Treatment and prevention of asthma exacerbations: how good are inhaled corticosteroids alone at preventing asthma exacerbations?
Viral infections are the major cause for asthma exacerbations in both children and adults. Current therapy for virus-induced wheezing generally includes the additional use of bronchodilators, increasing doses of inhaled corticosteroids (ICS) and, if symptoms persist or worsen, the administration of systemic corticosteroids. With the development of higherpotency topical corticosteroids, recent trials have also investigated the efficacy of high-dose ICS given either prophylactically or as an acute intervention in the management of these wheezing episodes. The efficacy of various ICS therapeutic interventions for the acute symptoms of wheezing, tachypnea and hypoxemia that may occur as a result of viral upper respiratory tract infections (URTIs) has been controversial due to differences in study design, the inability to rapidly and conveniently measure pulmonary physiological variables and the choice of outcome measures evaluated. Furthermore, it has been difficult to extrapolate these recommendations to infants and young children who wheeze in the presence of viral
infections, yet in whom the diagnosis of asthma has not yet been fully established. In these children, recurrent episodic wheezing secondary to viral respiratory infections may represent a unique illness that is distinct from persistent allergic asthma. It is the goal of this chapter to review recent pediatric and adult experiences as they pertain to the use of high-dose ICS in preventing or attenuating asthma exacerbations due both to naturally occurring viral respiratory illnesses and to experimental colds.