Pathophysiology for Dietetics 2: Diseases of the Respiratory System (PDF)

NDT2359 Pathophysiology for Dietetics 2 Diseases of the respiratory system By: Ms Jamilah Abd Jamil [email protected] Key References Nelms M, Sucher K.P, Lacey K. Nutrition Therapy and Pathophysiology. 2nd ed. Place of Publication: Cencage Learning; 2016. Escott-Stumps S (2012), Nut...

NDT2359 Pathophysiology for Dietetics 2 Diseases of the respiratory system By: Ms Jamilah Abd Jamil [email protected] Key References Nelms M, Sucher K.P, Lacey K. Nutrition Therapy and Pathophysiology. 2nd ed. Place of Publication: Cencage Learning; 2016. Escott-Stumps S (2012), Nutrition and Diagnosis-Related Care. 7th ed. Mahan KL and Escott – Stumps (2009), Food Nutrition and Diet Therapy. 12th ed. W.B. Saunders Company, Philadelphia 2 Learning Outcomes At the end of the session, students should be able to: 1) Describe the normal anatomy and physiology of the respiratory system: pulmonary function 2) Explain the aetiology, pathophysiology and clinical manifestations of asthma, chronic obstructive pulmonary disease, cystic fibrosis, pneumonia, patients with tracheostomies, respiratory failure and transplantation 3 Learning Outcomes At the end of the session, students should be able to: 1) Describe the normal anatomy and physiology of the respiratory system: pulmonary function 2) Explain the aetiology, pathophysiology and clinical manifestations of asthma, chronic obstructive pulmonary disease, cystic fibrosis, pneumonia, patients with tracheostomies, respiratory failure and transplantation 4 Normal Anatomy and Physiology of the Respiratory System The pulmonary system includes two divisions: ○ Upper respiratory tracts ○ Lower respiratory tracts The lungs allow the body to obtain oxygen to support cellular metabolic functions and to remove carbon dioxide produced by this process. 5  The air enters the lungs through the trachea, which divides into the right and left bronchi, supplying the right and left lung The bronchi further divide again and again into smaller and smaller bronchioles. The bronchioles end in small air sacs called alveoli, which are paper thin. Each alveoli is imbedded with millions of capillaries that are responsible for the exchange of oxygen and carbon dioxide. Gas exchange occurs in the alveolar–capillary unit - covers approximately the area of a tennis court and contains more than 100 million capillaries https://www.youtube.com/watch?v=WzrN6sJ1i_g 6  The lungs has a role in protecting the body against infection and harmful environmental toxins. Inhaled particles such as smoke, bacteria, and viruses pass through the nose and are trapped in the lungs by a sticky mucus substance, which serves to keep the airway moist. Hair-like structures cells (cilia) lines the trachea, bronchi, and bronchioles. It beats with a rhythm fast and forceful enough to propel the mucus and unwanted cells upward toward the pharynx where they can be coughed out or swallowed. Additionally, the epithelial surface of the alveoli contains macrophages or scavenger cells that engulf and destroy the inhaled bacteria. 7  Measures of Pulmonary Function Spirometer - calculates the Impulse Oximetry (bedside or Gas diffusion measures how amount of air the lungs can outpatient setting) - able to detect well oxygen and other gases hold and the rate the air can the percentage of oxygen pass through the lung’s air be inhaled and exhaled. sacs and are absorbed by the blood. 8 Measures of Pulmonary Function An arterial blood gases (ABG) test measures the acidity (pH) and the levels of oxygen and carbon dioxide in the blood from an artery - used to find out how well your lungs are able to move oxygen into the blood and remove carbon dioxide from the blood. An ABG test requires that a small volume of blood be drawn from the radial artery with a syringe and a thin needle, but sometimes the femoral artery in the groin or another site is used. Example 9 Nutrition and Pulmonary Health Malnutrition has been shown to have an adverse effect on clinical outcomes. Have an impact on the strength and endurance of respiratory muscles, particularly the diaphragm, and may also cause reductions in lung parenchyma (respiratory bronchioles, alveoli, and capillaries). Evidence correlating the role of dietary antioxidants such as vitamin C, vitamin E, beta-carotene, and selenium with healthy lung function. 10 Learning Outcomes At the end of the session, students should be able to: 1) Describe the normal anatomy and physiology of the respiratory system: pulmonary function 2) Explain the aetiology, pathophysiology and clinical manifestations of asthma, chronic obstructive pulmonary disease, cystic fibrosis, pneumonia, patients with tracheostomies, respiratory failure and transplantation 11  Definition: ASTHMA Chronic inflammatory disorder of the airway involving many cells and cellular elements, such as mast cells, eosinophils, T lymphocytes, macrophages, neutrophils, and epithelial cells Inflammation is the primary problem in asthma and is thought to be primarily immunoglobulin E (IgE) mediated This inflammation causes recurrent episodes of wheezing, breathlessness, chest tightness, and coughing, particularly at night or in the early morning. These episodes are usually associated with airflow obstruction that is often reversible either spontaneously or with treatment. Etiology: Allergic and nonallergic asthma. Allergic asthma: most common, triggered predominantly by inhaled indoor allergens such as dust mite allergen, pet dander, pollen, and mold. Non-allergic: anxiety, stress, exercise, cold air, dry air, hyperventilation, smoke, viruses, or other irritants 12 Pathophysiology When asthma occurs, bronchi and bronchioles respond to stimuli by contraction of smooth muscle (bronchoconstriction). The mucosa is inflamed and edematous, with an increased production of mucus. This results in a partially or totally obstructed airway. 13 Clinical Manifestations Initial symptoms: ○ Cough ○ Dyspnea ○ Tight feeling in the chest. Signs include: ○ Wheezing ○ Increased respiratory rate ○ Laboured breathing (an abnormal respiration characterized by evidence of increased effort to breathe) ○ Increased heart rate (tachycardia) ○ Hypoxia (deficiency in the amount of oxygen reaching the tissues) 14 CHRONIC OBSTRUCTIVE PULMONARY DISEASE Definition and aetiology Chronic obstructive pulmonary disease (COPD) is a progressive disease that limits airflow through either inflammation of the lining of the bronchial tubes (bronchitis) or destruction of alveoli (emphysema). Frequently, both conditions coexist as part of this disorder. 15 Bronchitis Bronchitis is an infection of the main airways of the lungs (bronchi), causing them to become irritated and inflamed. Most cases of bronchitis happen when an infection irritates and inflames the airways, causing them to produce more mucus than usual. Acute (lasts up to 3 weeks) Chronic bronchitis, one of the principal classifications of COPD, is diagnosed in persons with a productive cough and shortness of breath that last about 3 months or more each year for 2 or more years in a row. 16 Chronic Bronchitis - Pathophysiology Repeated exposure to cigarette smoke and other pollutants Results in a generalized inflammatory response such as decreased cilia function, increased phagocytosis, and suppressed amounts of immunoglobulin A (IgA). Chronic inflammation causes hyperplasia of the mucus-secreting cells, resulting in edema of the bronchioles. The walls of the airways thicken and mucus glands become hyperplastic. The damaged cilia are unable to clean mucus from the airways. The thickened mucus provides an environment conducive to bacterial growth, and chronic respiratory infections are common. 17 Chronic Bronchitis: Clinical Manifestations Chronic bronchitis is characterised by decreased air flow, dyspnea (SOB), hypoxemia (low concentration of oxygen in the blood), and hypercapnia (buildup of carbon dioxide in your bloodstream). Cyanosis – signs of chronic hypoxemia 18 Emphysema - Pathophysiology Causes shortness of breath. The air sacs in the lungs (alveoli) are damaged. Over time, the inner walls of the air sacs weaken and rupture — creating larger air spaces instead of many small ones. Reduces the surface area of the lungs and, in turn, the amount of oxygen that reaches your bloodstream. When you exhale, the damaged alveoli don't work properly. Old air becomes trapped, leaving no room for fresh, oxygen-rich air to enter. 19 Emphysema – Clinical Manifestations Coughing Wheezing Shortness of breath, chest tightness, and an increased production of mucus. Often times, symptoms may not be noticed until 50 percent or more of the lung tissue has been destroyed People who develop emphysema have an increased risk of pneumonia, bronchitis, and other lung infections. 20  COPD Treatment Smoking cessation and/ or avoid Good nutrition Exercise as tolerated smoke and air pollutant 21 CYSTIC FIBROSIS Definition Cystic fibrosis (CF) is an inherited disorder characterised by abnormally thick mucus secretions from the epithelial surfaces Result in progressive lung disease, pancreatic insufficiency, and dysfunction of the gastrointestinal and genitourinary systems. The most common inherited disease among the Caucasian population in the United States, affecting approximately 30,000 children and adults. Etiology CF is caused by an abnormal mutation of the cystic fibrosis transmembrane conductance regulator gene (CFTR) found on chromosome 7. 22 CF - Pathophysiology In individuals with CF, CFTR’s failure to function properly results in thick, viscous secretions Lead to obstruction of the glands and ducts in the affected organs. Within the respiratory tract, the defective regulation leads to an inability to clear mucus from the lungs. There is an increased risk of infection due to defective cilia action, primarily from Staphylococcus aureus and Pseudomonas aeruginosa. 23 CF - Pathophysiology Pancreatic insufficiency secondary to blocked ducts occurs in CF patients Prevents enzymes from reaching the small intestine. Symptoms: frequent passage of bulky, foul-smelling, oily stools (steatorrhea); abdominal distension; and a poor growth CF patients have an increased amount of sodium and chloride in their sweat. Excessive sweating in hot weather or fever may lead to increased risk of dehydration and electrolyte imbalances. 24 CF - Treatment Aerosol therapies are used to increase airflow, reduce the thick mucus accumulation, and reduce infection. Inhaled bronchodilators, inhaled anti-inflammatory agents, inhaled mucolytics, and inhaled antibiotics. Chest physiotherapy – helps to reduce airway obstructions Lung transplantation - aggressive treatment option for CF patients with end-stage respiratory failure Pancreatic enzyme replacement therapy - It is used in conditions where the pancreas cannot make or does not release enough digestive enzymes into the small intestines to digest the food 25 End of part 1 26