Respiratory Failure

1. The department of pathophysiology 万用卡 Respiratory Failure SUN Huilan

2. O2 CO2 CO2 External respiration circulation Internal respiration

3. What is respiratory failure Respiratory failure is a pathological process In which the external respiratory dysfunction leads to an abnormal decrease of arterial partial pressure of oxygen with or without carbon dioxide retention.

4. How to Judge respiratory failure （1）PaO2< 8kpa（60mmHg） （2）PaCO2> 6.6 kpa（50mmHg） classification of RF： Hypoxemic(Group Ⅰ）RF——（1） Hypercapnic（ Group Ⅱ）RF——（1）＋（2）

5. Etiology and Pathogenesis of RF Ventilatory disorders Diffusion disorders Ventilation-perfusion imbalance Anatomic shunt

6. Etiology and Pathogenesis of RF (1) Ventilatory disorder Restrictive Ventilatory disorders Obstructive Ventilatory disorders

7. Etiology and Pathogenesis of RF (1) Restrictive Ventilatory disorders Paralysis of the respiratoy muscles Decreased compliance of chest wall Decreasedcompliance of lungs Hydrothorax or pneumothorax

8. 大脑皮层——调节呼吸肌作随意运动 外伤、中毒 出血、感染 脑桥、延髓——不随意的自主节律呼吸调节 脊髓灰质炎、高位截瘫 脊 髓 肋间神经 多发性神经炎 肋间肌 重症肌无力、多发性肌炎 大量腹水、上腹巨大肿物 胸 廓 隔肌 肋骨、胸骨 外伤、骨折 胸膜及胸膜腔 气胸、大量胸腔积液

9. Etiology and Pathogenesis of RF (1) Obstructive Ventilatory disorders Central airway obstruction Peripheral airway obstruction

10. O2 O2 气管、支气管 肺泡膜 肺血管 口 鼻 喉头 肺泡 CO2 CO2 意外 异物 肺水肿 肺泡癌 炎症 水肿 炎症 异物 异物 肿瘤 哮喘 纤维化 间质 水肿 休克 栓塞

11. Central airway obstruction Peripheral airway obstruction

12. Extrathoracic variable obstruction expiration inspiration

13. Intrathoracic variable obstruction expiration inspiration

14. Peripheral airway obstruction 0 ＋10 ＋20 0 ＋10 ＋20＋30＋20 ＋20＋20 ＋20 ＋25 ＋35 ＋20＋20 ＋20＋20 Chronic bronchitis emphysema nomal

15. Ventilatory disorders Blood gas LowPaO2 andHigh PaCO2

16. O2 O2 气管、支气管 肺泡膜 肺血管 口 鼻 喉头 肺泡 CO2 CO2 意外 异物 肺水肿 肺泡癌 炎症 水肿 炎症 异物 异物 肿瘤 哮喘 纤维化 间质 水肿 休克 栓塞

17. Etiology and Pathogenesis of RF (2) Areaof alveolar-capillary membrane↓ Thicknessof alveolar-capillary membrane ↑ Diffusion disorders Exchenge time ↓

18. alveolar-capillary membrane surfactant O2 CO2 Alveolar epithelium Capillary endotheliocyte

19. Diffusion disorders Blood gas LowPaO2 andnomal PaCO2

20. Etiology and Pathogenesis of RF (3) Local hypoventilation VA/Q ↓ Functional shunt Ventilation- perfusion imbalance Local hypoperfusion VA/Q ↑ Dead space like ventilation

21. Ventilation-perfusion imbalance Blood gas LowPaO2 and Nomal or low or high PaCO2

22. Ventilation-perfusion imbalance Functional shunt Blood gas

23. Ventilation-perfusion imbalance Dead space like ventilation Blood gas

24. Etiology and Pathogenesis of RF (4) Anatomic shunt abnormal anatomical shunt Be not ventilated at all Pulmonary edema Atelectasis Pulmonary arterio-venous fistulas

25. Anatomic shunt No blood –gas exchange Applying O2can’t increase PaO2 Functional shunt blood –gas exchange decrease Applying O2 can increase PaO2 Functional shunt andAnatomic shunt

26. Anatomic shunt Blood gas LowPaO2

27. ARDS adult/acute respiratory distress syndrome

28. What is ARDS? ARDS is a common form of acuterespiratory failure in adult that is characterized by dyspnea,hypoxia.

29. Recognition ofARDS. History:Systemic or pulnonary insult Chest radiograph:Diffuse pulnonary infiltrates Respiratorydistress:Labored breathing,tachypnea Severe hypoxemia:refractory to treatment with supplement of oxygen

30. Sequential development of ARDS

31. Trauma,Shock,Infection and other causative factor Pulmonary hypoperfusion and hypoxemia Platelet aggregation Damage to epithelium Damage to endothelium Mechamical obstruction Increased vascular permeability Release of vasoactive substances Leakage of fluid and plasma into lungs Stagnation of blood Noncardiogenic pulmonary edema or hemorrhage Decreased surfactant Alveolar filling Atelectasis Hypoxemia

32. Pathogenesis of ARDS

33. Stimulus Complement activation C5a Sequestration of neutrophils in lungs Active oxygen Arachidonic acid metabolites Lysosomal proteinase Epithelial and endothelial Cell damage Pulmonary vasoconstiction Increased pulmonary permeability Pulmonary hypertension Pulmonary edema

34. Pathophysiology of ARDS

35. causative factor alveolar-capillary membranedamage inflammation Pulmonary edema Bronchia constriction Atelectasis Pulmonary vasoconstriction Microvascular thrombus Diffusion disorders Dead space ventilation Pulmonary shunt Hypoxemia

36. COPD Chronic obstructive pulmonary disease

37. What is COPD? COPD is a kind of chronic obstructive ventilatory disorders caused by chronic bronchitis and emphysema

38. Pathophysiology of RF in COPD

39. COPD surfactant ↓ respiratory muscles failure Peripheral airway obstructed and convulsion diffusion membrane↓ underventilated or Poor perfusion Obstructive ventilatory disorders Ventilation-Perfusion mismatching Restrictive ventilatory disorders Diffusion disorders Respiratory Failure

40. Functional and Metabolic Alterations in Respiratory Failure (1) 1.Metabolic acidosis K＋↑ 、Cl－ ↑ 2.respiratory acidosis K＋↑ 、Cl－↓or normal 3.respiratory alkalosis K＋ ↓ 、Cl－ ↑ Acid-base disturbance

41. Functional and Metabolic Alterations in Respiratory Failure (2) Ventilation increase 60mmHg 50mmHg carotid medulla PaCO2 80mmHg PaO2 30mmHg medulla medulla 90mmHg Ventilation depression 20mmHg Respiratory system 1

42. Functional and Metabolic Alterations in Respiratory Failure (2) Cheyne-stokes respiration PaCO2↑ Central depression Central excitement PaCO2↓ Respiratory system 2

43. Functional and Metabolic Alterations in Respiratory Failure (3) Hypoxia、Hypercapnia ↓ 【H＋】↑ Pulmonary embolism、Pumonary ateriolitis Pulmonary ateriolosclerosis Pulmonary hypertension chronical polycythemia Blood viscidity↑ right ventricle Afterload ↑ Dyspnea R Hypoxia acidosis Heart failure Heart extrusion Cardiovascular system

44. Functional and Metabolic Alterations in Respiratory Failure (4) Neural cell cerebrovascular Activity of Glutamate decarboxylase↑ Activity of phospholipase↑ acidosis Cerebrovascular Vasodilation Damage endothelium Membrane potential↓ neurotransmitters↓ ATP ↓ IntracellularCa2＋ ↑ Hypoxia ATP ↓ ↓ Na＋－K＋bump Nervous system

45. Principlesof treatment of Respiratoryfailure • Correcting the cause • Relieving the hypoxemia and hypercapnia

46. 男,32岁, 有肺结核病史，咳血水样痰,伴胸闷、气短、乏力。 查体: 发热,体温 39.2℃,脉搏120次/分 ,呼吸38次/分, 急性病容 , 极度呼吸困难, 贫血外观,口唇末稍明显发绀, 双肺可闻及中、小水泡音, 用支气管解痉剂无效。 血气分析 Pa2 :42.3ｍｍＨｇ,PaＣＯ2 :28.2ｍｍＨｇ 胸片 :肺野出现磨玻璃状伴弥漫性斑点状阴影 ,比粟粒影大, 大小不等 ,边缘不清 ,有的融合成片状，肝功不全。

47. 结合病史 ,临床表现 ,胸片 ,血气分析诊断为 “急性粟粒型肺结核合并ARDS” ,给予抗结核治 疗,间断吸40%浓度氧,以及激素、利尿剂、 保肝降黄治疗,1周后病情逐渐好转,呼吸平稳, 紫绀减轻。氧分压逐渐升高。胸片示粟粒状阴影。

48. 讨论： 1.分析患者ARDS的发病机制 2.分析血气变化