What are the indications for intubation in a patient with asthma (bronchial asthma)?

From the Guidelines

Intubation in asthma patients should be done semielectively and before respiratory arrest occurs, with consideration of maintaining or replacing intravascular volume and avoiding high ventilator pressures to minimize the risk of barotrauma 1. When intubating an asthma patient, it is essential to consider the potential complications and take steps to prevent them.

• The use of permissive hypercapnia or controlled hypoventilation as the recommended ventilator strategy can provide adequate oxygenation while minimizing airway pressures and the possibility of barotrauma 1.
• Maintaining or replacing intravascular volume is crucial to prevent hypotension, which commonly accompanies the initiation of positive pressure ventilation 1.
• The choice of induction agent and paralytic should be carefully considered, with options such as ketamine and succinylcholine or rocuronium, to facilitate rapid sequence intubation.
• Pre-treatment with bronchodilators such as albuterol nebulization and IV magnesium sulfate can help optimize bronchodilation before the procedure.
• Ventilation parameters should be carefully managed to prevent dynamic hyperinflation and barotrauma, with the use of low tidal volumes and longer expiratory times.
• Consultation with or comanagement by a physician expert in ventilator management is essential due to the complexity and risks associated with ventilation of patients with severe asthma 1.

From the Research

Asthma Intubation Overview

• Asthma intubation is a critical procedure for patients with severe asthma exacerbations that do not respond to initial intensive therapy 2, 3.
• The in-hospital mortality rate for critically ill asthmatics that require intubation is between 10% to 25%, primarily due to anoxia and cardiopulmonary arrest 2.
• Timely evaluation and treatment in the clinic, emergency room, or intensive care unit (ICU) can prevent morbidity and mortality associated with respiratory failure 2.

Management of Life-Threatening Asthma

• Treatment strategies for life-threatening asthma focus on achieving effective bronchodilation and reducing inflammation 3.
• Endotracheal intubation and mechanical ventilation should not be delayed if clinical improvement is not achieved with conservative therapies 3.
• Mechanical ventilation in these patients often requires controlled hypoventilation, adequate sedation, and occasional use of muscle relaxation to avoid dynamic hyperinflation 3.

Use of Ketamine in Refractory Severe Asthma Exacerbations

• Ketamine has been explored as a pharmacological option for refractory severe asthma exacerbations, but a systematic review found no clear benefit and some signals towards side effects 4.
• The review suggests that ketamine should not be used in refractory severe asthma exacerbations, and well-designed multicenter randomized controlled trials are desirable to further investigate its use 4.

Complications and Mortality in Severe Asthma

• A retrospective review of medical records found that complications occurred in 45% of patients with severe asthma requiring intubation and mechanical ventilation, but the mortality rate was low (6%) 5.
• The most frequent precipitating events for exacerbation of asthma were medication noncompliance and upper respiratory tract infections 5.

Anaesthetic Management in Asthma

• Anaesthetic management in asthmatic patients should focus on avoiding bronchoconstriction and inducing bronchodilation 6.
• Regional anaesthesia is preferred when feasible, and a laryngeal mask airway is safer than endotracheal intubation if general anaesthesia is unavoidable 6.
• Propofol and ketamine can inhibit bronchoconstriction and decrease the risk of bronchospasm during anaesthesia induction 6.