1
Introduction
Obstructive sleep apnea/hypopnea syndrome (OSAHS) is often the result of obstruction at multiple anatomic sites. Nasal, palatal, and hypopharyngeal obstruction, acting alone or in concert, are frequently identified as the cause of snoring and OSAHS. Even in cases where a single site is primarily involved, the increase in negative pressure may induce further obstruction in other areas. When surgical management of OSAHS is considered, a clear understanding of the complex relationship between the sites of obstruction is essential to surgical success.
The importance of determining the sites of obstruction has led to the development of numerous methods that attempt to predict the location of the upper airway obstruction. These include snoring sound analysis, physical examination, computed tomography, magnetic resonance imaging, cephalometric studies and fluoroscopy, nasopharyngoscopy, and drug-induced sleep endoscopy (DISE). Although these methods have demonstrated value, the number of methods described is evidence of the lack of agreement that any single method is perfect. Historically, a commonly used method was the Mueller maneuver (MM). Borowiecki and Sassin first described this maneuver for the preoperative assessment of sleep-disordered breathing (SDB). The MM consists of having the patient perform a forced inspiratory effort against an obstructed airway with fiber-optic endoscopic visualization of the upper airway. The test is widely used and simple to perform. Despite this, its use is controversial, and certainly no studies have been able to position the maneuver as a tool for patient selection. It is within this context that the Friedman tongue positions (FTP) emerged.
DISE (described in Chapter 6 ) provides information on the airway with the patient in a supine position while asleep. It is clearly a more definitive assessment of the airway when major surgery is planned. Nevertheless, FTP is a valuable tool in clinical assessment of the airway for many reasons. DISE requires an operating room procedure with associated costs and risks and is therefore not routinely indicated for most patients with obstructive sleep apnea (OSA). It is reserved for patients who will undergo upper airway surgery. Clinical screening with FTP allows evaluation of the patient with a simple examination. Patients with favorable anatomy (FTP I or II and large tonsils) will often be directed toward surgery. Patients with severe disease and unfavorable anatomy (FTP III or IV) will be directed toward continuous positive airway pressure (CPAP), and only after CPAP failure will they be candidates for surgery. Patients with mild disease and CPAP failure who have unfavorable anatomy can be directed to mandibular advancement therapy. Anatomic staging is simple and should be the initial part of every patient’s treatment plan.
Initially presented by Friedman et al. in 1999, FTP (previously identified as the Mallampati palate position and subsequently as the Friedman palate position) has been found to be a simple method to approximate obstruction at the hypopharyngeal level. This classification is based on observations by Mallampati et al., who published a paper on palate position as an indicator of the ease or difficulty of endotracheal intubation by standard anesthesiologist techniques. The Mallampati stages had only been studied in the context of difficult intubations; therefore two major modifications were incorporated into FTP for its use in sleep medicine. First, the anesthesiologist assessment of the airway is based on the relationship of the soft palate to the protruded tongue. FTP is based on evaluating the tongue in a neutral, natural position inside the mouth. Second, the Mallampati system had only three grades. FTP includes five positions that best describe the position of the tongue relative to the tonsils/pillar, uvula, soft palate, and hard palate ( Table 15.1 ). FTP has been studied extensively as it relates to OSAHS, and therefore it is a more accurate evaluation of the airway.
| Original | New | ||||
|---|---|---|---|---|---|
| FTP | Anatomic structures visualized | Anatomic structures not visualized | FTP | Anatomic structures visualized | Anatomic structures not visualized |
| I | Tonsils and pillars | I | Tonsils and pillars | ||
| Entire uvula | Entire uvula | ||||
| II | Uvula | Tonsils and pillars | IIa | Uvula | Tonsils and pillars |
| III | Most of the soft palate | Uvula | IIb | Most of the soft palate | Uvula |
| Base of the uvula | Tonsils and pillars | Base of the uvula | Tonsils and pillars | ||
| IV | Only the hard palate | Tonsils and pillars | III | Some of soft palate | Tonsils and pillars |
| Uvula | Distal soft palate | ||||
| Base of the uvula | |||||
| IV | Only the hard palate | Tonsils and pillars | |||
| Uvula | |||||
Identifying FTP requires the patient to open the mouth widely without protruding the tongue. This is repeated a minimum of five times, allowing the observer to assign the most consistent FTP. FTP I allows the observer to visualize the entire uvula and tonsils or pillars ( Fig. 15.1 ). FTP IIa allows visualization of the uvula, but only parts of the tonsils are seen. FTP IIb allows visualization of the complete soft palate down to the base of the uvula, but the uvula and the tonsils are not seen. FTP III allows visualization of some of the soft palate, but the distal soft palate is eclipsed. FTP IV allows visualization of the hard palate only ( Fig. 15.1 ).
Earlier publications have described only four FTPs. This resulted in a majority of patients being classified as FTP III. With such a large number of subjects categorized into this one position, it was clinically relevant to further stratify this group based on anatomy and response to surgical outcomes. Expanding FTP II into two groups, FTP IIa and FTP IIb, provides the means for achieving this stratification. Patients with FTP IIb, although they may have been formerly classified as FTP III in the earlier staging system, share surgical response rates more characteristic of FTP II.
Once FTP is determined, the information can be incorporated into two distinct algorithms, which can provide insights on the diagnosis and management of OSAHS. First, the use of FTP enables the clinician to predict the presence of OSAHS. A thorough history is often the best screening for OSAHS. Unfortunately, many patients who are in denial about their symptoms cannot be identified by history alone and therefore go undiagnosed. Routine use of FTP can be utilized as a cost-effective, noninvasive screening tool that will allow ready identification of patients that may suffer from OSAHS. Second, because FTP estimates the presence of hypopharyngeal obstruction, determining FTP before surgical intervention can be instrumental in guiding the surgical management of OSAHS. Previous studies have demonstrated its ability to separate patients that will likely benefit from uvulopharyngopalatoplasty (UPPP) as a single modal treatment from those that will require multilevel surgical intervention.
2
The OSAHS Score
The estimated prevalence of OSAHS is 5% in women and 14% in men. There is also clear evidence that associates OSAHS with hypertension, insulin resistance, coronary heart disease, myocardial infarction, and stroke, as well as compromised quality of life and significant social and emotional problems ; yet it is estimated that approximately 80% of cases remain undiagnosed. The primary screening for OSAHS is by a thorough history. Patients who complain of snoring, excessive daytime sleepiness, or observed apnea are usually the only ones who are further tested for OSAHS. The major inaccuracy of such a screening system is that history in the context of OSAHS has a low sensitivity. The obstacles in eliciting history in sleep apnea patients are twofold. First, because the patient is asleep when the pathology occurs, they are largely unaware of the problem and often deny symptoms. In such cases, only a history elicited from a bed partner can offer sufficient insight into symptomology. Second, symptoms of OSAHS often overlap with other pathologies, requiring physical findings to help direct further testing. For example, a patient complaining of excessive sleepiness and fatigue may very likely receive a full workup for depression and not OSAHS.
History is always the starting point for the screening and diagnosis of any medical condition. This is generally followed by a physical examination that can confirm the history or can bring to attention new concerns not identified in the history. The known physical findings that are associated with OSAHS include body mass index (BMI), neck circumference, and tonsil size; are routinely assessed; and are well defined. Descriptions of hypopharyngeal obstruction, however, have not been standardized. Oftentimes the similar physical findings are reported with many arbitrary terms such as “crowded oropharynx,” “macroglossia,” “retrognathia,” etc. This causes much confusion in both patient care and in reporting data. The routine use of FTP in the context of OSAHS can help standardize the description of hypopharyngeal obstruction.
FTP can be employed in an algorithm that can help identify patients with OSAHS. This system is based on three readily identifiable and reproducible physical exam findings and can provide a simple means for screening patients. The system relies on calculating the patient’s BMI, along with the assessment of the patient’s tonsil size and FTP. FTP position is assessed according to the system stated in the previous section. Tonsil size and BMI are assessed as follows. Tonsil size is graded from 0 to 4. Tonsil size 1 represents tonsils contained within the pillars. Size 2 tonsils extend to the pillars. Size 3 tonsils extend beyond the pillars but not to the midline. Size 4 represents tonsils that extend to the midline ( Fig. 15.2 ).
BMI is derived from the height and weight of the patient and is calculated using the formula BMI = weight (kg)/height (m 2 ). The BMI is graded as grade 0 (<20 kg/m 2 ), grade 1 (20–25 kg/m 2 ), grade 2 (25–30 kg/m 2 ), grade 3 (30–40 kg/m 2 ), and grade 4 (>40 kg/m 2 ) according to previously published standards for obesity. Neck circumference has been shown to correlate well as a clinical predictor, but BMI is an alternative measure that was used.
Once known, these three findings can be combined to calculate an OSAHS score. The OSAHS score can help identify patients that may have OSAHS via physical exam alone and does not rely on history. To calculate the OSAHS score, the numerical values of these findings are summed:
OSAHS score = FTP ( 0 − IV ) + tonsil size ( 0 − 4 ) + BMI value ( 0 − 4 )
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