Shock and Hypertension Flashcards
what is shock
generalised loss of blood flow to organs leading to hypoxia, necrosis and tissue death
what are the 5 types of circulatory shock
hypovolaemic, cardiogenic,septic, anaphylactic, neurogenic
hypovolaemic
arisesfrom loss of blood or blood fluid
cause by trauma,burns,vommiting,diarrhoea
decreaes stroke volume to decrease blood pressure
EDV↓,venous return↓,preload↓,SV↓,CO↓,BP↓
how does body respond to hypovolaemic shock
BP =COTPR
CO = HRSV
since SV is decreasing to maintain BP TPR has to increase
heart rate increases
short term: activate sympathetic nervous system to vasoconstrict vessels and releasecatecholamine
long term: activate RAAS
cardiogenic
reduction in perfusion due to problem with heart
often involves SV↓
cardiogenic
myocardial failure leads to ↓ejection fraction which leads to ↑ESV
this causes ↑pressure in LA which causes ↑blood pressure in pulmonary capillaries which pushes blood into lungs which is pulmonary oedema.
this means less O2 is absorbed and leads to further heart problems which keep the problem going
how does body respond to cardiogenic shock shock
similar response to hypovolaemic
tachycardia could compensate for low heart rate
septic
occurs when bacteria or fungi enter bloodstream
increase temp
they release endo/exotoxins
they damage cells and cause mast cells to release pro-inflammatory mediators
this causes vasoconstriction throughout blood vessels which reduces TPR and causes blood to leak into tissue which reduces CO
anaphylactic
occurs in response to allergic reaction
increased temp
allergen consumed activates basophils and mast cells which releases histamine(pro-inflammatory) which leads to reduced CO
neurogenic
occurs sometimes with spinal cord injury, concussion or deep anaesthesia
caused by massive increase in vascular capacity
this reduces blood pressure and therefore venous return
what are the 3 main stages of circulatory shock
non-progressive- treatment is sufficient
progressive - needs treatment quickly or condition will get worse
irreversible- even with treatment condition is fatal
how does shock trigger baroreceptors
shock decreases venous return which leads to reduced cardiac output
this decreases blood pressure which is detected by baroreceptors
how do baroreceptors restore blood pressure and volume
the baroreceptors activate sympathetic nervous system which activates peripheral vasoconstriction and elevates RAAS activity which releases catecholamines which acts to restore blood pressure and volume
non-progressive shock
haemorrhage that results in blood pressure >45mmHg can often be compensated by body without much medical help
but this can steal lead to ischaemic damage of organs and tissues
progressive shock
haemorrhage that results in blood pressure <45mmHg causes progressive shock which is more difficult to recover from
decrease in CO results in intravascular clotting and increased acidosis which leads to coagulation.
this slows down blood flow in small vessels which leads to organ damage
