Shock Flashcards
what is shock
inadequate perfusion of the vital organs to sustain normal organ function
what is hypovolaemic shock
insufficient circulating volume
insufficient circulating volume in hypovolaemic shock leads to reduced _____ and __
preload and CO
what are some causes of hypovolaemic shock
haemorrhage dehydration loss of interstitial fluid excessive vomiting burns
shock from burns is a combination of what kinds of shock
hypovolaemic and distributive
what is the BP like in hypovolaemic shock
initially normal due to compensation then suddenly drops when body can no longer compensate
what is the patients skin like in hypovolaemic shock
pale and cool
what are 4 compensatory mechanisms is hypovolaemic shock
baroreceptor reflex
sympathetic mediated neurohormonal response
capillary absorption of interstitial fluid
HPA response
how does the baroreceptor response work in hypovolaemic shock
stretch sensitive receptors in the carotid and aortic arch sinus detect decreased stretch and so they fire less - decreased afferent input to the medullary cardiovascular centres leading to inhibition of parasympathetic and enhanced sympathetic output
what cranial nerve is the afferent from the carotid sinus
CN IX
what cranial nerve is the afferent from the aortic arch
CN X
increased sympathetic output increases ___ and ____
chronotropy and inotropy
name 4 vasoconstrictors that are released in response to increased sympathetic output
adrenaline
angiotensin
noradrenaline
vasopressin
how does lactic acid build up in hypovolaemic shock
vasoconstrictors redirect fluid from peripheral secondary organs leading to lactic acidosis
the lactic acidosis drives what
chemoreceptors to enhance response
what causes the decompensation towards the end of hypovolaemic shock
circulating vasodilators also increases
why do capillaries absorb interstitial fluid
reduced capillary hydrostatic pressure so net inward filtration
what is the Hypothalamus-pituitary-adrenal response to hypovolaemic shock
intrarenal baroreceptors mediate renin release from the JGA - resulting angiotensin II enhances vasoconstriction and ADH release so enhanced renal reabsorption of Na and water
CO = ?
HR x SV
in order to increase CO what can you do
increase HR or SV or both
who isnt able to increase SV
young children
what does the frank starling relationship say about SV
greater EDV results in greater SV within physiological limits
inotropy results in increased contractility making the FS curve shift ____
upwards
a failing heart has decreased contractility so the FS curve is shifted
downwards
what can happen if a large fluid challenge is given to someone with HF and hypovolaemic shock
EDV increases to maintain SV - results in pulmonary congestion
who should get a smaller fluid challenge
HF
what is cardiogenic shock
inability of the heart to act as an effective pump to meet circulatory demands
what causes cardiogenic shock
most commonly a complication of an MI acute valve dysfunction - acute mitral valve prolapse myocarditis cardiomyopathy myocardial contusion
even a small MI may affect the ______ ____ leading to valve dysfunction
papillary muscle
in cardiogenic shock you cannot increase the ___
CO
what are some clinical signs of cardiogenic shock
poor forward flow - lethargic, hypotension/shock, syncope
back pressure - pulmonary oedema, elevated JVP, hepatic congestion
what is positive inotropy
increase in force of contraction for any given preload
how is positive inotropy achieved physiologically
increased sympathetic output
how can positive inotropy be acheived pharmacologically
dobutamine
adrenaline
dopamine
dopexamine
what is dobutamine
B1 agonist
what is dopexamine
synthetic dopamine analogue
how does an intra-aortic balloon pump work
provides counterpulsion
an intra-aortic balloon pump is ____ during ventricular diastole
inflated
intra-aortic balloon pump is ___ during ventricular systole
deflated
intra-aortic balloon pump is inflated during ventricular diastole to
increase diastolic pressure and increase coronary perfusion
intra-aortic balloon pump is deflated during systole to
decrease systolic pressure so force that heart has to contract against is lower
adrenaline is a _____ and increases ___ and therefore __
vasopressor
TPR
BP
dobutamine increases _____ and so ___
force of contractility
SV
what is obstructive shock
physical obstruction to filling of heart (obstruction to heart of great vessels) leading to reduced preload and cardiac output
what are some causes of obstructive shock
PE
cardiac tamponade
obstructive shock mainly affects cardiac ____ rather than ___
filling rather than ejection
how is a PE treated
anticoagulation +/- thrombolysis
how is cardiac tamponade treated
pericardiocentesis
how is tension pneumothorax treated
decompression and chest drainage
how is obstructive shock diagnosed
echo
what would be seen on ECHO of PE
right side of heart not contracting well - dilated and hypokinetic RV
McConnells sign
Bowing of interventricular septum
what is Mcconnells sign
hyperkinetic RV apex
what is pericardial effusion/tamponade
fluid accumulation in pericardial sac which compresses each of the chambers impairing cardiac filling an contraction
what is a tension pneumothorax
air trapped in pleural cavity under positive pressure - creates a one way valve effect that subjects lung to increasing pressure
tension pneumothorax prevents patient getting __
venous return - impairs cardiac filling and distribution
tension pneumothorax leads to
collapsed lung
what is the problem in distributive shock
circuit is too big - problem is with distribution of fluid rather than volume
what are 2 other names for distributive shock
vasodilatory
warm
what are 3 causes of distributive shock
septic shock
anaphylactic shock
neurogenic shock
what is distributive shock
significant reduction in SVR beyond compensatory limits of increased CO
what is the BP like in distributive shock
low
what is the skin like in cardiogenic shock
warm and flushed
what is the skin like in distributive shock
initially warm then cold
how does septic shock occur
bacteria releasing toxins causes capillary dysfunction - WBCs encounter pathogen leading to inflammation, vasodilation and leeky vessels –> hypotension
what is the treatment for septic shock
SEPSIS 6
what is sepsis 6
give 3 take 3 BUFALO Bloods urine output fluids antibiotics lactate oxygen
what if given early in septic shock improves perfusion and reduces excessive fluid volumes
vasopressors
what can detect hypoperfusion before hypotension occurs
rising lactate levels
what is seen on the skin of anaphylactic shock
hives
itching
flushing
what occurs in anaphylactic shock
allergens enter blood stream and bind to b cells which produce IgE
IgE binds to mast cells causing degranulation
histamine is released causing widespread vasodilation —> hypotension
cytokines also released by mast cells recruit WBCs causing widespread inflammation
what is the treatment of anaphylactic shock
adrenaline
how does adrenaline fix anaphylactic shock
vasoconstricts
stabilises mast cells
also causes bronchodilation
what level is diagnostic of anaphylactic shock
serum mast cell tryptase level
what is neurogenic shock
loss of thoracic sympathetic outflow following spinal injury
loss of sympathetic outflow leads to what
unopposed vasodilation and bradycardia from parasympathetic stimulation –> hypotension
is neurogenic shock the same as spinal shock
no
what is spinal shock
loss of spinal reflexes despite cord being intact
is there compensatory tachycardia in neurogenic shock
no - unopposed vagal tone
how is neurogenic shock treated
dopamine alongside vasopressors e.g. adrenaline
what is hypotension
below 90/60
or 25-30% fall from baseline
what is MAP equation
[ 2(DBP) + SBP ] / 3
what is hypotension
below 90/60
or 25-30% fall from baseline
what is MAP equation
[ 2(DBP) + SBP ] / 3
hypovolaemic shock class I is blood loss of up to
750 ml (15%)
hypovolaemic shock class II is blood loss of
750 - 1500 (15-30%)
hypovolaemic shock class III is blood loss of
1500 - 2000 (30-40%)
hypovolaemic shock class IV is blood loss of
> 2000 (>40%)
hypovolaemic shock class (?) is when BP starts to fall
III
hypovolaemic shock class I has pulse of
< 100
hypovolaemic shock class II has pulse of
100 - 120
hypovolaemic shock class III has pulse of
120 - 140
hypovolaemic shock class IV has pulse of
> 140