NURS 251 Module 5 Portage Learning

NURS 251 Module 5 Portage Learning Module 5 5.1: Introduction to Pulmonology The main function of the respiratory system is two-fold: (1) to deliver oxygen to the cells of the body and (2) remove carbon dioxide from the body. This is accomplished through the combination of the upper respiratory tract working in communication with the lower respiratory tract. A diagram of the anatomy of the respiratory tract is shown in Figure 5.1. The upper respiratory tract (URT) is outside the chest cavity and includes the nose, and nasopharynx (down to the larynx). The lower respiratory tract (LRT) includes the organs within the chest including the trachea, bronchial tree, and lungs. When a person breathes in air, oxygen diffuses across the alveoli (microscopic sacs) in the lungs where it is exchanged for carbon dioxide. The diffused oxygen is then taken to the rest of the body through the circulatory system. Figure 5.1 Anatomy of the Respiratory Tract. Above is a diagram of the anatomy of the respiratory tract broken down between the Upper Respiratory Tract (URT) and the Lower Respiratory Tract (LRT). There are several common diseases that affect the airways and this exchange of gas, the most common of which are asthma and chronic obstructive pulmonary disease (COPD). Asthma is the general term for recurrent and reversible shortness of breath resulting from the narrowing of the bronchi and bronchioles. COPD consists of both emphysema and chronic bronchitis. Emphysema is a disease process involving inflammation of the alveoli. Chronic Bronchitis is characterized by chronic inflammation or irritation on the lower respiratory tract, specifically the bronchi. The primary drugs used in the treatment of both asthma and COPD include bronchodilators and a variety of antiinflammatory and antiallergic agents. Pathophysiology All three of these diseases have one primary similarity in that they all involve obstruction of airflow through the airways. Chemical Mediators are defined as a substance released from mast cells and white blood cells during inflammation and allergic reactions. As such, chemical mediators are responsible for most of the symptoms and complications associated with asthma and COPD. The only chemical mediator with a known involvement where drug therapy has been shown to This study source was downloaded by from CourseH on :52:08 GMT -06:00 help patient symptoms is leukotrienes. Leukotrienes are potent bronchoconstrictors with a long duration of action. They stimulate receptors responsible for bronchoconstriction, edema and other inflammatory actions. There is a class of drugs called leukotriene inhibitors that inhibit these actions and have an important role in treating asthma specifically. Asthma The narrowing of the bronchioles can be caused by bronchospasm, inflammation, edema and the production of mucus. This ultimately obstructs airflow meaning that the carbon dioxide cannot get out and the oxygen cannot get in. There are different types of asthma. Some asthma is caused by outside factors such as allergens; this is often referred to as allergic asthma. Conversely, intrinsic asthma is caused by unknown factors. In some cases, certain factors have precipitated the asthma attack such as respiratory infections, stress, or cold weather. It is not fully understood why some people seem to be predisposed to asthma attacks. Emphysema Emphysema occurs when the air spaces within the bronchioles enlarge as a result of the destruction of the alveolar walls. As the alveolar walls are destroyed, there is less surface area available for oxygen and carbon dioxide exchange. The cause of this appears to be enzymes that are released in response to inflammation. These enzymes are increased by air pollution, tobacco smoke, and other irritants to the respiratory tract. Hyperinflation is the result of the air spaces being enlarged. These patients have difficulty expelling air from the lungs. This results in a reduction in gas exchange and the feeling of shortness of breath. Emphysema causes irreversible lung damage over time. Chronic Bronchitis Chronic irritation, usually from cigarette smoke or other environmental pollutants, can lead to chronic bronchitis. The irritants cause mucus secretions to increase and thicken which can then begin to interfere with gas exchange within the lungs. These patients often present with a chronic cough, difficulty breathing, and increased respiratory infections. Drug therapy can provide relief, but it cannot reverse the damage. Drug Therapy Historically, the treatment of both asthma and COPD has centered around bronchodilation. Recently, there has been a shift in focus to the anti-inflammatory component of treatment. Treatment still includes bronchodilators, so we will cover both types of treatment since they are often used in combination. Table 5.1 provides a summary of the most common treatment options used in asthma and COPD management. Table 5.1 Asthma and COPD Treatment Options Drug Class Select Examples Common Administration Use Beta2 adrenergic agonist (bronchodilators) Short Acting Beta agonist (SABA)- albuterol, levalbuterol Long acting Beta Agonists (LABA)- salmeterol, formoterol Inhalation- inhaler or nebulizer SABA- Rescue medication LABA- long term controller Asthma and COPD Anticholinergic (bronchodilators) Ipratropium (Atrovent)- short acting Tiotropium (Spiriva)- long acting Inhalation- inhaler or nebulizer Prevention of bronchospasm associated with COPD Can also be used when additional bronchodilation in asthma is needed Xanthine derived bronchodilator Theophylline Tablet Asthma and COPD This study source was downloaded by from CourseH on :52:08 GMT -06:00 Inhaled corticosteroids (ICS) (Anti-inflammatory) Fluticasone Beclomethasone Budesonide Triamcinolone Mometasone Inhalation- inhaler Leukotriene Inhibitors (anti-inflammatory) Montelukast (singular) Tablet Asthma prophylaxis and maintenance Bronchodilators include medications that improve airflow by relaxing smooth muscle cells in the bronchials, leading to dilation and increased airflow. Examples of this include :(1) Beta-adrenergic agonists, (2) Anticholinergics and (3) Xanthines. Beta-adrenergic Agonists are a group of drugs that are agonists of the adrenergic receptors in the sympathetic nervous system. Specifically, selective beta2 adrenergic agonists are useful in the treatment of asthma and COPD. Beta1 receptors are located in the heart while beta2 receptors are located in the smooth muscles found in the lungs. Mechanism of Action- beta agonists relax and dilate the airways by stimulating the beta2 adrenergic receptors within the lungs. At therapeutic concentrations, there is little to no effect on the heart. The bronchioles are surrounded by smooth muscle that contracts when a patient experiences shortness of breath. The contraction narrows the airway and reduces the amount of oxygen and carbon dioxide being exchanged. Beta2 agonists relax these smooth muscles by acting on the receptors. There are also many reactions taking place at the cellular level to accomplish this bronchodilation. Specifically, when the beta agonist stimulates the receptor, an enzyme called adenylate cyclase is activated which in turn produces cyclic adenosine monophosphate or cAMP. This increase in cAMP causes the relaxation of the bronchial smooth muscles. Ultimately, this is what causes the bronchodilation and increased airflow. Uses- The beta agonists are categorized by their onset of action. Short-acting beta agonists (SABA) are used to quickly alleviate airway constriction and restore airflow. Therefore, SABA’s are often used in emergency situations but can also be used to prevent a situation from escalating into an emergency. Conversely, long-acting beta agonists (LABA) are only used as long-term controller medications due to their longer onset of action. It is very important to educate patients that LABA should NOT be used in an emergency situation. Adverse Events- These drugs are well tolerated and have few systemic side effects since they are administered directly to the lungs; however, some patients do experience skeletal muscle tremors and increased heart rate. Anticholinergics Mechanism of Action- There are receptors for acetylcholine on the surface of the bronchioles within the lungs. Acetylcholine (Ach) is a neurotransmitter known to cause bronchoconstriction and increased mucus secretion. As the name would indicate, anticholinergic drugs block ACh receptors, thereby blocking the effects of acetylcholine. Therefore, taking an anticholinergic ultimately producing bronchodilation and reduced volume of respiratory secretions. Uses- These drugs are not as potent of a bronchodilator as the beta agonists and as such, they are primarily used to treat asthma when other options are not able to be used or if additional bronchodilation is needed. However, there seems to be an increase in cholinergic (the bronchoconstriction and mucus secretion caused by acetylcholine) activity in COPD, so these drugs are especially useful. In fact, they are considered first line treatment for COPD. Adverse Events- These drugs are very poorly absorbed into systemic circulation, so there are very few side effects. Most commonly, patients may experience excessive drying of the mouth and upper respiratory passages. Xanthine Derived Bronchodilators- There are several plant compounds found naturally in tea, cocoa, and coffee that are classified as methylxanthines. These include caffeine, theophylline, and theobromine. These compounds are known to produce mild stimulation of the central nervous system as well as relaxation of the smooth muscle of bronchodilation. In particular, theophylline is used for its bronchodilating actions. This study source was downloaded by from CourseH on :52:08 GMT -06:00 Mechanism of Action- Theophylline inhibits the enzyme phosphodiesterase (PDE). PDE is known to inactivate a compound called cyclic adenosine monophosphate (cAMP). Upon treatment with theophylline, the resulting increase in active cAMP causes smooth muscle relaxation and (ultimately) bronchodilation. Notably, cAMP is especially important in maintaining open airways in patients with COPD. There is also a decrease in specific chemical mediators like histamine that are known to drive allergic reactions. Uses- Theophylline can be used in the management of both asthma and COPD. However, due to their potential for drug interactions (for example: cimetidine, macrolide antibiotics, quinolone antibiotics, flu vaccine, birth control) and interpatient variability, they are not typically first line. Instead, xanthines are only used for the prevention of symptoms and are not used for immediate relief due to the slow onset of action. Adverse Events- Nausea, vomiting, and anorexia are common side effects. There are also cardiac side effects such as: increased heart rate, palpitations and dysrhythmias. Increased urination and blood glucose can also occur. Anti-Inflammatory Drugs are considered to be “controller” drugs because they reduce and control the inflammatory response. When the inflammatory response is under control, bronchodilator drugs can work more effectively. Examples of anti-inflammatory drugs are (1) Corticosteroids and (2) Leukotriene Inhibitors. Inhaled Corticosteroids (ICS) all have actions related to the natural steroid hormone cortisol (See Module 4) and are used for their anti-inflammatory effects. Mechanism of Action- The exact mechanism of action is unknown. However, it is generally accepted to be a combination of their anti-inflammatory effects along with enhancing the activity of beta agonists. Corticosteroids are known to inhibit inflammatory mediators and the production of allergic antibodies. Specifically, ICS’s work to stabilize the membranes of cells so that inflammation causing substances are not released. Corticosteroids exert their effect by acting on the different types of white blood cells, ultimately preventing the release of their inflammatory mediators. A second way that corticosteroids exert their anti-inflammatory effect is to inhibit the activation of arachidonic acid which decreases the formation of prostaglandins and leukotrienes which are both pro-inflammatory substances. Uses- Inhaled corticosteroids can be used both in the treatment of COPD and asthma. Systemic corticosteroids are also used during acute asthma attacks either by oral or parenteral route. For chronic control, however, inhalation is the preferred route of administrations. This greatly limits the systemic side effects that patients experience. Adverse Events- When used systemically (orally or parenterally), there are many side effects such as fluid retention, muscle wasting, metabolic disturbances, and increased susceptibility to infection. However, when the route of administration is inhalation, these side effects are not generally seen. When given via inhalation, the most common side effects include oral infection such as thrush and vocal cord disturbances. For these reasons, it is recommended to always rinse your mouth out after using an inhaled corticosteroid. Leukotriene Inhibitors- As mentioned earlier in this module, Leukotrienes are chemical mediators that are known to cause bronchoconstriction, mucus production, and inflammation. There are two subclasses of Leukotriene inhibitors including: (1) Zileuton (Zyflo) and (2) Montelukast (Singular) or Zafirlukast (Accolate). Mechanism of Action- Zileuton works by inhibiting the enzyme necessary for leukotriene synthesis. Montelukast and Zafirlukast work by blocking the leukotiren-1 receptor. Uses- Chronic control of asthma Adverse Events- Zileuton- headache, nausea, dizziness, and insomnia Montelukast and zafirlukast- Headache, nausea, and diarrhea. 5.2: Inhaler Types This study source was downloaded by from CourseH on :52:08 GMT -06:00 Two of the most common inhaler types available are the metered dose inhaler (MDI) and Dry powder inhalers. Metered dose inhalers contain a pressurized canister that deliver a reliable, consistent amount of medication via an aerosolized mist. Dry powder inhalers are breath activated, meaning the medication in the form of a powder is released only when you take a deep, fast breath. As shown in Figure 5.2, the basic directions for using an MDI are reviewed, while Figure 5.3 reviews the basic directions for using an example dry powdered inhaler called a diskus. Examples of medications that are available in an MDI include: albuterol (Ventolin), ipratropium (Atrovent), fluticasone (Flovent). Examples of medications that are available in a diskus dry powdered inhaler include: salmeterol (Serevent Diskus), fluticasone (Flovent Diskus). Figure 5.2 Instruction for proper use of a metered dose inhaler. The above diagram demonstrates the proper inhaler technique for a metered dose inhaler. Figure 5.3 Instructions for proper use of a dry powdered inhaler diskus. The above diagram demonstrates the proper inhaler technique for a dry powdered inhaler. There are other dry powder inhalers besides the diskus. As shown in Figure 5.4, examples include the Asmanex twisthaler® (mometasone) and the Spiriva handihaler® (tiotropium). This study source was downloaded by from CourseH on :52:08 GMT -06:00 Figure 5.4 Example dry powder inhalers. Mometasone marketed under the name Asmanex is available in a dry powder inhaler called a twisthaler®. Tiotropium marketed under the name Spiriva is available in a dry powder inhaler called a handihaler®. Another way to get medication into the lungs in via a nebulizer and nebulizer solution. Nebulizers are liquid formulations that can be poured into the nebulizer machine. Inside the nebulizer is a pump that pressurizes the air and then dispenses the medication in a fine mist. The patient simply places a mask over their face and breathes in the medication. An example of a nebulizer machine is shown in Figure 5.5. Common drugs that are given via nebulization include albuterol and ipratropium. Nebulization is a good option for both pediatric and elderly patients who may not have the dexterity required to use an inhaler. Figure 5.5 Nebulizer Machine. The left image shows the different parts of a nebulizer machine. The right image shows how a patient would wear the mask in order to breath in the medication. General Treatment Recommendations Asthma There is a stepwise approach to the management and treatment of Asthma. See Table 5.2 for a summary of the recommended management of Asthma therapy. COPD Appropriate treatment is dependent on the severity of disease. It is generally not recommended to use an inhaled corticosteroid as monotherapy in the treatment of COPD. It is also not recommended to rely on regular use of short acting beta agonists (SABA) or rescue inhalers. COPD treatment centers on the use of long acting beta agonists (LABA) and the long acting anticholinergics. These two drug classes can be used in combination when necessary for symptom management. Inhaled corticosteroids are an additional option to be tried in combination with LABA or long acting anticholinergics. This study source was downloaded by from CourseH on :52:08 GMT -06:00 Problem Set Question 1 Define the terms asthma and COPD, chronic bronchitis/emphysema. - Asthma is the general term for recurrent and reversible shortness of breath resulting from the narrowing of the bronchi and bronchioles. - COPD consists of both emphysema and chronic bronchitis. - Emphysema is a disease process involving inflammation of the alveoli. - Chronic Bronchitis is characterized by chronic inflammation or irritation on the lower respiratory tract, specifically the bronchi. Question 2 Describe the pathophysiology related to asthma and COPD (including emphysema and chronic bronchitis) - Asthma: The narrowing of the bronchioles can be caused by bronchospasm, inflammation, edema and the production of mucus. This ultimately obstructs airflow meaning that the carbon dioxide cannot t get out and the oxygen cannot get in. - COPD- Emphysema occurs when the air spaces enlarge as a result of the destruction of the alveolar walls. The cause of this appears to be enzymes that are released in response to inflammation. Hyperinflation is the result of the air spaces being enlarged. This results in a reduction in gas exchange and the feeling of shortness of breath. - Chronic Bronchitis- irritants cause mucus secretions to increase and thicken which can then begin to interfere with gas exchange within the lungs. Question 3 Describe the mechanism of action for the three types of bronchodilators- beta adrenergic agonists, anticholinergic, and theophylline. Beta adrenergic agonists- relax and dilate the airways by stimulating the beta2 adrenergic receptors within the lungs. Anticholinergic- By blocking the effects of acetylcholine these drugs can produce bronchodilation and reduce the volume of respiratory secretions. Theophylline- Theophylline inhibits the enzyme phosphodiesterase. This enzyme is known to inactivate a compound called cyclic adenosine monophosphate (cAMP) that leads to bronchodilation. Question 4 List the two classes of drugs considered to be anti-inflammatory respiratory medications. corticosteroids and leukotriene receptor antagonists. Question 5 Describe the mechanism of action of the Leukotriene inhibitors. Leukotrienes are chemical mediators that are known to cause bronchoconstriction, mucus production and inflammation. Zileuton works by inhibiting the enzyme necessary for leukotriene synthesis. Montelukast and Zafirlukast work by blocking the leukotiren-1 receptor. This study source was downloaded by from CourseH on :52:08 GMT -06:00 Question 6 Define the following abbreviations: LABA, SABA, ICS. Provide an example of each. Long Acting Beta Agonist- salmeterol, Short Acting Beta Agonist- albuterol, Inhaled Corticosteroid- fluticasone Question 7 Explain the basic treatment approach for persistent asthma. Starting with a low dose ICS and increasing stepwise by either increasing the dose of the ICS and/or adding a LABA. Once a patient is on a high dose ICS and LABA oral corticosteroids may also need to be used to get patient’s symptoms under control. Question 8 COPD treatment centers around the used of which two long term controller medications? LABA and Long acting anticholinergics Question 9 In your own words, how would you instruct a patient to use a metered dose inhaler? Remove the cap and shake the inhaler, exhale completely, simultaneously press down on inhaler while breathing in, hold your breath for 10 seconds and then slowly exhale. Question 10 In your own words how would you instruct a patient to use a dry powdered inhaler? Start by opening the inhaler, exhale completely, take a deep breath in while holding the inhaler to your mouth, hold your breath for about 10 seconds and then slowly exhale. Close the inhaler. This study source was downloaded by from CourseH on :52:08 GMT -06:00 Powered by TCPDF ()