Oxygen toxicity: Difference between revisions

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**Most common in hyperbaric oxygen therapy, scuba divers and prolonged administration of normobaric supplemental oxygen
**Most common in hyperbaric oxygen therapy, scuba divers and prolonged administration of normobaric supplemental oxygen
**Pulmonary toxicity occurs sooner and at lower partial pressures than CNS toxicity<ref name="Hedley" />, however there is no predictable pattern or sequence of symptoms for CNS toxicity (initial symptom may be seizure/coma)<ref name="Bitterman" />
**Pulmonary toxicity occurs sooner and at lower partial pressures than CNS toxicity<ref name="Hedley" />, however there is no predictable pattern or sequence of symptoms for CNS toxicity (initial symptom may be seizure/coma)<ref name="Bitterman" />
{{Diving Physiology}}


==Clinical Features==
==Clinical Features==

Revision as of 13:15, 18 July 2020

Background

  • The harmful effects of breathing oxygen at higher partial pressures than normal
    • Partial pressure of O2 at sea level = 0.21 ATM
  • Toxicity based on both time of exposure and partial pressure of oxygen
    • Generally, FiO2 of 40% or less (0.40 ATM) can be tolerated indefinitely[1]
    • Most common in hyperbaric oxygen therapy, scuba divers and prolonged administration of normobaric supplemental oxygen
    • Pulmonary toxicity occurs sooner and at lower partial pressures than CNS toxicity[1], however there is no predictable pattern or sequence of symptoms for CNS toxicity (initial symptom may be seizure/coma)[2]

Diving Physiology

  • Pascals Law applies to the diving body (without air filled areas such as lungs) states that the pressure applied to any part of the enclosed liquid will be transmitted equally in all directions through the liquid.
  • Boyles Law applies to the diving body's air filled areas such as lungs, sinuses, middle ear, and states that the volume and pressure of a gas at a given temperature are inversely related.
    • At 2 ATA (10m/33ft) a given gas would be 1/2 it's volume, at 3 ATA (20m/66ft) it would be 1/3 it's volume and so on.
Boyle's Law

Clinical Features

Pulmonary

Central nervous system

Ocular

  • Retinopathy of prematurity (retrolental fibroplasia) - seen in premature infants
  • Hyperoxic myopia - seen in adults exposed to repeated toxic levels of oxygen[4]
    • Resolves spontaneously over several weeks

Differential Diagnosis

Diving Emergencies

Evaluation

  • Generally clinical

Management

  • Lower inhaled partial pressure of oxygen to as low as tolerated while maintaining tissue perfusion[5]

Disposition

  • Admit

See Also

External Links

References

  1. 1.0 1.1 Hedley-Whyte J. Pulmonary Oxygen Toxicity: Investigation and Mentoring. The Ulster Medical Journal. 2008;77(1):39-42.
  2. 2.0 2.1 Bitterman H. Bench-to-bedside review: Oxygen as a drug. Critical Care. 2009;13(1):205. doi:10.1186/cc7151.
  3. Thomson L, Paton J. Oxygen toxicity. Paediatr Respir Rev. 2014 Jun;15(2):120-3.
  4. Anderson B, Farmer JC. Hyperoxic myopia. Transactions of the American Ophthalmological Society. 1978;76:116-124.
  5. Deutschman, C. S., & Neligan, P. J. (2010). Evidence-based practice of critical care. Philadelphia, PA: Saunders/Elsevier.