Upper airway volumetric changes of obstructive sleep apnoea patients treated with oral appliances: a systematic review and meta-analysis.

BACKGROUND Obstructive sleep apnoea (OSA) is a common sleep-related breathing disorder, attributed to the collapse of the pharyngeal walls and the subsequent complete or partial upper airway obstruction. Among different treatment options for OSA, Continuous Positive Airway Pressure, and oral appliances (OAs) have been used, with various outcomes and side effects. OBJECTIVE The aim of this study was to summarize current knowledge in an evidence-based manner regarding the upper airway volume increase of OSA patients while treated with OAs. SEARCH METHODS Electronic search was conducted in Pubmed, Cochrane Library, and Scopus, up to May 2020. SELECTION CRITERIA Studies were selected after the application of predetermined eligibility criteria. DATA COLLECTION AND ANALYSIS Mean airway volume differences and the corresponding 95% confidence intervals were calculated, using the random effects model. Sensitivity, exploratory, and meta-regression analyses were also implemented. RESULTS Eleven studies filled the inclusion criteria and were included in the systematic review, while 10 of them were suitable for meta-analysis. In total, 291 patients were included, with mean upper airway volume increase of 1.95 cm3 (95% CI, 1.37-2.53; P < 0.001) with Mandibular Advancement Devices in place. In all studies, post-treatment Apnea Hypopnea Index (AHI) was either <10 events/hour or was reduced by more than 50% from baseline levels. A greater increase of the velopharynx volume was observed, regarding airway compartments. CONCLUSIONS Treatment with OAs in OSA may lead to a significant increase of the upper airway volume with a subsequent decrease of AHI. The velopharynx seems to be affected the most from OA therapy.