Patho Respiratory

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Patho Respiratory
2012-04-30 18:04:43
Lecture 20

Lecture 20
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  1. ARDS
  2. What are the mechanism of lung changes in ARDS?
  3. What happens with ARDS acutre respiratory failure?
    • - decreased oxygen exchange hypoxemia
    • - decrease lung volume- atelectasis
    • Results in confusion, decreased responsiveness, progressive metabolic and respiratory acidosis, cariac arrhythmias, shock
    • Acute respiratory failure- deteriorating trent- end result of many pulmonary conditions
  4. Partial pressures of respiratory gases
  5. What are the acute respiratory failures?
    • Severe hypoxemia PaO2 < 50mmHg norm 80-100
    • Hypercapnia PaCO2 >50 norm 35-45
    • Ph decreasing <7.3 norm 7.35-7.45
  6. What happens as a result of acute respiratory failure?
    • complicated by relex pulmonary vasoconstriction from the hypoxia or acidosis
    • impairs lung perfusion and increases cardiac workload
    • Respiratory arrest
  7. What are the gas diffusion problems of Acute respiratory failure?
    • Partial pressure- gas concentration or partial pressure changes, obstruction.
    • Diffusion- SA, respiratory membrane thickness, fluid excess
    • Posture- upright ventilation and perfusion best in lower lobe, upper lobe less compliant than lower lobes, BP lower in apices (top/ apex) of the lung.
    • Supine/ side lying change regional perfusion and ventilation
  8. What is the normal ventilation and perfusion ratio of the lungs?
    • - Normal approx 0.8- 0.9
    • - Limited autoregulation
  9. What happens if there is a mismatch with the perfusion and ventilation of the lungs?
    • - Inadequate ventilationbut good perfusion = blood is not ventilated resulting in right to left shunt - decrease systems O2 and hypoxemia
    • - Inadequate perfusion but well ventilated = alveolar dead space
  10. How much O2 is dissolved in the plasma?
  11. How is O2 transported?
    • bounded to haemoglobin
    • O2 exchanges between 20-40 PO2 and when only 50% of Hb is saturated.
    • The exchange depends on O2, CO2, temp and plasma pH.
  12. How much carbon dioxide is dissolved in plasma?
  13. What % of CO2 is loosely bound to the globin portion of Hb?
  14. How is most of the CO2 carried around the body?
    diffused into RBC for carbonic acid- bicarbonate buffer system for serum pH maintenance
  15. CO2
  16. Acid- Base Balance
  17. Respiratory Acidosis
  18. Acidosis?
  19. Alkalsis?
  20. Summary Acidosis- Alkalosis: