Fig. 1. Nasal Polyps

Fig. 2. Friedman tongue position 3

Fig. 3. Friedman tongue position 4

must however take in to account that as this assessment is done during wakefulness it may not truly reflect what happens to the upper airway during sleep as there must undoubtedly be some variation in the muscle tone in the state of wakefulness and different stages of sleep.

Fig. 1. Nasal Polyps

Fig. 2. Friedman tongue position 3

Fig. 4. Friedman tongue position 1

Probably the most useful equipment in assessing the upper airway is the flexible fibreoptic nasopharyngoscope which is widely available and allows brilliant visualisation of all aspects of the naso, oro and hypopharynx. Local anaesthesia in the form of a nasal spray can be used in allowing an easier and tolerable insertion of the scope and the different segments of the pharynx are carefully assessed. The patient could be asked to simulate a snoring sound to try and ascertain the level responsible for causing the turbulent airflow resulting in the snoring sound. Herzog3 has reported a study based on simulating snoring sound in order to establish a model of grading upper airway obstruction. However, not all patients can simulate snoring and some may do this with mouth open or closed and these patients are usually sitting up whilst during sleep patients may be supine, prone or in lateral

Evaluation of the Upper Airway in Patients with Snoring and OSA 69

One of the more recent devices illustrated in figures 5 and 6 and known as Apnea-Graph AG200 (MRA, Medical UK) seems quite promising in that it is capable of combining polysomnography data with pressure recording thus providing the clinician with information regarding the severity of OSA as well as giving some idea regarding the anatomical obstructive segment in the individual patient. Essentially, it relies on measuring pressure and airflow simultaneously at different levels in the pharynx. It stores and analyses the cardio-respiratory data of a patient with simultaneous recording of two different sites in the upper airway using a micro-pressure and temperature transducer catheter. Tvinnereim11 *et* al published an encouraging study illustrating the importance of using this pressure catheter evaluation before embarking on surgical treatment. Singh12 *et* al also demonstrated some usefulness of this technique, though they had some reservations about the ability of this device to accurately detect hypopharyngeal obstruction. They compared the Apnea-Graph to polysomnography. In addition they assessed correlation in some of these patients pharyngeal obstruction data to that seen whilst performing drug induced sleep endoscopy (DISE) and concluded the latter to be superior as it allowed visualisation of the upper airway and was also more useful in indentifying lateral wall collapse. They also commented that in their group of patients, some found it difficult to tolerate the catheter for the whole night and stressed that as the catheter moves during respiration the transducers would also move thus the accuracy of the levels identified could be questioned. Another point to note is that this device has fixed transducers on a catheter and has a fixed reference transducer and does not take in to account that all patients are morphologically different and therefore the

Fig. 5. The Apnea-Graph device with its components: a pulsoximeter and the fine bore nasal

positioning will not be identical in all patients.

catheter with four transducers

positions. In any case the fact that the muscle tone variation in sleep and wakefulness must also be borne in mind. Another commonly used technique during the flexible endoscopic assessment is the Mullers4 manoeuvre. This essentially is a reversed Valsalva procedure which some patients do find difficult to perform. Furthermore, there is subjective variation in the assessment of the degree of collapse noted in different segments of the pharynx and thus the reliability of this technique may be questioned.
