Shock

Question 1

What is circulatory shock?

Answer 1

rapid hypoperfusion that is life threatening

Question 2

What are the different classifications of circulatory shock?

Answer 2

1) cardiogenic - failure of heart to pump adequately
2) hypovolemic - problem with blood volume
3) obstructive - inability of heart to fill properly, obstruction to outflow of blood from heart
4) distributive - problem with tone of blood vessels

Question 3

What classification of shock is anaphylactic shock?

Answer 3

distributive

Question 4

What happens in anaphylactic shock?

Answer 4

• severe allergic reaction, reaction is systemic
• IgE antibody on mast cell and antigen bind, form immune complex
• mast cell degranulates, releases inflammatory mediators
• mediators trigger excessive vasodilation, increase capillary permeability systemically
• widespread vasodilation = inadequate vascular resistance = decrease in blood pressure
• low blood pressure = hypoperfusion
• edema from increased capillary permeability is fluid loss, also decreases blood pressure
• circulatory failure
• in this case, problem is compounded because the mediators that cause vasodilation also cause bronchospasm… causing person’s airway to constrict

Question 5

What classification of shock is septic shock?

Answer 5

distributive

Question 6

What happens in septic shock?

Answer 6

• severe infection
• systemic inflammatory response
• vasodilation and fluid loss from increased capillary dilation
• decreased blood pressure
• hypoperfusion

Question 7

What happens in hypovolemic shock?

Answer 7

• rapid decrease in blood volume by ~20%
• sympathetic nervous system increases heart rate (to increase CO) and causes vasoconstriction to non-vital organs (to increase peripheral resistance)
• because of this, blood pressure will initially remain unchanged
• endocrine and renal systems also try to compensate:
• —- hypothalamus stimulates thirst center, triggers secretion of ADH (vasoconstriction, increase water reabsorption)
• —- RAAS activated by decrease BP at glomerulus (vasocontriction, increase sodium reabsorption… followed by water)
• compensations no longer adequate
• blood pressure decreases
• inadequate perfusion
• hypoxia… eventually cell death

Question 8

What are three main causes of hypovolemic shock?

Answer 8

1) blood loss
2) plasma loss (can occur with severe burns)
3) extracellular fluid loss (dehydration)

Question 9

What factors affect blood pressure?

Answer 9

1) blood volume
2) cardiac output
3) perfipheral resistance

Question 10

What is the formula for cardiac output?

Answer 10

CO = SV x HR

Question 11

What are main signs of hypovolemic shock?

Answer 11

early:

• increased heart rate
• increased respiratory rate
• cool, clammy skin
• decreased urine output

later:

• weak, thready pulse
• decreased BP
• altered mentation/LOC

Question 12

How is hypovolemic shock treated?

Answer 12

• stop the cause of decreased blood volume
• administer oxygen
• administer IV fluids