Association Between Pulmonary Function Parameters and Apnea Hypopnea Index in Asthmatic Children Living at High Altitude

INTRODUCTION: Obstructive sleep apnea (OSA) has been associated with poorer asthma outcomes in children, including reduced disease control and a greater risk of exacerbation. However, little is known about the relationship between sleep-disordered breathing severity and pulmonary function in pediatric patients residing at high altitude. METHODS: We conducted a cross-sectional study including children aged 3-12 years with physician-diagnosed asthma who underwent overnight polysomnography at a referral center in Bogotá, Colombia (2640 m above sea level), between 2012 and 2017. Clinical characteristics, spirometric measurements, oscillometry parameters, and polysomnographic variables were collected and analyzed. Associations between pulmonary function indices and apnea-hypopnea measures were evaluated using Spearman correlation analysis. RESULTS: Sixty-four children were included, of whom 59.4% had moderate-to-severe asthma and 59.4% had uncontrolled disease. In oscillometry, airway resistance at 5 Hz (R5) demonstrated an inverse correlation with AHI before bronchodilator administration (r = -0.440, p < 0.05) and after bronchodilator administration (r = -0.491, p < 0.05). Similar inverse correlations were observed between R5 and OAHI. Among spirometric variables, postbronchodilator FEV1 was negatively correlated with OAHI (r = -0.329, p < 0.05). No significant associations were found between OSA severity and asthma severity, body mass index, or nocturnal oxygen saturation. CONCLUSIONS: Our findings revealed an association between the AHI and VEF1 in asthmatic children residing in a tropical city at high altitude. However, the results regarding the relationship between AHI and R5 were contradictory.