Tuesday, November 1, 2011
Oropharyngeal Examination to Predict Sleep Apnea Severity
In obstructive sleep apnea (OSA), there have been few physical exam findings that accurately correlate with the risk of having OSA. Elevated body mass index (BMI), increased neck circumference, male gender, older age, and elevated blood pressure all relate to increased risk of OSA. Other characteristics, such as the shape of the back of the mouth, have not been strongly predictive of OSA. However, in the October edition of the Archives of Otolaryngology - Head & Neck Surgery is a study about a certain way sleep physicians classify the level of crowding in the back of the mouth. It's called the Friedman tongue position (FTP), after Dr. Friedman, an ENT surgeon who does research in this area. The picture at the top left shows the FTP classification, with level 1 (upper left picture) being the least crowded and level 4 (lower right) being the most crowded. In my experience, the more crowded the back of the mouth (as in levels 3 & 4), the higher risk of having significant upper airway collapse while asleep that results in OSA.
In the study, researchers assessed 301 patients with an average age of 51 who presented to a sleep lab for suspected OSA. On physical exam, these study subjects were 71.1% were male, had a mean BMI of 29.8, and a neck circumference of 40.5 cm. Results of their sleep study showed that 94% had some degree of OSA - meaning that the population studied was relatively high risk. Subjects with FTP levels of 2 and 3 accounted for 74.1% of the whole population studied. And 14.3% had an FTP level 1, with 11.6% having an FTP level 4. In the first analysis, researchers found that the size of the tonsils, the size of the uvula, BMI, neck circumference, nasal airflow, and age were related to OSA severity. However, in the multiple regression model, only the FTP score showed a relevant relationship to OSAS severity.
The study authors concluded that since the FTP score is almost the only measurement related to OSA severity, a simple oropharyngeal examination can provide key information on this issue. And, since researchers think that almost 80% of patients with OSA have not been diagnosed, I think the FTP level could be an easy screening tool for primary care physicians to assess the potential risk of OSA and get their patients treated.