Shock Flashcards
What is shock?
the clinical syndrome of tissue hypoperfusion due to circulatory failure
What MAP is required for tissue perfusion?
50-60mmHg
What is mean arterial pressure?
average pressure in patients arteries in a cardiac cycle
How is MAP calculated?
1/3rd (pulse pressure) + DBP or (SBP + sDBP)/3
How is pulse pressure calculated?
SBP-DBP
What is the result of inadequate perfusion?
systemic acidosis- bad for enzymes; microcapillary thrombus; eventual cellular necrosis
What is seen dermatologically with macro circulatory changes?
mottling of lower limbs: degree correlates with mortality
What are the isigns of hypoperfusion?
mottling; GCS; UO <0.5ml/kg/hr
How can shock be tested for?
lactate
Why might lactate be very low in a very shocked patient?
perfusion is so bad that lactate isn’t getting into the bloodstream
What 2 things contribute to MAP?
CO and systemic vascular resistance
What is cardiogenic shock?
reduced force of cardiac contraction—CO and MAP
What are the peripheries like in cardiogenic shock and why?
compensatory inc. in SVR so cool clammy peripheries
What is obstructive shock?
obstruction to cardiac outflow
What are the clinical signs associated with obstructive shock?
raised JVP; distended neck veins
What are the causes of obstructive shock?
cardiac tamponade; tension pneumo; PE
What is hypovolaemic shock?
reduced blood volume—dec. venous return–reduced cardiac contraction
What is seen clinically with hypovolaemic shock?
tachycardia; cool clammy peripheries
Why does resp rate increase in shock?
compensate for acidosis
What is distributive shock?
reduced SVR due to vasodilation; reduced MAP–increase CO
What is the difference between peripheries in distributive shock and other types of shock?
warm and red peripheries vs cold and clammy
What is the most common type of distributive shock?
sepsis
What are the main types of distributive shock?
septic; anaphylactic; neurogenic
What are the results of fluid challenge?
if good systolic function: SV will increase if bad function- no inc. in SV after volume expansion
