Emboli

Emboli definition

Emboli are detached intravascular mass of solid, liquid or gaseous material that is carried by the blood to a site distant from its point of origin

Embolic material

•    Air/nitrogen embolus

•    Fat/bone marrow embolus

•    Thromboembolus

•    Amniotic fluid embolus

•    Foreign bodies (eg. bullet)

•    Tumour embolus

•    Cholesterol (atherosclerotic debris) embolus

Air Emboli

o    Air emboli may enter the circulation during obstetric procedures or after chest wall injury

o    Excess of 100cc needed to cause clinical effect

The air bubbles coalesce and physically obstruct blood flow to right side of heart and pulmonary circulation causing sudden death

o    Decompression sickness caused when individuals are exposed to sudden changes in pressure which can be seen in scuba/deepsea divers, underwater construction workers, individuals in unpressurized aircraft

o    Gas breathed in under pressure bubbles out into vasculature when these individuals undergo rapid ascent

o    Gas bubbles within skeletal muscle and supporting tissues in and around joints causes “the bends”

o    May cause focal ischemia in organs such as the brain, heart, etc.

o    In lungs, edema, hemorrhage, and focal atelectasis or emphysema may occur leading to dyspnea

o    Chronic decompression disease (caisson disease) occurs in workers working in pressurized tunnels under bridges

o    Results in persistent gas emboli of the skeletal system causing ischemic necrosis of femoral, humeral and tibial heads

Fat and bone marrow emboli

o    Occurs after long bone fractures or after soft tissue trauma and burns

o    Occurs in 90% of patients with severe skeletal trauma, however <10% manifest symptoms

o    Characterized by pulmonary insufficiency, neurologic symptoms, anemia, and thrombocytopenia

o    Symptoms begin 1-3 days after injury with sudden onset of tachypnea, dyspnea, and tachycardia

o    Neurologic symptoms include irritability, restlessness, delirium and coma

o    Platelets adhere to fat globules and are removed from circulation causing thrombocytopenia

o    Erythrocytes aggregate and undergo hemolysis

o    Diffuse petechial rash is seen in non-dependent areas in 20-50% of patients

o    Fatal in up to 10% of cases

Thrombus

Pulmonary thromboembolus

-    >95% are due to above knee deep venous thrombosis

-    60-80% are clinically silent because of their small size

-    Complications include:

•    Sudden death

•    Pulmonary hypertension (especially from multiple thromboemboli)

•    Cor pulmonale (right heart failure)

•    Cardiovascular collapse

•    Pulmonary hemorrhage

•    Pulmonary infarct

Systemic thromboembolus

-    80% arise from intracardiac mural thrombi (2/3 associated with left ventricular wall infarcts and ¼ associated with atrial fibrillation secondary to mitral valve disease)

-    Remainder arise from aortic aneurysms, thrombi on ulcerated atherosclerotic plaques, fragmentation of valvular vegetation, or paradoxical emboli

-    Can cause abscesses (if septic), death

Major sites for embolization (and ischemic necrosis) are:

•    Lower extremities (75%)

•    Brain (10%)

•    Intestines

•    Kidney

•    Spleen

•    Upper extremities

Amniotic fluid

o    Uncommon complication of labour and post-partum period

o    Mortality rate of 20-40%

o    Due to infusion of amniotic fluid into maternal circulation via tear in placental membranes or rupture of uterine veins

o    Characterized by severe dyspnea, cyanosis, hypotensive shock, seizures and coma

o    If patient survives initial crisis, pulmonary edema can occur and 50% develop DIC