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Drugs for treating shock. Shock. shock: a syndrome characterized by collapse of the circulatory system. vital tissues do not receive enough blood to function properly cells cannot carry on normal metabolism. Symptoms of shock. shock is a collection of signs and symptoms, many nonspecific:
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Shock • shock: a syndrome characterized by collapse of the circulatory system
vital tissues do not receive enough blood to function properly • cells cannot carry on normal metabolism
Symptoms of shock • shock is a collection of signs and symptoms, many nonspecific: • skin: pale, cool, or clammy • respiratory: breathing rapid and shallow
CV: low b.p., low cardiac output, weak pulse • neurologic: restlessness, anxiety, lethargy, confusion
Classification of shock • 1. cardiogenic • failure of the heart to pump sufficient blood to tissues
due to: left heart failure, ischemia, MI, arrhythmias, pulmonary embolism, myocardial/pericardial infection
2. hypovolemic • loss of blood volume
due to: hemorrhage, burns, profuse sweating, excessive urination, vomiting, diarrhea
3. septic • multiple organ dysfunction as a result of pathogenic organisms in the blood
due to: widespread inflammatory response to bacterial, fungal or parasitic infections
4. anaphylactic • acute allergic reaction
due to: severe reaction to allergens (penicillin, nuts, shellfish, animal proteins)
Treatment of shock • initial treatment includes basic life support while identifying the underlying cause
maintain ABC of life support: airway, breathing, circulation
administer fluids/electrolytes and blood products if patient has lost a significant amount of blood
Drug categories in treating shock • There are 3 categories of drugs that play a role in treating shock: • vasoconstrictors • cardiotonic drugs • fluid replacement agents
Vasoconstrictors used to treat shock • early stages of shock: body compensates for initial fall in b.p. by ↑ activity of sympathetic nervous system
this sympathetic activity results in vasoconstriction which: • ↑ b.p. • ↑ heart rate and force of myocardial contractions
Purpose: maintain blood flow to vital organs (heart, brain) and ↓ blood flow to other organs (kidneys, liver)
Body’s ability to compensate is limited • Severe hypotension may develop
vasoconstrictors are used to maintain b. p. • given IV they immediately raise b. p. • patients monitored continuously during infusion to avoid HT due to overtreatment
Specific Vasoconstrictors used to treat shock • 1. epinephrine: a nonselective adrenergic agent • b.p. rises due to stimulation of alpha1 receptors in smooth muscle of blood vessels
cardiac output increases due to stimulation of beta1 receptors in heart • airway opens due to stimulation of beta2 receptors in the bronchi
2. norepinephrine (Levarterenol, Levophed) has both alpha and beta1 activity • 3. methoxamine hydrochloride (Vasoxyl) selective to alpha receptors
Cardiotonic drugs used to treat shock • aka inotropic agents • as cardiogenic shock progresses, the heart begins to fail:
cardiac output ↓, lowering amount of blood reaching vital tissues and worsening shock
cardiotonic drugs are used in the treatment of shock to ↑ the force of contraction and increase cardiac output
Specific Cardiotonic drugs used to treat shock • 1. digoxin (Lanoxin)
2. dobutamine (Dobutrex): a beta1 adrenergic agent that is often drug of choice for short term (1/2 life of only 2 min.) treatment of shock
has the ability to cause heart to beat more forcefully without significantly increasing heart rate • increase in cardiac output assists in maintaining blood flow to vital organs
3. dopamine (Dopastat, Intropin) • mechanism of action is dependent on dose
low doses: selectively stimulates beta1 receptors in kidneys that cause vasodilation and an ↑ blood flow to kidneys (used in treating hypovolemic and cardiogenic shock)
moderate doses: stimulates beta1 receptors, causing heart to beat with more force and increasing cardiac output
higher doses: stimulates alpha receptors causing vasoconstriction and raising b.p.
Fluid replacement agents used to treat shock • Used to replace blood or other fluids lost during hypovolemic shock
Fluid replacement agents are generally placed into the following 3 categories: • blood, colloids, crystalloids
Blood • Whole blood indicated for treatment of acute, massive blood loss when there is a need to replace plasma volume and supply RBC’s
Colloids • Used when up to 1/3 of adult blood volume is lost
colloids are proteins that stay suspended in the blood for a long period and draw water from the body’s cells and tissues into the blood vessels
colloids include: normal serum albumin, plasma protein fractions, dextran and hetastarch
Crystalloids • IV solutions that contain electrolytes in amounts resembling those of natural plasma
Unlike colloids, crystalloid solutions leave the blood and enter cells
include: normal saline, lactated Ringer’s, hyperotonic saline, 5% dextrose in water