Shock Flashcards
What is the definition of ‘shock’?
A condition of inadequate perfusion to sustain normal organ function
Name the 5 main classes of shock?
Hypovolaemic Cardiogenic Obstructive Distributive Cytotoxic
Hypovolaemic is solely due to loss of blood. true/false?
FALSE
It can also be a loss of interstitial fluid or pure water
Which hypovolaemic compensation mechanism involves:
inhibition of the vagus nerve and enhancement of sympathetics via nerve signals that originate from stretch receptors in the carotids and aortic arch?
Baroreceptor reflex
Describe the sympathetic mediated neurohormonal response to hypovolaemia
Sympathetic chronotropy and inotropy
Release of vasoconstrictors (adrenaline, NA, angiotensin, vasopressin etc.)
Redirection of fluids from peripherals and secondary organs
Lactic acidosis causing enhanced chemoreceptor response
When decompensating- increased vasodilators
What does capillary absorption of interstitial fluid do when in a hypovolaemic state?
Reduces capillary hydrostatic pressure
Describe the hypothalamic-pituitary-adrenal response to hypovolaemia?
Intrarenal baroreceptors=> renin release from juxtaglomerular apparatus
Angiotensin II enhances vasoconstriction and ADH secretion
=> enhanced renal reabsorption of Na and H20
What are the three basic ways to increase cardiac output?
Increase HR
increase SV (inotropy)
Increase both
Young people struggle to control HR. true/false?
FALSE
they often struggle to control stroke volume!
What happens to the Frank-Starling curve when inotropes are physiologically released/given?
Curve shifts up
= increased contractility
What happens to FS curve when contractility is decreased?
Shifts down
Describe some compensations made in HF, and what the consequences are?
Failing heart= decreased contractility
End diastolic volume increases to maintain stroke volume.
end result in pulmonary congestion
Patients with heart failure often respond poorly to fluid challenges, true/false?
true.
lower challenges are given and it is impossible to get a full response due to decreased contractility of the heart
What must you remember when prescribing fluids?
They are a drug.
Appropriate dose
Appropriate fluid and electrolyte components for that patient
Remember the difference between resuscitation and maintenance!
What is the main principle behind cardiogenic shock?
Heart pump failing to meet circulation demands.
name some causes of cardiogenic shock?
Acute MI Acute mitral prolapse Myocarditis Cardiomyopathy Myocardial Contusion (traumatic bruising)
What would be the resulting symptoms/signs resulting from failure to pump blood forward?
hypotension/shock
fatigue
syncope
What would be some symptoms/signs resulting from cardiac back pressure?
Pulmonary oedema (struggle to breath lying down, SOB)
sacral oedema
ankle oedema
What does positive inotropy mean?
an increase in the force of cardiac contraction for any preload
what has a positive inotropic effect physiologically?
the sympathetic nervous system
what exogenous drug can induce a positive inotropic effect?
B-Adrenoceptors: Dobutamine, adrenaline
Dopaninergic: dopamine, dopexamine
describe what inotropes and fluids do to the Frank-Starling Curve?
Inotropes=> UP
Fluids=> RIGHT
What device can be used to:
- provide counter pulsation
- assist inflation during ventricular diastole and deflation during ventricular systole?
Intra-aortic balloon pump
What is the main factor behind obstructive shock?
Something is obstructing the filling of the heart
