drugs for treating shock
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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: - PowerPoint PPT PresentationTRANSCRIPT
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:
• 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
• used to replace fluids lost, and to increase urine output
• include: normal saline, lactated Ringer’s, hyperotonic saline, 5% dextrose in water