Shock Flashcards
What is circulatory shock?
rapid hypoperfusion that is life threatening
What are the different classifications of circulatory shock?
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
What classification of shock is anaphylactic shock?
distributive
What happens in anaphylactic shock?
- 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
What classification of shock is septic shock?
distributive
What happens in septic shock?
- severe infection
- systemic inflammatory response
- vasodilation and fluid loss from increased capillary dilation
- decreased blood pressure
- hypoperfusion
What happens in hypovolemic shock?
- 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
What are three main causes of hypovolemic shock?
1) blood loss
2) plasma loss (can occur with severe burns)
3) extracellular fluid loss (dehydration)
What factors affect blood pressure?
1) blood volume
2) cardiac output
3) perfipheral resistance
What is the formula for cardiac output?
CO = SV x HR
What are main signs of hypovolemic shock?
early:
- increased heart rate
- increased respiratory rate
- cool, clammy skin
- decreased urine output
later:
- weak, thready pulse
- decreased BP
- altered mentation/LOC
How is hypovolemic shock treated?
- stop the cause of decreased blood volume
- administer oxygen
- administer IV fluids