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64 Cards in this Set
- Front
- Back
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What is shock?
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physiologic state caused by significant reduction of systemic tissue perfusion, creates imbalance between oxygen delivery and consumption
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What are the cellular changes of shock?
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cell membrane ion pump dysfunction, failure to maintain normal ionic gradients, IC edema, leakage of intracellular contents into EC space, inadequate regulation of IC pH
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What are the systemic effects of shock?
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alterations in serum pH, endothelial dysfunction, inflammatory and anti-inflammatory cascades
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How does shock progress?
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oxygen deprivation becomes a downward spiral towards cell death, organ failure, death
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What determines systemic tissue perfusion?
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cardiac output, systemic vascular resistance, mean arterial pressure
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What changes SVR?
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vasodilation increases flow
vasoconstriction decreases perfusion vasomotor tone is regulated to match O2 delivery to demands |
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What is preload?
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amoung of distending force stretching ventricular myofilaments
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What is the Frank-Starling Mechanism?
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as ventricular filling pressure increases, cardiac output increases
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At what LV pressure does cardiac output plateau?
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15-18 mm Hg
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What happens when LV filling pressure goes above 25 mm Hg?
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fluid leaks into airspaces, producing pulmonary edema
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What happens when LV contractility is normal and afterload is increased?
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not much
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What happens when LV contractility is low and afterload is increased?
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cardiac output is sensitive to it, CO falls
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What is hypovolemic shock?
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decreased preload due to intracvascular volume loss
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What causes cardiogenic shock?
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cardiac pump failure secondary to a severe myocardial injury
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What is distributive shock?
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pathologic processes that produce excessive vasodilation of systemic arteries and veins
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How do you measure central venous pressure?
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proximal port in right atrium
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What does CVP measure?
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overall volume status
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Where do you measure pulmonary wedge pressure?
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from distal port while pulmonary artery is transiently occluded by balloon inflation proximal to distal port
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What does wedge pressure measure?
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LV preload
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What does CO measure?
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tissue perfusion
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How do you measure CO?
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thermodilution or mixed venous O2 saturation
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Where do you insert a Swan-Ganz catheter?
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right internal jugular or left subclavian veins
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What are the serious complications of a Swan-Ganz catheter?
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sepsis, pneumothorax, hemorrhage
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What are the hemodynamics for hypovolemic shock?
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low wedge pressure, low CO, high SVR, low oxygen saturation
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What are the hemodynamics for cardiogenic shock?
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high wedge pressure, low CO, high SVR, low oxygen sat
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What are the hemodynamics for distribute shock?
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low or normal wedge pressure, high CO, low SVR, high oxygen sat
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What are the clinical manifestations of shock?
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hypotension with tachycardia
oliguria < 30 ml/hr cool, clammy skin metabolic acidosis altered mental status |
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Why is there lactic acidosis in shock?
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decreased lactic acid clearance by liver, kidney, skeletal muscle
lactic acid increases due to anaerobic metabolism |
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What is the pathology of hypovolemic shock?
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loss of intravascular volume due to acute blood loss/excessive loss of salt and fluid
fall in CO, fall in BP, compensatory increased SVR |
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What does reduced CO in hypovolemic shock do?
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poor perfusion of the tissue, low BP, high SVR
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What does poor perfusion in hypovolemic shock do?
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hypoxia, acidosis, depletion of ATP, organ dysfunction
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What causes hypovolemic shock?
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hemorrhagic: trauma, GI bleed, hematoma rupture, hemorrhagic pancreatitis, fractures, ruptured aneurysm
fluid loss: diarrhea, vomiting, heat stroke, inadequate replenstishment, burns, third-space in post-op patients |
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How do you treat hypovolemic shock?
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restore normal tissue perfusion, find/fix causes, stabilize patient with fluid
can give inotropes and vasopressors for temporary fix |
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What is the pathology of cardiogenic shock?
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acute injury to the myocardium, reduces left ventricle contractility, reduces pump performance, CO falls
diastolic compliance in LV falls |
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What are the consequences of low left ventricular filling pressure in cardiogenic shock?
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poor renal perfusion, salt/fluid buildup, pulmonary edema
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What are the consequences of low CO in cardiac output?
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low BP, activates baroreceptors, SVR increases
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What causes cardiogenic shock?
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myocardial dysfunction: left ventricular damage due to MI or non-ischemic cardiomyopathy
arrhythmias: bradycardia, tachycardia valvular problems, rupture of septum or free wall pulmonary embolism, tension pneumothorax pericarditis, pericardial tamponade |
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How do you pharmacologically treat cardiogenic shock?
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loop diuretics, furosemide, inotropic agents
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How do diuretics change the Frank-Starling in cardiogenic shock?
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decrease left ventricular filling pressure
don't change CO |
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How do inotropic agents change the Frank-Starling in cardiogenic shock?
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increase CO
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How do vasodilators change the Frank-Starling in cardiogenic shock?
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increase CO, decrease left ventricular filling pressure
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Why would you give loop diuretics?
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to relieve pulmonary edema
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What are loop diuretic's MOA?
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blocks sodium and water absorption in distal tubules
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How do you give loop diuretics for cardiogenic shock?
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IV becasue it's more rapid and more reliable bioavailability
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From where is Furosemide not well absorbed?
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edematous gut
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What is the duration of action of Furosemide?
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4 hours
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How long does it take for Furosemide to take action?
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about 30-45 minutes
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What are the common side effects of Furosemide?
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electrolyte disturbances (K, Na, Mg)
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What kind of drug is Furosemide?
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loop diuretic
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How do you give Milrinone?
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IV
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What are the non-pharmocologic treatments of cardiogenic shock?
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fix the underlying cause, intra-aortic baloon pulsation, left ventricular assist device, cardiac transplant
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What is intra-aortic balloon pulsation?
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device into femoral artery, inflate a balloon in the thoracic aorta during diastole, used as a bridge to surgery or cardiac transplant
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What is the MOA of intra-aortic balloon pulsation?
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inflation during diastole augments diastolic pressure, increases coronary perfusion, relieves ischemia, decreases angina
deflation during systole reduces LV afterload, increase CO, decreases myocardial oxygen demand |
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What are the complications of intra-aortic balloon pulsation?
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potential for vascular complications, portal for serious infection
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What is LV Assist Device?
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implanted through sternotomy, circulatory assist drains blood from LV apex through external pump that provides non-pulsatile blood flow back to the aorta
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Why would you use a LV Assist Device?
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circulatory assist for patients iwth severely impaired LV function who cannot come off bypass, bridge to transplant
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What are the complications of an LV Assist Device?
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thromboembolic complications, including stroke, serious hemorrhagic complications, portal for infections
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What can cause distributive shock?
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sepsis, systemic inflammatory response syndrome, toxic shock, anaphylaxis, reactions to drugs or toxins, Addisonian crisis, Myxedema coma
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What is the mechanism of distributive shock?
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vasodilation
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What is the first step in treating distributive shock?
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stabilize the patient with IV fluids and vasopressors
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What should you give as IV fluids for distributive shock?
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crystalloid, colloid, albumen
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What should central venous pressure be?
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8-12 mm Hg
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What should central venous oxygen saturation be?
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>70%
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What should mean arterial pressure be?
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> 60 mm Hg
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