CME/Answers: Obstructive Sleep Apnea: How to Deal with Night- To-Night Variability of Respiratory Events?

Abstract.According to current recommendations, the diagnosis of obstructive sleep apnea (OSA) is established by a single-night sleep study. However, recent reports suggest a remarkable night-to-night variability of OSA severity. We report on a 76-year-old man with suspected OSA who underwent six sleep studies within 13 months. Sleep studies demonstrated a remarkable variability of respiratory events based on an apnea-hypopnea index (AHI) varying between 1.1 and 43.1/h. There were no changes in body weight, alcohol intake, medication or comorbidities during the evaluation period. Due to diagnostic uncertainty and missing subjective benefit, the initially implemented CPAP therapy was stopped after one year of therapy. Considering night-to-night variability of OSA severity, single-night sleep studies might not be accurate enough in order to reliably diagnose or exclude OSA.