Prevention of Sleep Apnoea After General Anaesthesia Using a Thermoplastic Mandibular Advancement Device: A Randomised, Controlled, Single-Blind Trial

Background: Sleep apnoea is associated with increased postoperative morbidity and worsens after surgery under general anaesthesia. A thermoplastic mandibular advancement device (MAD) might prevent postoperative sleep apnoea worsening. This randomised, controlled, single-blind trial tested the hypothesis that a thermoplastic MAD would reduce apnoea–hypopnoea index (AHI) on the first postoperative night after general anaesthesia. Methods: One hundred patients undergoing various elective orthopaedic procedures on the lower limb under general anaesthesia were randomly allocated to two groups: use of a thermoplastic MAD during the first postoperative night (intervention) or no MAD during the first postoperative night (control). All patients underwent respiratory polygraphy on the first postoperative night. The primary outcome was the AHI on the first postoperative night. Secondary outcomes included the obstructive apnoea index, mixed apnoea index, central apnoea index, hypopnoea index, oxygen desaturation index, and self-reported tolerance of the device (on a numeric rating scale from 0 to 10, where higher scores indicate better tolerability), all measured during the first postoperative night. Results: The mean [95% confidence interval] AHI was similar in the MAD and control groups (9 [6–12] and 11 [7–15] events·h−1, respectively; p = 0.26). There were no significant between-group differences in the secondary outcomes. The median (interquartile range) score for MAD tolerance was 7.5 (5.0, 8.5). Conclusions: In conclusion, a thermoplastic MAD did not demonstrate to reduce AHI after general anaesthesia for lower limb orthopaedic surgery on the first postoperative night. However, this finding should be interpreted cautiously, as dexamethasone administered to all participants may have reduced postoperative respiratory events or increased nocturnal wakefulness, thereby artificially lowering the apnoea–hypopnoea index calculated.