Severe acute asthma: an attempt to identify the quiet before the storm.

Asthma is a serious and prevalent public health problem that spans the entire world. It is estimated that asthma affects over 300 million people worldwide.1 Its prevalence is approximately 21 million citizens in the United States, according to the Centers for Disease Control and Prevention.2 Other reports indicate that as many as 9.5 million children currently have asthma in the United States.3 Asthma care and management have undergone much scrutiny over the last 30 years, which has led to the development and implementation of guidelines throughout the world that have recently gravitated toward being evidencebased. Evidence-based clinical practice guidelines offer both evidence and instructional components, and represent the ideal for bringing current scientific knowledge to the clinician and bedside.4 The topic of fatal or near fatal or severe acute asthma has intrigued the respiratory, pulmonary, and epidemiology communities over several decades. The treatment and management of severe acute asthma is often the least scientifically supported subject documented in asthma guidelines. In fact, a precise definition of a severe asthmatic exacerbation is an issue that presents difficulties.5 The term “status asthmaticus” relates severity to outcome and has been used to define a severe asthmatic exacerbation that does not respond to and/or perilously delays the repetitive or continuous administration of short-acting inhaled 2 adrenergic receptor agonists in the emergency setting.6 Despite this lack of clarity of what constitutes severe acute asthma, it occurs across the entire disease severity spectrum in pediatrics. In a study by Fuhlbrigge and colleagues,7 they explored the relationship between percentpredicted FEV1 (FEV1%) and subsequent asthma attacks in a longitudinal study of pediatric lung health. This study documented that, regardless of FEV1%, approximately 30– 65% of children with asthma reported an exacerbation over the past year. Most asthma guidelines offer evidence-based or best practice approaches to the management of asthma exacerbations.4 Most guidelines struggle with the presentation of a robust evidence-based approach for life-threatening or severe asthma exacerbations. Despite the lack of evidence, much ongoing scientific interest exists and is written about when it comes to life-threatening asthma or severe asthma exacerbations.8 The rationale, of course, is that if the pathophysiology or phenotype of children who suffer severe asthma attacks could be better understood, the interventions and treatments provided could be instituted much sooner, leading to quicker resolution of the exacerbation, with less functional morbidity.