Shock Flashcards
What is shock?
A state of inadequate oxygen delivery to tissues resulting in cellular dysoxia which is often accompanied by, but may be independent of a decreased systemic arterial BP
What is does oxygen delivery NOT equal?
Oxygen consumption
What are the three main types of shock?
1) Hypovolaemic
2) Distributive
3) Cardiogenic
What is cardiogenic shock subdivided into?
1) Obstructive (RV)
2) LV (cardiogenic?)
What are causes of hypovolaemic shock?
1) Haemorrhage
2) GI losses
3) Dehydration
4) Capillary leak
What are the causes of distributive shock?
1) Sepsis
2) Anaphylaxis
3) SIRS
4) Massive transfusion
5) Post-cardiac arrest
6) Adrenal crisis
7) Neurogenic
What are causes of obstructive shock?
1) Tamponade
2) Tension PTX
3) Massive PE
4) RV infarction
5) Cor pulmonale
6) Pulmonary HTN
What are causes of cardiogenic (LV) shock?
1) MI
2) Myocarditis
3) Septic cardiomyopathy
4) Arrhythmia
5) Acute mitral regurgitation
6) Critical aortic stenosis
What can shock in the RV lead to?
Shock in the LV
How does anaphylaxis cause low BP?
Vasodilation
What are the two most common causes of shock?
1) Sepsis
2) Anaphylaxis
What is tamponade?
Fluid in the cardiac sac
What is the symbol for oxygen delivery?
DO2
What is the long oxygen delivery equation?
DO2 = CO x (Hb x SaO2 x 1.34 + (PaO2 x 0.003))
What is the short oxygen delivery equation?
DO2 = CO x arterial oxygen content (CaO2)
What does a problem with any part of the oxygen delivery equation lead to?
Shock (impaired oxygen delivery)
What is the equation for the amount of oxygen dissolved in the blood?
PaO2 x 0.003
What is the equation for CO?
CO = SV x HR
What factors affect stroke volume?
1) Preload
2) Afterload
3) Contractility
What factors affect the arterial oxygen content?
1) Haemoglobin
2) SaO2 (arterial oxygen saturation)
3) PO2 (arterial oxygen tension)
Between what ranges of BP does the body compensate and what happens outside these ranges?
~ 55-250 mmHg → outside these ranges = shock
What is VO2?
Oxygen extraction from the blood
What is MRO2?
Metabolic requirement of oxygen in the cell
When does shock happen (at cellular level)?
VO2 < MRO2 → shock
What are the (non-specific) manifestations of shock?
1) Anxiety, restlessness, confusion, aggression, lethargy, coma → brain is being deprived of oxygen
2) Rapid shallow breathing
3) Nausea/vomiting
4) Rapid (weak) pulse
5) Low BP and pulse pressure
6) Pale, grey or cyanotic with clammy skin
7) Reduced urine output
8) Acidosis
9) Decreased coagulation time and increased neutrophils (after 2-5 hours)
10) Intense thirst
11) Delayed capillary refill (cold)