Elizabeth A Hunt

 Unearthing good evidence for better care of acute asthma attacks 

 By Elizabeth A. Hunt, MD, and Ian Paul, MD 

 The World Wide Web is the place to go when you need to examine   quality literature that addresses a specific clinical question. The authors   illustrate how to use this tool effectively and what it reveals about novel   protocols for treating acute attacks of asthma. 

A debate has arisen in your pediatric practice. The pediatric emergency   department (ED) where you and your partners send and see patients has put into   place a new protocol. Children who are brought to the ED with an acute attack   of asthma are now routinely treated with systemic corticosteroids, albuterol,   and multiple-dose ipratropium bromide. Magnesium sulfate (MgSO

)   is to be added for pediatric patients whose condition is most severe. The debate   centers on the addition of ipratropium bromide to the ED protocol, the change   in the way albuterol is deliveredfrom nebulizer to metered-dose inhaler   (MDI) with a spacer and the addition of MgSO

. It is unclear   what prompted these changes, and your practice is concerned about their relative   risks and benefits. Your concerns can be summarized in three questions:

Is albuterol as effective delivered by MDI with a spacer as it is delivered     by nebulizer?

Do data support the use of ipratropium bromide?

A quick look in standard textbooks leads you to realize that getting answers   is going to require more current sources. You plan a literature search but wonder   how to go about it and what resources can help you assess the quality of the   evidence that you find. 

The practice of primary care pediatrics is difficult: You have to see a large number of patients with a wide variety of problems, yetlike the majority of your colleaguesyou have little time for continuing education even though you know that learning can't stop when you leave medical school. As the scenario above shows, physicians today need access to the current literature and to be adept at determining its quality. It is also essential for you to create an efficient way to keep abreast of new clinical research findings and practice guidelines.

 One way to keep up with research is to visit the Web sites of journals relevant   to your practice and follow directions for having the table of contents of each   issue sent to you by e-mail (Table 1). Generally, journals do not charge for   this service. By scanning the table of contents, you can target articles of   interest. As for current pediatric practice guidelines, they are available on   the Web site of the American Academy of Pediatrics ( 

Selected research journals for pediatricians

Of course, answering specific questions, like the three posed above, requires   more than keeping up with the current literature as it comes your way. You must   undertake an active search of the literature, using the World Wide Web, for   relevant articles and assess their qualityall part of the process known   as evidence-based medicine, or EBM. As we take you step by step through that   journey in this article, we have two goals: to familiarize you with how the   technique of EBM can be applied to any clinical question; and, at the same time,   offer you answers to those three important, real-world questions about the treatment   of acute attacks of asthma. 

 Search #1: What's the best way to deliver albuterol? 

The first step in your investigation is to create a researchable question. One accepted strategy for formulating such a question is to focus on four basic elements, the first letters of which create the acronym "PICO": 

ntervention (cause, prognostic factor, or treatment) 

 These four elements, applied to our question, will direct our search using   PubMed, the online database and search engine of the National Library of Medicine   (NLM) ( 

 ). PubMed, which includes NLM's premier   bibliographic database, MEDLINE, allows you to make multiple searches of more   than 11 million citations in more than 4,300 journals, using various terms relevant   to the subject. During any one search session, PubMed keeps in memory all your   searches, allowing you to combine and limit them in ways that are most likely   to produce a useful set of citations. (Visit 

http://www.ncbi.nlm.nih.gov/entrez/query/static/overview.html

   for an introduction to PubMed and MEDLINE.) 

. For the "P" in "PICO"our patient   population or the primary problemwe might enter "asthma" on the search   line (Figure 1). Consider also conducting separate searches using the term "reactive   airways disease" or other synonyms for asthma. Clicking on "History" will give   you a numbered list of all your searches. By listing these numbers with the   separator "OR" (which must be typed in upper case letters) between each one   (for example, #1 OR #2 OR #3) you direct the search to citations that relate   to 

 of the selected terms. Opting to look only in the title   of articles for your search word or term? Type that word followed by "[ti],"   (for "title"); the search is narrowed accordingly. Extending the search to full   text of articles? Type your word followed by "[tw]" (for "text word"). 

A pediatrician may be tempted to make "children" a search term, but it is generally   more effective to enter the clinical problem in which you are interested. Then,   if your search yields an adequate number of articles, you can limit the set   to the age group of interest (setting limits is discussed more fully later in   this article). 

"I," the intervention, is albuterol. In conducting the search for this element of the question, it may be important to consider names given to this drug in other countries (such as "salbutamol"). 

 To identify other appropriate search terms, it is useful to determine how   the NLM classifies a term. To do this, click on the heading "MeSH Browser" ("MeSH"   stands for "Medical Subject Headings") to the left of the PubMed search field.   This is a list of terms that the NLM uses to index articles. Entering "albuterol"   produces a series of hierarchical tree structures of terms from which you can   select items that match your area of interest (Figure 2). Three terms seem promising   for finding more articles about albuterol: "adrenergic b-agonists," "bronchodilator   agents," and "anti-asthmatic agents." Again, you can conduct an independent   search of each term, gain access to the search history, and combine searches   by entering "OR" between each numbered search. 

"C" in this example signifies a comparison of albuterol delivered by an MDI with spacer and nebulizer-delivered albuterol. You might consider entering the term "metered-dose inhaler" within quotes, but you're aware that some authors use only the abbreviation "MDI"; by entering "MDI," you come up with 987 citations. By entering the string "meter* dose* inhaler" (the "*" is a variable that represents any letter, a function that is valuable here because the words in the term are spelled variously"meter," "metered," "dose," "dosed"), you come up with 1,461 citations, giving you the highest yield of citations. Then, combining the two groups of citations with an "OR" yields the most inclusive set: 2,057 citations.

Another searchable term is "nebulize" followed by an asterisk ("*"), directing the search engine to include  "nebulized" and "nebulizer" in the search in this example. Again, you can isolate articles that emphasize delivery system by listing on the search line the numbered searches you have performed, separated by "OR."

"O," for "outcome," might refer to hospitalization, or improvement in the 1-second forced expiratory volume (FEV

). In this instance, however, you are interested in 

difference between delivery systems and may choose not to enter a specific term. 

 You now have three separate categories of searches for your PICO formulation   of the question: problem, intervention, and comparison. You combine the three   using the "History" button again and listing the appropriate numbered searches   with "AND" between them (to choose only citations that apply to all three categories)   (Figure 3, line 17). At this point, you have 306 articles on line 17; to further   limit articles to those most likely to be useful, click on "Limits" and use   PubMed's pull-down menus to select English language, human, and children (Figure   4). Another approach is to click on the drop-down menu of the search page (next   to "Sort") and choose "Pub Date" to arrange your citations in reverse chronologic   order. Also, because you would like to see a study that compares the two methods   of albuterol delivery, you might choose "randomized clinical trials" from the   "Publication types" menu. 

 Another helpful technique is to scan search results for an article whose title   suggests that it directly addresses your question. Once you locate the citation   or abstract, you can click on "Related articles" to the right (Figure 5). This   often gives you several more articles that fit your question exactly. Using   the pull-down menu to the right of "Display," you can click on "Citation" to   see what MeSH terms the indexers used for a particular article, which may offer   terms that you had not thought to use in your own search (Figure 6). 

Now that you have a list of relevant articles, you need to assess their quality. You scan the titles, use the pull-down menu next to "Display" to view some abstracts, and select several articles that appear relevant to your question. With some citations, you'll see an icon in the upper left-hand corner, above the abstract; click on this icon, and you are connected to the Web site of the publisher of the journal in which the article appeared. At a limited number of journal sites, you view the full text of articles at no charge; at the Web sites of many, however, you must use a password (yours or one belonging to your practice or the institution that employs you) to gain access to the full text of the articlea benefit that comes only with a paid subscription or purchase of one- time access to the individual article.

. For assistance determining   the quality of the articles you have selected on albuterol delivery, you turn   to the series of users' guides to the medical literature that have been published   in the 

Journal of the American Medical Association

 (Table   2). These articles will guide you in determining whether the conclusions of   a particular article can be applied to your patient population. They address   each major type of research question, including how to appraise articles about   therapy, diagnostic tests, harm, prognosis, and etiology. An online tutorial,   adapted from these users' guides and developed by Duke University Medical Center   and the University of North Carolina, takes you through the critical appraisal   process step by step ( 

 ). Other Web sites,   known as "CATbanks" ("CAT" standing for "critically appraised topic"), feature   step-by-step dissection of particular articles and follow the questions posed   by 

's users' guides to determine the quality of an article (Table   3). Not only does using these CATbanks enhance one's article-appraisal skills,   but the lists are worth scanning from time to time to follow the current literature   and sort out the quality of the evidence it describes. 

If you are fortunate, your question may already have been addressed by the   Cochrane Collaboration, a group of centers that search particular questions   and perform a systematic analysis of all high-quality data available for those   questions. Full-text reviews, protocols, and quarterly updates are available   from Cochrane by subscription only, but it costs nothing to gain access to the   Cochrane Library ( 

 ) to view a list of review topics   and the summary sheet of each systematic review. Once in the database, click   on "The Cochrane Library," then "Abstracts," then scroll down to the"Search"   window. You enter "asthma," then scan the top 50 titles that match your term.   Bingo! All three subjects that you are researching (the problem, the intervention,   and the comparison) have been studied in systematic fashion. 

 You now have several independent articles on comparative albuterol delivery systems and a systematic review that specifically addresses whether one delivery system is significantly better for exacerbations of asthma. So what is the answer to your question? 

Chou and colleagues used an urban ED setting to compare albuterol delivery methods in 152 known asthmatics at least 2 years old.

 Although this study was not blinded, it was randomized and the MDI with spacer and nebulizer groups had nearly identical baseline characteristics. Using the objective criteria of respiratory rate, inspiratory to expiratory ratio (I:E), the presence or absence of wheezing and retractions, oxygen saturation, peak expiratory flow rate, number of treatments given, percentage of patients receiving steroids, and admission rate, the investigators determined that the two groups did not differ at the end of the treatment period. Other significant differences were seen between the groups, however: Children in the nebulizer group spent a longer mean amount of time in the ED (103 vs. 66 minutes), experienced more emesis (20% vs. 9%), and had a greater mean percentage increase in heart rate (15% vs. 5%).

Another study performed in Canada yielded similar results. Also performed in an ED setting, the study compared nebulized albuterol with albuterol by MDI with spacer given for 33 mild to moderately severe flares of acute asthma in children 6 to 14 years of age.

 The study was double-blinded and used placebo: Each patient used an MDI and a nebulizer without knowing which one contained albuterol. Again, baseline characteristics were similar; clinical features evaluated included heart rate, respiratory rate, pulsus paradoxus, dyspnea, use of accessory muscles, wheezing, FEV

, and oxygen saturation. These investigators also found no difference between the groups in improvement in respiratory effort and function and the hospital admission rate. As in the Chou study, however, tachycardia was a side effect of nebulized albuterol. 

The Cochrane review of the two delivery systems for treatment of acute asthma was not limited to children or albuterol, but its findings were consistent with those of the other two studies.

 Sixteen trials, constituting 686 children (2 years and older) and 375 adults, were analyzed. Taken as a whole, these trials did not show a significant difference between administration by nebulizer or by MDI with spacer in regard to change in respiratory rate, peak flow, FEV

, development of tremor, number of patients given steroids, or admission rate. Consistent with the two trials cited above, the MDI group stayed in the ED for a significantly shorter time than the nebulizer group did and was less likely to have tachycardia.

Leversha and colleagues recently published the findings of a randomized, double-blind, placebo-controlled trial in the ED in which they demonstrated fewer hospitalizations and side effects when albuterol was delivered by an MDI and spacer than when it was delivered by nebulizer. The investigators made two other important findings

: Eighty-six percent of children and 85% of parents preferred the MDI with spacer over the nebulizer, and the MDI was more cost-effective. The mean cost of ED care for the MDI group was 64% of that for the nebulizer group.

Convincing data also exist for using an MDI with spacer during inpatient hospitalization. Parkin and colleagues studied 60 hospitalized children 1 to 5 years old with moderate acute asthma.

 Children with similar baseline characteristics were assigned to one of the two albuterol delivery systems. Outcome measures included respiratory rate, wheezing, indrawing, I:E, observed dyspnea, time to discharge, time to four-hour dosing interval, and total number of inhaled doses required.  Parents were asked to report symptoms at one and two weeks after discharge. Nine patients did cross over and received nebulized albuterol, but only four met predetermined criteria for treatment failure with an MDI. At 60 hours after admission, no difference was seen between the two groups in regard to respiratory effort or the results of a physical exam. Hours to discharge, hours to four-hour dosing interval, and number of inhaled doses were similar in both groups. One and two weeks after discharge, the difference between the two groups in the percentage of symptom-free patients was insignificant.

A second, more recent study examined the clinical effectiveness and cost of both methods of albuterol delivery among the inpatient asthmatic population.

 Sixty-one children, 3 years and older, received albuterol through a nebulizer or an MDI and spacer. Again, the groups had comparable clinical and baseline characteristics on admission. At discharge, both had improved to a similar degree. Because this study contained a few patients whose prolonged stay skewed the mean hospital stay data, the median stay data were reported and were approximately the same for both groups.

Of great significance, the cost of using the MDI with spacer was approximately one quarter the cost of the nebulizer during the hospital stay. Investigators observed a trend toward fewer readmissions during the study period (six in the nebulizer group, two in the spacer group) and during a 12-month follow-up period (27.2% for the nebulizer group, 13.8% for the spacer group), although this difference was not statistically significant. 

Taken together, these studies demonstrate that, in both ED and inpatient settings, albuterol is as effective when delivered by an MDI with spacer as it is when delivered by a nebulizer. The ED studies reported decreased time to discharge and fewer side effects in the MDI group; the inpatient studies showed similar efficacy and length of stay with decreased cost and  rate of readmission. Despite these convincing data, more research is needed in this area. Because data in both the clinic setting and with severe asthmatics are limited, drawing conclusions about administering albuterol in those situations is premature.

In addition, whereas the dose of nebulizer-delivered albuterol is standardized at 0.15 mg/kg up to 5 mg, consistent guidelines are unavailable on the amount of albuterol to be delivered by MDI. Among 16 studies deemed of sufficiently high quality to be in the Cochrane review, the dosage of b-agonist delivered by an MDI with spacer varied greatly

from two puffs per dose to a weight-based daily regimen of six puffs for children weighing <25 kg, eight puffs for 25 to 35 kg, and 10 puffs for >35 kg. The ratio of the b-agonist dosage administered by MDI with spacer and by nebulizer ranged from 1.3:1 to 1:25; in most studies, the ratio was 1:2 to 1:7. Even though the MDI dosage was generally much smaller than the nebulized dosage, patients in the MDI group did at least as well as those in the nebulizer group and experienced fewer side effects.

Last, it became clear, on reviewing many of these papers, that teaching patients about asthma and the use of an MDI with a spacer 

 is critical to the effectiveness of the medication being delivered. A randomized, double-blind, placebo-controlled trial by Mandelberg demonstrated that, compared with a nebulized b-agonist, an MDI and spacer with a face mask attached could be used to treat infants and young children without a significant difference in response to treatment.

 Search #2: What's the effect of ipratropium bromide? 

Earlier studies of the effectiveness of inhaled ipratropium bromide in an acute asthmatic exacerbation were inconclusive. Has a determination been made in the current literature? 

 You turn to the same technique you used to answer the first question. First, you create the clinical question in the PICO format: Of children with asthma, (

roblem), does ipratropium bromide plus standard therapy (

ntervention), compared with standard therapy alone (

utcome (hospitalization, oxygen saturation, etc.)? Your PubMed search of the terms "asthma" and "ipratropium bromide," limited to children, English language, and randomized clinical trials, yields a reasonable number of citations to be scanned. In addition, the Cochrane database once again reveals a systematic analysis of the subject. 

 published a relevant prospective, randomized, double-blind, placebo-controlled trial by Quereshi and colleagues.

 All children brought to the ED with an acute exacerbation of asthma received a corticosteroid, 2 mg/kg; nebulized albuterol every 20 minutes (total, three doses); and either placebo or ipratropium bromide with the albuterol at the first and second doses. The hospitalization ratethe primary outcome measurewas reduced significantly in the treatment group overall. No significant difference in the hospitalization rate was noted between the treatment and placebo groups in children with mild or moderate disease; in those who had a severe exacerbation, however, the treatment group had significantly fewer admissions. Analysis showed that, for every seven children with a severe asthmatic exacerbation treated with ipratropium bromide in addition to steroids and albuterol, one hospitalization was prevented.

The Cochrane review included 13 trials and came to several conclusions.

 Addition of a single dose of an inhaled anticholinergic drug does improve lung function but does 

 reduce hospitalizations. Addition of multiple doses of an anticholinergic to b-agonist therapy does reduce hospitalizations by 25% in children with moderate or severe exacerbations. Measurable side effects, including nausea, vomiting, and tremor, did not increase.

 in severe exacerbations   you turn directly to the Cochrane Library, which has a review. The authors included   seven trials (five adult and two pediatric)a total of 665 patients.

 was compared with placebo. Overall, the   peak flow rate improved only insignificantly and the admission rate did not   change. In patients with severe asthma, the peak flow rate improved overall   by 52.3 L/min; FEV

 improved by 9.8% above predicted overall; and   the admission rate was reduced significantly in the treatment groups. The optimal   dose of MgSO

 remains unclear but, in studies included in the Cochrane   review, the dosage ranged from 25100 mg/kg and 2 g was the predominant   dosage in the adult studies. 

Your review of the literature on pediatric asthma shows that the local hospital's decision to add multiple-dose ipratropium bromide to the ED protocol appears appropriate. Likewise, an MDI and spacer is a reasonable alternative to a nebulizer for delivering albuterol: Using an MDI and spacer results in a statistically significant decrease in heart rate and length of ED stay, and is a more cost-effective option. Also important, the use of an MDI with spacer does not require electricity, which can be an important consideration. Last, it appears that IV MgSO

 improves lung function and reduces the hospitalization rate in asthmatic children who are clearly having a severe exacerbation on presentation or whose condition is refractory to initial therapy. 

 You and your partners have learned a great deal from this exerciseabout   current treatment of asthma and how to research a clinical question. Your patients   will benefit from your dedication to continuing education. 

Dr. Hunt thanks Drs. Corey, Keitz, and Greenblatt, her         former colleagues and mentors at Duke University, for introducing her         to evidence-based medicine and training her in its daily application as         part of her residency in medicine; Drs. Kredich and Frank for offering         her, while she was chief resident, a forum in which to teach EBM to pediatric         residents; and medical librarians Connie Schardt and Anne Powers for making         the weekly EBM journal club operational and enjoyable.    

 1. 	Chou KJ, Cunningham SJ, Crain EF: Metered-dose inhalers   with spacers vs nebulizers for pediatric asthma. 

 	2.	 Kerem E, Levison H, Schuh S, et al: Efficacy   of albuterol administered by nebulizer versus spacer device in children with   acute asthma. 

 	3.	 Cates CJ, Rowe BH: Holding chambers versus   nebulisers for beta-agonist treatment of acute asthma. 

 	4.	 Leversha AM, Campanella SG, Aickin RP, et al:   Costs and effectiveness of spacer versus nebulizer in young children with moderate   and severe acute asthma. 

 	5.	 Parkin SR, Diamond SA, Winders PM, et al: Randomised   trial spacer v nebuliser for acute asthma. 

 	6.	 Dewar AL, Stewart A, Cogswell JJ, et al: A   randomised controlled trial to assess the relative benefits of large volume   spacers and nebulisers to treat acute asthma in hospital 

 	7.	 Mandelberg A, Tsehori S, Houri S, et al: Is   nebulized aerosol treatment necessary in the pediatric emergency department?   

 	8.	 Qureshi F, Pestian J, Davis P, et al: Effect   of nebulized ipratropium on the hospitalization rates of children with asthma.   

 	9.	 Plotnick LH, Ducharme FM: Combined inhaled   anticholinergics and beta2-agonists for initial treatment of acute asthma in   children (Cochrane Review). 

 	10.	Rowe BH, Bretzlaff JA, Bourdon C, et al: Magnesium   sulfate for treating exacerbations of acute asthma in the emergency department.   

Articles

The Web is the place to go when you need to examine literature that addresses a specific clinical question. The authors illustrate what this tool reveals about novel protocols for treating acute attacks of asthma.

Author | Elizabeth A Hunt

Articles

Unearthing good evidence for better care of acute asthma attacks