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Hyperoxyc test in man

Hyperoxyc test in man. MUDr. Dobroslav Hájek, CSc. MUDr. Michal Jurajda. The atmosphere. N 2 78,1% O 2 20,9% CO 2 0,03% noble gases 1%. Concentration of gases. Partial pressure- pressure of the given gas in the mixuture of gases. atmospheric pressure ????.

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Hyperoxyc test in man

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  1. Hyperoxyc test in man MUDr. Dobroslav Hájek, CSc. MUDr. Michal Jurajda

  2. The atmosphere • N2 78,1% • O2 20,9% • CO2 0,03% • noble gases 1%

  3. Concentration of gases • Partial pressure- pressure of the given gas in the mixuture of gases.

  4. atmospheric pressure ????

  5. Ventilation under extrem pressure conditions • High altitudes – low pressure • Diving – high pressure • Remember: optimal pO2 cca 21 kPa

  6. Hyperbaric oxygenation • - increases physically dissolved oxygen in blood and tissues

  7. Hyperbaric therapy is used in: • CO intoxication. • Air embolism. • Decompression. • Anaerobic infections. • Non healing wounds

  8. Hemoglobinu saturation

  9. Oxygen measurements • saturometer – saturation of Hb (%) • oxymeter - paO2 (Pa) lung function Fi O2 paO2

  10. Right to left shunt • Hypothetical fraction of blood flow (right ventricle output) passing the lungs without beeing oxygenated.

  11. Right to left shunt • Anatomical • Functional

  12. Functional

  13. Dead space The dead space (alveoli with low ventilation/perfusion ratio) incrase the right-to left shunt.

  14. paO2 = S.pvO2+(1-S).piO2 • paO2 = S.pvO2-S.piO2+ piO2 • S.pvO2-S.piO2 = paO2-piO2 • S.(pvO2-piO2) = paO2-piO2 • S = (paO2-piO2)/(pvO2-piO2) • S = (piO2-paO2)/(piO2-pvO2)

  15. Remember • When the increased right-to left shunt is caused by vascular bed involvement (typically: lung embolism) the response of partial oxygen pressure in arterial blood (paO2)to oxygen administration is very poor. (The paO2 increase is very low when oxygen is administered)

  16. Clinical cases • Poisoning by hyptotic or sedative drugs (e.g. barbiturates, benzodiazepins, morphin) • Foreign body (corpus alienum) in bronchus with its obstruction • Ventilation/perfusion unbalance.

  17. The objective • Estimate rght to left shunt

  18. Material • Transcutaneous oxymetr • Medicinal oxygen in gas bottle with pressure reduction valve and flow regulation valve. • Mask with gas blender and delivery hose

  19. Leland C. Clark

  20. The method • Increasing FiO2 increases paO2 • paO2 can be measured in arterial blood or in arterialised capillary blood by transcutaneous oxymeter (heated electrode). • The incerease of paO2 is dependent on FiO2 and right to left shunt.

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