Rationale and indications for surgical treatment

Chapter 12 Rationale and indications for surgical treatment

1 INTRODUCTION

Obstructive sleep apnea syndrome (OSAS), upper airway resistance syndrome (UARS) and snoring are collectively referred to as sleep-related breathing disorders (SRBD). Although the specific etiology is unknown, SRBD involves repeated partial or complete obstructions of the upper airway during sleep. The obstructions can be due to anatomical or central neural abnormalities. Loss of airway patency may cause sleep fragmentation and subsequent neurocognitive derangements, such as excessive daytime sleepiness.1 The objective of surgical treatment is to alleviate this obstruction and the associated cardiovascular and neurobehavioral sequelae by increasing airway patency.

Tracheotomy was the first therapeutic modality employed to treat OSAS. Although effective, tracheotomy is not readily accepted by most patients due to its morbidity. Sullivan et al. reported the application of nasal continuous positive airway pressure (CPAP) to maintain upper airway patency as an alternative to tracheotomy.2 Because of its efficacy, CPAP is usually the first-line treatment for OSAS.3 Yet, a subset of patients struggle to accept or comply with CPAP therapy.4 Thus, those patients who cannot tolerate medical therapy may be candidates for surgery.

Recognizing that multiple levels of airway obstruction exist in OSAS is essential to achieve a cure. Consequently, the surgical armamentarium has evolved to create techniques which address the specific anatomical sites of obstruction. The surgeon must be willing to treat all levels of obstruction in an organized and safe manner. Therefore, we developed a two-phase surgical protocol (Powell–Riley protocol) to target the specific anatomical sites of obstruction (nasal cavity/nasopharynx, oropharynx and hypopharynx). This protocol was created to minimize surgical interventions and avoid unnecessary surgery, while alleviating SRBD.5,6

Prior to any intervention, the surgeon must be familiar with the rationale and indications for each surgery. A systematic review of the patient will aid in identification of regions of obstruction and minimize risk and potential complications. Hence, this chapter will summarize our approach to the surgical treatment of OSAS.

2 RATIONALE FOR SURGICAL TREATMENT

The rationale for surgical treatment of the upper airway is to eliminate or minimize the neurocognitive and pathophysiologic derangements associated with OSAS. These neurocognitive derangements are the result of sleep fragmentation and hypoxemia. Patients with excessive daytime sleepiness (EDS) may experience emotional, social and economic problems.7 Furthermore, uncontrollable fatigue may predispose a patient to automobile or occupational accidents.8 Morbidity is seen from the associated sequelae of these pathophysiologic derangements such as hypertension, congestive heart failure, myocardial infarction, cardiac arrhythmias and cerebrovascular disease.9,10 Thus, reducing the Apnea/Hypopnea Index (AHI) by 50% is no longer deemed acceptable. Rather, the goal is to treat to cure (elimination of hypoxemia and normalization of respiratory events). Ultimately, the surgeon’s objective is to achieve outcomes that are equivalent to those of CPAP management. Ideally, surgical intervention seeks to improve the quality of life, enhance longevity and reduce the risk of medical morbidity.

3 SURGICAL INDICATIONS

The indications for surgery are listed in Table 12.1. For patients whose AHI is less than 20, surgical treatments may still be an option. Surgery is considered appropriate if these patients have associated EDS which results in impaired cognition or comorbidities as recognized by the Center for Medicare and Medicaid Services (including hypertension, stroke and ischemic heart disease). Consideration may be given to obtaining a multiple sleep latency test (MSLT) or the maintenance of wakefulness test (MWT) to determine other etiologies of EDS for those patients whose symptoms are not obviated with CPAP therapy or for those whose symptoms of fatigue seem out of proportion to the severity of their apnea. In this subgroup of patients, surgery is unlikely to be beneficial. Other factors exist which could predict poor surgical outcomes and consequently render a patient to be an unsuitable candidate for surgery.11 These factors are detailed in Table 12.2.

Table 12.1 Surgical indications

*Surgery may be indicated with an AHI <20 if accompanied by excessive daytime fatigue.

From Powell NB, Riley RW, Guilleminault C. Surgical management of sleep-disordered breathing. In: Kryger MH, Roth T, Dement WC, eds. Principles and Practices of Sleep Medicine, 4th edn. Philadelphia: Elsevier Saunders; 2005, pp. 1081–97.

Table 12.2 Contraindications for surgery

From Powell NB, Riley RW, Guilleminault C. Surgical management of sleep-disordered breathing. In: Kryger MH, Roth T, Dement WC, eds. Principles and Practices of Sleep Medicine, 4th edn. Philadelphia: Elsevier Saunders; 2005, pp. 1081–97.

4 PATIENT SELECTION

Proper screening and selection of patients for surgery is vital to achieve successful outcomes and to minimize postoperative complications. Because daytime fatigue has numerous etiologies, such as periodic limb movement disorder and narcolepsy, a complete sleep history must be obtained. Furthermore, the preoperative evaluation requires a comprehensive medical history, head and neck examination, polysomnography (PSG), fiberoptic nasopharyngolaryngo-scopy and lateral cephalometric analysis. A thorough review of these data will identify probable sites of obstruction and direct a safe, organized surgical protocol.11

A complete physical exam with vital signs, weight and neck circumference should be performed on every patient. Specific attention is focused in the regions of the head and neck that have been well described as potential sites of upper airway obstruction, such as the nose, palate and base of tongue. Nasal obstruction, which can occur as a result of septal deviation, turbinate hypertrophy, alar collapse orsinonasal masses, can be identified on anterior rhino-scopy. The oral cavity should be examined for periodontal disease and dental occlusion. Examination of the oropharyngeal and hypopharyngeal regions includes a description of the palate, lateral pharyngeal walls, tonsils and tongue base. Mallampati and Friedman have proposed standardized grading systems to describe the degree of obstruction caused by these structures.12,13

Fiberoptic examination is used to identify obstruction of the nasopharynx, oropharynx and hypopharynx, as well as any laryngeal abnormalities. The airway is examined at rest and during provocative maneuvers. One such technique, Mueller’s maneuver, exposes the upper airway to negative intraluminal pressure in an attempt to identify anatomical regions of obstruction. Fiberoptic examination is not only important to evaluate the upper airway for obstruction, but aids in determining ease of intubation. Furthermore, photodocumentation of the airway findings may be a useful tool in patient education.

The lateral cephalogram allows measurement of the length of the soft palate, posterior airway space, hyoid position and skeletal proportions. It is the most cost-effective radiographic study of the bony facial skeleton and soft tissues of the upper airway. Studies have shown the cephalogram to be valid in assessing obstruction, and in fact, it compares favorably to three-dimensional volumetric computed tomographic scans of the upper airway.14 Since the cephalogram is not performed while the patient is sleeping, the degree of obstruction may be underestimated. Therefore, the results of this imaging test should be correlated with the fiberoptic examination.

The polysomnogram (PSG) is critical in the evaluation of a patient with OSAS. No patient should undergo airway surgery without this study. An attended, full-night PSG is considered the gold standard. Surgeons should pay particular attention to the AHI and the oxygen desaturation nadir. These data will guide appropriate surgical treatment, as well as preoperative and postoperative management. Patients must be counseled about the need for a postoperative PSG to assess their response to surgery. A patient may be inadequately treated if this study in not obtained.

Proper patient selection requires the surgeon to determine if a patient is medically stable for surgery. We recommend obtaining a comprehensive metabolic panel, complete blood count, thyroid stimulating hormone, electrocardiogram and chest x-ray on all patients. Additional testing or consultation with the appropriate medical specialist should be sought in patients with comorbid medical conditions.

Preoperative CPAP can alleviate the issues associated with sleep deprivation and may reduce the risk of postobstructive pulmonary edema. Consequently, all patients who are tolerant of CPAP are encouraged to use this modality for at least 2 weeks prior to surgery. In 1988, Powell et al. recommended the use of preoperative CPAP for all patients who have a Respiratory Disturbance Index (RDI) greater than 40 and an oxygen desaturation of 80% or less. According to this protocol, the surgeon must consider insertion of a temporary tracheotomy for those patients with a RDI greater than 60 and/or a SaO2 less than 70% who are intolerant of CPAP therapy.15

Prior to surgical intervention, all medical and surgical options should be reviewed with the patient. A discussion regarding the potential risks, benefits and likelihood of success should occur. Only after the patient fully comprehends the process and has consented to surgery can the treatment plan proceed.

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Jul 24, 2016 | Posted by in General Dentistry | Comments Off on Rationale and indications for surgical treatment
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