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Hypercarbia and Hypoxemia

Hypercarbia and Hypoxemia. 11.7.11. What happens to our cells if we don’t get enough O 2 ?. What happens to our cells if we don’t get enough O 2 ?. Cannot make ATP. What happens to our cells if we don’t remove CO 2 ?. What happens to our cells if we don’t remove CO 2 ?.

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Hypercarbia and Hypoxemia

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  1. Hypercarbiaand Hypoxemia 11.7.11

  2. What happens to our cells if we don’t get enough O2?

  3. What happens to our cells if we don’t get enough O2? Cannot make ATP

  4. What happens to our cells if we don’t remove CO2?

  5. What happens to our cells if we don’t remove CO2? CO2 is not bad by itself but can combine with H2O in the blood  makes carbonic acid  change in pH can cause structure changes in proteins  if 3D structure can lead to loss in function.

  6. Why is PIO2 150 mmHg if atmospheric PO2 is 160 mmHg?

  7. Why is PIO2 150 mmHg if atmospheric PO2 is 160 mmHg? Saturation with H2O in the lung space decreases the PO2

  8. Causes of Hypoxemia 1. 2. 3. 4.

  9. Causes of Hypoxemia 1. Diffusion Impairment 2. V/Q Abnormalities 3. Shunt 4. Hypoventilation

  10. Diffusion impairment . VO2 = K x A x (PAO2 – PaO2)/T

  11. Diffusion impairment . VO2 = K x A x (PAO2 – PcapO2)/T How does the rate of transport change with: -Increased thickness, ie. with fibrosis? -Decreased surface area, ie pneumonia? -Decreased PcapO2, less O2 in the capillary blood?

  12. Diffusion impairment . VO2 = K x A x (PAO2 – PcapO2)/T How does the rate of transport change with: -Increased thickness, ie. with fibrosis? Slow -Decreased surface area, ie pneumonia? Slow -Decreased PcapO2, less O2 in the capillary blood? fast, increased diffusion

  13. V/Q Abnormalities • Upper parts of the lung receive more/less blood supply than the lower parts (gravity). • Upper parts of the lung also receive more/ less of the tidal volume.

  14. V/Q Abnormalities • Upper parts of the lung receive more/lessblood supply than the lower parts (gravity). • Upper parts of the lung also receive more/ less of the tidal volume.

  15. V/Q Abnormalities • The result is that the upper parts of the lung receive relatively more/less ventilation than they do blood flow, while the lower parts of the lung receive relatively more/less ventilation than they do blood flow.

  16. V/Q Abnormalities • The result is that the upper parts of the lung receive relatively more/less ventilation than they do blood flow, while the lower parts of the lung receive relatively more/lessventilation than they do blood flow.

  17. Shunt Definition: Let’s take a short cut! But is it a good short cut?

  18. Shunt Definition: When blood passes from the right heart to the left heart without becoming oxygenated?

  19. Shunt Which causes blood to go from the right to left heart without going through the lungs? • Foreign object (ie. Peanut) • Bronchial circulation • Pneumonia or abundant pus • Foramen Ovale

  20. Shunt Which causes blood to go from the right to left heart without going through the lungs? • Foreign object (ie. Peanut) • Bronchial circulation • Pneumonia or abundant pus • Foramen Ovale

  21. Shunt Bronchial circulation- only goes through the larger airways and does not reach the alveolar region Foramen Ovale- system established in utero that may not close when the baby is born

  22. Shunt What happens with these two? Foreign object (ie. Peanut) Pneumonia or abundant pus

  23. Shunt What happens with these two? Foreign object (ie. Peanut) Pneumonia or abundant pus Blood goes through the lungs but does not come into contact with the gas exchange region.

  24. Does hypoventilation cause hypoxemia or hypercarbia?

  25. Does hypoventilation cause hypoxemia or hypercarbia? BOTH!!

  26. Hypoventilation What things can cause hypoventilations? 1. 2. 3. 4.

  27. Hypoventilation What things can cause hypoventilations? 1. Problems with nerves 2. Problems with muscles 3. Drugs that suppress resp. drive (morphine) 4. Problems with central resp. drive (CCHS, Ondine’s)

  28. Hypercarbia In addition to hypoventilation, Think ALVEOLAR VENTILATION Think DEAD SPACE

  29. How to calculate alveolar ventilation?

  30. How to calculate alveolar ventilation? VA = (VT ‑ VD) x f

  31. What happens when you increase dead space? VA = (VT ‑ VD) x f

  32. What happens when you increase dead space? VA = (VT ‑ VD) x f Incr. dead space  decrease alveolar ventilation  increase PaCO2 = hypercarbia if above 40 mmHg

  33. Dead Space Name 3 things that cause changes in dead space.

  34. Equipment -Snorkel -Gas Mask -Ventilator

  35. Deep Vein Thrombosis How does DVT cause dead space?

  36. Deep Vein Thrombosis How does DVT cause dead space? Sedentary  blood clot travels to lung  embolus creates dead space  decreased gas exchange  air in and out is unchanged

  37. Air can get in but gas exchange surface is destroyed.

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