SFP: embolism, infarction, and shock Flashcards
define embolus
a detached intravascular solid, liquid, or gaseous mass that is carried by the blood to a site that is distant from its origin
where do most emboli come from
existing thrombus (thromboembolism)
what are the rare origins of emboli
fat, air, amniotic fluid
what are three big outcomes of embolism
- occlusion of downstream vessels
- infarct of tissues supplied by the vessel
- ischemic necrosis
what does venous occlusion lead to
congestion and infarction
what does arterial occlusion lead to
infarct of tissues
what is the most common pulmonary thromboembolism
DVT
what are some risk factors for DVT
40+, prolonged immobility, surgery, trauma, cancer, clotting disorders, birth control
what deficiencies can lead to DVT
FACTOR 5!!!!!
also protein C and protein S
describe a saddle embolus
blocks the main pulmonary artery and its branches. this causes a sudden increase in pulmonary artery pressure, a drop in cardiac output, and sudden death
what occurs if 60% of pulmonary vasculature is obstructed
sudden death, right ventricular failure, cardiovascular collapse
multiple smaller emboli can occur as….
sequential or a showering
what percentage of pulmonary emboli are clinically silent
60-80%
how do most pulmonary emboli resolve
fibrinolytic activity and incorporation into the vascular wall
describe how repeated pulmonary emboli can cause pulmonary hypertension
- showers of pulmonary emboli cause fibrosis in the lung
- it becomes difficult for the heart to pump blood into the lung due to scar tissue
- pulmonary hypertension occurs
are those who had a previous embolism at increased risk for another?
yes
describe systemic thromboembolism
emboli that originate in the arterial system. they result in infarct downstream of occluded vessels. the result of damage is highly tissue dependent
where do 80% of systemic thromboemboli come from
cardiac mural thrombi; left ventricular wall with dilated left atrium and mitral valve disease
where do 20% of systemic thromboemboli come from
aortic aneurysm, ulcerated atherosclerotic plaques, and fragmented valve vegetation
where do the majority of systemic emboli go?
75% to lower extremities, 10% to the brain
what is a paradoxical emboli
emboli originating from a thrombus in a vein that travels through the septal defect from vein to artery in the heart; travels from right atrium, to right ventricle, through the defect, left ventricle, and the aorta. ends up in systemic artery.
describe fat embolism
can be caused by fracture of long bones or soft tissue trauma
what is fat embolism syndrome
results from a fat embolism and can result in sudden onset of symptoms 1-3 days post injury. causes respiratory distress, neurologic symptoms, and anemia/thrombocytopenia
what is a common hemorrhagic condition seen with fat embolisms?
petechiae from occlusion of cerebral and pulmonary vasculature
describe an air embolism
more than 100 mL of air entering the vasculature. can be caused by chest wall injury, obstetric procedure, and sudden changes in atmospheric pressure. can cause focal ischemia, edema, hemorrhage, and necrosis.
describe amniotic fluid embolism
amniotic fluid enters maternal circulation due to placental tear or rupture of uterine veins. results in 40% mortality.
what is the pathogenesis of amniotic fluid embolism
pulmonary emboli and edema, systemic thrombogenesis with DIC
what are the sudden onset symptoms of amniotic embolism
severe dyspnea, cyanosis, hypotensive shock, seizures and coma
what is an infarct?
an area of ischemic necrosis caused by occluding arterial supply or venous drainage.
___ causes infarct, while ___ causes obstruction and congestion
arterial events; venous occlusion
what is the most common cause of infarct
thrombosis or thromboembolic events
what is a red infarct
it occurs due to dual blood supply; it is an venous occlusion/congestion followed by arterial reperfusion. this can occur in loose tissues like the lungs and gut
what is a white infarct
occurs in organs with single arterial supply. this occurs in solid organs such as heart, spleen, and kidney
the majority of infarcts lead to…
coagulative necrosis
what is shock
a common outcome for several lethal events. it is characterized by systemic hypo perfusion. this results in reduced cardiac output and circulating blood volume. this leads to hypotension, hypoxia, cell injury, irreversible injury, then death
describe cardiogenic shock
failure of the pump. it has 70% mortality and can be from MI, ventricular rupture, cardiac tampenade, pulmonary embolism
describe hypovolemic shock
loss of blood or plasma volume that results from hemorrhage, fluid loss from burns, vomiting or diarrhea
what is septic shock
occurs from a microbial infection. the most common is gram-positive septicemia such as MRSA
describe endotoxic shock
a type of septic shock
- bacterial cell wall segments get into vascularture
- segments bind macrophage
- TLR4 activates mononuclear cells
- TNF, IL1, IL6 release
- systemic acute phase reactions occur
what are the fatal outcomes of endotoxic shock
DIC and multi-system organ failure
what is neurogenic shock
can occur due to anesthetic accident or spinal cord injury and results in loss of vascular tone and peripheral pooling of blood
what is anaphylactic shock
IgE hypersensitivity reaction that causes systemic vasodilation and increased permeability that leads to swelling of the throat and fluid loss
what are the 3 stages of hypovolemic shock
- nonprogressive: reflex compensatory mechanisms try to make up for fluid loss and nervous system changes
- progressive: widespread hypoxia and dependence on glycolysis results in low pH, endothelial injury, and DIC
- irreversible: necrosis and organ failure
