Respiratory Pathophysiology

Transcription

1 Respiratory Pathophysiology Objectives: Respiratory infections and lung cancer. Pleural effusion & edema, pleuritis, pneumothorax and atelectasis. Obstructive airway disease and chronic interstitial lung disease Pulmonary embolism, pulmonary hypertension, acute respiratory distress syndrome and acute respiratory failure Part 1: Respiratory Infections and Lung Cancer 1

2 Pneumonia: infection and inflammation of lung parenchyma tissue Primarily caused by bacteria, but also viral, fungal, protozoan and parasites. Pathogens can reach lungs by inhalation, aspiration, or hematologic spread. Pneumonia: Types: Community Acquired Pneumonias: H. influenzae, S. aureus, gram negative bacteria Hospital Acquired Pneumonias: P. aeruginosa, S. aureus, enterobacter, K. pneumoniae, E. coli Immunocompromised Pneumonias: S. aureus, Aspergilus, Candida, gram negative bacteria, pneumocystitis carinii Acute Bacterial Pneumonia: S. pneumonae Legionnaire Disease: L. pneumophila Pneumonia: Manifestations: High fever, chills, fatigue/weakness Bronchial inflammation, productive cough, sputum rusty (bacterial) or yellow or green. Shortness of breath, tachypnea Tachycardia Nausea, diarrhea, vomiting 2

3 Pneumonia: Diagnosis: Blood tests Chest X-rays Pulse oximetry Sputum testing 3

4 Pneumonia: Treatment: Fluids and electrolytes Antibiotics for bacterial pneumonia Antiviral medications for viral pneumonia Fever reducing medications Cough medications Cortiocosteroids Oxygen, ventilation, humidified air Pneumonia: Complications: Pleuritis, pleural effusion Lung abscesses Sepsis Pulmonary Tuberculosis (TB): a bacterial infectious disease caused by M. tuberculosis Spread by air-borne particles in respiratory fluids of individuals with active TB. 4

5 Tuberculosis: Primary TB: Largely asymptomatic Develops in people who are previously unexposed (unsensitized) Develop a latent TB infection, organism is walled-off in granulomas (tubercles) Rarely, individuals can progress to progressive primary TB Progressive (secondary) or active TB: Can develop from a reinfection via respiratory droplets or reactivation from previous lesions Tuberculosis: Diagnosis: Tuberculin skin test Bacteriologic studies (acid fast stain and culturing) of sputum, bronchial washings or gastric aspirations Chest X-ray Tuberculosis: Treatment: Latent TB: antibiotic treatment dependent on individual risk TB disease: several antibiotic regimen for 6-9 months Multi-drug resistant TB 5

6 Lung Cancer: Small Cell Lung Cancer: Cells appear small and arise from central bronchi Highly associated with smoking Paraneoplastic effect is common Non-Small Cell Lung Cancer: Cells appear larger 3 types of non-small cell lung cancer 6

7 Lung Cancer: Adenocarcinoma: Begins in peripheral edges of lungs and just beneath lining of bronchi Most common type of lung cancer Associated with non-smokers Large-Cell Carcinoma: Salt and pepper appearance to chromatin within cells Squamous-Cell Carcinoma: Men are at higher risk Highly associated with smoking Begins in bronchi Lung Cancer: General manifestations: Persistent cough, bloodtinged sputum Chest pain, referred pain in upper back Recurrent attacks of pneumonia and/or bronchitis Fatigue Lung Cancer: Risks: Tobacco use and exposure to tobacco smoke Exposure to asbestos, radiation, arsenic, radon COPD or other lung diseases 7

8 Lung Cancer: Treatment: Surgery Radiation and chemotherapy Part 2: Pleural effusion & edema, pleuritis, pneumothorax and atelectasis Pleural Effusion/Edema: abnormal accumulation of fluid in the pleural cavity Exudative pleural effusion: pleuritis, bacterial pneumonia, viral infections, pulmonary infarction, tumors. (empyema) Hemothorax: pleural effusion characterized by presence of blood Chylothorax: effusion of lymph fluid in to the pleural cavity 8

9 Pleuritis (pleurisy): inflammation of the pleural membranes Etiologies: viral and bacterial infections, pneumonia Manifestations: Pain in thorax, sometimes referred to shoulder (abrupt, made worse with deep breathing and coughing) Empyema and sometimes hemothorax Pneumothorax: presence of air/gas in the pleural space that leads to a partial or complete collapse of affected lung lobe/s due to idiopathic reasons or direct injuries/disease. Main Differentiation: Open Pneumothorax: air moves in and out from an external environment. Tension Pneumothorax: due to increased pressure in the pleural cavity resulting in a one-way entry of air, life-threatening. 9

10 Types of Pneumothorax: Spontaneous pneumothorax: (idiopathic) rupture of an air-filled bleb or blister on the surface of lungs Secondary pneumothorax: occurs in people with lung diseases Traumatic pneumothorax: caused by chest injuries Atelectasis: incomplete expansion or collapse of lung tissue Etiologies: airway obstruction or lung compression, pneumothorax, pleural effusion, respiratory complication at birth or neonatal period. Compression ateletasis: caused by external pressure Absorption atelectasis: can occur when alveoli collapse because most of the gas inside alveoli are absorbed into pulmonary blood (ex. If given 100% oxygen) 10

11 Part 3: Obstructive airway disease and chronic interstitial lung disease Obstructive Airway Disease: disorders characterized by airway obstruction Asthma COPD (chronic bronchitis, emphysema, bronchiectasis) Cystic Fibrosis 11

12 Asthma: acute and reversible inflammatory disease of bronchial tubes (most people have both types) Type I: hypersensitivity type 1 Type II: non-hypersensitivity causes such as respiratory tract infection, smoke/lung irritants, emotional upset Asthma: Manifestations: Wheezing and cough, shortness of breath, prolonged and painful expiration Chest tightness Increased respiratory rate Fatigue Moist skin Anxiety 12

13 Asthma: Events during asthmatic attack: Narrowing of airways due to bronchospasm Expiration is elongated because of airway obstruction due to edema and excessive mucus production. If attack continues, accessory breathing muscles are used to help with breathing. Air becomes trapped behind the obstruction causing a hyperinflation of the lungs. There is a mismatching of ventilation and perfusion leading to hypercapnia and hypoxemia, increased pulmonary hypertension, increased work of the right side of the heart, could eventually lead to respiratory failure. Asthma: Treatment: Recognition and avoidance of triggers Short-term relief medications: short-acting beta agonists, immediate bronchodilators, oral and IV corticosteroids Long-term relief medications: inhaled corticosteroids, leukotriene modifiers, long-acting beta agonists, combination inhalers, bronchodilators Chronic Obstructive Pulmonary Disease (COPD): A catch-all clinical term used for lung diseases characterized by chronic airway obstruction. The most common etiology for COPD is smoking. 13

14 Two general clinical types (most COPD patients are a combination of both): Blue Bloaters: chronic bronchitis is the primary problem. They suffer from hypoxemia and hypercapnia (tend to be more cyanotic than emphysemia, so Blue ). Because of increasing obstruction, their residual lung volume increases so bloating ) Pink Puffers: Emphysema is the primary problem, compensation involves excessive hyperventilation ( puffer ). They have less hypoxemia and the neck/chest muscles are overworking with pursed-lip breathing so appear pink. Emphysema: chronic inflammatory lung disease in which there is a loss of elasticity of lung alveoli and enlargement of air spaces past the terminal bronchioles. Eventually alveoli wall and capillaries are damaged. Lungs become hyperinflated with increased total lung capacity. 14

15 Emphysema: Etiologies (result in destruction of elastic fibers in lung tissue): Injury to lung tissue from smoking Inherited deficiency of alpha-trypsin (an antiprotease enzyme that protects lung tissue) Emphysema: Types: Centriacinar: begins in bronchioles of the upper lobes and spreads into the peripheral alveoli Pancinar: begins in the lower lobes in the peripheral alveoli and spreads to the bronchioles. 15

16 Chronic Bronchitis: chronic bronchial inflammation characterized by excessive mucus production that obstructs major and smaller airways. Etiologies: Irritation by smoking and frequent infections Characterized by: Hypersecretion of mucus in bronchi Hypertrophy of submucosal glands lining trachea and bronchi Increased number of goblet cells, inflammatory infiltration, fibrosis of the bronchial walls (in smaller airways) Bronchiectasis: Is a rare type of COPD characterized by a permanent dilation of the bronchi and bronchioles caused by destruction of muscle and elastic supporting tissue. Characterized by cycles of infection and inflammation. 16

17 Cystic Fibrosis: an autosomal recessive disorder that causes severe damage to the lungs and the digestive and reproductive systems. Major cause of chronic respiratory disease in children It is caused by a dysfunctional gene that encodes for a membrane protein that functions as a chloride channel protein in epithelial membranes. The altered protein makes epithelial cell membranes. mostly impermeable to chloride. Cystic Fibrosis: In epithelium associated with the respiratory tract, this defective channel leads to increased absorption of Na+ and water from the airways into blood resulting in lower water content in the mucus coating the respiratory epithelium. The mucus becomes thick and is not easily moved by the cilia. In sweat glands, Na+ and Cl- is not reabsorbed properly and so there are large concentrations of NaCl in the sweat of CF patients. There are also problems with the pancreas, the biliary ducts of the gall bladder and the male vas deferens. General Pathogenesis of Obstructive Disease: Obstruction increases airway resistance. Lungs can fill to full volume, but do so much more slowly. Patients can t fully exhale. There is CO2 trapping that occurs over time leading to hypercapnia and respiratory acidosis. This also leads to the desensitization of central chemoreceptors (eventually respiratory drive is driven primarily by peripheral chemoreceptors).** This results in increased respiratory effort. 17

18 General Pathogenesis of Obstructive Disease: This breathing causes intercostal and diaphragm muscles (including the neck muscles) to be over-worked and hypertrophic requiring more oxygen and energy (this is especially true with emphysema): barrel chest, lucky strike syndrome, slight kyphosis, weight loss and fatigue. General Pathogenesis of Obstructive Disease: There is inadequate gas exchange resulting in hypoxemia, hypoxia and cyanosis (especially with chronic bronchitis). A ventilation perfusion mismatch occurs. Ventilation/Perfusion Mismatch: is a mismatch between the movement of air into and out of the alveoli (ventilation) and the blood supply to alveolar capillaries (perfusion). These two parameters are usually described as a ratio of V/Q and ideally these should be matched. If the ratio is too high in a part of the lung (that is ventilation without enough perfusion) that lung behaves as a dead space. If the ratio is too low (perfusion with not enough ventilation) the area behaves as a shunt. 18

19 Treatment for COPD: Bronchodilator drugs (inhaled adrenergic and anticholinergic agents) and inhaled corticosteroids. Oxygen therapy when there is significant hypoxemia (continuous, low flow oxygen). Lung reduction surgery (emphysema). Quit smoking and avoid other airway irritants. Prescribed exercise. Antibiotics for infections (particularly with chronic bronchitis). Avoidance of large crowds. Chronic Interstitial (restrictive) Lung Disease: characterized by stiff lungs and chest Inability to get air into lungs because lungs and/or chest can t expand properly due to decreased lung tissue elasticity and recoil. This leads to reduced lung volume. Etiologies: scar tissue from pneumona, black lung, brown lung, sarcoidosis, pulmonary fibrosis Chest Wall Restrictions: Etiologies: Substances or injuries that affect the respiratory centers in the brain Problems with the phrenic nerve Disorders of neuromuscular junction (myasthenia gravis) Problems with the lung cavity (obesity, rib fractures, pleurisy, pneumothorax, flail chest, kyphosis) 19

20 Part 4: Pulmonary embolism, pulmonary hypertension, acute respiratory distress syndrome and acute respiratory failure Pulmonary Embolism: occlusion of a pulmonary artery or arterioles Etiologies: Deep venous thrombosis (DVT), hypercoagulability problems Major consequences: pulmonary blood flow causes backup, pulmonary edema, could lead to right-sided heart failure and hypoxic organs/tissues. 20

21 Pulmonary Hypertension: involves the elevation of arterial pressure in pulmonary circulation which increases resistance to blood flow putting extra work on the right heart. Cor Pulmonale: right-sided heart failure due to pulmonary vasoconstriction. Normally, hypoxic tissue causes blood vessels to dilate, only pulmonary blood vessels in the lungs will vasoconstrict when hypoxic. Acute Respiratory Distress Syndrome: A clinical term used to describe changes that occur in the lungs. Lungs become heavy, filled with fluid and airless. Etiologies: shock, trauma, burns, acute cardiac failure, pneumonia, toxic lung injury, aspiration of fluids, premature lungs 21

22 Acute Respiratory Failure: Manifestations: Rapid onset Increased respiratory rate, respiratory distress in infants Hypoxemia Complications can lead to respiratory failure and multiple organ failure Acute Respiratory Failure: Treatment: Oxygen Fluids and electrolytes Supportive care until lungs can recover Treat underlying disorder Pain medication 22