Pulmonary Pathophysiology

1. Pulmonary Pathophysiology

2. Histology of the lung Respiratory epithelium Connective tissue fibers, and cartilage: support and maintain open air way Alveolar cells (type I and type II)

4. Normal Lung

5. Function of the lung Gas exchange Protection against infection by alveolar macrophages Surfactant secretion: allow expansion of alveoli with air

6. Lung function tests Tidal volume (TV): it is the amount of gas inhaled or exhaled with each resting breath. Residual volume (RV): it is the amount of gas remaining in the lungs at the end of maximum exhalation.

7. Vital capacity (VC): it is the total amount of gas that can exhaled following maximum inhalation. Total lung capacity (TLC): it is the amount of gas in the lung at the end of maximum inhalation. TLC = RV+ VC

8. Reduction of Pulmonary Function Inadequate blood flow to the lungs: hypoperfusion Inadequate air flow to the alveoli: hypoventilation

9. Noso-comial infections Factors that reduce airflow also compromise particle clearance and predispose to infection. High rate of pneumonia in hospital patients due in large part to impaired ventilation and clearance.

10. Restricted lung movement and ventilation may arise due to: Positioning Constricting bandages Central nervous system depression Coma

11. Signs and Symptoms of Pulmonary Disease

12. 1- Dyspnea: subjective sensation of uncomfortable breathing, feeling �short of breath� Ranges from mild discomfort after exertion to extreme difficulty breathing at rest. Usually caused by diffuse and extensive rather than focal pulmonary disease.

13. Causes of Dyspnea : Airway obstruction Greater force needed to provide adequate ventilation Wheezing sound due to air being forced through airways narrowed due to constriction or fluid accumulation Decreased compliance of lung tissue

14. Signs of dyspnea: Flaring nostrils Use of accessory muscles in breathing Retraction (pulling back) of intercostal spaces

15. 2- Cough Attempt to clear the lower respiratory passages by forceful expulsion of air Most common when fluid accumulates in lower airways

16. Causes of Cough: Inflammation of lung tissue Increased secretion in response to mucosal irritation Inhalation of irritants Intrinsic source of mucosal disruption � such as tumor invasion of bronchial wall Excessive blood hydrostatic pressure in pulmonary capillaries Pulmonary edema � excess fluid passes into airways

17. When cough can raise fluid into pharynx, the cough is described as a productive cough, and the fluid is sputum. Production of bloody sputum is called hemoptysis Not threatening, but can indicate a serious pulmonary disease Tuberculosis, lung abscess, cancer, pulmonary infarction.

18. If sputum is purulent------- infection of lung or airway is indicated. Cough that does not produce sputum is called a dry, or nonproductive cough. Acute cough is one that resolves in 2-3 weeks from onset of illness or treatment of underlying condition. Acute cough caused by upper respiratory tract (URT) infections, allergic rhinitis, acute bronchitis, pneumonia, congestive heart failure, pulmonary embolus, or aspiration.

19. A chronic cough is one that persists for more than 3 weeks. In nonsmokers, almost always due to postnasal drainage syndrome, asthma, or gastroesophageal reflux disease In smokers, chronic bronchitis is the most common cause, although lung cancer should be considered.

20. 3- Cyanosis When blood contains a large amount of unoxygenated hemoglobin, it has a dark red-blue color which gives skin a characteristic bluish appearance. Most cases arise as a result of peripheral vasoconstriction � result is reduced blood flow, which allows hemoglobin to give up more of its oxygen to tissues- peripheral cyanosis. Best seen in nail beds Due to cold environment, anxiety, etc.

21. Central cyanosis can be due to : Abnormalities of the respiratory membrane Mismatch between air flow and blood flow Expressed as a ratio of change in ventilation (V) to perfusion (Q) : V/Q ratio Pulmonary thromboembolus ---- reduced blood flow Airway obstruction ---- reduced ventilation In persons with dark skin can be seen in the whites of the eyes and mucous membranes.

22. Lack of cyanosis does not mean oxygenation is normal!! In adults not evident until severe hypoxemia is present Clinically observable when reduced hemoglobin levels reach 5 g/ dl. Severe anemia and carbon monoxide poisoning give inadequate oxygenation of tissues without cyanosis Individuals with polycythemia may have cyanosis when oxygenation is adequate.

23. 4- Pain Originates in pleurae, airways or chest wall Inflammation of the parietal pleura causes sharp or stabbing pain when pleura stretches during inspiration Usually localized to an area of the chest wall, where a pleural friction rub can be heard Laughing or coughing makes pain worse Common with pulmonary infarction due to embolism

24. Inflammation of trachea or bronchi produce a central chest pain that is pronounced after coughing Must be differentiated from cardiac pain High blood pressure in the pulmonary circulation can cause pain during exercise that often mistaken for cardiac pain (angina pectoris).

25. 5- Clubbing The selective bulbous enlargement of the end of a digit (finger or toe). Usually painless Commonly associated with diseases that cause decreased oxygenation Lung cancer Cystic fibrosis Lung abscess Congenital heart disease

27. Introduction: Daily 10,000 liters of air - filtered..! Pneumonia: Inflammation of lung. Respiratory tract infections � commonest in medical practice. Enormous morbidity & mortality.

28. Etiology: Decreased general resistance Virulent infection - Lobar pneumonia Clearing mechanism Decreased Cough Reflex Injury of the cilia and mucosa Low alveolar defense Pulmonary edema or congestion Obstructions Retention of secretions

29. Types: Viral Bacterial Mycoplasmal Fungal

30. Patterns of infections: Airway - Bronchitis, Bronchiectasis Parenchyma Pneumonia Bronchopneumonia Lobar pneumonia Lung abscess Tuberculosis

31. Pneumonia Pathology: Alveolar Bronchopneumonia (Streptococcus pneumoniae, Haemophilus influenza, Staphylococcus aureus) Lobar (Streptococcus pneumoniae) Interstitial (Influenza virus, Mycoplasma pneumoniae) Pathogenesis Inhalation of air droplets Aspiration of infected secretions or objects Hematogenous spread

33. Bronchopneumonia Suppurative inflammation of lung tissue caused by Staph, Strep, Pneumo & H. influenza Patchy consolidation � not limited to lobes. Usually bilateral Lower lobes common, but can occur anywhere Complications: Abscess Empyema Dissemination

34. Broncho-pneumonia

35. Broncho-pneumonia

36. Broncho-pneumonia

37. Bronchopneumonia:

39. Lobar Pneumonia: Fibrinosuppurative consolidation � whole lobe Rare due to antibiotic treatment. ~95% - Strep pneumoniae The course runs in four stages: Congestion. Red Hepatization. Gray Hepatizaiton. Resolution.

42. Lobar Pneumonia:

43. Lobar Pneumonia � Gray hep�

44. Lung Abscess: Focal suppuration with necrosis of lung tissue Organisms commonly cultured: Staphylococci Streptococci Gram-negative Anaerobes Frequent mixed infections Mechanism: Aspiration Post pneumonic Septic embolism Neoplasms Productive Cough, fever. Clubbing Complications: Systemic spread, septicemia.

45. Lung Abscess:

46. Abscess formation

47. Bronchopneumonia - Abscess formation

48. Lung Abscess:

49. Pulmonary tuberculosis Caused by Mycobacterium tuberculosis. Transmitted through inhalation of infected droplets Primary Single granuloma within parenchyma and hilar lymph nodes (Ghon complex). Infection does not progress (most common). Progressive primary pneumonia Miliary dissemination (blood stream).

51. Pulmonary tuberculosis Secondary Infection (mostly through reactivation) in a previously sensitized individual. Pathology Cavitary fibrocaseous lesions Bronchopneumonia Miliary TB

54. Opportunistic pneumonias Infections that affect immunosuppressed patients Associated disorders: AIDS Iatrogenic Cancer patients Transplant recipients

55. Usual interstitial pneumonia / idiopathic pulmonary fibrosis Progressive fibrosing disorder of unknown cause Adults 30 to 50 years old Respiratory and heart failure (cor pulmonale) ~ 5 y