• Clinical science

Nonthrombotic embolism


Embolisms of fat, air, and amniotic fluid are uncommon but potentially life-threatening events caused when these substances enter the circulatory system. Fat emboli mostly originate from the bone marrow in patients with long bone fractures. Air can enter the circulatory system during surgical procedures (mostly neurosurgery), while amniotic fluid emboli occur during delivery. The emboli usually lodge within the pulmonary arteries and cause right ventricular outflow obstruction and circulatory collapse. Clinical features of special embolisms typically include acute onset of hypoxia, hypotension, and neurological symptoms (altered consciousness, seizures, coma). The diagnostic sign of fat embolism is a petechial rash on the upper body (if present), while that of venous air embolism is a mill wheel cardiac murmur. Diagnosis of any type of special embolism is primarily clinical, with arterial blood gas evaluation, ECG, and chest x-ray providing additional evidence. Treatment is mainly supportive and includes oxygenation, mechanical ventilation, and administration of vasopressors, if necessary. Mortality rates of all types of special embolisms are high.

Fat embolism

  • Treatment: supportive care in an intensive care unit
  • Prognosis: mortality rate ∼ 15%


Air embolism

Venous air embolism Arterial air embolism
Clinical features
  • Treatment
    • General measures
      • Compression of the suspected site of entry (airtight sealing)
      • Correction of hypoxia and hypotension
      • Initiate CPR, if necessary
    • Position change (venous air embolism): Trendelenburg (head down position) and left lateral decubitus (Durant's maneuver)
    • Central venous line insertion and direct aspiration of air bubbles from the cardiac chambers
  • Prognosis: high mortality rate (≥ 30%)


Amniotic fluid embolism