1. Respiratory Failure

3. Respiration  external respiration （ pulmonary ventilation and gas exchange in lung ）  transport of gas  internal respiration

4. concept and classification

5. The condition in which the lungs can not take in sufficient oxygen or expel sufficient carbon dioxide to meet the needs of the cells of the body. Also called pulmonary insufficiency. The condition in which the lungs can not take in sufficient oxygen or expel sufficient carbon dioxide to meet the needs of the cells of the body. Also called pulmonary insufficiency. respiratory insufficienc

6. respiratory failure Respiratory failure is a syndrome in which the respiratory system fails in one or both of its gas exchange functions: oxygenation and carbon dioxide elimination. In practice, respiratory failure is defined as a PaO 2 value of less than 60 mm Hg while breathing air or a PaCO 2 of more than 50 mm Hg.

7. respiratory failure normal reference values ： normal reference values ： PaO 2 < 60mmHg （ 8kPa ） PaO 2 < 60mmHg （ 8kPa ） with or without PaCO 2 > 50mmHg （ 6.67kPa ） with or without PaCO 2 > 50mmHg （ 6.67kPa ） RFI = PaO2/FiO2 ≤ 300

8. （ 1 ） according to PaCO 2 ■ Ⅰ ) ■ hypoxemic (Group Ⅰ ) respiratory failure a PaO 2 of less than 60 mmHg with a normal or low PaCO 2. Cause of: Edema, Vascular disease, Chest Wall. ■ ■ hypercapnic (Group Ⅱ ) respiratory failure a PaO 2 low 60 mmHg and PaCO 2 of more than 50 mmHg. Cause of: Airway obstruction, Neuromuscular disease. classification

9. （ 2 ） according to pathogenic mechanism ventilatory disorders ventilatory disorders gas exchange disorders gas exchange disorders

10. （ 3 ） according to primary site ■ central respiratory failure ■ central respiratory failure ■ peripheral respiratory failure ■ peripheral respiratory failure

11. （ 4 ） according to duration ■ acute respiratory failure ■ acute respiratory failure ■ chronic respiratory failure ■ chronic respiratory failure

12. ventilatory disorders gas exchange disorders respiratory failure obstructive ventilatory disorders disorders restrictive ventilatory disorders classification of respiration failure mechanism diffusion disorders ventilation-perfusion ventilation-perfusionmismatching

13. Ⅰ. ventilatory disorders 1. restrictive ventilatory disorders Restrictive hypoventilation is caused by the diseases Restrictive hypoventilation is caused by the diseases that affect the distensibility of the alveolar.

14. Respiratorymovement disorder disorder neuro-muscular disorders decreased strength, myasthenia gravis decreased strength, myasthenia gravis hypoxia, acidosis Respiratory movement ↓ Respiratory movement ↓ Depression of CNS damage of CNS drug overdose ▲ Disorders of the respiratory muscles alveolar distensibility Restrictiveventilatory disorders disorders respiratory failure

15. ● decrease of pulmonary surfactantsand increase of ● decrease of pulmonary surfactants and increase of surface tension force surface tension force ● diffuse interstitial fibrosis decreased lung compliance ▲ decreased lung compliance decreased thoracic compliance of lung ▲ decreased thoracic compliance of lung deformity of thorax, fracture of several ribs, tension pneumothorax, thickened constrictive pleural layer. pneumothorax, thickened constrictive pleural layer.

16. 2. obstructive ventilatory disorders ■ obstructive ventilatory disorders are caused by the diseases which share the common characterestic of causing enough narrowing within the tracheobronchial tree to increase resistance to the flow of air. etiology ■ etiology asthma, emphysema, chronic bronchitis, and bronchiectasis.

17. Obstruction is located in the airway outside the thorax ： inspiratory dysnea 1 ） central airway obstruction + expire inspire

18. ■ Obstruction is located in the airway inside the thorax ： expiratory dysnea 1 ） central airway obstruction + expire inspire

19. 2 ） peripheral airway obstruction 2 ） peripheral airway obstruction smaller airways less than 2 mm in diameter. smaller airways less than 2 mm in diameter. Determinants of airway closure are the intrinsic caliber of peripheral airways.

20. 2 ） peripheral airway obstruction 2 ） peripheral airway obstruction equal pressure point (EPP) In forced expiration, the point where intrapleural pressure and alveolar pressure are equal.

21. EPP moves distally as expiration progresses because as air leaves the alveolar unit, the pressure in the alveolar decreases hence the pressure in the airway decreases as well. Peripheral airway obstruction may be caused by: specific chemical mediators (such as histamine, leukotrienes, prostaglandins ), other substances released during inflammatory and allergic responses. forced expiration

23. 1 ） Low PaO 2 ： PaO 2 < 60mmHg 2 ） PaCO 2 change ： A. hypoventilation ： high PaCO 2. A. hypoventilation ： high PaCO 2. R=40/50 mmHg=0.8 ； R=40/50 mmHg=0.8 ； B. part hypoventilation: Low PaO 2 and normal or low PaCO 2. B. part hypoventilation: Low PaO 2 and normal or low PaCO 2. 3. The alteration of blood gas

24. Ⅱ. gas-exchanging dysfunction Ⅱ. gas-exchanging dysfunction 1. diffusion disorders The diffusion impairment is characterized by a disruption in the exchange of O 2 or CO 2 or both across the alveolar-capillary membrane. Causes: reduction and/or thicken of alveolar- capillary membrane or reduction of the diffuse time.

25. 1 ） etiology 1 ） etiology ■ reduction of diffusion membrane area Causes: emphysema, pneumonia, lobectomy Causes: emphysema, pneumonia, lobectomy increase of diffusion membrane thickness ■ increase of diffusion membrane thickness Causes: edema, fibrosis, capillary vessel dilatation Causes: edema, fibrosis, capillary vessel dilatation decreased time of blood contacts with alveolar ■ decreased time of blood contacts with alveolar

26. AA V A Q V A / Q Top 1.2L/min 0.4L/min 3.0 Middle 1.8L/min 2.0L/min 0.9 Bottom 2.1L/min 3.4L/min 0.6 ···· 2. ventilation/perfusion imbalance The dysfunction of gas exchange can arise secondary to ventilation /perfusion mismatching.

27. asthma, chronic bronchitis, obstructive emphysema, fibrosis, edema V A / Q↓ part alveolar ventilatory ↓ functional shunt↑>30% respiratory failure · · 1) type and cause of ventilation-perfusion-mismatching 1) type and cause of ventilation-perfusion-mismatching (1) decreased ratio of V A /Q underventilated in relation to their perfusion underventilated in relation to their perfusion ··

28. (2) increased ratio of V A /Q poor perfusion in relation to their ventilation with air poor perfusion in relation to their ventilation with air ·· pulmonary artery embolization, DIC in lung, vessels contract, pulmonary arteritis, dead space like ventilation V A /Q ↑ poor perfusion↓ respiratory failure

29. pulmonary consolidation,At electasis anatomical-like shunt increased of ▲ increased of anatomical-like shunt bronchiectasis anatomic shunt ↑ Pulmonary A-V shunt open↑ true shunt↑ Respiratory failure increased of anatomical shunt ▲ increased of anatomical shunt 3 ） increased of anatomical shunt Right-to-left shunts or anatomic shunt Right-to-left shunts or anatomic shunt

30. Effects of respiratory failure 1.Acid-base disturbances disorders of electrolyte balance disorders of electrolyte balance

31. Effects of respiratory failure 2.Alteration of the respiratory system peripheral chemoreceptor peripheral chemoreceptor ■ PaO 2 ↓ ＜ 60mmHg respiratory center(+) respiratory movement↑ ＜ 30mmHg respiratory center (-) respiratory movement ↓ ＜ 30mmHg respiratory center (-) respiratory movement ↓

32. Effects of respiratory failure 2.Alteration of the respiratory system PaCO2↑ central chemoreceptor (+) respiratory movement↑ PaCO2↑ central chemoreceptor (+) respiratory movement↑ ＞ 80mmHg respiratory center (-) respiratory movement ↓ ＞ 80mmHg respiratory center (-) respiratory movement ↓

33. 3. Alteration of the respiratory system 3. Alteration of the respiratory system compensatory reaction ■ compensatory reaction PaO 2 <60 mmHg ， PaCO 2 increase cardiovascular center(+) PaO 2 <60 mmHg ， PaCO 2 increase cardiovascular center(+)  increase in cardiac output : increase in stroke volume and heart rate  redistribution of blood flow

34. 3. Alteration of the respiratory system 3. Alteration of the respiratory system injurious changes PaO 2 80 mmHg cardiovascular center(-) PaO 2 80 mmHg cardiovascular center(-)  rate slow, decreased blood pressure  cardiac output decrease  pulmonary hypertension

35. ■ difficulty breathing Restricted diastolic co pulmonale ■ co pulmonale ■ pulmonary arterial embolism, capillary damage co pulmonale afterload to right ventricle ↑ chronic pulmonary hypertension Pulmonary vascular wall thickening and hardening ■ PaO 2 ↓ blood resistance ↑ blood resistance ↑ pulmonary vasoconstriction RBC ↑ blood viscosity ↑ Stenosis ■ Hypoxia, acidosis myocardial systolic and diastolic function(-) and diastolic function(-)

36. (1) Hypoxia: the nervous system is very sensible to oxygen lack. < 40~50 mmHg, serious but reversible deterioration in cerebral function ( orientation, arithmetic tasks, memory) occurs, and restlessness and confusion are common. < 40~50 mmHg, serious but reversible deterioration in cerebral function ( orientation, arithmetic tasks, memory) occurs, and restlessness and confusion are common. < 30 mmHg, loss of consciousness results. < 30 mmHg, loss of consciousness results. < 20 mmHg, irreversible damage of neural cells. < 20 mmHg, irreversible damage of neural cells. 4. Alteration of the nervous system 4. Alteration of the nervous system

37. (2) Hypercapnia: CO 2 nacosis. (2) Hypercapnia: CO 2 nacosis. a condition of confusion, tremors, convulsions, and possible coma that a condition of confusion, tremors, convulsions, and possible coma that may occur if blood levels of carbon dioxide increase to 80 mm Hg or higher. may occur if blood levels of carbon dioxide increase to 80 mm Hg or higher. 4. Alteration of the nervous system 4. Alteration of the nervous system

38. ■ Brain cell injury lysosomal membrane stability↓ lysosomal enzyme release nerve cell necrosis GABA↑ GABA↑ CSF pH↓ ＜ 7.25 EEG slow or stop PaCO 2 ↑, acidosis Cerebral vasodilation Cerebral blood flow↑ PaCO 2 ↑, acidosis Cerebral vasodilation Cerebral blood flow↑ hypoxia vascular endothelial damage extracellular brain edema hypoxia vascular endothelial damage extracellular brain edema edema on brain cell Vascular compression edema on brain cell Vascular compression Increased cerebral anoxia Increased cerebral anoxia ■ cerebrovascular injury Intracranial pressure ↑ pulmonary encephalopathy

39. 4. Alteration of the renal function 4. Alteration of the renal function 5. Alteration of the digestive system 5. Alteration of the digestive system

40. Thanks