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What is shock?
altered tissue perfusion and anaerobic cellular metabolism
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How is shock triggered
Drop in MAP
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What causes MAP to change
cardiac output, total blood volume, and size of vascular bed
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What is autorregulation
ability for tissue to regulate its own blood flow based on needs
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What patho changes occur before shock
MAP ↓10 and ↓blood volume by 500mL
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How does the body adjust to small change and what is the outcome
- SNS activated= ↑HR, CO, peripheral vasoconstriction
- perfusion to cells, tissue, and organs
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What patho changes occur in Stage 1 of shock (compensatory)
MAP↓ 10-15mmHg and ↓blood volume 1000mL
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What comp mechanisms are activated?
- SNS=release Epi and Norepi to stimulate α/β → vasoconstriction (nonvital) vasodilation (vital areas) → increase in CO and O2
- RAAS=VC and aldosterone release → absorb Na/H20 → maintains circ volume
- ADH=increase in renal absorption to maintain volume
- CHP ↓=fluid shifts from interstitial spaces to capillaries
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What patho changes occur in Stage 2 of shock (progressive) ?
MAP↓ 20mmHg+ and ↓blood volume 2500mL
comp mechanisms are still activated but no longer work
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What additional mechanism is activated to help with shock? Consequence?
- cells switch from aerobic to anaerobic metabolism=lactic acid formation=acidosis
- cells swell as Na/water moves in and K out (hyperkalemia)
- EVEN MORE FLUID AWAY FROM CAPILLARIES
- skin, skeletal muscles, kidneys, and GI no longer perfused
- Heart and Brain=anoxic
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What patho changes occur in Stage 3 of shock (refractory)?
- irreversible shock due to widespread tissue anoxia
- cell death=tissue death=organ death
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Can MAP be restored in Stage 3?
Yes, but cell damage is too severe and organ death causes death of body
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What are the sxs of each organ?
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What are the 4 classifications of shock?
Hypovolemic, cardiogenic, obstructive, and distributed
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What is hypovolemic shock?
- 15-25% blood volume loss
- decrease CO
- decrease tissue perfusion
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