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Letters to the Editor Indian Pediatrics 2000;37: 684-687 |
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Harmful Effects of Aerosolised Bronchodilator Therapy in Bronchiolitis |
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The final word on the use of bronchodilators in the management of acute bronchiolitis is not said as yet, in view of the conflicting reports in literature(2,3). Some studies have been performed during the recovery phase of bronchiolitis, when the patient may be less responsive to bronchodilators(4-8). In inter-preting Kellner’s(2) systematic review, the difficulty encountered is the lack of differ-entiation between bronchodilators. The validity of pulmonary function tests done in some studies has also been a subject of debate(9). It is likely that infants with bronchiolitis possibly fall into two clusters based on their response to bronchodilators and, therefore, it may sound logical to evaluate the effect of an inhaled bronchodilator initially as it is not possible to recognize the same beforehand(10), to categorize the infants. The authors tried administering Oxygen through a face mask initially. Even that could have contributed to the irritability of the infant, who tolerated the oxygen hood very well later. It would also have been prudent if pulse oximetry readings and respiratory distress scores were included in the optimal assessment of the infant. Another factor that could have contributed to the effect noted could be the frequency of nebulization, i.e., 4 nebulizations in 2 hours, soon after admission. The quantity of saline that is used during nebulization is another variable that merits consideration. Volumes below 1.5 ml are found to be acidic and hyperosmolar with time (though initially isosmolar) because of evaporation with increasing time of nebulization(11). The usual nebulization dose is 2-3 ml to be nebulized usually for 5 minutes. The age of the infant in the report could also have influenced the outcome as it is well known that younger the age, less would be the therapeutic effect of the aerosolised bronchodilators. The rapidity of the reported response of this infant to oxygen therapy is dramatic, if not unusual. S. Nagabhushana,
The role of bronchodilators in acute bronchiolitis remains controversial. Though prescribed very frequently, evidence of their efficacy in bronchiolitis is lacking. Results from several randomized controlled trials (RCT) have given conflicting reports. The systematic review or meta-analysis then becomes an important tool of synthesizing such varied results to produce the best evidence on which therapeutic decisions can be based. Two meta-analyses(1,2) have recently been published on the efficacy of bronchodilators in bronchiolitis. The more recent meta-analysis(2) did not find any conclusive evidence for the efficacy of b2-agonist therapy, while the previous one(1) showed only modest short term improvement with bronchodilators in mild to moderately severe bronchiolitis. However, an updated version(3) of this latter meta-analysis by the same authors has negated the previous results. It says ‘bronchodilators cannot be recom-mended for routine management of infants with first episodes of wheezing at this time, given the uncertain benefit and high costs of bronchodilator treatment’. Based on these findings it can be said that the conclusive evidence for the efficacy of b2-agonist therapy for bronchiolitis is not available. Therefore in the present era of evidence based medicine (EBM), routine use of bronchodilators in bronchiolitis, can hardly be recommended. As pointed out by Nagabhushana also, the meta analyses are not without limitations. It was, however, not possible to discuss these within the scope of a case report, but the critique has appeared in literature(4,5). The author advocates a trial of broncho-dilators to identify responders and non-responders in the beginning. Though this cannot be denied in a given case, especially when possibility of bronchial asthma cannot be ruled out, its use in all cases in the absence of an evidence of efficacy will add to the cost as well as unnecessarily expose the young infants to the toxicity. We do not know of any study which says that such an approach is beneficial, cost effective and safe. Face masks are poorly tolerated by infants. This point was clearly discussed in the article. Effect of osmolarity of the nebulizing solution on the bronchial airways was also referred to in the article. In the case described, volume of nebulizing solution was made upto 3 ml by adding normal saline. The duration of nebu-lization was 15-20 minutes as has been recommended(6). The most important point which we wanted to stress in the case report, as has also been stressed in literature, is that the mainstay of treatment of bronchiolitis is not bronchodilator therapy, but a careful attention to fluid balance and prevention as well as treatment of hypoxemia. Our patient had severe disease as indicated by clinical parameters alone (SaO2 < 85%). This prompted the use of nebulization therapy which in turn necessitated the use of facemask. The fact that face mask was inadequate in delivering high concentration of oxygen was overlooked in an over-enthusiastic approach to bronchodilator therapy. This however became amply clear when oxygen was administered through oxygen hood. Rapidity of response to oxygen therapy through headbox suggested that hypoxemia contributed greatly to irritability in our patient. The effect of age on response to bronchodilator therapy has not been studied in subgroup meta-analysis because of insufficient data(1). The aim of our communication was not as much to discuss the role of bronchodilators in bronchiolitis as it was to highlight the fact that treatment and prevention of hypoxemia should take precedence over all other interventions in a child with bronchiolitis. Jatinder S. Goraya,
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