Spacers appear to have several advantages over nebulizers for the delivery of β2-agonists in children with acute asthma, according to a Cochrane review of the literature.
However, the findings should be viewed with caution, according to Dr. Paul Williams, chair of the section on allergy and immunology, American Academy of Pediatrics.
The review was recently updated from 2003 to include four new trials that were conducted in emergency department and community settings as well as to add findings from six trials of inpatients with acute asthma. It includes data on 2,279 children and 642 adults enrolled in a total of 31 trials.
The data show that length of stay in the emergency department was significantly shorter in children (but not in adults) who used a spacer, compared with those who used a nebulizer (mean difference of −0.47 hours).
Pulse rate also was lower in children who used a spacer (mean difference, 7.6% of baseline), Dr. Christopher J. Cates of St. George's University of London and colleagues reported (Cochrane Database Syst. Rev. 2006;[2]:CD000052).
There did not appear to be any difference in admission rates in children treated with spacers vs. nebulizers (relative risk 0.65).
The findings are important because spacers are less expensive in the community setting, and unlike nebulizers, they do not require a power source, the investigators noted.
However, Dr. Cates and his associates also noted several limitations of the studies included in the review.
“Overall, this review supports the equivalence of wet nebuliser and MDI [metered-dose inhaler] with spacer administration of β2-agonists in the treatment of acute asthma, when treatments are repeated and titrated to the response of the patient.
“This review also suggests that paediatric patients given β2-agonists by spacer and MDI may have shorter stays in the ED, less hypoxia, and lower pulse rates, compared to patients receiving the same β2-agonist via wet nebulisation,” the investigators wrote.
But, they added, the findings of the review are limited by the relative lack of studies in the community setting, by the exclusion of patients with life-threatening asthma exacerbations from the studies, by the fact that few authors reported specifically on numbers of patients who were excluded from each study, and by a lack of reporting of intention to treat analyses.
In addition, the analysis of data regarding lung function tests was complicated by a lack of standardized reporting in many of the studies, and standard evaluations related to the changes that were measured were sometimes not reported.
“I agree with (these) comments mentioned by the authors. … There are several cautions that should be expressed when presenting the results,” said Dr. Williams, who also is with the University of Washington, Seattle.
For example, only two of the studies included in the review were conducted in a community emergency department; thus, the results may not be applicable to such settings, he said, stressing that more studies in this setting are needed.
In addition, the doses of albuterol given via spacer were different among the studies, which could be a source of confusion for the practitioner who is trying to decide whether to use the spacer or the nebulizer.
For the nebulizer, the doses are fairly well defined and accepted, but for the MDI and spacer, the doses have not been well studied or defined and varied from 2 puffs every 20 minutes, to 1 puff every 12 seconds, up to 12 puffs per hour, Dr. Williams explained.
As recommended by the authors, more studies are needed using frequent dosing titrated to patient response, Dr. Williams agreed.
But of most concern, he said, is that the studies included in the review used specially trained nurses to administer the medications.
“In a community setting, many, if not most, nurses and perhaps even M.D.s are not familiar with different spacers and techniques for using spacers, nor the developmental stage necessary to use spacers of different types.
Not only are the varied dosing regimens confusing, but the quality of medication administration may vary from staff person to staff person and shift to shift,” Dr. Williams said.
He added that he would like to see studies that look at a standardized regimen of dosing using the spacer and MDI. He said he would also like to see the dissemination of information on using spacers for children through a source such as the American Academy of Pediatrics online PediaLink Module (www.pedialink.org/index.cfm