1 Department of Pediatrics, University of Thessaly School of Medicine and Larissa University Hospital, Larissa, Greece. Electronic address: ealexop@uth.gr.
2 Department of Child Health, Division of Pediatric Pulmonology and Sleep, University of Missouri School of Medicine, Columbia, MO; MUHC Children's Hospital, and the First Department of Pediatrics, Division of Pediatric Pulmonology and Sleep Disorders Laboratory, National and Kapodistrian University of Athens School of Medicine and Agia Sofia Children's Hospital, Athens, Greece.