Indian Pediatrics 1999;36: 1052-1053

Harmful Effects of Aerosolized Bronchodilator Therapy in Bronchiolitis

From the Department of Pediatrics, Government Medical College Hospital, Sector-32, Chandigarh 160 047, India.
Reprint requests: Dr. Jatinder Singh Goraya, Senior Lecturer, Department of Pediatrics, Government Medical College Hospital, Sector-32, Chandigarh 160 047, India.
Manuscript Received: February 25, 1999;
Initial review completed: April 6, 1999;
Revision Accepted: May 20, 1999

Acute bronchiolitis is the most common cause of lower respiratory tract infection in infants. It is an important cause of morbidity and hospitalization of these infants(1). Treatment of acute bronchiolitis is largely supportive and includes supplemental oxygen and maintenance of fluid and electrolyte balance. Though bronchodilators are frequently prescribed, evidence of their efficacy in bronchiolitis is controversial(1). Even two recent meta-analyses on the subject have reported conflicting results(2-3). On the contrary some studies have reported increase in oxygen desaturation(4) and deterioration in lung function(5) following aerosolized therapy with bronchodilators. Over-reliance on bronchodilator therapy through nebulization may delay the delivery of adequate oxygen therapy as we encountered recently.

Case Report

A 2½-month-old infant was admitted to the  emergency pediatric services with fever, breathing difficulty with wheezing, excessive crying and poor feeding. There was no family history of atopic disorders. Examination revealed a sick looking infant with severe respiratory distress. Patient had respiratory rate of 86/min with marked chest retractions and an audible wheeze. Bilateral extensive rhonchi were found on auscultation. Additional physical findings included pallor, tachycardia and uprolling of eyeballs. Chest radiograph revealed bilateral hyperinflation and paracardiac infiltrates. A diagnosis of acute bronchiolitis was made and the patient started on intravenous fluids, and supplemental oxygen through a face mask. In addition, in view of severe disease, salbutamol (0.15 mg/kg/dose) was aerosolized using an oxygen driven nebulizer, with face mask. No improvement in clinical status was observed after 4 doses of salbutamol given over next 2 hours, rather the patient was noticed to be more distressed and irritable, during nebulization. Nebulization therapy was stopped and patient was given high concentration oxygen therapy through an oxygen hood. A significant improvement occurred in patient's general condition over the next few minutes. His irritability disappeared altogether and he became quiet. Over the next four hours his respiratory distress and wheezing had greatly reduced.

Discussion

The mainstay of treatment of bronchiolitis is prevention of hypoxemia through supple-mental oxygen, and maintenance of adequate fluid and electrolyte balance(1). Even in the absence of definite evidence of efficacy of bronchodilator therapy in acute bronchio-litis(3), the temptation to use it are great(1,6), probably reflecting the mental image of association of wheeze with bronchial asthma, though mechanisms of bronchiolar narrowing in these two disorders are quite different(2).
present case amply demonstrates the beneficial effects of adequate supplemental oxygen ther-apy vis-a-vis harmful effects of nebulization therapy with bronchodilators.

The important step in the management of this otherwise a self-limiting disease. It is therefore recommended that even if a trial of bronchodi-lator nebulization seems warranted in bronchio-litis, it should be either delayed or abandoned if it is found to be detrimental to adequate oxygen supplementation. In other words pre-vention and treatment of hypoxemia should take precedence over any other intervention in patients with acute bronchiolitis.

There are several ways bronchodilators can be harmful. It may be secondary to irritant or osmotic effect of the nebulizing solution on the airways(1,5) or bronchodilators may inhibit hypoxia induced pulmonary vasoconstriction resulting in increased intrapulmonary shunting and a decrease in oxygen saturation(1,4). Nebulization procedure also disturbs the baby, particularly face masks are poorly tolerated by the infants. More importantly nebulization therapy may interfere with or delay adequate oxygen therapy because, the fact that masks which are used to deliver nebulized broncho-dilators are not good for delivering high concentration oxygen may be overlooked, as happened in the present case. Though we used oxygen powered nebulizer, marked and rapid improvement in clinical status of the patient following oxygen therapy with a oxygen hood (which provided upto 90% oxygen concen-tration) indicates that oxygen delivery through a face mask (which provided upto 40% of oxygen concentration) was inadequate and nebulization procedure was detrimental to the delivery of appropriate oxygen concentration. It is not to imply that oxygen therapy in any way altered the natural course of the disease in our patient but prevention of hypoxemia is an

References

1. Walker TA, Khurana S, Tilden S. Viral respiratory infections. Pediatr Clin North Am 1994; 41: 1365-1381.

2. Kellner JD, Ohlsson A, Godomski AM, Wang EE. Efficacy of bronchodilator therapy in bronchiolitis.A meta-analysis. Arch Pediatr Adolesc Med 1996; 150: 1166-1172.

3. Flores G, Horwitz RI. Efficacy of b2 agonists in bronchiolitis: A reppraisal and meta-analysis. Pediatrics 1997; 100: 233-239.

4. Ho Ling, Collis G, Landau LI, Souef PN. Effect of salbutamol on oxygen saturation in bronchiolitis. Arch Dis Child 1991; 66: 1061-1064.

5. O' Callaghan C, Milner AD, Swarbarick A. Paradoxical deterioration in lung function after nebulized salbutamol in wheezy infants. Lancet 1986; ii: 1424-1425.

6. Nahata MC, Sehad PA. Pattern of drug usage in bronchiolitis. J Clin Pharma Ther 1994; 19: 117-118.