Shock Flashcards
What is shock?
An abnormal circulatory state in which tissue blood flow is reduced. Causes cellular hypoxia
What is cardiac output?
HR x SV
How does shock lead to lactic acidosis?
Reduced cellular oxygenation
Anaerobic metabolism
Lactic acidosis (reduced pH)
What are the 2 types of shock?
Haemorrhagic
Non haemorrhagic
What is haemorrhagic shock?
Hypovolaemia - Low blood volume when bleeding
Loss of fluid from intravascular space
What is non haemorrhaigc shock?
Cardiogenic
Septic
Anaphylactic
Nerurogenic (spinal)
Where does blood sit normally?
42 L total
1/3 in interstitial fluid
2/3 in cells
3L in plasma
What does haemorrhagic shock lead to?
Reduced venous return
Reduced cardiac output
Baroreceptor response (at bifurcation of carotid)
Increased SVR
Other than bleeding, what are other causes of hypovolaemia?
GI losses- sever diarrhoea
Burns
Diabetic ketoacidosis
What are the aims of shock management?
Resolve lactic acidosis
Prevent tissue ischaemia
Optimise CO
Maintain BP
How do we manage shock?
ABC
Support physiology
1) Inotropes improve myocardial performance and maintain perfusion pressure to keep blood flow to the organs
2) Vasopressors increase SVR and maintain mean arterial pressure
What is cardiogenic shock?
Non - haemorrhagic shock
Pump failure via either myocardial damage or abnormal contraction
1) Myocardial damage - MI (IHD), myocarditis, trauma
2) Abnormal contraction - LA, anti arrythmic drugs, beta blockers, caridac tamponade when fluid is in the pericardium and the heart cant pump
How do we improve cardiogenic shock?
Give chronotropes - increase rhythmic activity
What is septic shock?
Non haemorrhagic shock
Systemic response to infection
What is an endotoxin?
Released from gram -ve bacteria
What is an exotoxin?
Released from gram +ve bacteria
What is the process of septic shock?
Endo / exo toxin released
Cytokines released
Metabolites and free radicals
What does septic shock cause?
Hypotension
Increased blood lactate
Altered end organ perfusion - low urine output, altered CNS, clotting disorders, metabolic disorders
How do you manage septic shock?
support physiology
antibiotics
eliminate source
What is anaphylactic shock?
Non haemorrhaigc shock
exposure to allergen, mast cells, histamine, complement cascade, systemic effects
How do you manage anaphylactic shock?
adrenaline, O2, fluids, corticosteroids, antihistamines, beta 2 agonists
What is neurogenic shock?
Non haemorrhaigc shock
Loss of normal sympathetic activity
Due to trauma, drugs, tumor of spinal cord
What does neurogenic shock cause?
Vasomotor paralysis below level of injury
Decreased peripheral vascular resistance
Blood pools in capillary beds
Reduced venous return, CO and BP
