Pediatric Pulmonology 48:592–600 (2013) Nocturnal Phenotypical Features of Obstructive Sleep Apnea (OSA) in Asthmatic Children Maria J. Gutierrez, MD, 1,2 Junjia Zhu, PhD, 3 Carlos E. Rodriguez-Martinez, MD, MSc, 4,5,6 Cesar L. Nino, PhD, 7 and Gustavo Nino, MD 2,8 * Summary. Background: Asthma and obstructive sleep apnea (OSA) often coexists during childhood. To delineate this clinical association, we investigated the phenotypical features of OSA in asthmatic children. Specifically, we hypothesized that asthmatic children have a distinct OSA phenotype that involves a higher prevalence of Rapid-Eye-Movement (REM)-related breathing abnormalities relative to children with OSA alone. Methods: We conducted a retro- spective cross-sectional analysis of 141 children aged 2–12 years with OSA diagnosed by poly- somnography (PSG) in our sleep center. Outcomes included PSG parameters, maximal %SaO2 REM desaturations and prevalence of REM-related OSA. Multivariate linear regression model or logistic regression model was built to study the joint effect of asthma and OSA parameters with control for potential confounders (significance level P < 0.05). Results: Baseline respiratory parameters, obstructive apnea–hypopnea index (OAHI) severity, and oxygenation during NREM sleep were unaffected by the presence of asthma in children with OSA. In contrast, maximal %SaO2 REM desaturation, REM–OAHI and prevalence of REM-related OSA in children with moderate–severe OSA were significantly increased in asthmatic children with OSA compared to subjects with OSA alone. Multivariate analysis revealed that the association between asthma and REM-related OSA parameters is independent of asthma control, BMI, age, and gender. The presence of REM-related OSA in asthmatics was unaffected by rhinitis or atopic status. Conclu- sion: These results demonstrate that asthma is associated with REM-related breathing abnor- malities in children with moderate–severe OSA. The link between asthma and REM-related OSA is independent of asthma control and obesity. Further research is needed to delineate the REM-sleep biological mechanisms that modulate the phenotypical expression of OSA in asth- matic children. Pediatr Pulmonol. 2013; 48:592–600. ß 2012 Wiley Periodicals, Inc. Key words: asthma; OSA phenotype; OSAS; REM-related OSA; REM sleep. Funding source: none reported. INTRODUCTION Obstructive sleep apnea syndrome (OSAS) is a disor- der of breathing during sleep characterized by recurrent episodes of complete or partial upper airway obstruc- tion that interrupt nocturnal ventilation and alter normal sleep architecture. 1,2 The prevalence of pediatric OSAS can vary depending on diagnostic criteria, but it has 1 Division of Pulmonary, Allergy & Immunology and Critical Care Medi- cine, Pennsylvania State University College of Medicine, Hershey, Pennsylvania. 2 Penn State Sleep Research and Treatment Center, Pennsylvania State University College of Medicine, Hershey, Pennsylvania. 3 Division of Biostatistics and Bioinformatics, Department of Public Health Sciences, Pennsylvania State University, Hershey, Pennsylvania. 4 Department of Pediatric, School of Medicine, Universidad Nacional de Colombia, Bogota, Colombia. 5 Pediatric Critical Care Medicine, School of Medicine, Universidad El Bosque, Bogota, Colombia. 6 Research Unit, Military Hospital of Colombia, Bogota, Colombia. 7 Department of Electronics Engineering, Javeriana University, Bogota, Colombia. 8 Division of Pediatric Pulmonology, Department of Pediatrics, Pennsyl- vania State University College of Medicine, Hershey, Pennsylvania. Conflict of interest: None. *Correspondence to: Gustavo Nino, MD, Penn State Hershey Children’s Hospital, Division of Pediatric Pulmonary and Sleep Medicine, Pennsyl- vania State University College of Medicine, 500 University Drive, Her- shey, PA 17033-0850. E-mail: gninobarrera@hmc.psu.edu Received 26 March 2012; Accepted 2 August 2012. DOI 10.1002/ppul.22713 Published online 30 November 2012 in Wiley Online Library (wileyonlinelibrary.com). ß 2012 Wiley Periodicals, Inc.