Application of desaturation index in post-surgery follow-up in children with obstructive sleep apnea syndrome

Adenotonsillectomy is recommended for children who need surgery for obstructive sleep apnea syndrome (OSAS). Overnight, polysomnography (PSG) is suggested for post-surgery follow-up, but this diagnostic technique is time consuming and inconvenient. Desaturation index (DI) has been reported as a good tool for predicting both the presence and severity of OSAS in children. The purpose of this study was to determine the usefulness of the DI for post-surgery follow-up of children with OSAS. This retrospective study enrolled 42 children, aged 3-12 years, who were snorers diagnosed with OSAS by overnight PSG and who underwent an adenotonsillectomy. Pre- and postoperative PSG parameters, nocturnal pulse oximetry data, and modified Epworth sleepiness scale scores were assessed. Previously determined cut-off DI values (2.05, 3.50, and 4.15 for mild, moderate, and severe OSAS, respectively) were used to predict residual OSAS. Of the 42 children, obvious improvements were observed in apnea-hypopnea index (AHI, decreased 45.5 %), arousal index (decreased 30.5 %), DI (decreased 40.4 %), and snore index (decreased 100.3 %) compared with the preoperative measurements. Among these objective PSG measures, DI had the strongest correlation with AHI both pre- and post-surgeries (r = 0.947 and r = 0.954, respectively; p all <0.001). The DI change, before and after surgery, also had the strongest positive correlation to the AHI change (r = 0.482 and p = 0.001). Using the previously determined DI cut-off values to predict postoperative residual OSAS, there was a good positive predictive value (92.6 %) for mild residual OSAS and a good negative predictive value for moderate and severe residual OSAS (85.2 and 89.7 %, respectively). These findings suggest that DI, as determined using a nocturnal pulse oximeter, may be an alternative tool for postoperative evaluation and follow-up of children with OSAS.