HEMODYNAMICS LECTURE 3: Shock Flashcards
Blood pressure is the product of what?
Cardiac output x Systemic vascular resistance
Cardiac output is the product of what?
Heart rate x Stroke volume
What 3 factors determine systemic vascular resistance?
- Blood viscosity
- Blood vessel length (body size)
- Vasoconstriction
What are the two key signs of shock?
Systemic hypotension and hypoperfusion
Which type of shock is due to the heart’s inability to pump blood effectively?
Cardiogenic shock
Which type of shock is due to blockage that prevents adequate filling or output?
Obstructive shock
What are 2 examples of obstructive shock?
PE, cardiac tamponade
Which type of shock is due to a marked drop in blood volume?
Hypovolemic shock
Which type of shock involves systemic vasodilation resulting in impaired blood flow?
Distributive shock
What are 3 examples of distributive shock?
- Anaphylactic shock
- Neurogenic shock
- Septic shock
Why may a brain or spinal cord injury result in neurogenic shock?
Impaired sympathetic nervous system activity leads to vasodilation
Why may a type I hypersensitivity reaction result in anaphylactic shock?
Histamine is released, resulting in vasodilation and increased vascular permeability
Name the sequence of events that happens as a result of untreated shock
- Hypoperfusion and cellular hypoxia
- Production of free radicals, inflammatory cytokines, lactic acid
- Endothelial damage
- Increased vascular permeability causing further volume loss
- Acidosis, hypercoagulability
- End organ damage and death
What are the 3 stages of shock?
- Non-progressive
- Progressive
- Irreversible
What is the key difference between the non-progressive and progressive stages?
In the progressive stage the compensatory mechanisms begin to fail
What 4 compensatory mechanisms are activated in the non-progressive stage?
- Vasodilation to maintain perfusion
- BHP drops to prevent fluid being pushed out of vessels
- Increased heart rate, contractility, redirection of blood to central organs due to baroreceptors
- RAA pathway to increase volume
In the progressive stage, what 2 things happen in the lungs?
- Tachypnea, dyspnea, to compensate for hypoxia
- Pulmonary edema
In the progressive stage, what happens in the kidneys?
RAA pathway and vasocontriction lead to oliguria
What are 3 things lactic acid buildup leads to?
- Vasodilation causing blood stasis in capillary beds, this blood becomes hypoxic and coagulative
- Decreased cardiac output
- Endothelial injury
In the GI system, what are 3 clinical manifestations of shock?
- Nausea, abdo pain
- Paralytic ileus
- GI bleed
What are the 2 goals of treating shock?
- Increase blood pressure
- Increase urine output
Which 2 types of shock have the poorest outcomes?
- Cardiogenic
- Septic
