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Definition of circulatory shock?
Generalized inadequate blood flow through the body causing damage due to decreased oxygen and or nutrient delivery.
Two types of factors that will decrease the ability of the heart to pump blood
- Cardiac abnormalities; MI, valvular dysfunction, arrhythmias
- Decreased venous return; The heart can not pump what does not flow into it, diminished blood volume, decreased vascular tone, obstruction of blood flow.
Two factors that can cause circulatory shock without diminished cardiac output?
- Excessive metabolism
- abnormal tissue perfusion patterns
During shock what decreases more, the arterial pressure of cardiac output?
What does shock lead to?
- Tissue distraction and more shock
- As the tissues deteriorate and weaken causes by the inadequate blood flow, including the heart, the cardiac output will become even more depressed
Three stages of shock?
- 1. non progressive; full recovery without therapy
- 2. Progressive stage; without therapy the shock will become worse
- 3. irreversible stage; no known therapy will save the life
How does hypovolemia cause shock?
It decreases the filling pressure of the circulation and decreases venous return
How much volume can be removed with no effect
Initiation of the sympathetic response in hypovolemic shock?
Arterial baroreceptors and other stretch receptors
Three important effects of the sympathetic response in shock
- 1. constriction of the arterials
- 2. Veins and venous reservoirs constrict to maintain venous return
- 3. Increased heart rate.
- This can double the amount of blood lost before death occurs
Central nervous system sympathetic response
- occurs at 50mmHg and causes extreme stimulation of the sympathetic nervous system]
- Starts when the brain starts to suffer from lack of oxygen
Does the sympathetic system constrict all systems?
- No, the cardiac and cerebral vessels do not constrict
Shock is non progressive if?
It does not goes tissue deterioration
Rveerse stress relaxation of the circulatory system
Vessels constrict around the diminished blood volume to allow the volume to fill the vessel adequately
What two hormones are released during shock?
vasopressin and angiotensin II
Most important feature of progressive shock?
- Deteriation of the heart muscle
- occurs after 1 to 2 hours
Since tissue metabolism continues dispute low blood flow what happens?
- Large amounts of carbonic and lactic acid accumulate
- The large amount of acid causes local agglutination, resulting in minute blot clots leading to plugging of small vessels
Capillary hypoxia leads to?
- increased permeability and a loss of more volume from circulation
- Not till the late stages
Endotoxin can cause?
What organ is exposed to the greatest number of toxins during shock?
Deterioration of the lung leading to death in shock is called?
shock lung syndrome
In irreversible shock so many destructive enzymes have been reeased, acidosis has developed and so much destruction has occurred that even a normal cardiac output can not cause recovery/
What is the rate of ATP synthesis?
about 2% the normal cellular amount per hour, in shock ATP is depleted with no way to get it back
Affect of shock on insulin?
How does intestinal obstruction reduce plasma volume?
distension of the intestine block venous blood flow in the intestine which increases capillary pressure can causes high protein plasma to leak out
Causes of sever plasma loss?
severe burns and intestinal obstruction and dehydration
Main difference between hemorrhagic shock and plasma loss?
plasma loss has increased RBC concentration increasing viscosity adding to blood sludge
Causes of dehydration that lead to shock, 5
- excessive sweating
- diarrhea or vomiting
- nephrotic kidney
- inadequate fluid intake
- destruction of adrenal cortex with loss of aldosterone
Increased vascular capacity?
Neurologic shock , lose of vasomotor tone
Increase in vascular capacity leads to?
reduction in the mean systemic filling pressure
Three causes of neuralgic shock
- 1. Deep general anesthesia
- 2. spinal anesthesia
- 3. Brain damage
Allergic condition where cardiac output and arterial pressure decrease drastically
Effects of histamine?
- increase in vascular capacity due to venous dilation decreasing venous return
- arterial dilation decreasing blood pressure
- Increase in capillary permeability with rapid loss of fluid and protein into the tissues, also leads to decreased venous return
a bacterial infection widely disseminated to many areas of the body
five causes of septic shock
- 1. Peritonitis, spread of infection form the uterus of fallopian tubes
- 2. Peritonitis from a GI rupture
- 3. spread of staph of strep infection
- 4. gangrene infection
- 5. infection from th kidney of urinary tract
Five features of septic shock
- 1. high fever
- 2. vasodilation
- 3. high cardiac output due to arterial vasodilation
- 4. slugging of blood due to agglutination
- 5. DIC
best treatment for hemorrhagic shock, plasma loss shock, dehydration
Whole blood, plasma, electrolyte solution
What are trying to correct when treating shock
Two toes of shock when sympathetic drugs are useful
neurologic shock and anaphalactic shock
Why are pressers not useful in hemorrhagic shock
the sympathetic vasomotor system is already maxed out
Three reasons to giver glucocorticoids during shock
- 1. increase strength of the heart
- 2. stabilize lysosomes to prevent further enzyme release
- 3. aid in glucose metabolism
What rhythm can cause circulatory arrest
Two reasons for cardiac arrest during surgery
- 1. too little oxygen in the anesthetic gas
- 2. cardiac derisive effect of anesthetic gas
What causes the detrimental effect on the brain of circulatory arrest?
microclots in the brain