Shock Flashcards
Definition of shock
syndrome in which tissue perfusion not enough for body’s needs
Normal tissue perfusion relies on what 3 components?
heart - pump,
vascular bed - pipes,
circulating blood volume
Normal perfusion is difficult to measure, but what 4 surrogate markers do we use?
blood pressure,
consciousness,
urine output,
lactate
Measuring lactate measures perfusion of what?
General tissue perfusion
Measure consciousness measures perfusion of what?
Brain perfusion
Measuring urine output measures perfusion of what?
Renal perfusion
Mean arterial pressure =
CO x SVR
Why is blood pressure not always an accurate measurement of perfusion?
Because body can vary perfusion locally despite relatively constant BP
What are the 4(5) causes of shock?
hypovolaemic, cardiogenic, distributive, obstructive, (endocrine)
Give 3 examples of causes of hypovolaemic shock?
acute haemorrhage (most common),
fluid depletion due to severe dehydration,
burns
How does hypovolaemic shock affect the MAP equation?
Volume depletion leads to reduced SVR,
reduced volume returning to heart leads to reduced pre-load so reduced CO
How does cardiogenic shock affect the MAP equation?
reduced CO due to reduced contractility (SV) or reduced HR
List 4 causes of cardiogenic shock, what is the most common
ischaemia induced myocardial dysfunction (most common),
cardiomyopathies,
valvular problems,
dysrhythmias
If cardiogenic shock is due to MI this suggests that >40% of what is involved?
left ventricle
Unless correctable pathology such as valve problem, mortality with cardiogenic shock is greater than what?
> 75%
What is obstructive shock?
Mechanical obstruction to normal cardiac output in otherwise normal healthy heart
What are two causes of obstructive shock? give two examples of each
direct obstruction to CO e.g. PE, air/fat/amniotic fluid embolism,
restriction of cardiac filling e.g. tamponade, tension pneumothorax
Distributive shock AKA vasoplegic is known as what kind of shock
“hot” shock
List 4 causes of distributive shock
sepsis,
anaphylaxis,
acute liver failure,
spinal cord injuries
What happens in distributive shock?
due to disruption of normal vascular auto regulation and profound vasodilatation
What does it mean that there are regional perfusion differences in someone in distributive shock?
They may be awake and talking but some organs are not getting perfused
What happens in terms of CO and vasodilatation/constriction in endocrine shock?
Reduced CO and vasodilation
What causes endocrine shock? (3)
severe uncorrected hypothyroidism,
addisonian crisis,
thyrotoxicosis
List 4 types of shock in order of most common to least
distributive shock, (septic) cardiogenic, hypovolaemic, distributive (nonseptic), obstructive
List 2 types of response to shock
sympathy-adrenal response,
neuroendocrine response
List 5 hormones that are released in shock
ACTH, ADH, endogenous opioids, cortisol, glucagon
What does cortisol release do in shock (2)
fluid retention,
antagonises insulin
Inflammatory response in shock can occur as part of pathological process or consequences of and often both. Give example of pathological process its a part of and an example of a situation in which It is a consequence
pathological process - sepsis,
consequence of persisting hypo perfusion
List 7 components of inflammatory response
activation of complement cascade,
cytokine release,
platelet activating factor,
lysosomal enzymes,
adhesion molecules,
endothelium derived mediators (e.g. nitric oxide),
imbalance between antioxidants and oxidants
What does activation of complement cascade in inflammatory response cause?
attraction and activation of leucocytes
What does release of platelet activating factor in inflammatory response cause? (2)
increased vascular permeability (leaky),
platelet aggregation
What does release of lysosomal enzymes in inflammatory response cause? (2)
myocardial depression,
coronary vasoconstriction
List 5 haemodynamic changes in shock
vascular abnormalities (dilation or constriction), distribution of of blood flow messed up,
microcirculatory abnormalities (capillary beds flow interrupted),
inappropriate activation of coagulation systemic -> DIC,
reperfusion injuries
The loss of vascular reactivity (failure of vascular smooth muscle constriction) in shock is mostly caused by what?
Huge increase in release of nitric oxide
Myocardial dysfunction in shock is mostly caused by reduced coronary blood flow. T/F?
False!! its caused by
cytokines on myocardium,
beta receptor down regulation,
decreased cardiomyofilament calcium sensitivity
What symptom is almost always present in all types of shock?
Hypotension (usually)
Cardiogenic shock presentation (5)
cold, clammy, chest pain, oedema, not very tachycardic
Distributive shock presentation (3)
raised JVP,
pulsus paradoxus,
signs of cause
Distributive shock septic presentation (4)
pyrexia, vasodilatation, rapid cap. refill, warm and red hypotension
Distributive shock anaphylaxis presentation (4)
profound vasodilatation,
erythema,
bronchospasm,
oedema
Assessment of shock (7)
exam (skin temp, CRP), blood pressure monitoring, pulse contour analysis for CO, urine output, neurological, acidosis, lactate levels
Gold standard management for monitoring cardiac output?
thermodilution with a PA catheter but no one really happens
Management of shock
ABCDE,
wide bore IV access and treat underlying cause,
fluids,
noradrenaline
Biggest components of oxygen delivery (3) and how does this affect treatment aims
Hb, SpO2, CO Hb -> correct anaemia, ensure O2 normal, optimise CO
Why should you be careful with fluids in shocked patients
shocked patients more susceptible to pulmonary oedema due to microvascular dysfunction
Typical fluids for shock
300-500ml over 10-20 mins
MAP range target? but can vary depending on clinical picture
65-75
Pros and cons of crystalloids
convenient cheap and safe, but rapidly lost from circulation
Pros and cons of colloids
can cause anaphylaxis
What does noradrenaline do
predominantly alpha agonist so vasoconstrictions
Cardiogenic shock severe when drugs fail
balloon pumps,
L-VADs,
R-VADs
severe: VA-ECMO
Shock of blood loss <15% HR, BP, Cap refill, UO ml/hr, Mental state
HR <100, BP normal, Cap refill normal, UO ml/hr >30, Mental state normal
Shock of blood loss 15-30% HR, BP, Cap refill, UO ml/hr, Mental state
HR >100, BP normal, Cap refill >2sec, UO ml/hr 20-30, Mental state anxious
Shock of blood loss 30-40% HR, BP, Cap refill, UO ml/hr, Mental state
HR >120, BP low, Cap refill >2sec, UO ml/hr 10-20, Mental state confused
Shock of blood loss >40% HR, BP, Cap refill, UO ml/hr, Mental state
HR >140, BP low, Cap refill >2sec, UO ml/hr anuric, mental state lethargic
