardial depression
- Hypovolemic shock:
Etiology
Etiology
- Hypovolemic shock:
- Abdominal trauma, blunt or penetrating
- Abortion – complete, partial, or inevitable
- Anemia – chronic or acute
- Aneurysms – abdominal, thoracic, dissecting
- Aortogastric fistula
- Arteriovenous malformations
- Blunt trauma
- Burns
- Diabetes
- Diarrhea
- Diuretics
- Ruptured ectopic pregnancy
- Epistaxis
- Fractures (especially long bones)
- Hemoptysis
- GI bleed
- Mallory–Weiss tear
- Penetrating trauma
- Placenta previa
- Postpartum hemorrhage
- Retroperitoneal bleed
- Severe ascites
- Splenic rupture
- Toxic epidermal necrolysis:
- Vascular injuries
- Vomiting
- Cardiogenic shock:
- Cardiomyopathy
- Conduction abnormalities and arrhythmias
- MI
- Myocardial contusion
- Myocarditis
- Pericardial tamponade
- Pulmonary embolus
- Tension pneumothorax
- Valvular insufficiency
- Ventricular septal defect
- Septic shock:
- Acute respiratory distress syndrome
- Bacterial infection
- Bowel perforation
- Cellulitis
- Cholangitis
- Cholecystitis
- Endocarditis
- Endometritis
- Fungemia
- Infected indwelling prosthetic device
- Intra-abdominal infection or abscess
- Mediastinitis
- Meningitis
- Myometritis
- Pelvic inflammatory disease
- Peritonitis
- Pyelonephritis
- Pharyngitis
- Pneumonia
- Septic arthritis
- Thrombophlebitis
- Tubo-ovarian abscess
- Urosepsis
- Anaphylactic:
- Drug reaction (most commonly to aspirin, β-lactam antibiotics)
- Exercise (rare)
- Food allergy (peanuts, tree nuts, shellfish, fish, milk, eggs, soy, and wheat account for 90% of food-related anaphylaxis)
- Insect sting
- Latex
- Radiographic contrast materials
- Synthetic products
- Pharmacologic:
- Antihypertensives
- Antidepressants
- Benzodiazepines
- Cholinergics
- Digoxin
- Narcotics
- Nitrates
- Neurogenic:
- Spinal cord injury
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Citation
Schaider, Jeffrey J., et al., editors. "Shock." 5-Minute Emergency Consult, 6th ed., Lippincott Williams & Wilkins, 2020. Emergency Central, emergency.unboundmedicine.com/emergency/view/5-Minute_Emergency_Consult/307373/all/Shock.
Shock. In: Schaider JJJ, Barkin RMR, Hayden SRS, et al, eds. 5-Minute Emergency Consult. Lippincott Williams & Wilkins; 2020. https://emergency.unboundmedicine.com/emergency/view/5-Minute_Emergency_Consult/307373/all/Shock. Accessed January 16, 2025.
Shock. (2020). In Schaider, J. J., Barkin, R. M., Hayden, S. R., Wolfe, R. E., Barkin, A. Z., Shayne, P., & Rosen, P. (Eds.), 5-Minute Emergency Consult (6th ed.). Lippincott Williams & Wilkins. https://emergency.unboundmedicine.com/emergency/view/5-Minute_Emergency_Consult/307373/all/Shock
Shock [Internet]. In: Schaider JJJ, Barkin RMR, Hayden SRS, Wolfe RER, Barkin AZA, Shayne PP, Rosen PP, editors. 5-Minute Emergency Consult. Lippincott Williams & Wilkins; 2020. [cited 2025 January 16]. Available from: https://emergency.unboundmedicine.com/emergency/view/5-Minute_Emergency_Consult/307373/all/Shock.
* Article titles in AMA citation format should be in sentence-case
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BT - 5-Minute Emergency Consult
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PB - Lippincott Williams & Wilkins
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