Respiratory Emergency Medications

Respiratory Emergency Medications

• Respiratory distress is a common presentation in prehospital settings, affecting people across all demographics.
• Prehospital care often focuses on treating reversible bronchial constriction (bronchospasm), except in cases of acute pulmonary edema.
• Advanced life support interventions, including medication administration, significantly reduce mortality in respiratory distress cases.

Oxygen

• Oxygen is a frequently used prehospital medication.
• Oxygen use carries both benefits and risks.
• Oxygen use is becoming more nuanced, with careful titration to specific oxygen saturation ranges instead of indiscriminate application in situations like neonatal resuscitation, COPD exacerbations, and acute coronary syndrome.
• Ongoing research and guidelines updates are expected to change prehospital oxygen delivery methods.
• Some patients with COPD receive continuous oxygen therapy at home, often via transtracheal catheters for long-term use, which are surgically inserted.

Bronchodilators

• Asthma and COPD, characterized by reversible airway obstruction, cause respiratory distress through functional narrowing of airways.

• Bronchospasm (smooth muscle spasm) decreases airway diameter, while mucosal edema thickens the airways.

• Increased secretions also contribute to respiratory distress.

• Bronchodilators treat these conditions, categorized as selective or nonselective.

• Selective agents act preferentially on bronchial smooth muscle, minimizing side effects.

• Beta2 agonists, like albuterol, relax bronchial muscles without significant tachycardia or hypertension.

• Nonselective agents, like racemic epinephrine, act on multiple receptors including alpha, beta 1 & beta 2. Alpha receptor stimulation causes blood vessel constriction leading to higher blood pressure. Beta 1 receptors, found mostly in the heart, lead to an increase in heart rate and contractility. Beta2 receptor stimulation causes bronchodilation.

• Beta2 agonists should be used cautiously in patients with heart conditions. Continuous ECG monitoring is recommended.

• Examples of beta2 agonists include albuterol (Proventil, Ventolin), terbutaline (Brethine), formoterol (Foradil), and pirbuterol (Maxair).

• Ipratropium bromide (Atrovent) is an anticholinergic, not an adrenergic agent, used in severe asthma exacerbations or limited responses to albuterol. Its peripheral action is advantageous in COPD.

• A combined treatment of albuterol and ipratropium bromide (Combivent) is available to leverage both medications' different action mechanisms.

Management of Asthma

• Asthma triggers can be either intrinsic (within the body) or extrinsic (outside the body).

• Avoid triggers to prevent asthma attacks.

• First-line therapy for asthma includes inhaled beta2-specific drugs like albuterol.

• If the inhaled bronchodilators are unsuccessful, intravenous corticosteroids to treat inflammation are administered.

• Levalbuterol (Xopenex) is a newer, more beta-2 specific bronchodilator that was believed to cause fewer adverse effects than albuterol.

• Ipratropium bromide is used in severe cases, or with a limited response to albuterol.

Second-Line Therapy for Asthma Exacerbations

• Corticosteroids (methylprednisolone and dexamethasone) are used for severe asthma exacerbations with prolonged transport times, as they treat the underlying inflammatory process rather than simply treating symptoms.

• Peak expiratory flow rate (PEFR) measurement guides treatment decisions regarding exacerbation severity.

• When PEFR is less than 50% predicted, corticosteroids are recommended.

• Methylxanthines like aminophylline were once common, routine second-line agents for severe asthma exacerbations, but their use is now limited due to potential side effects and a narrow therapeutic window.

• Magnesium sulfate is a possible treatment for patients who do not respond adequately to beta2 agonist medications in suspected asthma exacerbations.

• Epinephrine should be used with caution in asthma treatment, primarily due to its strong and undesirable short-lived effects on the alpha and beta 1 receptors.

Chronic Obstructive Pulmonary Disease (COPD)

• COPD encompasses diseases causing pulmonary obstruction, specifically emphysema and chronic bronchitis.

• These conditions cause an increase in sputum production and bronchospasm, worsening with increased sputum.

• Initial treatment of mild-to-moderate COPD exacerbations focuses on reducing bronchospasm and clearing airways of secretions.

• Oxygen administration needs careful consideration, as COPD patients often have a hypoxic respiratory drive (a mild degree of hypoxia is necessary for triggering respiration).

• Supplemental oxygen may need to be titrated cautiously to avoid suppressing this natural respiratory stimulus.

Anaphylaxis

• Histamine is a chemical mediator found in body tissues, with higher concentrations in skin, lungs and GI tract.
• The body releases histamine when exposed to an antigen, resulting in increased blood flow, capillary permeability, tissue swelling bronchoconstriction, and urticaria..
• This reaction is called anaphylaxis.

Antihistamines

• There are two types of histamine receptors: H1 (acts on blood vessels and bronchioles) H2(acts on GI tract)
• Antihistamines are atropine-like with potentially unwanted side effects, including tachycardia, constipation, drowsiness, and sedation.
• Examples of antihistamines include dimenhydrinate (Dramamine), diphenhydramine, and Chlorphenamine.

Mucolytics

• Mucokinetic drugs alter respiratory secretion consistency, promoting easier clearance.
• Mucolytics thin mucus, making it less thick and sticky, improving expectoration.

Cough Suppressants

• Codeine, Benzonatate (Tessalon) are examples of antitussive cough suppressants.

Direct Respiratory Stimulants

• Direct respiratory stimulants, or analeptics, increase respiratory rate and depth, used for respiratory depression like from anesthesia.
• Doxapram (Dopram) is an example.