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Definition of circulatory shock?
Generalized inadequate blood flow through the body causing damage due to decreased oxygen and or nutrient delivery.
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Two types of factors that will decrease the ability of the heart to pump blood
- Cardiac abnormalities; MI, valvular dysfunction, arrhythmias
- Decreased venous return; The heart can not pump what does not flow into it, diminished blood volume, decreased vascular tone, obstruction of blood flow.
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Two factors that can cause circulatory shock without diminished cardiac output?
- Excessive metabolism
- abnormal tissue perfusion patterns
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During shock what decreases more, the arterial pressure of cardiac output?
Cardiac output
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What does shock lead to?
- Tissue distraction and more shock
- As the tissues deteriorate and weaken causes by the inadequate blood flow, including the heart, the cardiac output will become even more depressed
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Three stages of shock?
- 1. non progressive; full recovery without therapy
- 2. Progressive stage; without therapy the shock will become worse
- 3. irreversible stage; no known therapy will save the life
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How does hypovolemia cause shock?
It decreases the filling pressure of the circulation and decreases venous return
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How much volume can be removed with no effect
10%
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Initiation of the sympathetic response in hypovolemic shock?
Arterial baroreceptors and other stretch receptors
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Three important effects of the sympathetic response in shock
- 1. constriction of the arterials
- 2. Veins and venous reservoirs constrict to maintain venous return
- 3. Increased heart rate.
- This can double the amount of blood lost before death occurs
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Central nervous system sympathetic response
- occurs at 50mmHg and causes extreme stimulation of the sympathetic nervous system]
- Starts when the brain starts to suffer from lack of oxygen
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Does the sympathetic system constrict all systems?
- No, the cardiac and cerebral vessels do not constrict
- Autoregulation
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Shock is non progressive if?
It does not goes tissue deterioration
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Rveerse stress relaxation of the circulatory system
Vessels constrict around the diminished blood volume to allow the volume to fill the vessel adequately
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What two hormones are released during shock?
vasopressin and angiotensin II
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Most important feature of progressive shock?
- Deteriation of the heart muscle
- occurs after 1 to 2 hours
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Since tissue metabolism continues dispute low blood flow what happens?
- Large amounts of carbonic and lactic acid accumulate
- The large amount of acid causes local agglutination, resulting in minute blot clots leading to plugging of small vessels
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Capillary hypoxia leads to?
- increased permeability and a loss of more volume from circulation
- Not till the late stages
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Endotoxin can cause?
cardiac depression
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What organ is exposed to the greatest number of toxins during shock?
Liver
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Deterioration of the lung leading to death in shock is called?
shock lung syndrome
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In irreversible shock so many destructive enzymes have been reeased, acidosis has developed and so much destruction has occurred that even a normal cardiac output can not cause recovery/
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What is the rate of ATP synthesis?
about 2% the normal cellular amount per hour, in shock ATP is depleted with no way to get it back
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Affect of shock on insulin?
100% non-effective
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How does intestinal obstruction reduce plasma volume?
distension of the intestine block venous blood flow in the intestine which increases capillary pressure can causes high protein plasma to leak out
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Causes of sever plasma loss?
severe burns and intestinal obstruction and dehydration
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Main difference between hemorrhagic shock and plasma loss?
plasma loss has increased RBC concentration increasing viscosity adding to blood sludge
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Causes of dehydration that lead to shock, 5
- excessive sweating
- diarrhea or vomiting
- nephrotic kidney
- inadequate fluid intake
- destruction of adrenal cortex with loss of aldosterone
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Increased vascular capacity?
Neurologic shock , lose of vasomotor tone
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Increase in vascular capacity leads to?
reduction in the mean systemic filling pressure
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Three causes of neuralgic shock
- 1. Deep general anesthesia
- 2. spinal anesthesia
- 3. Brain damage
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Allergic condition where cardiac output and arterial pressure decrease drastically
anaphylaxis shock
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Effects of histamine?
- increase in vascular capacity due to venous dilation decreasing venous return
- arterial dilation decreasing blood pressure
- Increase in capillary permeability with rapid loss of fluid and protein into the tissues, also leads to decreased venous return
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Septic shock
a bacterial infection widely disseminated to many areas of the body
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five causes of septic shock
- 1. Peritonitis, spread of infection form the uterus of fallopian tubes
- 2. Peritonitis from a GI rupture
- 3. spread of staph of strep infection
- 4. gangrene infection
- 5. infection from th kidney of urinary tract
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Five features of septic shock
- 1. high fever
- 2. vasodilation
- 3. high cardiac output due to arterial vasodilation
- 4. slugging of blood due to agglutination
- 5. DIC
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best treatment for hemorrhagic shock, plasma loss shock, dehydration
Whole blood, plasma, electrolyte solution
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What are trying to correct when treating shock
Hemodynamics
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Two toes of shock when sympathetic drugs are useful
neurologic shock and anaphalactic shock
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Why are pressers not useful in hemorrhagic shock
the sympathetic vasomotor system is already maxed out
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Three reasons to giver glucocorticoids during shock
- 1. increase strength of the heart
- 2. stabilize lysosomes to prevent further enzyme release
- 3. aid in glucose metabolism
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What rhythm can cause circulatory arrest
V fib
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Two reasons for cardiac arrest during surgery
- 1. too little oxygen in the anesthetic gas
- 2. cardiac derisive effect of anesthetic gas
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What causes the detrimental effect on the brain of circulatory arrest?
microclots in the brain
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