Shock & Exercise - Quiz 11 Flashcards
What is Circlatory Shock?
Not enough blood flow in the body to where tissues are damange d/t lack of oxygen & nutrient delivery - gets worse once it begins
What is the “Last-Ditch Stand”
When the brain lacks O2 & increased CO2, it activates extreme stimulation of SNS as last effort to keep the MAP from falling too low
What Causes Shock?
- Shock is from inadequate Cardiac Output
- Cardiac Abrnomalities effecting pump
- Factors decreasing venous return
How can you have Circulatory Shock even with Normal Cardiac Output?
Excessive Metabolic Rate
&
Abnormal Tissue Perfusion
How much blood can be loss before going into Hemorrhagic/Hypovolemic shock?
> 10% will causes decreases in Cardiac Output & MAP
40-45% Total blood Loss = Cardiac Output & Map of Zero
What happens during the Sympathetic Reflex to shock?
- Arterioles constrict = Increased PVR
- Veins constrict = adequate venous return
- Increased HR
How is blood flow to the Brain & Heart affected by the Sympathetic Reflex during shock?
No Constriction in Brain or Heart
Autoregulation maintains Blood flow as long as MAP > 70 mmHg
What are the Compensatory Mechanisms in Hemorrhage?
- Baroreceptors
- Chemoreceptors
- Cerebral Ischemic Response
- Endogenous Vasoconstrictors
- Reabsorption of Tissue Fluids
- Salt and Water Conservation
How do Baroreceptors work?
Located in Carotid Sinus & Aortic Arch
Senses pressure changes and alters CNS, HR & Contractility accordingly.
How do the Peripheral Chemoreceptors respond to Severe Hypotension?
Decreased organ blood flow leads to acidosis activating the chemoreceptors.
Further increases SNS response & respiration to increase BP
How does the Reabsorption of Tissue Fluids happen in shock?
Hypotension & Vasoconstriction causes a drop in Hydrostatic Pressure and net fluid reabsorption from interstitium into capillaries up to 1L/hr
Can cause Hemodilution = ↓Hct
How does the Kidney come into play during Shock?
- Kidneys release more
- Angiotensin II - Vasoconstriction
- Aldersterone - Salt & Water Reabsorption to increase blood volume
- Stimulates Vasopressin Release
- Important for long-term recovery
What is Circulatory Decompensation or Progressive Shock?
When the body’s compensation mechanisms is not enough to maintain a sufficent MAP to perfuse organs and leads to irreversible shock where everything fails.
What is Cardiogenic Shock?
Poor blood flow to the heart from hypotension causes myocardial hypoxia & acidosis, which depress its function & cause arrythmias
What is Symptathetic Escape?
Buildup of tissue metabolic vasodilators impairs sympathetic vasoconstriction causing more hypotension & hypoperfusion
How does progressive shock affect the brain?
Cerebral Ischemia/Hypoxia
Loss of Sympathetic outflow = more vasodilation, hypotension, and poor cerebral perfusion
What are the Rheological (flow) effects of Progressive Shock?
Increased blood viscosity, reducing perfusion
&
Intravascular Coagulation
What are the Stages of Shock?
-
Non-Progressive/Compensated
- Body can compensate to full recovery
-
Progressive
- W/o therapy, shock gets worse til death
-
Irreversible
- Nothing you can do, patient will die
What are treatments for Hypotension?
Give Blood
Epi/Norepi
Head Down Position
Oxygen
Glucocorticoids
In shock, where is Vasoconstriction most prominent?
Skin, Skeletal Muscle, and Splanchnic Vascular Beds
Blood flow is preferentially redistributed to which body organs in shock states?
Brain and Heart
What are the Decompensatory Mechanisms?
Cardiac & CNS Depression
Acidosis
Vasomotor Failure
Abnormal Clotting
Reticulo-Endothelial System
Cellular Deterioration
Low Flow States
What are the Positive Feedback Decompensatory Mechanisms?
↓CO & Contractility
↓MAP & O2 Transport
Vasodilation
Tissue Hypoxia
What happens on the Cellular Level that leads to Irreversible Shock?
Depletion of high-energy phosphates
