1995 OPEN FORUM Abstracts
Albuterol Aerosolized By Ultrasonic Nebulizer Is Less Effective Then Jet Nebulization For The Treatment Of Acute Asthma In Children
Billy M Lamb BS, RRT, CPFT, Bruce K Rubin MD, FCCP, Albert K Nakanishi MD, Charles Foster BA, RRT, Cardinal Glennon Children's Hospital and St. Louis University Dept. of Pediatrics, St. Louis, MO
INTRODUCTION: A study of adults with stable asthma suggested that albuterol given by ultrasonic nebulization (UN) was more effective than the same dose of albuterol given by jet nebulization (JN). Considering nebulization time using an UN is half of the time required using a JN for an equal volume of medication, we hypothesized that efficacy of aerosolized albuterol when given by UN would be the same as for albuterol given by JN in producing bronchodilitation and that UN would represent a significant cost savings and a convenience to the patient. METHOD: we evaluated 125 children, aged 7-16 years (mean 10.5) who presented for treatment of acute mild to moderately severe asthma. After informed consent and randomization, 46 children received albuterol by UN (Microstat, Mountain Medical) and 67 were treated by JN (Whisper Jet, Marquest Medical) at a flow rate of 6-8 LPM. Dosage of albuterol for both groups: 0.15 mg/kg to a maximum 5 mg diluted in 2 cc normal saline. The UN group were treated with nebulized albuterol (NA) for six minutes and the JN group NA for 12 minutes (JN time in compliance with the AARC uniform time standard). Pulmonary function testing (PFT) was performed using Respiradyne (Sherwood Medical, St. Louis). FVC, FEV1, FEV1 to FVC ratio, PEFR and FEF25-75 were recorded as outcome measures 30 minutes following initiation of NA for both groups. Only patients with an initial percent predicted FEV1 of 70% or less were admitted to the study. Side effects and tremor were documented. Exclusion Criteria: patients requiring assisted ventilation. urgent or immediate intervention, patients with baseline respiratory rate > 70 breaths per minute, initial SpO2ɘ.90, or if intolerant of beta agonist medications.
Results: PFT on entry to the study was consistent in the two groups (FEV1; p>0.97). The change in FEV1 after therapy (UN +0.22 L vs. JN +0.37 L) was significant (p = 0.035) and favored JN. There was no difference in the improvement in PFT between JN and UN therapy in children with an initial FEV1/FVC >75%. however, when initial FEV1/FVC< 75%, the improvement in FEV1 favored JN (UN+0.2 vs. JN+0.47; p = 0.04). There was a trend toward a greater patient report of tremor after JN when compared to UN (p=0.14). DISCUSSION: UN is reported to deliver a smaller particle size then JN; the smaller particle size delivered by UN is thought to be advantageous for the delivery of medication to the lower respiratory tract; however, smaller particles may be more likely to be exhaled rather than deposited in the lower airway particularly in tachypneic and distressed patients who may be inhaling medication at tidal breathing rather than taking a deep breath with breath hold after each inhalation. Children with exacerbations of asthma are frequently tachypneic. dyspneic, and have high inspiratory flow rates; this can limit the efficacy of nebulized medications. CONCLUSION: This study demonstrates that for treatment of moderately acute asthma in children, delivery of albuterol by UN has no advantage over delivering the same amount of medication by JN. As different nebulization systems have different characteristics and outputs, these data do not indicate that JN is superior to UN for the administration of albuterol but rather that the specific nebulization systems used here, under these test conditions, did not support the use of UN.