[1] Childrens Natl Hosp, Div Otolaryngol Head & Neck Surg, Washington, DC USA
[2] Univ Maryland, Baltimore, MD USA
[3] Childrens Natl Hosp, Qual, Safety, Analyt, Washington, DC USA
[4] Childrens Natl Med Ctr, Div Otolaryngol, 111 Michigan Ave NW, Washington, DC 20010 USA