Lead author Dr. David Gozal, from University of Louisville in Kentucky, and team reported that although, adenotonsillar hypertrophy is known to play an important role in OSA in children in general, the role it plays in the growing number of obese children with OSA is unclear.

The team performed a retrospective examination of polysomnographic findings in 206 obese and 206 nonobese children with OSA of similar severity.

They found that there was a direct relationship between adenoid and tonsillar size scores and the obstructive apnea-hypopnea index (OAHI) in nonobese children, but not in obese children, and adenotonsillar size was significantly larger in nonobese children than in obese children.

On the other hand, there was no linear association between body mass index (BMI) z score and OAHI.

The researchers found a significant association between BMI z score and Mallampati scores (an estimate of crowding of the upper airway), which were significantly higher among obese children.

Although the assessment of BMI fails to reveal the mechanisms by which excess fat contributes to sleep-disordered breathing, the increased Mallampati scores found among obese children

The researchers write that it is unclear why excess fat is contributing to sleep-disordered breathing. However, the findings would suggest that fat deposition in the soft tissues of the upper airway are more likely to occur in the context of obesity and will lead to reductions in upper airway diameter, thereby facilitating the occurrence of OSA when lymphadenoid hypertrophy occurs, even if the latter is mild, the investigators conclude.

We not only anticipate that obese children will fare worse than nonobese kids after adenotonsillectomy, but in fact have already shown this in a previous study, Dr. Gozal told Reuters Health.

The size of the tonsils should not be a determining factor in the considerations as to whether a child has OSA or not, Dr. Gozal said. Sleep studies should be conducted both before adenotonsillectomy to define the severity and pattern of OSA in children, and in obese children adenotonsillectomy should not be considered as curative, but rather a sleep study should be performed in all obese children after the surgery.