Effective bronchodilator resuscitation of children in the emergency room: device or interface?

Aerosol therapy is a vital component in the treatment of children with asthma, and inhaled -agonists are the firstline therapy for bronchospasm in acute asthma. In the emergency department, bronchodilators are commonly administered to children via small-volume jet nebulizer (SVN) or large-volume jet nebulizer (LVN). SVNs have been widely used in hospitals and emergency departments for more than 50 years. An SVN delivers 1–5 mL over 8–15 min. In the United States the drug label for inhalation solution of albuterol is a 0.083% solution (2.5 mg in 3 mL), administered 3 or 4 times per day, but that dosage is often not sufficient to relieve a severe asthma exacerbation, even though such dosing may be sufficient for mild to moderate reactive airway disease in an ambulatory setting. Albuterol, like most drugs approved for inhalation, was approved based on trials with ambulatory patients with mild to moderate asthma. Patients presenting to the emergency department with severe bronchospasm may not respond to the standard label dose of albuterol and require higher doses at shorter intervals than the stable patient at home. This has led clinicians to devise effective “offlabel” strategies for administration of bronchodilators and other drugs to treat severely ill patients, including higher doses, higher drug concentration, shorter intervals between doses, and continuous nebulization. Continuous nebulization with an LVN or an SVN with a continuous feed and a delivery rate of 10–20 mg/h is as effective as, or superior to, intermittent doses via SVN.1-6 Comparison of 4 LVNs found relatively consistent emitted aerosol output, with similar performance during the first 5 hours of use.7 Breath-actuated nebulizers generate aerosol only during inhalation, which reduces aerosol waste but extends the treatment time.8,9 Since the introduction of the breath-actuated nebulizer in 2000, in vitro and in vivo studies have shown the breath-actuated nebulizer’s potential for better lung deposition and possibly greater efficacy. For example, Sangwan et al compared MistyNeb and AeroEclipse for particle-size distribution in vitro, with no breathing (standing cloud), and with simulated ventilation, and reported that the mass median aerodynamic diameter (MMAD) for both nebulizers was affected by ventilation: MistyNeb 5.2 m versus AeroEclipse 4.6 m for standing cloud, and MistyNeb 3.1 m versus AeroEclipse 2.2 m during ventilation. With inhaled radio-labeled interferongamma, lung deposition averaged 68.1 0.1% with AeroEclipse, and 30.9 0.0% with MistyNeb, with fill volumes of 2 mL and 4 mL, respectively.10 Those studies stimulated speculation that breath-actuated nebulizer might generate smaller aerosol particles and thus have greater lung dose with other drugs, such as bronchodilators. Despite the widespread interest in breath-actuated nebulizers for hospital practice, precious few studies have compared breath-actuated nebulizers to other bronchodilator delivery strategies in the emergency department. In this issue of RESPIRATORY CARE, Sabato et al present findings from their randomized study of the efficacy of albuterol administered via the AeroEclipse breath-actuated nebulizer versus their institution’s standard therapy (either SVN or LVN) in the treatment of pediatric patients presenting with asthma to the emergency department.11 They are the first to report significant differences in admission rate and symptom-score improvement between the 2 treatment groups. Sabato and colleagues made a multidimensional assessment, including clinical asthma score, heart rate, respiratory rate, peak expiratory flow, patient tolerance of the treatment, nausea, tremor, vomiting, and hyperactivity. Those variables are the best way to capture all domains of patients’ response to therapy, and they were measured at baseline and at follow-up to determine changes in health status. From the statistical point of view, the study was appropriately powered and had a very small sample loss, which are strengths of the study.