Shock Flashcards
Define Shock
A syndrome of inadequate tissue perfusion
What is the pathogenesis of shock
Decreased perfusion leads to decreased O2 delivery
Tissue O2 requirements exceeds O2 delivery
Cellular hypoxia leads to cell dysfunction
What are the two main determinants of tissue perfusion?
Cardiac Output
Peripheral Vascular Resistance
What is the formula for Cardiac Output
Stroke volume x Heart Rate
What are the three factors that affect cardiac output
Preload
Contractility
Afterload
What are the two factors that affect Peripheral Vascular Resistance
Blood vessel diameter
Blood viscosity
What are the 4 main types of shock
- Hypovolemic
- Cardiogenic
- Obstructive
- Distributive
What is the etiology of a hypovolemic shock
Excess Fluid Loss
What can cause a hypovolemic shock
Hypovolemic shock can be classified as Hemorrhagic or non-hemorrhagic
List some causes of hemorrhagic Hypovolemic shock
Hemorrhagic:
- Post partum hemorrhage
- upper GI bleed
- penetrating trauma
- A/V fistula
-
List some causes of non-hemorrhagic Hypovolemic shock
GI loss
Increased insensible fluid loss (burn)
Renal fluid loss (adrenal insufficiency, drug induced diuresis)
Third space fluid loss (SBO/LBO, pancreatitis)
What is the pathophysiology of Hypovolemic Shock?
< intravascular volume = <preload + SV= < Cardiac Output= compensatory inc. in vascular resistance and heart rate
What is the pathophysiology of cardiogenic shock?
An underlying pathology causes dysfunction of the heart =
< contractility/ <stroke volume leading to < cardiac output
List 9 causes of cardiogenic shock
- MI
- Arrythmias
- HF
- Cardiomyopathy
- Myocarditis
- VSD
- Valve Defect (aortic/mitral regurgitation)
- blunt cardiac trauma
- drugs (Beta blockers, CCBs)
What is the pathophysiology of obstructive shock
Obstruction of the heart and its Great Vessels> inability of the heart to circulate blood > dec. Cardiac Output > compensatory inc. in Systemic vascular resistance >