There are approximately 2 million emergency department visits for acute asthma per year with 12 million people reporting having had asthma ''attacks'' in the past year (1). Approximately 2% to 20% of admissions to intensive care units (ICUs) are attributed to severe asthma, with intubation and mechanical ventilation deemed necessary in up to one third in the ICU (2) and mortality rates in patients receiving intubation from 10% to 20% in this patient population (3).The onset of acute asthma symptoms ranges from hours to weeks. Type I acute asthma, also known as slow-onset asthma, often presents as a gradual deterioration of the clinical scenario, which is superimposed on a background of chronic and poorly controlled asthma. Type II acute asthma, or rapid-onset asthma, tends to be more dangerous and frequently presents with sudden narrowing of the airways (4).This article reviews the recent evidence-based data regarding the indications, techniques, and complications of intubation and mechanical ventilation in the treatment of acute asthma in the emergency department (ED). It also discusses possible strategies for preventing the need for intubation in patients with severe exacerbations who are not responding to conventional therapy. Finally, this article provides practical management recommendations in this clinical setting.
METHODSThree sets of keywords were used for the systematic literature review. The first set included the terms acute asthma, acute severe asthma, acute bronchospasm, acute reactive airways disease, asthma exacerbation, emergency asthma, and status asthmaticus. The second set of keywords included the following terms: mechanical ventilation, mechanical ventilator, invasive ventilation, mechanical ventilatory support, continuous mandatory ventilation (CMV), assist-control ventilation, synchronized intermittent mandatory ventilation (SIMV), intermittent positive-pressure ventilation, and complications of mechanical ventilation. The third set of keywords included the following terms: hypercapnea, hypercapnia, hypopnea, hypercapnic, respiratory failure, respiratory insufficiency, respiratory arrest, arrest, hypoventilation, hypoxemia, intubation, endotracheal intubation, oral intubation, orotracheal intubation, nasal intubation, nasotracheal intubation, intratracheal intubation, respiratory acidosis, fatal, and life-threatening. Additional details of the methodology for all literature reviews in this issue are provided in the introduction to this issue (5). The task force specified the level of evidence used to justify the recommendations being made, and the system used to describe the level of evidence is also defined in the introduction to this issue.
RESULTSThe search for the topic of intubation produced 41 randomized controlled trials (RCTs) and 6 meta-analyses. Five RCTs were deemed appropriate for this review. The search for the topic of mechanical ventilation revealed 5 RCTs and 4 meta-analyses. None of these RCTs or meta-analyses was deemed appropriate for this review because they did not deal...
