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Air embolism

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Aetiology

Pathophysiology

Clinical features

Management

Further reading

 

Aetiology

  • risk of air embolism whenever a surgical wound disrupts veins creating a blood-air interface that lies above the level of RA eg craniotomy
  • air may be left in circulation after arterial surgery
  • injection during medical procedures
  • open heart surgery
  • haemodialysis
  • vaginal insufflation during oral sex
  • crush injury of chest*
  • overpressure injury to lung during scuba diving due to ascent with a closed glottis*

* = may lead to injection of air into pulmonary veins and hence embolization into brain with prior pulmonary air emboli

Pathophysiology

- introduction of a small volume of air into venous circulation usually well tolerated
- primary pathophysiological event is intense vasoconstriction of pulmonary circulation (air lock effect interferes with RV outflow). Results in VQ mismatch, hypoxia, interstitial pulmonary oedema, systemic hypotension
- rise in RA pressure may create right to left shunt across patent foramen ovale (patent in 20-30%) with risk of paradoxical emboli

Clinical features

- sudden occurrence of unexplained cardiopulmonary dysfunction with neurological findings during or soon after a surgical procedure should suggest possibility of venous air embolism leading to paradoxical emboli
- churning murmur over L sternal border
- hypotension
- hypoxia
- crackles
- neurological abnormalities include coma, hemiplegia, visual disturbances, disorientation, apnoea

Management

- place in left lateral head down position to decrease air leaving through RV outflow tract
- insert CVP line and aspirate air
- supportive treatment
- avoid PEEP: impairs haemodynamic performance, does not protect patient against air embolism and probably further increases risk of paradoxical emboli
- uncontrolled data suggest that hyperbaric oxygen with recompression to the equivalent of 60 feet is beneficial in cerebral air embolism even if treatment is delayed for 4-6h

Further reading

Bove AA. Air embolism and decompression sickness. In Rippe, 3rd ed, 1996

© Charles Gomersall July 1999

 


©Charles Gomersall, April, 2014 unless otherwise stated. The author, editor and The Chinese University of Hong Kong take no responsibility for any adverse event resulting from the use of this webpage.
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