Respiratory Medications Flashcards
Structures of the respiratory system
The structures of the respiratory system can be divided in two different ways:
structurally into upper and lower respiratory tracts
functionally into the conducting and respiratory zones (McKinley et al., 2021).
The terminology of upper and lower respiratory is often used when describing diseases of the respiratory system.
Functions of the respiratory system
Movement of air - air is transported from the external environment to alveoli located in the lungs;
Exchange of oxygen and carbon dioxide - occurs between the alveoli and capillaries of the pulmonary circuit;
Detection of odours - olfactory receptors located in the nasal cavity detect odours in air as it passes by;
Production of sound - vocal cords, located in the respiratory system produce sound when air moves across them
Changes in the functioning of the respiratory system may indicate respiratory disease. For example, restricted air movement when breathing out may be a sign of chronic obstructive airway disease. Reduced air movement when breathing in may be a sign of asthma. It may also be possible to hear extra sounds such as a high-pitched wheeze when air moves in or out of the airways.
Respiratory cycle
Respiration consists of a cycle of inspiration, expiration and rest. It is during this cycle that gas exchange occurs. Respiration is controlled by a complex set of processes involving the interplay of the cerebral cortex, the respiratory centre, chemoreceptors, proprioceptors and stretch receptors (McKinley et al., 2021).
Changes in the respiratory cycle may indicate respiratory disease or other disorders. For example, a person’s respiratory rate may increase when they have a respiratory infection.
Understanding the respiratory cycle is important as you will learn that some respiratory medications work to stimulate respirations whereas others may depress respirations. Respiratory depression (slow and ineffective breathing) may be a side effect of a medication (e.g. opioids).
Gaseous exchange and respiratory drive
The primary function of the lungs is to facilitate gas exchange between inspired air and the circulatory system. Oxygen is critical for proper metabolism on a cellular level and the body has a homeostatic mechanism to maintain normal partial pressure of oxygen in the blood (PaO2 levels). PaCO2 levels are the partial pressure of carbon dioxide in the blood and reflect the respiratory control of the acid-base balance and pH of blood (McKinley et al., 2021).
The respiratory control centre responds to altered blood gases (PaO2 and PaCO2 levels) by changing the respiratory rate, rhythm, depth and effort of breathing. Hypoxia or low levels of oxygen in the blood, induces rapid, shallow breaths with an increase in respiratory rate (McKinley et al., 2021).
Understanding gaseous exchange and respiratory drive is important as you will learn that medications, including oxygen, may be administered to meet the body’s metabolic demand for oxygen.
Asthma
Definition
A respiratory condition marked by spasm attacks of the bronchi of the lungs, causing difficulty in breathing.
Processes at play
Bronchospasm - a sudden constriction of the muscles in the walls of the bronchioles caused by the release of substances from mast cells or basophils.
Types of asthma
Extrinsic asthma - caused by allergens irritating the airway and which cause the release of chemical mediators from the lungs. They cause vasodilation, increased permeability of the pulmonary capillaries, the production of viscous mucous and severe constriction of the bronchioles.
Intrinsic asthma - caused by an alteration in autonomic nervous system function. There is an imbalance between the sympathetic and parasympathetic stimulation of the bronchioles.
In both forms of asthma, air enters the lungs but cannot be expired. There is therefore an inspiratory wheeze.
Chronic obstructive airway disease (COAD)
Definition
A chronic inflammatory lung disease that causes obstructed airflow from the lungs.
Processes at play
Emphysema - A lower respiratory tract disease caused by enlarged airspaces in the lungs which results in reduced alveolar surface area, reduced gas exchange and reduced oxygen supply for the blood.
Chronic bronchitis - A lower respiratory tract disease associated with excess mucus production in the lungs and a productive cough.
Respiratory tract infections (RTIs)
Definition
Infections of the respiratory tract (sinuses, throat, airways or lungs).
Processes at play
Upper respiratory tract Infection (URTI) - A respiratory infection affecting the upper airways (sinuses, larynx and pharynx), caused by an infective agent (e.g. virus or bacteria)
Lower respiratory tract Infection (Pneumonia)- A respiratory infection affecting the lower airways (bronchi and lungs), caused by an infective agent (e.g. virus or bacteria).
Allergic rhinitis (Hay fever)
Definition
An allergic response from the immune system that causes sneezing, runny nose and watery, itchy eyes.
Processes at play
Exposure and reaction to allergens e.g. pollen, pet hair or dust.
Lung cancer
Definition
Primary lung cancer begins in the lungs when abnormal cells grow and multiply in an uncontrolled way.
Processes at play
Exposure to smoke and certain toxins.
Bronchodilators: Beta2 agonists
Medication examples: Generic (Trade) name
Salbutamol (Ventolin) [Inhaler] - short acting (usually blue)
Salmeterol (Serevent accuhaler) – long acting
Action
Acts to stimulate the beta 2 adrenergic receptors, causing the smooth muscles of the bronchioles to dilate (bronchodilation).
Used for the treatment of the bronchoconstrictive symptoms associated with asthma and Chronic Obstructive Pulmonary Disease (COPD), hence is known as a “reliever”.
May be short-acting (up to four hours) or long acting (up to 12 hours).
Nursing responsibilities / Patient education
Educate patient on how to use a pressure metered-dose inhaler (puffer).
Educate patient that it is preferable to use a inhaler with a spacer and explain how to use a puffer with a spacer.
Bronchodilators: Anticholinergics (anti-mucus producing agents)
Medication examples: Generic (Trade) name
Ipratropium (Atrovent) [Inhaler]
Action
Block the muscarinic receptors in the lungs which are associated with parasympathetic stimulation.
They reduce bronchomotor tone (the state of contraction or relaxation of the smooth muscles in the bronchial walls and controls the width of the airways) which results in bronchodilation.
Nursing responsibilities / Patient education
Educate patient on how to use an inhaler with a spacer.
Methylxanthines
Medication examples: Generic (Trade) name
Aminophylline (DBL Aminophylline Injection) [Solution for injection]
Theophylline (Nuelin SR) [Tablets]
Action
Has a direct relaxant effect on the smooth muscle of bronchial airways (bronchodilator) and pulmonary blood vessels (pulmonary vasodilator).
Used to treat bronchospasm (e.g. asthma) that is not responsive to beta2 agonists or inhaled corticosteroids.
Nursing responsibilities / Patient education
If giving aminophylline by injection, must be given by slow intravenous injection. A loading dose is administered followed by a maintenance dose.
Use with extreme caution in people with cardiovascular disease (arrhythmias, angina, severe hypertension) as the other actions associated with xanthines include cardiac stimulation, coronary vasodilatation, diuresis and increased gastric secretion.
Combined agents: Corticosteroid with a bronchodilator
Medication examples: Generic (Trade) name
Budesonide (corticosteroid) with Formoterol (long acting beta2 agonist) (Symbicort)
Fluticasone (corticosteroid) with Salmeterol (long acting beta2 agonist) (Seretide)
Action
A cortiocosteroid is combined with a long-acting bronchodilator to produce a combined steroid inhaler for maintenance treatment, referred to as a “preventer”.
Nursing responsibilities / Patient education
Educate patient that this inhaler is a “preventer” and should be used at the same time each day. It will not be effective for relief of acute symptoms, this is when a “reliever” should be used.
If both a “reliever” and a “preventer” are due at the same time, use the “reliever” first to open the airways and allow better absorption of the other medications.
Side effects include a sore throat or feel hoarse, so advise patient to rinse their mouth after using the inhaler. This may help avoid oral thrush (as corticosteroid use may change the normal flora of the mouth).
Methylxanthines are used to treat asthma upon first treatment
False - Correct. The answer is false. Methylxanthines are used to treat asthma that continues despite treatment and that is not responsive to beta2 agonists or inhaled corticosteroids.
Methylxanthines appear to increase the sensitivity of the brain’s respiratory centre to carbon dioxide and stimulate the carbon dioxide drive
True - Correct. The answer is true. Methylxanthines appear to increase the sensitivity of the brain’s respiratory centre to carbon dioxide and stimulate the carbon dioxide drive.
