Saturday, June 12, 2010

Saturday June 12, 2010
Oxygen toxicity!

Oxygen is essential to life but can turn into a poison too. Most molecular oxygen used by mitochondria is metabolically reduced completely to water during normal cellular respiration, but a certain quantity of partially reduced, reactive oxygen metabolites is also generated. Chief among these toxic metabolites are superoxide anion, hydrogen peroxide and reactive hydroxyl radicals. Of these, the last are believed to be the most toxic.

According to literature available - On 100% oxygen breathing

  • After 6 hours - decreased tracheal mucus velocity is detectable
  • After 12 hours - signs of tracheobronchitis appear
  • Between 24 - 30 hours - abnormalities in gas exchange are detectable
  • At 72 - 96 hours - edema can be documented
  • After 96 hours - fibrosis may began

Jackson RM. Oxygen therapy and toxicity. In: Ayres SM, Grenvik A, Holbrook PR, Shoemaker WC, eds. Textbook of Critical Care. 3rd ed. 784-789