Uvulopalatopharyngoplasty: analysis of failure

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Chapter 60 Uvulopalatopharyngoplasty: analysis of failure

2 PATIENT SELECTION

The first step in the process of patient selection is diagnosing the severity of the condition. This starts with a thorough history from the patient and possible partner as well as general ENT examination. Body Mass Index (BMI) and neck circumference are noted at this stage too. The severity of disease is important only to determine if the patient is a candidate for surgery or whether the patient should have non-surgical minimally invasive techniques. Severity will not be a guide to determine the type of surgery. The location of the obstruction will determine the correct surgical procedure.

The next step in the work-up of suspected OSAS patients is a polysomnogram (PSG). This objective tool allows qualitative and quantitative measurements such as differentiation between SUS and OSAS and evaluation of the degree of disease severity. There are four levels of polysomnographic testing of which level I is the most elaborate, including recordings such as an electroencephalogram, registration of eye movements, submental electromyogram, registration of thoracic and abdominal respiratory movement, limb movements, oxygen saturation and the intensity of snoring all recorded in a clinical setting for the duration of at least 6 hours. The other levels are less extensive and not performed in a clinical setting.4 Events recorded during PSG and most commonly used to estimate severity and treatment outcome are the Apnea Index (AI), Apnea/Hypopnea Index (AHI), Respiratory Distress Index (RDI), Respiratory Arousal Index (RAI), Respiratory Effort Related Arousals (RERA) and Oxygen Desaturation Index (ODI). Recently the American Academy of Sleep Medicine (AASM) formulated recommendations for clinical and research definitions of PSG studies.5

A subjective measuring tool is the Epworth Sleepiness Scale (ESS), a questionnaire regarding hypersomnia. It was originally designed as an easy, non-invasive tool to distinguish SUS from OSAS.6 Although practical in use, it has been shown to have a low predictive value, and it cannot show the severity of the disease.

After assessment of the severity of the disease by polysomnography it is of equal importance to determine the level of obstruction(s) in the upper airway.

Mallampati et al. developed the Mallampati clinical scoring system in the mid-1980s to predict difficulty in tracheal intubation based on the ability to visualize the faucial pil-lars, soft palate and uvula base.7 The Mallampati score has been modified by Friedman et al. who then studied the value of this type of assessment in patients with obstructive sleep apnea.

Friedman modified the original Mallampati score in the following ways.

The Friedman staging system represents a clinical, anatomical staging system, independent of disease severity. Friedman et al. found patients classified with stage 1 disease had an 80.6% chance of successful cure with UPPP as opposed to success rates of respectively 38% and 8% in stage 2 and stage 3. The major advantage of this system is its easy use in various settings and its ability to predict which patients are most likely to fail (stage 3).8

Sleep(naso)endoscopy (sedated endoscopy) is another way of determining the levels of obstruction during induced sleep. This approach attempts to simulate the natural situation during snoring. Although this is a relatively time-consuming and costly method it is also the best option for topical preoperative dynamic diagnostic work-up for an ENT practice.9

Despite reports that each method is capable of good preoperative work-up, it is intriguing that the correlation between Friedman tongue position (or Friedman staging system) and findings with sleep endoscopy is low.10

The importance of determining the level of obstruction or collapsibility of the pharynx is increasingly recognized. Globally one way of describing the level of pharynx anatomy involves the subdivision into retropalatal and retrolingual obstruction. This has led to the following, much applied, preoperative classification: Type 1 refers to collapse at retropalatal level, Type 2 indicates collapse at both retropalatal and retrolingual level and Type 3 means collapse at the retrolingual area.11

5 SUBJECTIVE AND OBJECTIVE TREATMENTOUTCOMES

A distinction should be made between subjective and objective treatment outcome. Although a reasonable correlation usually exists between objective and subjective outcome, unexplained discrepancies still occur in many circumstances. A clinical reality is that a rise in AHI or RDI can occur with subjective improvement and vice versa. One of the consequences is that repeated polysomnography should be performed in all OSAS patients after surgery. Unresolved ethical issues occur for instance in a happy (e.g. reduced snoring and/or improvement of hypersomnolence) patient after surgery who in repeated PSG is shown to have a rise in AHI or an unhappy patient with no subjective improvement but a distinctively lower AHI in repeated PSG recordings. Concerning these discrepancies between objective and subjective UPPP outcome, Lu et al. noted a long-term subjective improvement in 80% of their cases which was not correlated with the polysomnographic results.14 This raises the following question: if help-seeking behavior is mostly symptom driven and the patient now feels these symptoms no longer exist, how to motivate the patient for additional treatment to prevent long-term negative effect on health? The importance of treatment in (severe) OSAS is underlined by findings by Keenan et al. who showed that UPPP increases long-term survival in OSAS patients.15

5.1 OBJECTIVE DEFINITIONS OF OUTCOME

These can be defined as:

Success is most commonly objectively assessed by polysomnography. Over the past decades various cut-off points have been used in different studies estimating UPPP outcome of which a brief review follows. Fujita was the first to define the cut-off value for success as an AI reduction of 50%. Other variables taken into account included the level of oxygenation (SaO2>85%) and the number of arousals.3 The large meta-analysis of Sher et al. used an AI reduction with an absolute AI of 10 and/or an RDI reduction of 50%, with an RDI of less than 20 to evaluate treatment outcome.11 Larsson et al. also used an RDI reduction of 50% together with a reduced RDI of 20 or less for their long-term evaluation of UPPP outcome.16 A 50% reduction of the AHI was also used by Janson et al. and combined with an absolute AI value of 10 or less.17

Another frequently used outcome measure is the Oxygen Desaturation Index (ODI) where responders are defined as having a postoperative ODI of <20 with an ODI reduction of at least 50% compared to preoperative values.16,18

We propose this subdivision into responders (success and response) and non-responders (comprising both no change and deterioration) to achieve a simplified subdivision in treatment outcome and ease study comparison.

Issues that require attention in patient classification by PSG measurements are night-to-night variability and the influence of different types of leads when interpreting PSG values close to the cutoff point between responders and non-responders.5

For UPPP, another clinical distinction can be proposed: