Bronchodilators

Introduction

• Bronchodilators remain the standard of care for the treatment of bronchospasm.
• Traditionally, bronchodilators are characterized into two main classes: beta-2 agonists and anticholinergics (also known as muscarinic antagonists).¹
• In addition to these traditional classes, combination bronchodilators and methylxanthines, many of our anesthetic agents also have a relaxation effect on smooth muscle.^1,4
• In the perioperative period, bronchospasm can be associated with chronic medical conditions, such as asthma or COPD, or with acute perioperative events. Patient factors, airway manipulation, introduction of new medications with the potential for an allergic response, and pulmonary aspiration can all trigger perioperative bronchospasm requiring bronchodilator intervention.^2,4
• The use of bronchodilators to improve acute bronchospasm is necessary to prevent hypoxia, hypercarbia, and hyperinflation syndrome.⁴

Perioperative Bronchospasm

• Bronchospasm is the acute narrowing of the bronchioles, resulting in reduced airflow.
• In the perioperative period, bronchospasm can be triggered by activation of parasympathetic pathways (i.e., vagal nerve stimulation) or histamine release (via allergic or nonallergic mechanisms).^2,4
• Risk factors related to the patient, anesthetic, and surgery can cause acute perioperative bronchospasm. Differential diagnoses of perioperative bronchospasm should be considered before selecting a bronchodilator.³
• Please see the OA Summary: “Bronchospasm” for more details. Link

Anesthetic and IV Agents with Bronchodilatory Effects

• Bronchodilator selection is based on the likely cause of bronchospasm, the availability of IV access, the severity of the bronchospasm, and potential medication side effects.⁴

Inhaled and Oral Bronchodilators

• Bronchodilators are used for patients with respiratory conditions such as asthma or COPD to reverse symptoms or improve lung function.
• These agents are available in several inhaled formulations and provide localized action in the pulmonary tree, typically with minimal systemic absorption.¹
• Patients who are prescribed bronchodilators for long-term management of their pulmonary disease should continue taking these medications in the perioperative period.
• Short-acting beta-2 agonists can also be used in the perioperative period for the treatment of acute bronchospasm.^2,4
• Preoperative bronchodilator administration has been shown to decrease perioperative adverse respiratory events in children with current or recent upper respiratory infections undergoing anesthesia.⁸
• Albuterol is the most common agent used and can be administered via a metered-dose inhaler (with or without a spacer in awake patients) or via a nebulizer. The delivery of albuterol via a metered-dose inhaler with a spacer has been shown to have a similar clinical effect to nebulized albuterol.⁷
• In anesthetized patients, albuterol can be administered with the endotracheal tube (ETT). Inhaled agents such as albuterol can precipitate in the ETT, so at least eight puffs should be administered to ensure delivery to the bronchial mucosa.
• Albuterol can cause tachycardia and hypokalemia; these side effects should be taken into consideration when choosing to administer albuterol.¹