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*,*,Click to edit Master title style,Click to edit Master text styles,Second level,Third level,Fourth level,Fifth level,*,Respiratory Failure,呼吸衰竭,Respiratory Failure,Respiratory Failure is a syndrome in which the respiratory system fails in one or both of its gas exchange function:oxygenation,氧,&carbon dioxide,二氧化碳,elimination.,PaO,2,60 mmHg or PaCO,2,50 mmHg,Acute respiratory failure is present when alveolar ventilation is inadequately to meet the bodys need;the lung can no longer adequately oxygenate the blood.,Respiratory Failure,Risk factor:,The critically ill patient,The patient who has undergone recent abdominal,腹部,or thoracic,胸部,surgery,as a result of splinting,夹板,of the incision,切口,abdominal distention,restrictive bandages,绷带,tubes,引流管,and reduced ventilation,通气减少,because of pain.,The extremely obese,肥胖,patient because of restriction of ventilation.,The patient who has sustained a thoracic or spinal cord,脊髓,injury,The comatose,昏迷,patient or patient with decreased level of consciousness and depression of the respiratory center.,The patient who has lung disease or who smokes,especially when an infection develops or surgery is needed.,The,immunosuppressed,免疫抑制,patients,The older adults,Chronic respiratory failure,-days or longer,-pH is slightly decreased;allowing time for renal,compensation and an increase in bicarbonate,concentration,Classification,Acute respiratory failure,-minutes or hours,-pH,7.3,Type I:Hypoxemia Respiratory Failure,低氧血症呼吸衰竭,PaO2,60 mmHg with a normal or low PaCO2,Most common:,Associated to all acute diseases of the lung,Involve fluid filling or collapse,塌陷,of alveoli(,cardiogenic,or,noncardiogenic,pulmonary edema,pneumonia,hemorrhage,出血,),Classification,Type II:,Hypercapnia,Respiratory Failure,高碳酸血症呼吸衰竭,PaCO2,50 mmHg with hypoxemia,(severe airway disorders e.g.asthma,COPD,drug overdose,吸毒过量,neuromuscular disease,神经肌肉疾病,chest wall abnormalities,胸壁畸形,),Classification,Mechanisms of type I respiratory failure,Mechanisms that may cause hypoxemia and subsequent hypoxemic respiratory failure are:,Ventilation-Perfusion(,V/Q),mismatch,通气血流比例失调,Shunts,分流,Diffusion abnormalities,弥散障碍,Alveolar ventilation,肺泡通气不足,Mechanisms of type I respiratory failure,Ventilation-Perfusion(V/Q)mismatch,通气血流（,V/Q),比例失调,:,alter(V/Q)relationship in the lungs or V/Q mismatch,is the most common cause of hypoxemia,低氧血症,.,The V/Q relationship,means that where there is ventilation in the lungs,there must be matching blood perfusion to that area for efficient gas exchange occur.,In the normal lung the overall V/Q ratio is,0.8,.,Mechanisms of type I respiratory failure,Ventilation-Perfusion(V/Q)mismatch,An alteration or mismatch occurs if there is,blood flow to areas of decrease or absent ventilation or if there is ventilation to areas of decrease or absent blood flow.,Examples of process that cause V/Q mismatch are:,pneumoniam,肺炎,atelectasis,肺不张,chronic acute bronchitis,severe emphysema,肺气肿,asthma,哮喘,and pulmonary embolism,肺栓塞,.,Mechanisms of type I respiratory failure,Shunts,分流,A shunt occurs when blood enters the arterial system,动脉系统,from venous system,静脉系统,without being exposed to ventilated areas,通气区域,of the lung.,Essentially,the blood is shunted from the right to the left side of the heart without participating in gas exchange.,Blood that has a PO,2,similar to venous blood is mixed with arterial blood as it enters the left atrium,左心房,of the heart.,Mechanisms of type I respiratory failure,Shunts,A shunt can be viewed as extremely V/Q imbalance.,The most common shunts are,extrapulmonary,肺外分流,and include those that occur in congenital heart disease,先天性心脏病,through,atrial,or,septal,defects,房或室间隔缺损,or a patent,ductus,arteriosus,动脉导管未闭,.,Intrapulmonary anatomic shunts,肺内解剖相关的分流,are associated with,arteriovenous,fistulas,动静脉瘘,in congenital defects.,Mechanisms of type I respiratory failure,3.Diffusion abnormalities,扩散异常,Diffusion abnormalities indicates an impairment in the equilibration between the O,2,pressure in the alveoli and in the pulmonary,capillarie,.,Disease in which a a diffusion abnormalities may contribute to hypoxemia include:,Diffuse interstitial fibrosis,弥漫性间质纤维化,Collagen vascular disease,胶原血管疾病,of the lung(e.g.,scleroderma,硬皮病,systemic lupus,erythematosus,系统性红斑狼疮,),Asbestosis,石棉病,Sarcoidosis,结节病,Interstitial pneumonia,间质性肺炎,Cardiogenic,pneumonic,edma,心源性肺水肿,Mechanisms of type I respiratory failure,Alveolar hypoventilation(PaCO,2,50mmHg):is generalized decrease in ventilation of the lungs with buildup of CO,2,in the blood.,Although,alveolar hypoventilation,肺泡通气不足,is primarily a mechanism of type II respiratory failure,it is mentioned here because in can cause hypoxemia,低氧血症,.,Hypoventilation,通气过低,is commonly the result of diseases outside the lungs.,Pathophysiologic,effects of hypoxemia,Hyhoxemia,低氧血症,occurs when the amount of oxygen in the blood is not adequate to support aerobic metabolism.,CO,2,is the waste product of aerobic metabolism,有,氧代谢,.When O,2,insufficiency persists,the cell must shift from a
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