What percentage of maternal deaths annually are due to air embolism?

Maternal Deaths from Air Embolism

Air embolism is a rare but catastrophic cause of maternal mortality, with amniotic fluid embolism occurring in approximately 1/8,000-1/80,000 pregnancies and resulting in high maternal mortality rates of up to 80%. 1

Incidence and Mortality

• Amniotic fluid embolism (AFE) remains one of the leading causes of direct maternal death in high-income countries, with a reported incidence of approximately 2-2.5 cases per 100,000 maternities 1
• The case fatality rate for amniotic fluid embolism ranges from 13-19% in recent prospective population-based studies, though historical reports indicated mortality rates as high as 80% 1
• Venous air embolism occurs in more than half of all cesarean sections, though most cases are subclinical and do not result in death 2
• The lethal volume of air in adults has been described as between 200-300 ml, or 3-5 ml/kg injected at a rate of 100 ml/s 1

Risk Factors for Fatal Air Embolism in Pregnancy

• Pre-existing cardiac, cerebrovascular, and renal disorders increase the risk of fatal embolism during pregnancy 1
• Procedures involving central venous catheter manipulation or placement pose significant risk for air embolism 3
• Uterine surgery, maternal hypovolemia, and certain maternal positions increase risk during cesarean sections 2
• The presence of an intracardiac septal defect significantly increases the risk of fatal air embolism 2
• Other risk factors for amniotic fluid embolism include placenta previa, polyhydramnios, stillbirth, chorioamnionitis, hypertensive disorders, instrumental delivery, and cesarean section 1

Pathophysiology

• Venous air embolism causes obstruction of the right ventricular pulmonary outflow tract or obstruction of pulmonary arterioles by a mixture of air bubbles and fibrin clots 1
• This obstruction results in cardiovascular dysfunction and failure, which can rapidly lead to death if not promptly treated 1
• Amniotic fluid embolism occurs when amniotic fluid is forced into uterine veins during labor or when the placenta is disrupted by surgery or trauma 1
• The resulting pulmonary vessel obstruction by cell groups and meconium, along with an inflammatory reaction, can lead to seizures, pulmonary edema, and acute respiratory distress syndrome 1

Recognition and Management

• Immediate recognition is critical - consider air embolism in any pregnant woman with sudden cardiorespiratory collapse, particularly when associated with central venous catheter manipulation 3
• For suspected venous air embolism:
  • Administer 100% oxygen immediately to reduce bubble size 3
  • Position the patient in left lateral decubitus position 1, 3
  • If a central line is present, attempt to aspirate air 3
  • Initiate high-quality CPR following standard protocols if cardiac arrest occurs 3
• For significant pulmonary hypertension from air embolism, consider pulmonary vasodilators to unload the right ventricle 3
• Consider hyperbaric oxygen therapy for arterial air embolism with neurological symptoms 3, 4
• Activate a specialized maternal code team immediately upon recognition of the emergency 3

Prevention Strategies

• Use Trendelenburg position during central venous catheter insertion and removal 5
• Flood the surgical field with normal saline during cesarean sections when air embolism risk is high 2
• Maintain adequate hydration to prevent hypovolemia during procedures 2
• Use precordial Doppler monitoring during high-risk procedures to permit earlier diagnosis 2
• Implement proper technique for central line insertion and removal to minimize air entry 5

Common Pitfalls

• Air embolism can be easily missed if not specifically considered in the differential diagnosis of sudden cardiovascular collapse in pregnancy 3
• Pregnant patients develop hypoxemia more rapidly than non-pregnant patients, making rapid airway management essential 3
• Delay in recognition and treatment significantly increases mortality 3, 4
• The risk of air embolism is increased in pregnancy due to the hypercoagulable state and increased venous pressure 3