Respiratory System Notes PDF

Applied Bioscience for Health Instability 2 Module: Respiratory System Key Terms Acute bronchitis Asthma Bronchiolitis Chronic bronchitis...

Applied Bioscience for Health Instability 2 Module: Respiratory System Key Terms Acute bronchitis Asthma Bronchiolitis Chronic bronchitis Chronic obstructive pulmonary disease (COPD) Croup Cyanosis Cystic fibrosis Diluents Dyspnoea Emphysema Expectorants Haemoptysis Hypercapnia Hypoxaemia Hypoxia Mucolytic drugs Muscarinic antagonists Non-small cell lung cancer Orthopnoea Pertussis Pneumonia Pulmonary embolism Small cell lung cancer Status asthmaticus Tuberculosis Summary Disorders of the pulmonary system Obstructive lung disease is characterised by airway obstruction that causes difficult expiration. Obstructive lung disease can be acute or chronic in nature and includes asthma, chronic bronchitis and emphysema. Asthma is the result of a type 1 hypersensitivity immune response involving the activity of lymphocytes, IgE, mast cells and eosinophil’s. Asthma can be caused by exposure to irritants or allergens. Exposure to allergens leads to bronchoconstriction and bronchiole airway oedema. In asthma, obstruction is caused by exacerbation episodes of bronchospasm, bronchial inflammation, bronchiole mucosal oedema and increased mucus production. Asthma staging is based on clinical severity and is used to determine therapy. Faculty of Health Sciences | School of Nursing CRICOS Provider Code 00301J  Applied Bioscience for Health Instability 2 Asthma is a prevalent and important childhood problem. Its origins are probably multifactorial, including genetic, allergic and viral-triggered mechanisms. Effective management is aimed at eliminating known triggers from the environment, decreasing chronic inflammation in the lungs, and early recognition and treatment of acute symptoms. Acute bronchitis can be caused by bacteria. Typical assessment and investigations include full patient history, respiratory assessment, sputum MC&S, and if severe CXR and arterial blood gases (ABG) Routine care includes chest physiotherapy, supplemental oxygen as prescribed by Dr, vital sign observations, respiratory observations monitor all input and output via fluid balance chart, administer oxygen as prescribed and other general care. Chronic bronchitis causes airway obstruction resulting from bronchial smooth muscle hypertrophy and production of thick, tenacious mucus. Chronic obstructive pulmonary disease (COPD) is the coexistence of chronic bronchitis, emphysema and sometimes asthma. COPD is an important cause of hypoxaemic and hypercapnic respiratory failure. In emphysema, destruction of the alveolar septa and loss of passive elastic recoil lead to airway collapse and obstruct gas flow during expiration. With emphysema expiration becomes difficult because loss of elastic recoil reduces the volume of air that can be expired passively and air is trapped in the lungs. Air trapping causes an increase in expansion of the chest, which puts the muscles of ventilation at a mechanical disadvantage. This results in increased workload of breathing. COPD is the fourth leading cause of death after cardiovascular disease, cancer and stroke, and forms a large percentage of all respiratory deaths (45%). Approximately 600,000 Australians are affected by COPD. Infections of the pulmonary system Serious lower respiratory tract infections occur most often in the elderly and in individuals with impaired immunity or underlying disease. Viral pneumonia can be severe, but is more often an acute self-limiting lung infection usually caused by the influenza virus. The most common community-acquired pneumonias are caused by bacteria, particularly those caused by Streptococcus pneumoniae (also known as the pneumococcus), which has a relatively high mortality rate in the elderly. The alveoli and terminal bronchioles fill with infectious debris and exudates and further damage can lead to fibrin deposition. Patients can manifest with fever, chills, productive cough, malaise, pleural pain and sometimes dyspnoea and haemoptysis (blood in the sputum). The white blood cell count is usually elevated, although it may be low if the individual is debilitated or immunocompromised. Chest X-rays show infiltrates that may involve a single lobe of the lung or may be more diffuse. Tuberculosis is a lung infection caused by Mycobacterium tuberculosis. In tuberculosis, the inflammatory response proceeds to isolate colonies of bacterium by enclosing them in tubercles and surrounding the tubercles with scar tissue. These may remain dormant within the tubercles for life or, if the immune system breaks down, cause recurrence of active disease. Bronchiolitis is the inflammatory obstruction of bronchiolar small airways. It is most common in children. Childhood pulmonary disorders Faculty of Health Sciences | School of Nursing CRICOS Provider Code 00301J  Applied Bioscience for Health Instability 2 Croup is an acute respiratory illness of young children, usually caused by parainfluenza virus. This infection causes swelling of the upper trachea. The typical sign is a seal-like barking cough, which appears after a few days of rhinorrhoea, sore throat and low-grade fever. Cystic fibrosis is an autosomal recessive genetic disease that affects many organ systems, especially the lungs and digestive system. Airway secretions are particularly thick and tenacious and the airways develop chronic bacterial infection with pathogens such as Pseudomonas aeruginosa and Staphylococcus aureus. Chronic infection, plugged airways and severe inflammation cause long-term lung damage and ultimately death. However, the prognosis is improving and most patients with cystic fibrosis now survive to adulthood. Alterations of pulmonary blood flow and pressure Pulmonary vascular diseases are caused by embolism or hypertension in the pulmonary circulation. Pulmonary embolism is occlusion of a portion of the pulmonary vascular bed by a thrombus (most common), tissue fragment or air bubble. Depending on its size and location, the embolus can cause hypoxic vasoconstriction, pulmonary oedema, atelectasis, pulmonary hypertension, shock and even death. Clinical manifestations of pulmonary alterations Hypercapnia is an increased carbon dioxide level in the arterial blood. Most causes of hypercapnia are a result of decreased drive to breathe or an inadequate ability to respond to ventilatory stimulation. Some of these causes include: (1) depression of the respiratory centre in the brainstem by narcotic drugs such as morphine and heroin; (2) diseases of the medulla, including infections of the central nervous system or trauma; (3) thoracic cage abnormalities, as in chest injury; (4) large airway obstruction, as in tumours or sleep apnoea; and (5) increased work of breathing or physiological dead space, as in emphysema. Hypoxaemia is a reduced oxygen level in the arterial blood caused by (1) decreased oxygen content of inspired gas, (2) hypoventilation and (3) diffusion abnormality at the alveolar level. Hypoxaemia, or reduced oxygenation of arterial blood (reduced PaO2), is caused by respiratory alterations. Hypoxia, or reduced oxygenation of cells in tissues, may be caused by alterations of other systems as well e.g. low blood pressure or loss of blood and loss of Hb. Hypoxaemia can also be caused by central nervous system disorders or depression of the respiratory centre in the brainstem by drugs such as morphine and heroin; and result in a decreased drive to breathe. Dyspnoea is described as ‘feeling short of breathe’, increased respiratory effort or difficulty in breathing. It is a common pulmonary disorder symptom. Haemoptysis is expectoration of bloody mucus, which can be caused by bronchitis, tuberculosis, abscess, cancers (neoplasms) and other conditions that cause haemorrhage from damaged vessels. Cyanosis is a bluish discoloration of the skin caused by desaturation of haemoglobin, polycythaemia or peripheral vasoconstriction. Respiratory tidal volume (TV) or size of breath multiplied by respiratory rate (RR) equals minute volume (MV). E.g. an average size adult male has a 700ml TV multiplied by a RR of 18/min = 12,600 mls/min or 12.5 litres/min minute volume. Therefore you can assume a MV of 12.5 litres/min is required to maintain normal cellular metabolism and normal cellular oxygenation for this adult male. Faculty of Health Sciences | School of Nursing CRICOS Provider Code 00301J  Applied Bioscience for Health Instability 2 A reduced tidal volume results in a decreased minute volume e.g. in the case of an overdose of narcotic analgesia like morphine. The morphine overdose can cause reduced consciousness, shallow breathing/reduced size of breath (reduced respiratory tidal volume) and reduced respiratory rate e.g. 350ml TV multiplied by a RR of 12/min = 4,200 ml/min or 4.2 litres/min. This is a significant decrease from the normal MV of 12.5 litres/min. Therefore normal cellular oxygenation and cellular metabolism cannot be maintained. Be mindful that any patient that presents with reduced respiratory rate (bradypnoea) may also have shallow breathing (reduced TV) and therefore reduced minute volume. A decreased minute volume can result in reduced oxygen/carbon dioxide gas exchange at the alveoli level, reduced oxygen saturations and cellular hypoxia. Pharmacotherapy Oxygen is a therapeutic gas that is essential to sustaining life and is used in many clinical situations, especially to treat hypoxia. Patients may demonstrate low oxygen saturations or hypoxia and supplemental oxygen therapy may be prescribed by the Dr e.g. oxygen via nasal prongs, Hudson mask or non-rebreather mask. Patients with abnormal or excessive respiratory tract secretions often need mucoactive drugs. These promote the removal of respiratory tract secretions by thinning hyperviscous secretions, thus enhancing the ciliary action of the respiratory tract. Mucolytics such as acetylcysteine may break down and reduce the viscosity of sputum. Expectorants aid in the removal of sputum. Asthma is a major cause of morbidity and mortality in the community. Treating asthma involves educating the patient; regular monitoring of lung function, progress and compliance; avoiding trigger factors; and stepwise use of various antiasthma drugs. The main drug groups used in asthma are: o reliever (bronchodilator) medications (short-acting β2 agonists, xanthine’s and antimuscarinic agents) e.g. ventolin o symptom controllers (long-acting β2 agonists) e.g. salmeterol o preventer medications (inhaled corticosteroids, leukotriene-receptor antagonists and mast-cell stabilisers). E.g. pulmicort Cough suppressants such as the opioid antitussive drugs are used for non- productive coughs. Viral respiratory tract infections (cold, influenza, croup) are treated largely symptomatically. Bacterial respiratory tract infections (pneumonia, tuberculosis, and infections in COPD) are treated with antibiotics specific to the pathogenic organism. Glossary Acute bronchitis: is an acute infection or inflammation of the airways or bronchi and is usually self-limiting. Asthma: obstruction is caused by exacerbation episodes of bronchial inflammation, bronchiole mucosal oedema, bronchospasm and increased mucus production. Bronchiolitis: is a rather common, viral-induced lower respiratory tract (bronchiolar) infection that occurs almost exclusively in infants and young toddlers. Chronic bronchitis: is a chronic infection or inflammation of the airways or bronchi Faculty of Health Sciences | School of Nursing CRICOS Provider Code 00301J  Applied Bioscience for Health Instability 2 Chronic obstructive pulmonary disease (COPD): is a syndrome that includes the pathological lung changes consistent with emphysema, chronic bronchitis or chronic asthma. Croup: is an acute inflammation of the upper airways and almost always occurs in children between 6 months and 5 years of age. In 85% of cases, croup is caused by a virus. Airway obstruction occurs in the subglottic region of the trachea, just below the vocal cords. Cyanosis: is a bluish discoloration of the skin and mucous membranes caused by increasing amounts of desaturated or reduced haemoglobin (which is bluish) in the blood Cystic fibrosis: is an autosomal recessive inherited disease that results from defective epithelial chloride ion transport. Although cystic fibrosis affects many organs the most important effects are on the lungs and in 90% of cases, chronic pulmonary infections eventually lead to respiratory failure and death. Diluents: The agent most commonly used to dilute respiratory secretions is normal saline, administered by ultrasonic nebulizer. Dyspnoea: is the subjective sensation of uncomfortable breathing, the feeling of not being able to get enough air. Sometimes referred to as difficulty in breathing. Emphysema: is abnormal permanent enlargement of gas-exchange airways accompanied by destruction of alveolar walls. Obstruction results from changes in lung tissue. Expectorants: act by an irritant action on the mucous membranes, which increases the secretion of mucus from bronchial secretory cells, facilitating ciliary action and productive coughing and soothing and lubricating dry tissues. Haemoptysis: is the coughing up of blood or bloody secretions. Hypercapnia: increased carbon dioxide in the arterial blood (increased PaO2). Hypoxaemia: reduced oxygenation of arterial blood (reduced PaO2) Hypoxia: reduced oxygenation of cells in tissues e.g. oxygen saturations below 90%. Mucolytic drugs: exert a disintegrating effect on mucus, facilitating removal of mucus or other exudates from the lung, bronchi or trachea by postural drainage, coughing, spitting or swallowing e.g. acetylcystine Muscarinic antagonists: one of the many pharmacological effects of muscarinic- receptor antagonists (antimuscarinic drugs) such as atropine is inhibition of bronchial secretions. Dries secretions. E.g. ipratropium Non-small cell lung cancer: Squamous cell carcinoma accounts for about 30% of bronchogenic carcinomas. These tumors are typically located near the hilum and project into the bronchi. Adenocarcinoma (meaning that the tumor arises from the glands) constitutes 35–40% of all bronchogenic carcinomas. Orthopnoea: dyspnea when a patient is lying down. Pertussis: is caused by the bacterium Bordetella pertussis. The symptoms are thick secretions, a chronic cough and spasm following coughing fits, which give a characteristic ‘whoop’ sound — hence the common name ‘whooping cough’ Pneumonia: is infection of the lower respiratory tract caused by bacteria, viruses, fungi, protozoa or parasites. The alveoli and terminal bronchioles fill with infectious debris and exudate. Pulmonary embolism: is occlusion of a portion of the pulmonary vascular bed by an embolus, which can be a thrombus (blood clot), tissue fragment, lipids (fats), foreign body or an air bubble (air embolism). More than 90% of pulmonary emboli result from clots formed in the veins of the legs and pelvis. Small cell lung cancer: Small cell carcinomas constitute 15–20% of bronchogenic carcinomas. Most of these tumors are central in origin Status asthmaticus: defined as a severe asthmatic episode that does not respond to pharmacological management. Tuberculosis: is an infection caused by Mycobacterium tuberculosis, a bacterium that usually affects the lungs but may invade other body systems. Inflammation in the lung causes activation of alveolar macrophages and neutrophils. Faculty of Health Sciences | School of Nursing CRICOS Provider Code 00301J  Applied Bioscience for Health Instability 2 Medications Key Drugs: Learning activity > list some common side effects in the tables below. Go to MIMS online (right click hyperlink and open) Pharmaceutical Salbutamol Terbutaline Salmeterol name Brand name Ventolin Bricanyl Turbuhaler Serevent Indications for use Relief of Relief of Adjunct to steroids bronchospasm bronchospasm in in asthma (incl (asthma, COPD); asthma, COPD nocturnal, exercise acute asthma induced) prophylaxis (incl exercise induced asthma); Drug class Bronchodilator Bronchodilator Bronchodilator aerosols and aerosols and aerosols and inhalations inhalations inhalations Pharmacological Short acting beta 2 Beta 2 -agonist Selective long action/mechanism -adrenoreceptor acting beta 2 - of action stimulant agonist Physiological effect Bronchial smooth sympathomimetic sympathomimetic muscle dilation bronchodilator bronchodilator Route of Inhaled Inhaled Inhaled administration Common side Tachycardia, Tremor and Thrush of effects hypotension, headache mouth/throat, headache tremor, headache, tachycardia Pharmaceutical Budesonide name Brand name Pulmicort Turbuhaler Indications for use Bronchial asthma; Drug class Preventive aerosols and inhalations Pharmacological Glucocorticoid. action/mechanism of action Physiological effect Anti-inflammatory Route of Inhaled administration Common side Sore throat, oral effects thrush Faculty of Health Sciences | School of Nursing CRICOS Provider Code 00301J  Applied Bioscience for Health Instability 2 References Bryant, B. & Knights, K. (2011) Pharmacology for Health Professionals (3rd ed). Elsevier Mosby. Craft, J., Gordon, C., Huether, S., McCance, K., & Brashers, V. (2020). Understanding Pathophysiology (4th ed.). Elsevier Mosby. Faculty of Health Sciences | School of Nursing CRICOS Provider Code 00301J