ABSTRACT
Aim: To identify the clinical predictors and assist surgeons in their clinical management of obstructive sleep apnoea (OSA) – a prospective study with a new approach to analyse the static and dynamic upper airway morphology between patients with OSA and normal subjects. To introduce a new method of assessment for surgical outcome. Materials and Methods: Quantitative computer-assisted videoendoscopy (validated with upper airway magnetic resonance imaging) was performed in 49 (43 males, 6 females) patients with OSA and compared with 39 (22 males, 17 females) controls (apnoea-hypopnoea index <5). Absolute cross-sectional areas, transverse and longitudinal diameters at the retro-palatal and retro-lingual levels were measured during end of quiet respiration and during Mueller’s manoeuvre in the erect and supine positions, allowing us to study static and dynamic morphology (collapsibility) of the upper airway. We analysed 3744 parameters. Results: In males, retro-palatal and retro-lingual areas during Mueller’s manoeuvre in the supine position of 0.7981 cm2 [receiver operating characteristics (ROC) = 0.9284, positive predictive value (PPV) = 86.05%, negative predictive value (NPV) = 84.62%] and 2.0648 cm2 (ROC = 0.8183, PPV = 76%, NPV = 83.33%), respectively, were found to be good predictors/ cut-off values for OSA. Retro-palatal area measured in the supine position during Mueller’s manoeuvre (AS1M) and collapsibility of retro-palatal area in the supine position calculated (CAS1) were found to have significant correlations with severity of OSA. In females, areas measured during Mueller’s manoeuvre in the supine position of 0.522 cm2 at retro-palatal level (ROC = 1, 100% PPV and NPV) and transverse diameter at retro-lingual level during erect Mueller’s manoeuvre of 1.1843 cm (ROC = 0.9056, PPV = 100%, NPV = 83.33%) were found to be predictive. All measurements at the retro-palatal level and in the supine position had higher predictability. Area measurements obtained during Muller’s manoeuvre were more predictive (ROC >0.9910) than resting measurements (ROC >0.8371). Several gender and anatomical-site specific formulas with excellent predictability (ROC close or equal to 1) were also devised. Examples of surgical outcome assessment were introduced. Conclusion: Upper airway Mueller’s studies are predictive and useful (independent samples t-test/Mann Whitney U test, ROC) in identifying patients with OSA. With these gender and anatomical-site specific OSA predictors/formulas and this innovative clinical method, we hope to assist other surgeons with quantitative clinical diagnosis, assessment, surgical planning and outcome assessment tools for OSA patients.
Obstructive sleep apnoea (OSA) is a common disease, which is estimated to affect up to 2% of middle-aged women and 4% of middle-aged men.1 Various attempts have been made to obtain predictive indicators of OSA, ranging from clinical predictors using body mass index (BMI), Malampatti score2 and tonsil size to lateral cephalometric measurements3,4 and nasopharyngoscopic assessment with or without Mueller’s manoeuvre. Nasopharyngoscopy is a widely available technique commonly performed by otolaryngologists to evaluate the upper airway. This technique is easily performed in outpatient setting and does not involve radiation exposure. Nasopharyngoscopy permits direct observation of the dynamic appearance of the pharynx and has been used in a number of research studies to evaluate the physiologic changes in a hypotonic airway in patients with OSA. Nasopharyngoscopy with Mueller’s manoeuvre is an ideal modality to examine dynamic changes in upper airway calibre, it can be used to determine the extent of retropalatal or retro-glossal obstruction. The Mueller’s manoeuvre is thought to simulate the upper airway collapse that occurs during apnoea but is performed in wakefulness as the patient voluntarily inspires against a closed mouth and occluded nose.
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