Tonsil size and body mass index are important factors for efficacy of simple tonsillectomy in obstructive sleep apnoea syndrome

Objectives: To evaluate the efficacy of simple tonsillectomy to treat obstructive sleep apnoea syndrome (OSAS) in adults. Design: Prospective study. Setting: Tertiary referral centre. Participants: Thirty patients (28 males) underwent simple tonsillectomy under general anaesthesia. The patients' mean age was 33.2 ± 6.8 years and body mass index was 30.7 ± 6.0 kg/m ². Seven patients (23%) were classified with grade 4, 16 patients (53%) with grade 3, and seven patients (23%) with grade 2 according to the tonsil size of Friedman's classification. Main outcome measures: The number of apnoea episodes per hour (apnoea index), the number of apnoea and hypopnoea episodes per hour (apnoea-hypopnoea index), lowest nocturnal oxygen saturation and oxygen desaturation time were measured during overnight polysomnography before and after surgery. A successful tonsillectomy was defined as an apnoea-hypopnoea index improvement ratio of ≥50% and an apnoea-hypopnoea index <20 after operation. Results: Apnoea-hypopnoea index decreased from 69.0 ± 28.4/h to 30.1 ± 24.0/h (P < 0.0001). Simple tonsillectomy was successful in all six patients with body mass index <25 kg/m². Concerning success rate of simple tonsillectomy with tonsil, size 2 was lowest (42.9%). Eight of the 13 patients who used continuous positive airway pressure before simple tonsillectomy did not use continuous positive airway pressure after simple tonsillectomy because of a significant reduction of excessive daytime sleepiness. Continuous positive airway pressure decreased significantly after simple tonsillectomy from 13.6 ± 2.5 cmH₂O preoperatively to 10.6 ± 1.3 cmH₂O postoperatively (P < 0.05). Conclusions: These data suggest that simple tonsillectomy is a beneficial modality to treat OSAS in selected patients (larger tonsil, low body mass index), even in adults.