According to "Harrison's Principles of Internal Medicine," shock is defined as multisystem organ hypoperfusion. Blood flow and oxygen delivery to tissues are impeded.
Shock may be due to trauma, heatstroke, blood loss, an allergic reaction, infection, or severe burns. If untreated, it can lead to permanent organ damage or death. There are four categories of shock.
Cardiogenic Shock
Cardiogenic shock, which occurs after an acute myocardial infarction, is due to failure of the heart to pump.
According to the "Washington Manual of Medical Therapeutics," the goals of treatment include maintaining adequate oxygen levels as well as hematocrit. Dopamine, a pressor drug, is usually given to increase blood pressure.
For patients who do not respond to medical therapy or those who have a heart valve problem, intra-aortic balloon counterpulsation (IABP) can increase cardiac output.
Finally, the patient is considered for angioplasty or coronary artery bypass surgery.
Hypovolemic shock
Hypovolemic shock is caused by severe blood and fluid loss that makes the heart unable to pump enough blood to the body. Significant hypovolemic shock lasting for more than several hours is often associated with death.
Goals of treatment include increasing the intravascular volume with blood (if shock is due to hemorrhage) and/or fluids. Simultaneously, surgical intervention may be needed to control bleeding.
Distributive Shock
Distributive shock is due to sepsis or anaphylaxis. Septic shock results from bacteria multiplying in the blood and releasing toxins. Common causes are pneumonia, a ruptured appendix and meningitis.
Goals of treatment include fluid resuscitation and treatment of the underlying infection.
Anaphlactic shock results from a rapidly developing allergic reaction. Treatment goals include epinephrine (immediately), and airway management with 100 percent oxygen. Intubation may be needed as well as volume expansion with fluids.
Obstructive Shock
Obstructive shock is most often due to a massive pulmonary embolism. It may also be due to air, amniotic fluid or tumor embolism. Goals of treatment include fluids and vasoconstrictor agents to preserve blood pressure. Definitive therapy consists of dissolving the clot (thrombolytic therapy) or surgical removal of the embolus (embolectomy).
References
- "Harrison's Principles of Internal Medicine"; Dennis Kasper, M.D.; 2005
- The Mayo Clinic: Shock: First Aid
- "The Washington Manual of Medical Therapeutics"; Gopa Green, M.D., 2004.
