Relationships between pulmonary function testing and polysomnography in adolescents with severe obesity

Severe obesity (BMI ≥ 35 kg/m² or ≥ 120% of the 95% for age) is increasingly prevalent in adolescents and is associated with respiratory compromise including obstructive and restrictive lung disease and obstructive sleep apnea hypopnea syndrome (OSAHS). The prevalence of respiratory impairment and the relationships between lung volumes measured by pulmonary function tests (PFT) and polysomnography (PSG) in this group with the most severe form of obesity have not been well-studied. The objective of this study is to describe PFT and PSG results in a cohort of adolescents with severe obesity and identify relationships between PSG and PFT variables. Inclusion criteria for 215 patients: ages 12-17 years, diagnosis of severe obesity, completion of both PFT and PSG between 2014 and 2018. The following were collected from EMR: age, sex, BMI, BMI Z-score and percentile, and PFT and PSG results. Descriptive statistics were calculated; multiple regressions were performed to characterize associations between PFT and PSG variables, controlling for age, sex, and BMI. In this cohort of youth with severe obesity, there were high rates of OSAHS (66% met criteria for OSAHS). While spirometry was generally normal, lung volume measurements by body plethysmography reveal low-normal residual volume and low expiratory reserve volume. In addition, there were multiple associations between PFT parameters (especially TLC) and PSG abnormalities. Full PFT and PSG should be considered for adolescents with severe obesity.