Tongue Volume Influences Lowest Oxygen Saturation but Not Apnea-Hypopnea Index in Obstructive Sleep Apnea.
OBJECTIVE
The aim of this study was to identify correlations between sleep apnea severity and tongue volume or posterior airway space measured via three-dimensional reconstruction of volumetric computerized tomography (CT) images in patients with obstructive sleep apnea (OSA) for use in predicting OSA severity and in surgical treatment. We also assessed associations between tongue volume and Mallampati score.


METHODS
Snoring/OSA male patients (n = 64) who underwent polysomnography, cephalometry, and CT scans were enrolled in this retrospective study. OSA was diagnosed when the apnea-hypopnea index (AHI) was greater than 5 (mild 5-14; moderate 15-29; severe>30). The patients were also categorized into the normal-mild group (n = 22) and the moderate-severe group (n = 42). Using volumetric CT images with the three-dimensional reconstruction technique, the volume of the tongue, posterior airway space volume, and intra-mandibular space were measured. The volumes, polysomnographic parameters, and physical examination findings were compared, and independent factors that are related to OSA were analysed.


RESULTS
No associations between tongue volume or posterior airway space and the AHI were observed. However, multivariate linear analyses showed that tongue volume had significantly negative association with lowest O2 saturation (r = 0.365, p = 0.027). High BMI was related to an increase in tongue volume. Modified Mallampati scores showed borderline significant positive correlations with absolute tongue volume (r = 0.251, p = 0.046) and standardized tongue volume (absolute tongue volume / intramandibular area; r = 0.266, p = 0.034). Between the normal-mild and moderate-severe groups, absolute tongue volumes were not different, although the standardized tongue volume in the moderate-severe group was significantly higher.


CONCLUSIONS
Absolute tongue volume showed stronger associations with lowest O2 saturation during sleep than with the severity of AHI. We also found that high BMI was a relevant factor for an increase in absolute tongue volume and modified Mallampati grading was a useful physical examination to predict tongue size.
Department of Otorhinolaryngology, Severance Hospital, Yonsei University College of Medicine, Seoul, Korea.
Sang Hyeon
SH
Ahn
Department of Radiology, Severance Hospital, Yonsei University College of Medicine, Seoul, Korea.
Jinna
J
Kim
Department of Otorhinolaryngology-Head and Neck Surgery, Chung-Ang University College of Medicine, Seoul, Korea.
Hyun Jin
HJ
Min
Department of Otorhinolaryngology, Severance Hospital, Yonsei University College of Medicine, Seoul, Korea.
Hyo Jin
HJ
Chung
Department of Otorhinolaryngology, Severance Hospital, Yonsei University College of Medicine, Seoul, Korea.
Jae Min
JM
Hong
Department of Otorhinolaryngology, Severance Hospital, Yonsei University College of Medicine, Seoul, Korea.
Jeung-Gweon
JG
Lee
Department of Otorhinolaryngology, Severance Hospital, Yonsei University College of Medicine, Seoul, Korea; The Airway Mucus Institute, Yonsei University College of Medicine, Seoul, Korea.
Chang-Hoon
CH
Kim
Department of Otorhinolaryngology, Severance Hospital, Yonsei University College of Medicine, Seoul, Korea; The Airway Mucus Institute, Yonsei University College of Medicine, Seoul, Korea.
Hyung-Ju
HJ
Cho
D000328:Adult; D000368:Aged; D002508:Cephalometry / Q000379:methods; D006801:Humans; D008297:Male; D008334:Mandible / Q000378:metabolism / Q000503:physiopathology; D008875:Middle Aged; D010100:Oxygen / Q000378:metabolism*; D017286:Polysomnography / Q000379:methods; D012189:Retrospective Studies; D012720:Severity of Illness Index; D012890:Sleep / Q000502:physiology; D020181:Sleep Apnea, Obstructive / Q000378:metabolism / Q000503:physiopathology*; D012913:Snoring / Q000378:metabolism / Q000503:physiopathology; D014059:Tongue / Q000503:physiopathology*; D055815:Young Adult
D010100:Oxygen