The efficacy of nebulized metaproterenol in wheezing infants and young children
A. J. Alario, W. J. Lewander, P. Dennehy, R. Seifer and A. L. Mansell
Department of Pediatrics, Brown University School of Medicine, Providence, RI.
The benefit of beta-adrenergic agonists in the treatment of acutely
wheezing infants and young children has not been well documented in the
outpatient setting. To determine the efficacy of nebulized metaproterenol
sulfate, 74 children aged 36 months or younger with acute wheezing
participated in a double-masked, randomized, placebo-controlled clinical
trial. Children received nebulized metaproterenol, either as an initial
treatment or after a control treatment with normal saline solution. At
baseline and 20 minutes after each treatment, an assessment was made that
included measurements of heart rate, respiratory rate, oxygen saturation,
and clinical variables related to respiratory compromise with the use of a
standardized respiratory distress index (RDI). Children who received saline
solution as initial therapy had no significant differences from baseline in
any of the assessment measures. After metaproterenol therapy, children
demonstrated an increase in heart rate ([mean +/- SD] 147 +/- 14 beats per
minute vs 153 +/- 16 beats per minute), a decrease in respirations (50/min
+/- 5/min vs 45/min +/- 7/min), improvement (lower scores) on the RDI (24
+/- 4 vs 15 +/- 2), and an increase in oxygen saturation (94.1% +/- 2.7% vs
95.3% +/- 3.0%). Patients aged 12 months or younger (n = 37) benefited from
metaproterenol treatment (improvement in respiratory rate and RDI) but not
to the same degree as children aged 24 months or older (n = 23)
(improvement in respiratory rate, RDI, and oxygen saturation). Compared
with assessments made before metaproterenol treatment, patients with
respiratory syncytial virus infection (n = 21) had improvement in
respirations (52/min +/- 7/min vs 45/min +/- 6/min) and RDI scores (22 +/-
4 vs 14 +/- 3). Based on a priori criteria (reduction in a premedication
respiratory rate of 20% and an RDI score of 50%), responders to
metaproterenol therapy included 45% of the entire sample and, respectively,
40% of those aged 12 months or younger, 52% of those aged 24 months or
older, and 48% of patients who tested positive for respiratory syncytial
virus. Although there appears to be an age-dependent degree of response,
metaproterenol is effective in relieving the respiratory distress of young
acutely wheezing children, including those with documented respiratory
syncytial virus bronchiolitis.
