Nebulized fenoterol versus intravenous aminophylline treatment of acute severe asthma

Nebulized fenoterol versus intravenous aminophylline treatment of acute severe asthma


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Correspondence NEBULIZED FENOTEROLVERSUS INTRAVENOUS AMINOPHYLLINETREATMENTOF ACUTE SEVEREASTHMA To the Editor:--We read the letter by Pan et all with surprise, and we belive that it deserves important corrections. From a conceptual point of view, the superiority of adequate doses of beta-agonists over aminophylline has long been known. When used alone, intravenous aminophylline is three to four times less effective in relieving airflow obstruction than repetitively administered beta-agonist bronchodilators in both adults and children. Consistently, it is emphasized that methyxanthines play no a significant role in the acute relief of airflow obstruction. This thinking is reflected in the recommendations released by the National Heart, Lung and Blood Institute, National Asthma Educational Program Expert Panel Report 2 on the diagnosis and management of asthma? They have excluded theophylline from the treatment recommendations for the emergency department management of acute asthma exacerbations. Even more, when used in combination with repetitively administered beta-agonists, intravenous aminophylline causes increased adverse side effects without effecting additional bronchodilation.3-5 Therefore, the aim of this kind of research should not be the comparison of aerosolized fenoterol and intravenous aminophylline. That issue has been resolved, and monotherapy with aminophylline can no longer be recommended in the treatment of acute severe asthma. From a methodological and statistical point of view, we have several grave concerns about this article. Thus, we have great doubts that this study with 20 patients has sufficient power to exclude beta-error: the absence of a statistical significant difference is not equivalent to the absence of a real difference between groups. Consequently, the mean percentage improvements in forced expiratory volume in one second (FEV1) and peak expiratory flow rate (PEFR), and the mean improvements in symptom scores between groups, could be statistically significant at 30, 60, and 120 minutes. Further, the two groups do not seem completely comparable. Although not statistically significant (the authors use the student t test to compare data entry values, when they should have used a nonparametric test), there is a trend towards the fenoterol group being "sicker." The fenoterol group has lower FEVb forced vital capacity (FVC), and PEFR values, and a higher heart rate on study entry. Finally, in this study, fenoterol was administered as a single large dose by nebufizer;however, is well known that repetitive administration of beta-agonists every 10 or 20 minutes produces significant dosedependent increases in response to pulmonary function testing.6-8 In summary, the conclusion that "the administration of a single large dose of aerosolized fenoterol by nebulizer and intravenous aminophylline were both effective in producing bronchodilator effect in 2 hours" is not supported by the data provided. In contrast, the findings are consistent with the notion that aerosolized betaagonists are more effective than intravenous aminophylline in the treatment of acute severe asthma in the emergency department. GUSTAVORODRIGO,MD Departamento de Emergencia Hospital Central de las FF.AA CARLOSRODRIGO,MD Centro de Tratamiento Intensivo Association Espanola la. de Socorros Mutuos Montevideo, Uruguay

References 1. Pan JF, Yang PC, Chang DB, et al: Nebulized fenoterol versus IV aminophyllinetreatment of acute severe asthma. Am J Emerg Med

1995; 13:677-680 (letter)

2. National Asthma Education and Prevention Program Expert Panel Report 2: Guidelines for the diagnosis and management of asthma. Bethesda, MD, NIH, Publication No. 55-4051,1997 3. Fanta CH, Rossing TH, McFadden ER Jr: Emergency room treatment of asthma: Relationships among therapeutic combinations, severity of obstruction, and time course of response. Am J Med 1982;72:416-422 4. Siegel D, Sheppard D, Gelb A, Weinberg PF: Aminophylline increases the toxicity but not the efficacy of an inhaled betaadrenergic agonist in treatment of acute exacerbations of asthma. Am Rev Respir Dis 1985; 132:283-286 5. Rodrigo C, Rodrigo G: Treatment of acute asthma: lack of therapeutic benefit and increase of the toxicity from aminophylline given in addition to high doses of salbutamol delivered by metered dose inhale with a spacer. Chest 1994; 106:1071-1076 6. Rodrigo G, Rodrigo C: Comparison of salbutamol delivered by nebulizer or metered-dose inhaler wit a pear-shaped spacer in acute asthma. Curr Ther Res 1993;54:797-808 7. Rodrigo C, Rodrigo G: High doses MDI salbutamol treatment of asthma in the ED. Am J Emerg Med 1995;13:21-26 8. Rodrigo G, Rodrigo C: MDI salbutamol treatment of asthma in the ED: Comparison of two doses with plasma levels. Am J Emerg Med 1996;14:144-150

SENSITIVITY, SPECIFICITY,AND PREDICTIVEVALUES To the Editor.'--The article by Peredy and Powers, "Bedside Diagnostic Testing of Body Fluids," which appeared in the July issue, 1 addresses a topic of particular interest in emergency medicine and adequately reviews the majority of fields in which bedside testing possibilities have been developed as an alternative or a complement to conventional laboratory tests. I have, however, a comment about this review. The authors affirm that "sensitivity and specificity for urinary tract infection of the leukocyte esterase test alone are commonly quoted as 76% to 96% and 79% to 98%, varying with the disease prevalence in the test population." It should be reemphasized that sensitivity and specificity are characteristics of the test used and are independent of the population in which it is used. Conversely, positive and predictive values of the test result are populationdependent. As an example, the ability of a particular brand of dipstick urine test to detect leukocyte esterase remains the same regardless of the demography of the tested population. However, the interpretation of the test result will be different according to the prevalence of urinary infections in the screened population; it may be quite different in such dissimilar populations as children at school, pregnant women, diabetic patients, or those presenting to an emergency department with urinary complaints. P~mn~vgLHEUREUX,MD, PHD Department of Emergency Medicine Erasme University Hospital, Brussels

Reference 1. Peredy TR, Powers RD: Bedside diagnostic testing of body fluids. Am J Emerg Med 1997;15:400-407

RECOGNIZING EARLYSIGNS OF NEUROLEPTICMALIGNANT SYNDROME To the Editor:--Neuroleptic malignant syndrome (NMS) is a potentially life-threatening form of drug-induced hyperthermia. Estimates of the incidence of NMS have ranged from 0.02% to 3.23% in neuroleptic-treated patients, probably reflecting differences in diagnostic criteria and treatment practices. ~ In the past decade, a significant body of literature has developed pertaining to 95