EHS 202 Pharmacology for EMS Week 11 Respiratory Emergencies PDF

EHS 202 Pharmacology for EMS Week 11 - Respiratory Emergencies 11/1/2022 RESPIRATORY EMERGENCIES Introduction Acute respiratory distress affects many people Pre-hospital care of acute respiratory distress aims to treat reversible bronchial constriction...

EHS 202 Pharmacology for EMS Week 11 - Respiratory Emergencies 11/1/2022 RESPIRATORY EMERGENCIES Introduction Acute respiratory distress affects many people Pre-hospital care of acute respiratory distress aims to treat reversible bronchial constriction (bronchospasm) The exception of this treatment goal is in the case of acute pulmonary edema ALS interventions have been shown to significantly reduce mortality in patients with respiratory distress 11/1/2022 RESPIRATORY EMERGENCIES 2 Learning Objectives By the end of this lesson you will be able to: Define nasal cannula, rebreather face mask, nonrebreather face mask, and venturi mask; Discuss the use of oxygen in a respiratory emergency; Describe bronchodilator agents; Discuss the benefits of the metered-dose inhaler; Discuss medications used in the treatment of asthma: salbutemol (albuterol) and ipratropium bromide; 11/1/2022 RESPIRATORY EMERGENCIES 3 Learning Objectives By the end of this lesson you will be able to: Discuss medications used as second-line therapy for acute exacerbation of asthma. Describe the key treatment for patients with chronic obstructive pulmonary disease. 11/1/2022 RESPIRATORY EMERGENCIES 4 Oxygen Oxygen is a common medication used in the prehospital setting Provided to trauma and medical patients Considerations in medical patients: In situations such as neonatal resuscitation, chronic obstructive pulmonary disease (COPD) exacerbations, and acute coronary syndrome/stroke patients, oxygen use is carefully titrated to prescribed saturation levels rather than applied indiscriminately. Oxygen is stored in green/aluminum cylinders at 1,800-2,400 psi, then decreased to 60 psi as it passes through the regulator 11/1/2022 RESPIRATORY EMERGENCIES 5 Oxygen Cylinders: Capacity and Duration of Use RESPIRATORY EMERGENCIES 6 Oxygen Quantity of oxygen delivered is considered in terms of the concentration of inspired oxygen and flow Concentration of inspired oxygen: fraction of inspired oxygen (FiO2) Percentage of oxygen in the atmosphere is 21%, so FiO2 in normal room air is 21% Increasing administered FiO2 increases oxygen content delivered to the body 11/1/2022 RESPIRATORY EMERGENCIES 7 Oxygen Delivery Oxygen delivery devices include nasal cannula and face mask; simple & nonrebreather. Nasal cannula delivers oxygen vis two small prongs that fit in the patient’s nostrils, in a low-flow, non intrusive fashion Set with a flow rate of 1 - 6 L/min, can deliver oxygen concentration of 24-44% Simple / partial rebreather masks do not have reservoir bag or one directional side ports. Set with a flow rate of 6-10 L/min, can deliver 35 – 60% concentration 11/1/2022 RESPIRATORY EMERGENCIES 8  Oxygen Delivery Nonrebreather face masks - Have face mask and reservoir bag Has a one-way exhalation valve on one side of mask, and one on reservoir The valve prevents exhaled oxygen being breathed back in to the reservoir bag Require higher flow rate of 12-15 L/min, can deliver oxygen concentration up to 90% concentration (Fi02) 11/1/2022 RESPIRATORY EMERGENCIES 9 Oxygen Delivery Venturi mask Have small plastic inserts that fit ports on the mask Changing insert - alters oxygen concentration 24%, 28%, 35% or 40% Often used by COPD patients For a step-by-step procedure to initiating oxygen therapy, refer to: p.603 (JRCALC, 2020) p. 275 (Guys 2020) 11/1/2022 RESPIRATORY EMERGENCIES 10 Nebuliser Nebulisers use oxygen, compressed air or ultrasonic power to break up medication solutions and deliver a therapeutic dose of aerosol particles directly to the lungs. 11/1/2022 RESPIRATORY EMERGENCIES 11  Management of Wheezing 11/1/2022 RESPIRATORY EMERGENCIES 12 Bronchodilators Asthma: inflammatory lung disease characterized by typically reversible airway obstruction Functional narrowing of conducting airways cause respiratory distress Bronchospasm: spasm of the bronchial smooth muscles resulting in a decrease in airway diameter 11/1/2022 RESPIRATORY EMERGENCIES 13 Bronchodilators Asthma involves three distinct phases: Narrowing of the airways Bronchial spasm Increased mucus production An additional factor in respiratory distress is edema of respiratory tract mucosa Thickens mucosal lining, restricting airway diameter 11/1/2022 RESPIRATORY EMERGENCIES 14 Bronchodilators Bronchodilators can be divided into selective and nonselective agents Nonselective agents Act on alpha, beta1, beta2 adrenergic receptors Alpha receptors constrict peripheral blood vessels Beta1 receptors increase heart rate, cardiac contractility Beta2 receptors result in bronchodilation Selective agents Act preferentially on bronchial smooth muscle and improve patient’s condition; minimising the side effects Beta2 agonists target beta2 receptors, cause relaxation of bronchial smooth muscle Does not stimulate tachycardia or hypertension 11/1/2022 RESPIRATORY EMERGENCIES 15 Inhalation Delivery of Medications Delivery of beta2-specific medications can be done by nebulization, parenteral or oral administration Nebulization Converting liquid medication into fine mist to be inhaled Pneumatic nebulizers use a gas to drive conversion Ultrasonic nebulizers use ultrasonic sound to drive conversion Metered-dose inhaler (MDI) uses propellant spray to deliver medication Goal is to deliver small particles of medication directly to receptors in lung by inhalation For a step-by-step procedure on performing nebulization therapy, refer to page 277 (Guys, 2020) 11/1/2022 RESPIRATORY EMERGENCIES 16 Metered-Dose Inhaler MDI delivers predetermined amount of medication in correct particle size propelled by small amount of gas Two parts: canister and mouthpiece If MDI is used improperly, medication will not reach intended site in lung MDI propellant can force medication at a rapid speed, causing the particles to hit the walls of the oropharynx rather than their intended sites Spacer device can slow forward movement of particles. When one is not available, hold MDI 2 inches from mouth For step-by-step procedures to administering an MDI, refer to pages 279 and 280 (Guys, 2020) 11/1/2022 RESPIRATORY EMERGENCIES 17 Asthma Asthma is caused by a trigger reaction Intrinsic trigger: within the body Exertion (exercise), anxiety related to stress Extrinsic trigger: outside the body Reactions to animal dander, dust, pollen, cleaning chemicals, animal droppings 11/1/2022 RESPIRATORY EMERGENCIES 18 Asthma Management First line of medication is inhaled beta2 drugs If inhaled bronchodilators fail, IV medications are then administered Salbutamol (albuterol) is most common inhaled drug to treat reversible bronchospasm Developed to only target beta2 receptor 11/1/2022 RESPIRATORY EMERGENCIES 19  Asthma Management Ipratropium bromide - severe asthma/chronic obstructive pulmonary disease (COPD) salbutamol ineffective – acetylcholine antagonist – blocks cholinergic receptors -decreases smooth muscle contraction. Indications: Acute severe or life-threatening asthma Acute asthma unresponsive to salbutamol Exacerbation of COPD 20 Second-Line Therapy for Acute Exacerbation of Asthma Clinical picture of asthma or COPD Gasping for breath, accessory muscles use, wheezing If prolonged transport time is likely, consider corticosteroids to treat inflammatory processes Also consider when PEFR does not improve by at least 10% after bronchodilator therapy or when PEFR > 70% after 1 hour 11/1/2022 RESPIRATORY EMERGENCIES 21 Second-Line Therapy for Acute Exacerbation of Asthma Peak expiratory flow rate (PEFR): an objective assessment that can guide determination of the severity of an exacerbation; patient’s response to therapy; indication for therapy 11/1/2022 RESPIRATORY EMERGENCIES 22 Acute Exacerbation of Asthma (Pre-hospital) Severe / life threatening asthma - Hydrocortisone (IV preferably or IM if no IV) 100mg slowly 2 mins – to suppress inflammation and immune response. Adrenaline – life threatening asthma – 500mcg every 5 minutes. Adrenaline is a sympathomimetic which stimulates alpha and beta cells, relieving bronchospasm in acute severe asthma. 11/1/2022 RESPIRATORY EMERGENCIES 23 Chronic Obstructive Pulmonary Disease (COPD) COPD is classification for diseases that obstruct the pulmonary system Most common diseases: emphysema, chronic bronchitis Management In severe exacerbations, treatment is aimed at oxygenation and ventilation Chronic COPD patients breath on hypoxic respiratory drive Patient requires mild degree of hypoxia to continue breathing SpO2 level in low 90s is adequate Steroids and bronchodilators are used to manage COPD in a similar fashion for treatment of asthma 11/1/2022 RESPIRATORY EMERGENCIES 24 Hypoxic Drive Why should we not give COPD patients too much oxygen? What might happen? What is the correct oxygen regime for these patients? 11/1/2022 RESPIRATORY EMERGENCIES 25 11/1/2022 RESPIRATORY EMERGENCIES Medication Review for Next Week’s Quiz Salbutamol Ipratropium bromide Hydrocortisone Dexamethasone 11/1/2022 RESPIRATORY EMERGENCIES 27 References Andrew Pollak (2018). Nancy Caroline’s Emergency Care in the Streets, Eighth Edition. Jones & Bartlett Learning. Guy J (2020). Pharmacology for the Prehospital Professional, Second Edition. Jones & Bartlett Learning. Jones & Bartlett Learning (2020). Pharmacology for the Prehospital Professional, Second Edition Instructor's Toolkit. Jones & Bartlett Learning. Restrepo R.D. (2007) Use of Inhaled Anticholinergic Agents in Obstructive Airway, Respiratory care, 52,7. http://rc.rcjournal.com/content/respcare/52/7/833.full. pdf 11/1/2022 RESPIRATORY EMERGENCIES 28