Circulatory shock and treatment

  1. Decreased cardiac output or cardiogenic shock
    Cardiac abnormalities that decrease the heart's ability to pump blood
  2. 3 causes of cardiogenic shock
    • myocardial infraction
    • severe valve dysfunction 
    • arrhythmias
  3. What percentage of people who develop cardiogenic shock die?
  4. 3 factors that decrease venous return causing a decrease in cardiac output
    • diminished blood volume (hypovolemic shock)
    • decreased vascular tone 
    • obstruction of blood flow
  5. In the rare case where we have cardiac shock without diminished cardiac out, what two characteristics are to be expected?
    • excessive metabolic rate (cardiac output is inadequate to meet demand)
    • abnormal tissue perfusion patterns
  6. Define abnormal tissue perfusion patterns
    most of the cardiac output is passing through vessel in which filtration and reabsorption do not occur

    **maybe in the case of systemic edema
  7. What is the result of abnormal tissue perfusion patterns?
    A lack of nutrients and oxygen to local tissues
  8. In most types of shock , ______ blood pressure drops at the same time that _____ output drops.
    • Arterial blood pressure
    • cardiac output
  9. Arterial BP and cardiac output dropping at the same time leads to a _____ feedback loop leading to more shock. Explain this feedback loop.
    • Positive feedback loop 
    • Inadequate blood flow to the tissues leads to deterioration. This will include deterioration of the cardiac tissues which decreases cardiac output even more
  10. Three stages of shock
    • Non-progressive stage 
    • Progressive stage 
    • Irreversible stage
  11. Non-progressive stage
    normal compensatory mechanisms cause full recovery
  12. progressive stage
    without medical assistance, shock becomes progressively worse leading to death
  13. irreversible stage
    shock has progressed to the point where medical intervention is not effective resulting in death
  14. Hypovolemic shock
    aka hemorrhagic shock: emergency situation in which severe blood loss makes the heart unable to pump blood to the rest of the body
  15. What percent of blood can be lost before cardiac output declines?
  16. Compensatory mechanisms can manage to keep _____ pressure normal until about ___% of blood volume loss
    • arterial pressure
    • 20%
  17. What happens when blood loss reaches 40-45%?
    Arterial pressure drops to zero
  18. The sympathetic reflex to shock?
    Increase cardiac output to compensate for more than 10% by increasing contractility
  19. Sympathetic reflex compensation in shock is the decrease in arterial pressure after bleeding causes a sympathetic ANS response. What is the result (3)
    • Vasoconstriction of most arterioles in the systemic circulation increasing total peripheral resistance 
    • venous constriction to maintain venous return 
    • increase in heart rate
  20. In order to compensate from a non progressive hemorrhagic shock, the following factors are implemented by the body. (5)
    • baroreceptor reflexes
    • CNS ischemic response 
    • increased secretion of renin and formation of angiotensin II
    • increased secretion of ADH
    • increased secretion of epinephrine and norepinephrine by the adrenal medulla
  21. What type of response are your baroreceptor reflexes
  22. CNS ischemic response is a ____ stimulation that is activated when?
    • Sympathetic 
    • arterial pressure falls below 50mmHg
  23. Increased secretion of renin and formation of angiotensin II induces what two things?
    • vasoconstriction of peripheral arteries 
    • decreases water loss through the renal system
  24. Increased secretion of vasopressin stimulates what two things?
    • vasoconstriction of peripheral arteries
    • water reabsorption by kidneys
  25. Results of increases secretion of epinephrine and norepinephrine (2)
    • vasoconstriction of peripheral arteries 
    • increase in heart rate
  26. Two factors that lead to rapid response to hemorrhage in 30 seconds to a few minutes
    • sympathetic reflexes 
    • release of catecholamines
  27. Which response takes 10 minutes to 1hr?
    vasopressin & angiotensin responses
  28. Exepcted factors of progressive hemorrhagic shock (7)
    • cardiac depression 
    • vasomotor failure 
    • blockage of very small vessels 
    • increased capillary permeability 
    • generalized cellular deterioration 
    • tissue necrosis in severe shock 
    • acidosis in shock
  29. What causes cardiac depression in progressive hemorrhagic shock ?
    Blood flow is decreased below what is required to adequately provide nutrients and oxygen to the heart.
  30. In progressive hemorrhagic failure, how does vasomotor failure occur?
    Diminished blood flow to the brain's vasomotor center depresses the center so that it becomes progressively less active and finally shuts down
  31. The blockage of very small vessels is caused by sluggish blood flow. It leads to ____ of blood and is due to the accumulation of _____ ____ & _____ ____ and other products of ischemic tissues.
    • clotting 
    • carbonic acid & lactic acid
  32. _____ _____ leads to increased capillary permeability which further reduces _____ _____ as fluid accumulates in tissues.
    • Capillary hypoxia 
    • blood volume
  33. When does hypoxia induced capillary permeability occur?
    In the late stages of prolonged shock
  34. Which pump is decreased during generalized cellular deterioration? What is the result?
    • Na+/K+ pump 
    • Accumulation of Na+ & Cl- and a loss of K+ in the cell. The tissues then swell due to osmosis
  35. What are the three other results of generalized cellular deterioration?
    • Mitochondrial activity decreases (especially in liver)
    • lysosomes begin to break down releasing hydrolases leading to further deterioration 
    • cellular metabolism decreases
  36. Two things to expect because some tissues experience greater damage than others during shock due to smaller blood supplies
    • Cells nearer to arterial capillaries have better blood flow than venous capillaries
    • Lesions may develop in the liver, kidneys, heart and lungs
  37. Acidosis results from poor oxygen delivery to the tissues. What are 2 expectations?
    • cells shift to anaerobic respiration, producing large amounts of lactic acid
    • poor perfusion leads to impaired removal of CO2 as well, which also contributes to acidosis
  38. Irreversible shock
    at some point, intervention cannot stop the progression of shock to death
Card Set
Circulatory shock and treatment
Physiology lecture