内科学英文课件：Respiratory Failure

1、Respiratory Failure,1.Abstracts,Respiratory failure, whether acute or chronic, is a frequently faced problem and a major cause of death in our country. For example, mortality from COPD, which ends in death from respiratory failure, continues to increase. More than 70% of the deaths in patients with

2、pneumonia are attributed to respiratory failure.,2.Definition,Respiratory failure affects the lungs ability to maintain arterial oxygenation or carbon dioxide(CO2) elimination. It is defined as a condition in which this gas exchange deteriorates below the usual level, so that arterial oxygen tension

3、 decreases, with or without an abnormal rise in arterial carbon dioxide tension.,Definition,Standard of diagnosis PaO250mmHg 海平面大气压静息,呼吸空气,3.Classification,acute respiratory failure chronic respiratory failure Central respiratory failure Peripheral respiratory failure Type respiratory failure Type r

4、espiratory failure,Classification :Type respiratory failure,Type respiratory failure is also called hypoxic respiratory failure, which means that severely reduces arterial oxygen tension(PaO260mmHg), CO2 retention is not exist.,Classification : Type respiratory failure,Type respiratory failure is al

5、so meant that hypercapnic-hypoxic respiratory failure. Arterial blood gas values shows that arterial carbon dioxide tension is more than 50 mmHg and arterial oxygen tension is less than 60 mmHg Type respiratory is mainly caused by hypoventilation.,Pathogenesis,Mainly discuss chronic respiratory fail

6、ure we have known that the lungs ability is gas exchange. The gas exchange involves not only oxygenation but also carbon dioxide elimination.,Pathogenesis,Respiratory failure is mainly associated with pulmonary gas exchange and pulmonary ventilation.,1. pulmonary gas exchange is mainly determined by

7、 ventilation-perfusion(V/Q) ratios and diffuse ability,V/Q mismatch: An effective lung gas exchange needs not only sufficient lung ventilation and lung blood volumes but also an adequate V/Q ratios. Usually, the volume of ventilation is 4 liters/min. The volume of lung blood is 5 liters/min. So the

8、ratios is 0.8,V/Q mismatch,Any of the factors influenced the ratios may mainly cause hypoxemia respiratory failure. For example, V/Q0.8, including emphysema,pulmonary embolism.(无效腔） V/Q0.8, including atelectasis, severe COPD.（动静脉分流）,V/Q mismatch,V/Q mismatch is mainly associated with hypoxic,Diffusi

9、on abnormality mainly influence oxygen exchange.,Diffuse ability,2.Pulmonary hypoventilation,central nervous system peripheral nervous system chest wall respiratory muscles The resistance of pulmonary ventilation,2.Pulmonary hypoventilation,It may cause hypercapnic-hypoxic respiratory failure. Pulmo

10、nary hypoventilation includes restrictive hypoventilation and obstructive hypoventilation.,restrictive hypoventilation,Some diseases influenced central nervous system, peripheral nervous system, chest wall respiratory muscles and pulmonary compliance may all cause restrictive hypoventilation. Such a

11、s brain stem lesion, altered neuromuscular transmission(guillain-barre syndrome), muscle weakness(malnutrition, shock, hypoxemia, hypokalemia), decreased lung compliance(infection, atelectasis, interstitial fibrosis, acute lung injury), decreased chest wall compliance(chest wall trauma, pleural effu

12、sion, pneumothorax).,obstructive hypoventilation.,COPD and asthma are the most common disease associated to obstructive hypoventilation. Increased airway resistance(upper airway obstruction, increased bronchial secretions and edema),Multifactors involve in the course of respiratory failure. For exam

13、ple, a COPD patient with severe pulmonary infection, his pulmonary gas exchange ability and pulmonary ventilation are all abnormal.,hypoxic,hypercapnic-hypoxic.,V/Q mismatch,Diffuse ability,. restrictive hypoventilation,obstructive hypoventilation.,Pathophysiology,Hypoxia and hypercapnic may influen

14、ce functions of many important organs and systems, including respiratory system, cardiovascular system, central nerve system,blood system and digestive system and renal function.,Pathophysiology,CNS Cardiovascular system Respiratory system Other systems,Clinical manifestations,HYPOXEMIA HYPERCAPNIA

15、Somnolence Tachypnea Lethargy Anxiety Restlessness Altered mental status Slurred speech Confusion Headache Cyanosis Asterixis Hypertension Papilledema Hypotension Coma Bradycardia Tachycardia Seizures Lactic acidosis,The unbalance of acid-alkalose metabolic and dielectric abnormality are usually exi

16、st in the course of respiratory failure.,Diagnosis,According to history, clinical manifestations, physical examination and blood gas analysis, we can diagnose respiratory failure. Especially arterial blood gas analysis may reveal hypoxemia and hypercapnia.,Diagnosis,The diagnosis standard include: T

17、ype respiratory failure:PaO2 50mmHg, PaO2 60mmHg. In the condition of oxygen therapy, PaO2/Fi O2300mmHg indicates respiratory failure.,Treatment,The principle of treatment includes ： primary disease treatment airway maintenance correction of hypoxemia and hypercapnia management of symptoms caused by

18、 hypoxemia and hypercapnia.,(1)Airway maintenance and enhance the volume of ventilation,Assurance of an adequate airway is a key in the patient with respiratory failure. correctly use of bronchodilators Use of effective antibiotics In severe cases intubation and mechanical ventilation may be used.,T

19、o most of the chronic respiratory failure, correctly use of bronchodilators is very important. Table 2. Bronchodilators Route Dose salbutamol MDI and spacer 400-600g q1-4h Aerosol solution 2.5-7.5mg q1-4h Ipratropium MDI and spacer 80-120g q4-6h Theophylline IV 5.6mg/kg 0.3-0.6mg/kg/hr,Mechanical ve

20、ntilation The aim of mechanical ventilation is to improve hypoxemia and to prevent hypercapnia. When do you select mechanical ventilation? This is a question we always meet in our clinical work. 1.progressive elevation in PaCO270-80mmHg 2.severe hypoxemia, after oxygen therapy, PaO235 per minute or

21、severe breathlessness 4.pulmonary encephalopathy,How to select artificial airway? face mask or nasal noninvasive intermittent positive pressure ventilation are delivered to augment alveolar ventilation and reducing the work of breathing. If hypoventilation can not be effectively reverses by noninvas

22、ive methods, intubation must be adopted. When artificial ventilation is required for more than 2 weeks, a tracheotomy is often required. Tracheotomy carries some risk of bleeding, pneumothorax, and local infection and incidence of aspiration.,(2)Antiinfectious therapy,Repeated bronchial and pulmonar

23、y infection is a major cause of chronic respiratory failure. About 90% of COPD patients with respiratory failure is caused by acute bronchial or pulmonary infection. Infection may also increase bronchial secretion and CO2 production. So antiinfectious therapy is an important method to treat respirat

24、ory failure.,Select effective antibiotics According to sputum culture, we can select sensitive antibiotics Using combined antibiotics Because of multibacteria infection, it needs several kind of antibiotics. For example, we may combine second or third generation cephalosporin to aminoglycoside or fl

25、uoroguinolone.,(3)Oxygen therapy,The goal of oxygen therapy is to improve PaO2. It makes PaO260mmHg. In general, the lowest FiO2 achieving adequate oxygenation. sometimes, arterial oxygen saturation90% should be used.,The methods of oxygen therapy: nasal prongs 1-3L/min to chronic respiratory failur

26、e venti mask 1-3L/min For type 1 respiratory failure, we can elevate the percentage of oxygen to maintain the PaO2. We can use higher inspirated fration of oxygen in type 1 respiratory failure oxygen therapy. But in type 2 respiratory failure we must select lower inspirated fration of oxygen .,(4)Ac

27、id-base and electrolytes disturbance,There are many factors lead to acid-base and electrolytes disturbance. These factors include severe pulmonary infection, hypoxemia or (and) hypercapnia. So airway maintenance, antibiotic therapy and use of bronchodilators are beneficial to treat it.,The acid-base

28、 disorder types in respiratory failure,Usually the disorders are compound types. It is difficult to judge the type of disorder according to the clinical symptoms and signs. Arterial blood gas analysis is the major method to judge the type of disorder.,How to judge the acid-base disorder,PH PaCO2 BE,

29、the acid-base index.,the index of respiratory,the metabolism,The common types of acid-base disorder,Metabolic acidosis (compensated and Uncompensated) Metabolic alkalosis Respiratory acidosis Respiratory alkalosis,Common compound acid-base disorders,Metabolic acidosis with Respiratory acidosis Metab

30、olic acidosis with Respiratory alkalosis Respiratory acidosis with Metabolic alkalosis Metabolic acidosis with Metabolic alkalosis,Treatment of acid-base disorders,looking for the etiology of the disorder is the most important .,Respiratory acidosis,It is most commonly encountered in clinical practi

31、ce of respiratory diseases.(COPD) It is essential to improve alveolar ventilation, while alkaline supplement is not necessary. For example: PH:7.32;PCO276mmHg; PO276mmHg SO2%94% BE13.9 HCO3- 41mmol/L,Respiratory acidosis complicated with metabolic acidosis,First of all, the cause of metabolic acidos

32、is should be clarified and treated, such as severe hypoxia may lead to increase in lactic acid or it is due to renal dysfunction or diabetic ketoacidosis. If the level of PH is less than 7.2, alkaline drugs should be treated. 5%NaHCO3(ml)=normal HCO3-(mmol/L)-actual HCO3-(mmol/L) 0.2weight(Kg),Respi

33、ratory acidosis complicated with metabolic acidosis,Arterial gas analysis: PH:7.19;PCO276mmHg; PO256mmHg SO2%86% BE-7; HCO3- 20mmol/L,Respiratory acidosis complicated with metabolic alkalosis,PH:7.28;PCO276mmHg; PO266mmHg SO2%92% BE5.1; HCO3- 33.8mmol/L 利尿剂，过量补碱，等,Respiratory alkalosis,Causes: Pulmo

34、nary edema ARDS Over use of MV PaCO2,(5)Use of respiratory stimulant,(6)Corticosteroids,Methyprednisone is usually used to reduce the airway inflammation, and to improve FEV1. The treatment is recommended in all patients but it is not used for a longer time.,(7)Gastrointestinal bleeding treatment,Be

35、cause of hypoxemia, hypercapnia and by using corticosteroids, gastrointestinal bleeding always be happened. The treatment method include correct hypoxemia and hypercapnia, use of H2-blocker and some block bleeding drugs.,(8)Nutritional support therapy,Acute Respiratory Distress Syndrome,ARDS,1.Defin

36、ition,ARDS, which is a form of acute lung injury . It is characterized by rapid respiratory rates and a sensation of profound shortness of breath, and accompanied by severe arterial hypoxemia.,2.Pathogenesis,ARDS can result from many disorders, including systemic or pulmonary infection,(viral, bacte

37、rial, fungal, ect.), aspiration, inhalation of toxins, metabolic disorders and severe sepsis or septic shock. The initial insult cause release of cytokines, mediators from cell membranes and activation of a number of cascades with injury to the pulmonary endothelium.,pathology,pathology,It is a form

38、 of pulmonary edema, distincts from cardiogenic pulmonary edema. Since hydrostatic pressure are not elevated.,3.Clinical manifestations,The early manifestations are an increased respiratory rates. Usually respiratory rates are more then 28 per minute. Sometimes the patient may be free of respiratory

39、 signs. Cough and sputum production. severe hypoxemia cyanosis is a common physical signs in ARDS patients. Tachycardia,X-ray shows a progressive, usually symmetrical, fluffy alveolar infiltrate that progresses to involve all potions of the lung. X-ray features of ARDS may be divided into three stag

40、es: First stage- sometimes normal, sometimes small patches may be exist Second stage- diffused small or large patches, usually in lower lung field Third stage- pulmonary infiltrate involved all potions of the lung, called white lung,The X ray features of ARDS,Arterial blood gas analysis,Arterial blo

41、od gas analysis shows PaO2/FiO2300mmHg andPaO260mmHg.(ALI), PaO2/FiO2200mmHg(ARDS),acid-base disorders,Respiratory alkalosis Metabolic acidosis Respiratory acidosis,4.Diagnosis,There is a disorder which may lead to ARDS. For example, severe infection ects. According to clinical manifestation, X-ray,

42、 arterial blood gas analysis, we can make a diagnosis.,The main diagnosis standard includes:,A factor which may leads to ARDS The onset is acute. Tachypnea is exist. Hypoxia Chest X-ray shows pulmonary infiltrate involved two lungs. PCWP18mmHg or except cardiogenic pulmonary edema.,5.Treatment（一）,Tr

43、eatment of initial disorders which lead to ARDS Improve hypoxemia Severe arterial hypoxemia is a characteristic clinical sign of ARDS. In genaral, the lowest inspired fration of oxygen(FiO2) should be used to give the desired result. There are multiple means for delivering O2, including soft nasal p

44、rongs, simple face masks. But in the condition of ARDS, these methods are not effective. Mechanical ventilatory support should be used early to improve hypoxemia.,Use of PEEP PEEP means positive end-expiratory pressure. It helps maintain alveolar potency in the presence of destabilizing factors and

45、therefore reverses hypoxemia and atelectasis by improving V/Q matching. PEEP level between 5-15cmH2O are safe and effective.,Use of PEEP,The physiologic effects of PEEP include: 1.redistribution of capillary blood flow, resulting in improved V/Q matching; 2. The recruitment of previously collapsed a

46、lveoli and prevention of their collapse during exhalation.,Treatment（二）,Control the input of liquid Use of Corticosteroids Nutritional support therapy,Another treatments are similar to those chronic respiratory failure, including antiinfectious therapy, administration of pulmonary surfactant, acid-b

47、ase and electrolytes disturbance.,Mechanical ventilatory support,（1）NIPPV （2）Artifical airways Endotracheal intubation is usually adopted during mechanical ventilation. Intubation should be by the orotracheal or nasotracheal route is highly controversial.,Orotracheal tubes are larger and easier to place in an emergency but are harder to stabilizer and are more uncomfortable. Nasotrached tubes are better tolerated and oral hygiene, but have greater airway resistance and more diffi