chapter 24 ( circulatory shock and its treatment) Flashcards
define circulatory shock
inadequte blood flow through the body to the extent tissue is damaged because ot too little oxygen and nutrient delivery
Circulatory shock can be caused by reduced cardiac output. Name 1 way cardiac output is reduced
any cardiac abnormality that decreases the ability of the heart to pump blood. ( myocardial infartion, arrhythmias, valve disfunction)
name 1 other way cardiac output is reduced
anything that reduces venous return ( diminished blood volume, decreased vascular tone)
what % of people who develop cardiogenic shock die?
70 %
circulatory shock that occurs without diminished cardiac shock
- excessive metabolic rate
- abnormal tissue perfustion patterns, so that most cardiac output is going to vessels that dont supply local tissue ( that needs it)
1st stage of circulatory shock
nonprogressive stage-( compensated stage) normal circulatory compensatory mechanisms eventually cause full recovery without outside help
2nd stage of circulatory shock
progressive stage- in which without therapy , the shock becomes steadily worse until death
3rd stage of circulatory shock
irreversable stage- shock has progressed to such an extent that all forms of therapy dont work to save the persons life.
hemorrhagic shock
caused by hypovolemia ( means diminished blood). Filling pressure of circulation decreases which decreases the cardiac output
sympathetic reglex compensations in shock
- The arterioles constrict in systemic circulation causing an increase in total peripheral resistance
- veins and venous reservoires constrict to help maintain adequate venous return
- heart rate increases ( sometimes from the 72 beats/min normal to 160 beats/min)
what is the value of the sympathetic nervous reflexes?
without them only 15-20 % of blood can be lost for 30 min before death. With them 30-40% can be lost until death
name the ways someone can come out of the non-progressive shock stage
Baroreceptor reflex, CNS ischemic response, Reverse stress-relaxation of circulatory system, increased secretion of renin by the kidneys and formation of angiotensis 2, increased secretion by the posterior pituitary gland of vasopressin, increased secretion by the adrenal medullae of epinephrine and norepinephrine, compensatory mechanisms that return the blood volume back toward normal
Whats happening in deteriation during shock
active transport of sodium and potassium is diminished, mitochondria activity goes down, lysosomes begin to open, cellular metabolism of nutrients like glucose become depressed
during shock the body will turn to acidosis. Why is this a problem?
cells use the anaerobic process of glycolysis which creates alot of lactic acid
what happens to energy compound during irreversible shock?
they greatly diminish. This is the most significant for the development of the final state of irreversable shock
name some causes of hypovolemic shock caused by plasma loss
excessive sweating, diarrhea/vomiting, excess fluid loss from kidneys, inadequate intake of fluid and electrolytes, destruction of adrenal corices with loss of aldosterone secretion.
describe neurogenic shock
instead of having blood loss, the vascular capacity increases( more flexible) and the blood volume is not enought to fill the circulatory system adequayely.
what does neurogenic shock do to the vessels
Loss of vascular tone throughout the body especially in the veins
What causes neurogenic shock?
deep general anesthesia, Spinal anesthesia, Brain damage
Whats anaphylactic shock and histamine shock
allergic condition in which the cardiac output and arterial pressure often decreases drastically. The release of histamine from basophils causes this
what 3 things does histamine do?
1.increased vascular capacity which causes decrease in venous return
2. dilation of arterioles which decreases arterial pressure
3. increased capillary permeability with rapid loss of fluid and protein into the tissue spaces.
( the net effect of all these causes reduction in venous return)
Septic shock
blood poisening, bacteria in blood ( most common cause of shock-related death in the modern hospitals)
Common causes of septic shock
- peritonitis caused by infection from the uterus and fallopian tubes
- peritonitis from rupture of GI system
- body infection from spread of skin i nfection such as streptococcal or staphylococcal infection
- gangrenous infection
- infection that spread into the blood from the kidney or urinary tract
treatment of shock , blood and plasma transfusion is best for what kind of shock?
shock caused by hemorrhage
treatment of shock, dextran solution as a plasma substitue
this is used as a plasma substitue. The substance has large molecular sizes to exert colloid osmotic pressure.
treatment of shock with sympathomimetic drugs
sympothomimetic drugs are drugs that mimic sympathetic stimulation. Examples of these are norepinephrine and epinephrine
which kinds of shock have sympathomimetic drugs been proven usefull?
neurogenic shock and anaphylactic shock
why are sympathomimetic drugs usefull in neurogenic shock?
because the sympathetic nervous system is severely depressed. The drug picks up the slack the nervous system needs
why are sympathomimetic drugs usefull in anaphylactic shock?
anaphylactic shock has excess histamine which dilates the vessels and capillaries. The drugs have vasoconstrictor effects with control the effect of histamine
whats another way to help someone in shock? Especially neurogenic and hemorrhagic shock?
place their head 12 inches below their feet
Treatment with glucocorticoids for shock
- They actually increase the heart strength in late stages of shock
- stabilize lysosomes in the cells thus preventing deteriation.
- they “ might” aid in metabolism of glucose by severly damaged cells.
Is oxygen therapy very usefull?
it can be but usually the problem is delivering nutrients and oxygen. Not bonding the oxygen
what is circulatory arrest?
complete stop of blood flow.
in general what time frame for most individuals causes some brain damage while in circulatory arrest?
5-8 minutes
