Shock, including sepsis Flashcards
What is shock?
An abnormal circulatory state in which TISSUE BLOOD FLOW IS REDUCED. This causes to CELLULAR HYPOXIA.
Reduced cellular oxygen > anaerobic metabolism > lactic acidosis (enzymes don’t function)
What does shock cause? (1)
Loss of perfusion to end organs
Cardiac output =
CO = HR x SV
Blood pressure =
BP = CO x SVR
Oxygen delivered =
Oxygen delivered = CO x O2 content of blood
What are the different types of shock?
- HAEMORRHAGIC
a. hypovolaemia - loss of circulating blood vol. - NON-HAEMORRHAGIC
a. Cardiogenic
b. Septic
c. Anaphylactic
d. Neurogenic (spinal)
What factors do you need for end organ perfusion? (3)
Airways + Breathing + Circulation = end organ perfusion
How do you improve circulation? (4)
- INOTROPES - improve myocardial performance, maintain perfusion pressure, blood flow to organs.
- VASOPRESSORS - increase SVR, maintain arterial pressure.
- IV fluids
- Bloods
(5. medicines)
What are the aims of management of shock? (4)
- Resolve lactic acidosis
- Prevent tissue ischaemia
- Optimise cardiac output
- Maintain BP
What is haemorrhagic shock?
Loss of fluid from intravascular space. Plasma vol
- Reduced venous return
- Reduced cardiac output
- Baroreceptor response
- Increased SVR
What happens when blood is lost? (3)
- RAAS is activated
- Catecholamine release
- Vasopressin release
- Vasoconstriction, increased vol, cardiac stimulation
Vasoconstrict small vessels to incr volume returning to heart to stimulate CO.
–> restore end organs perfusion
What are other causes of hypovolaemia: loss of extracellular fluid/plasma proteins
> Bleeding from trauma
GI losses (diarrhoeal, inflammatory bowel disease e.g. Crohns)
Burns
Diabetic ketoacidosis
How do you treat haemorrhagic shock?
Replace blood with blood and repair any injury.
Shock management: support physiology
1) airway
2) breathing
3) circulation
What is cardiogenic shock?
pump failure due to myocardial damage or inhibited contraction.
What causes myocardial damage? (4)
MI (coronary artery blocked)
Cardiomyopathy (heart muscle disease affects function)
Myocarditis (inflammation of heart muscle wall)
Trauma (stab)
What causes inhibited contraction (which can cause cardiogenic shock)? (3)
Local anaesthetics (effect contractility)
Anti-arrhythmic drugs
B-blockers.
What is cardiac tamponade?
When fluid collects btw inner lining of pericardium and outer surface of heart.
External pressure on heart wall muscle
- myocarditis
- trauma
- rupture heart muscles
How do you manage cardiogenic shock?
Improve myocardial O2 delivery.
preload, contractility, afterload.
If STEMI - stenting of coronary artery to open it up to allow blood flow to heart.
If cardiac tamponade - remove fluid from pericardium with needle.
What is septic shock?
It is a systemic response to infection where pathogenic organisms have released toxins.
What releases endotoxins and how?
Gram negative bacterial from cell wall.
What releases exotoxins and how?
Gram positive bacteria when they are lysed.
How does endo/exotoxin release cause altered end organ perfusion?
Endo/exotoxin release > Cytokines released (interleukins, TNF) > Cytokines release metabolites and free radicals > Blood vessels become leaky as plasma proteins are not able to retain fluid > Hypotension, low BP > Reduced delivery of blood to end organs > Increased blood lactate > Altered end organ perfusion
What does altered end organ perfusion cause?
low urine output
altered CNS functio
clotting disorders
metabolic disorders
What does the cytokine cascade cause?
increased vascular permeability, cardiac dysfunction, bone marrow dysfunction (clotting problems), thermoregulation.
