Referencia:

1. National Heart, Lung, and Blood Institute, National Asthma Education and Prevention Program, National Institutes of Health, US Department of Health and Human Services. Expert Panel Report 3: Guidelines for the Diagnosis and Management of Asthma. Bethesda, MD: National Heart, Lung, and Blood Institute. 2007.
2. Global Initiative for Asthma (GINA). Global Strategy for Asthma Management and Prevention: Updated 2015. http://www.ginasthma.org/.Acessed November 20, 2015.
3. Szefler SJ, et al. A phase III randomized controlled trial of tiotropium add-on therapy in children with severe symptomatic asthma. J Allergy Clin Immunol. 2017;140(5):1277-1287.