Obstructive sleep apnoea and oral breathing in patients free of nasal obstruction

¹ Center of Sleep Disorders, Medical School of Athens University, Dept of Critical Care and Pulmonary Services, Evangelismos Hospital

^* To whom correspondence should be addressed. E-mail: szakynthinos{at}yahoo.com.

	Abstract

Although there is an association between nasal obstruction, oral breathing and obstructive sleep apnoea syndrome (OSAS), it remains unknown whether increased oral breathing occurs in patients with OSAS free of nasal obstruction. This study evaluated the relationship between breathing route and OSAS in patients without nasal obstruction.

We examined during an overnight polysomnography the breathing route of 41 snorers (25 men; aged 26-77 yrs) with normal nasal resistance by using a nasal cannula/pressure transducer and an oral thermistor.

Twenty-eight patients had OSAS (apnoeics) and 13 patients were simple snorers. Apnoeics had higher percentage of oral (p=0.004) and oro-nasal (p<0.001) breathing epochs. Oral and oro-nasal breathing epochs were positively related with apnoea-hypopnoea index (AHI), duration of apnoeas/hypopnoeas and inversely related to oxygen saturation. Additionally, oro-nasal breathing epochs correlated with body mass index. In multiple linear regression analysis, oral breathing epochs were independently related only to AHI (R²=0.443), and oro-nasal breathing epochs were independently related to AHI (R²=0.736) and body mass index (R²=0.036).

In conclusion, apnoeics spend more time breathing orally/oro-nasally than simple snorers, and AHI is a major determinant of the time that they spend breathing orally and oro-nasally.

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