Shock Flashcards
What is shock?
Severe imbalance between O2 supply and demand, leading to inadequate cellular energy production
Oxygen delivery =
CO x arterial O2 content
Name some consequences of shock
Na+/K+ ATPase dysfunction
Cellular necrosis and apoptosis
Acidemia
Endothelial dysfunction
Activation of inflammatory and coagulation cascades
MODs
Death
Three main types of shock
Circulatory
Hypoxic
Metabolic
T/F: A vast majority of shock is metabolic
False - vast majority is circulatory
What are the four types of circulatory shock?
Hypovolemic
Distributive
Obstructive
Cardiogenic
Explain the physiology of hypovolemic shock
Decreased intravascular volume
Decreased preload
Decreased CO
Name some causes of hypovolemic shock
Hemorrhage
Severe dehydration (GI, Renal)
Third space fluid loss
Severe burns
What is meant by distributive shock?
Maldistribution of fluid from changes in vascular tone and increased vascular permeability
Decreased SVR +/- Preload +/- Contractility
“We’ve got fluid in the pipes, just not where it needs to be”
How might anaphylactic shock be classified?
Distributive
Histamine-induced vasodilation
Anaphylaxis is a kind of distributive shock. What are some other causes?
Septic shock
Neurogenic shock
Pheochromocytoma or extreme fear
What is meant by obstructive shock?
Compression of heart or great vessel that interferes with venous return
Decreased diastolic filling and preload
Decreased CO
What are some causes of obstructive circulatory shock?
GDV
Obstruction of vena cava
Tension pneumothorax
Cardiac tamponade
PPV
Physiology behind cardiogenic shock
Decrease in forward flow from the heart due to “pump failure”
Primary decrease in CO
What are some causes of cardiogenic shock?
Systolic failure
Diastolic failure
AV valve degeneration of defects
Brady or tachy-arryhythmias
What is hypoxic shock? How common is this?
Decreased arterial oxygen content leading to decreased tissue oxygen delivery
Significantly less common than circulatory shock
Severe pulmonary disease, anemia, or dyshemoglobinemias can lead to ____________ shock
Hypoxic
What is metabolic shock?
Tissues are getting enough oxygen, but for some reason aren’t able to use it
Deranged cellular metabolism leading to inappropriate O2 tissue use
Potential causes of metabolic shock
Severe hypoglycemia
Mitochondrial dysfunction
T/F: regardless of the type of shock, the body tends to respond to all shock in a similar way
True
Discuss the baroreceptor reflex in response to shock
Baroreceptors detect decreased volume and stretch d/t decreased CO
Signal sent to increase sympathetic tone leading to direct catecholamine release from the adrenal glands
Catecholamines increase HR, contractility, and peripheral vasoconstriction
Discuss the role of chemoreceptors in response to shock
Located peripherally and centrally and sense changes in blood stream components
Result in increased respiratory rate and tidal volume (faster, deeper breaths)
What is RAAS’s role in shock?
Decreased BP detected and RAAS activated
Angiotensin II vasoconstricts and promotes Na reabsorption
ADH promotes water reabsorption
What is the hallmark for shock?
Hypotension
What is the hyperdynamic phase and what types of shock is it associated with?
Initial vasodilation instead of vasoconstriction
Seen w anaphylactic and septic shock
What is the shock organ in cats? Dogs?
Cats = lungs
Dogs = GIT
What is the overall goal for the treatment of shock?
Restore O2 delivery to tissues asap
What are some good initial treatments when managing shock?
Flow-by O2
Obtain IV access
IV fluid bolus resuscitation (unless suspect cardiogenic shock)
What kind of fluid bolus might we give in a shocky (non-cardiogenic) patient?
Isotonic crystalloid bolus
5-20mL/kg IV over 10-20 minutes
Repeat as needed up to 90mL/kg in dogs and 66mL/kg in cats
What should you always do following a fluid bolus?
REASSESS
What is the mainstay of treating obstructive shock?
Removing the obstruction
GDV - trocarize
Pleural effusion - thoracocentesis
Cardiac tamponade - pericardiocentesis
A shocky patient comes in 3 days after a GI FB removal and small intestine R&A. Based on the history, you suspect dehiscence, subsequent septic peritonitis, and septicemia. What treatments can you initiate?
Broad-spectrum antibiotics
Vasopressors like NE (remember that hyperdynamic phase?)
A few hours after vaccine administration, a dog presents to the ER with a swollen face and difficulty breathing. Based on the history, you believe the dog might be in anaphylactic shock. What should you do?
Vasopressors like E (remember that hyperdynamic phase?)
Anti-histamines
Mainstays of treating cardiogenic shock?
Correct underlying etiology
O2 therapy
NO IV FLUIDS
Minimize stress
How often should patients that have undergone resuscitation be reassessed?
Every 5-10 minutes or after every therapeutic intervention during stabilization
