Diseases of the Respiratory System

1. Diseases of the Respiratory System

4. Lung Volumes & Capacities • Forced vital capacity (FVC) • amount of air expelled from maximum inspiration to maximum expiration regardless of time • Forced expiratory volume (FEV1) • amount of air expelled from maximum inspiration in the first second of effort • FEV1/FVC ratio is critical in separating obstructive & restrictive lung disease

5. Obstructive Lung Disease • Limitation of airflow • Rate of expiration is slowed • Volume usually normal

6. Restrictive Lung Disease • Limitation of lung expansion • Limit to both volume & flow rate

7. Major Determinants of Disease • Diseases of one lung compartment tend to affect the others • The lungs are open to the environment, exposing them to infectious agents, allergens, irritants, & carcinogens • Most lung disease is caused by inhalation of material; the most common exception is autoimmune lung disease • Lost pulmonary membrane is not recoverable • Smoking is a major cause of lung disease • The heart & lungs are a functional unit; lung disease usually affects the heart; & heart disease usually affects the lungs

8. Upper Respiratory Infections • Allergic rhinitis • “hay fever” • nasal mucosal edema • nasal discharge • sneezing • allergic conjunctivitis • “Colds” • transmitted through respiratory droplets • clear nasal discharge • low grade fever • if nasal discharge becomes colorful, it is an indication of secondary bacterial infection • Acute pharyngitis • “sore throat” • usually viral • bacterial infections more serious • red, swollen tonsils

9. Carcinoma of the Larynx • Common • Mostly in male smokers over 40 • Alcohol abuse increases the risk • Presents with • hoarseness • pain • cough • dysphagia • hemoptysis

10. Atelectasis • Collapse of a lung or part of a lung • Resorption • bronchial obstruction • air below obstruction completely absorbed • obstructions are • mucous plug • asthma • bronchitis • tumors • Compression • pressure exerted from pleural space or upward pressure on diaphragm • Contraction • scars cause constriction & collapse • TB

11. Asthma • Chronic inflammatory disease of small bronchi & bronchioles • Characterized by bronchospasm & air trapping • Airflow out is impaired • Triggered by inhaled irritants & classified by irritant • Allergic • type I hypersensitivity • Occupational • Exercise-induced • Infectious • Others • drug reactions • emotional stress • severe air pollution • Hyperplastic mucous glands in bronchi, hypertrophied smooth muscle, edema, & marked inflammation

12. Chronic Obstructive Pulmonary Disease (COPD) • Related diseases • Chronic bronchial outflow obstruction • Overlapping features

13. Emphysema • Destruction of alveolar walls, alveoli merge to form large air spaces • Loss of surface area affects diffusion • 90% of cases are smokers

14. Cigarette smoke irritates lung & causes inflammation • Inflammatory cells release digestive enzymes • These enzymes normally inhibited by alpha-1 antitrypsin • AAT inhibited by smoke & so enzymes digest lung tissue

15. Shortness of breath • Wheezing & coughing • Weight loss • Barrel-chested • Exhibits “tripoding”

16. Chronic Bronchitis • Chronic cough that produces sputum for 3 consecutive months 2 years in a row • Primary cause is cigarette smoking • Chronic inflammation of bronchi • Simple chronic bronchitis • Chronic asthmatic bronchitis • Obstructive chronic bronchitis

17. Most patients have chronic bronchitis & emphysema in varying degrees • “pink puffers” • emphysema • usually thin • barrel-chested • short of breath but well oxygenated • “blue bloaters” • obstructive chronic bronchitis • wheezing, coughing • sputum production • cyanotic • no lost pulmonary membrane • All at risk of chronic hypoxia

18. Bronchiectasis • Marked, permanent dilation of small bronchi • Destruction of smooth muscle & elastic supporting tissue • Must have obstruction & infection • obstruction causes mucus retention • infection damages bronchial walls which causes excess mucus production • Not a primary condition • Typically involves lower lobes • Persistent cough

19. Restrictive Lung Disease • Chronic inflammation making lungs stiff & inelastic • Affects diffusion • Scar tissue accumulates in the interstitium • Mostly cause is unknown • Equal decline in FEV1 & FVC • Usually presents with shortness of breath • Can lead to pulmonary HTN

20. Interstitial Fibrosis without Granulomatous Inflammation • Usually middle-aged men at time of diagnosis • Shortness of breath; may progress to cor pulmonale, hypoxia • Pneumoconioses • black lung disease • silicosis • most common chronic occupational disease • asbestosis • mesothelioma

21. Interstitial Fibrosis with Granulomatous Inflammation • Sarcoidosis • cause unknown • affects many tissues but mostly lungs • present with shortness of breath, cough, chest pain, hemoptysis

22. Pulmonary Edema • Fluid in alveoli • Increased BP in lung • normal is 25/8 mmHg with average at 15 mmHg • Microvascular injury • due to • toxic fumes • hot gases • septicemia • IV drug abuse • Main symptom is SOB

23. Pulmonary Thromboembolism • About 50,000 deaths annually • Mostly from DVT • Inflammation predisposes you to it • Promoted by • CHF • pregnancy • birth control pills • prolonged bed rest • metastatic cancer • genetics • Most associated with no symptoms but some • cause lung infarcts • chest pain & dyspnea • death

24. Pulmonary Hypertension • Sustained systolic pressure over 30 mmHg or average in excess of 25 mmHg • Vicious cycle • Most common cause is increased pulmonary vascular resistance • Usually secondary to • COPD • heart disease • collagen vascular diseases • recurrent pulmonary thromboemboli • With R heart failure is cor pulmonale • Thickening of arteriolar walls • SOB • chest pain • fatigue

25. Adult Respiratory Distress Syndrome • ARDS • Alveolar or pulmonary capillary damage • Pathogenesis • injury to endothelium or alveoli • neutrophils infiltrate • protein-rich fluid exudes into alveolar space • SOB occurs with rapid breathing which dries the fluid into a thick membrane • stiffens lungs • limits airflow & interferes with diffusion • hypoxia • 50% fatality • Causes • sepsis • smoke inhalation • near drowning • O2 toxicity • burns • DIC • fat embolism • endotoxic shock

26. Pneumonia • Inflammation of the lungs • Usually caused by bacteria • 80,000 deaths/yr • Alveolar pneumonia • usually acute • fill with inflammatory exudate • most common

27. Bronchopneumonia • patchy inflammation • involves alveoli of more than 1 lobe • usually in basilar parts • Lobar pneumonia • consolidation of an entire lobe • almost always caused by S. pneumoniae

28. Interstitial Pneumonia • Inflammation in septa • Diffuse & bilateral • Usually viral

29. Etiology mostly bacterial S. pneumoniae Haemophilus influenzae Staph E. coli Pseudomonas Pathogenesis inhalation of droplets, aspiration of gastric contents, blood-borne spread those susceptible include immune deficiency decreased cough reflex impaired cilia accumulated secretions pulmonary congestion

30. Community-acquired acute pneumonia bronchopneumonia lobar pneumonia Legionnaire’s disease atypical pneumonia Mycoplasma Nosocomial Commonly S. aureus & E.coli Seen in People with severe disease Prolonged antibiotic therapy People with internal mechanical devices Aspiration Inflammatory reaction due to corrosive effects Those who are comatose or those with a stroke Hi mortality rate

31. Seen mostly in the young & the elderly • Hypoxia & death • Bacterial • high fever & chills • purulent sputum • increased neutrophils • cough • SOB • Interstitial • less severe • increased lymphocytes • cough • SOB

32. Lung Abscess • Purulent inflammation with tissue necrosis & liquefaction • Usually have several types of bacteria with anaerobic • Most commonly due to aspiration of gastric contents • Foul-smelling sputum

33. Tuberculosis • Mycobacterium tuberculosis • Chronic granulomatous inflammation with caseous necrosis

34. Pathogenesis

37. Affects about 2 billion worldwide • Kills about 2 million/yr • 2nd only to AIDS • Associated with poverty, crowding, malnourishment, & chronic disease • PPD

38. Low-grade fever • Night sweats • Malaise • Weight loss anorexia

39. Mycoses • Histoplasmosis • Coccidiomycosis • Cryptococcus

41. Lung Neoplasms • Mostly due to metastasis • Bronchogenic carcinoma is the most common • most common of all cancers • #1 cancer death • about 90% are cigarette smokers

42. Bronchogenic Carcinoma • Mostly caused by cigarettes • Direct relationship between incidence of cancer & number of cigarettes smoked • Direct relationship between precancerous changes in bronchial mucosa & number of cigarettes smoked

44. Small cell carcinoma 20% of cases arise from specialized neuroendocrine cells of the bronchus strongest relationship to cigarettes aggressively malignant Squamous cell carcinoma 30% of cases bronchial epithelium that has undergone metaplasia arises centrally most common in men who smoke grows slower so better prognosis Adenocarcinomas 30% of cases most well-differentiated somewhat better prognosis more peripheral in smaller bronchi less associated with smoking Large cell carcinoma 15% of cases poor prognosis metastasizes early

45. Bronchial Carcinoid Tumor • 5% of lung cancers • Arise from bronchial neuroendocrine cells • Much less aggressive • Grows slow

46. Pneumothorax • Air in pleural space • Causes atelectasis • May occur spontaneously • More frequent in people with emphysema who have large blebs near pleura • Traumatic penetration • Can be fatal • Tension pneumothorax • air in but not out

47. Pleural Effusion • Fluid in pleural space • Transudate from CHF most common • If blood, called hemothorax

48. Pleuritis • Inflammation • Pleurisy with each breath • Mostly caused by pneumonia