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Diagnostic and Surgical Advances in Obstructive Sleep Apnea
From: ENT Today, January 2007
by Alice Goodman
Sleep disorders pervade all levels of our society, affecting people of all ages, races, and socioeconomic levels. Up to 70 million Americans are estimated to have chronic disorders of sleep and wakefulness. Obstructive sleep apnea is the second most common sleep disorder after insomnia, affecting approximately 20 million Americans. Since the prevalence of sleep apnea increases with age, the graying of America over the next decade could dramatically escalate the cost of diagnosing and treating this disorder by the year 2010, according to a 2006 report by the Institute of Medicine. ENToday spoke with experts who treat obstructive sleep apnea about the latest advances in management and potential new approaches in the future.
According to Peter Catalano, MD, who is Chairman of the Department of Otolaryngology at the Lahey Clinic in Burlington, Mass., and Associate Professor of Otolaryngology at Boston University, testing is going to become an area of active investigation. The polysomnogram (PSG) is the most widely used test for the degree of sleep apnea and other sleep disturbances, but this test has several limitations. Mainly, it lacks test-to-test reproducibility and it does not provide enough information to manage patients appropriately. The reliability of PSG depends on the experience and expertise of the technician, which is another variable, he added. Also, patients may be tested at more than one sleep laboratory, which further compromises reproducibility.
The test itself is uncomfortable and adversely affects sleep quality. Patients are vulnerable when they undergo PSG testing, because the test is done at night and sleeping is usually a private experience. Patients are usually awakened if they have apnea and a mask is strapped to their faces and they are told to go back to sleep. But they really have trouble going back to sleep and are frightened to move with equipment strapped to their faces, Dr. Catalano said.
Without question, PSG is a very fickle test that doesn't always capture the true metrics. PSG does not identify sites of obstruction or which site is most critical, Dr. Catalano continued.
Site(s) of Obstruction
Three potential sites can be involved in obstructive sleep apnea: the nasal, palatal, and oropharyngeal sites. Apnea always involves the oropharyngeal site, but can also involve either the nasal or palatal sites-or all three sites. There may be a domino effect, Dr. Catalano explained, where obstructions in the first two sites affect the third site; or all three sites could be dominant in a given patient with obstructive sleep apnea.
The site of obstruction is critical for selecting an intervention. Use of CPAP or BIPAP with nasal prongs would be appropriate for someone with less severe nasal obstruction, he explained.
Identifying the site of obstruction in patients with sleep apnea is currently based on a thorough physical exam by an otolaryngologist. At the Lahey Clinic, CT scan of the sinuses is also performed, because we feel that many patients have a major nasal component to their sleep apnea, Dr. Catalano said.
The goal of intervention in obstructive sleep apnea is to restore normal physiology. Uvulopalatopharyngoplasty (UPPP) is an aggressive operation with high morbidity and suboptimal success rates, in Dr. Catalano's view, and some patients cannot be cured with UPPP or any other surgical interventions. Therefore, the goal is not always cure but to restore a more physiologic CPAP pressure-for example, reducing CPAP pressure from 18, 16, or 14 to between 5 and 7, Dr. Catalano said.
A Better 'Mousetrap'?
The ideal test for obstructive sleep apnea would identify the severity of the disorder and the sites of obstruction, and would be highly reproducible. Otolaryngologists in Europe have used an instrument that promises to be an improvement over PSG. Called an apneagraph, this instrument attempts to provide information on the degree of sleep apnea and identify the sites of obstruction by using a small pressure sensor places in the nose and going down the throat.
The European doctors I've spoken to say that this device is well tolerated and better tolerated than PSG. Also, reportedly, the test-to-test reliability is much greater, Dr. Catalano said. He noted that the apneagraph is a tool in development and said that probably more modifications will evolve. Even if we added it as a component of PSG, it could provide additive information, he said. He is currently trying to obtain an apneagraph from his European colleagues so that he can study it.
One of the biggest impediments in using PSG is that patients hate it and refuse to follow through on serial testing. In one multisite study reported at the recent AAO meeting, 50 percent of patients failed to complete post-treatment PSG testing, he said.
Drug-Induced Sleep Endoscopy
Preliminary research suggests that drug-induced sleep endoscopy (DISE) may be a useful diagnostic tool to guide surgical therapy and to understand why patents do not achieve desired outcomes after undergoing surgery, said Eric J. Kezirian, MD, Director of the Division of Sleep Surgery and Assistant Professor at University of California, San Francisco.
The procedure, first described in 1991, involves sedating patients and passing a fiberoptic telescope through the nose to identify sites of obstruction in the airway, with the premise that appropriate surgery directed to those areas can improve sleep apnea, Dr. Kezirian said.
Some patients with primarily palatal obstruction are greatly improved after palate surgery and tonsillectomy. But many patients have multiple sites of obstruction, and palate surgery alone is less successful in these patients, he said. DISE is designed to identify which procedures may provide the most benefit for individual patients.
Dr. Kezirian and his colleagues are systematically studying DISE to determine if is a reliable test, whether it provides useful information to direct surgical treatment, and whether DISE findings are associated with surgical outcomes. At the 2006 annual meeting of the American Association of Otolaryngology-Head and Neck Surgery (AAO-HNS), he presented a study of 50 patients without previous sleep apnea surgery, and his results showed that DISE findings were not closely related to those of other evaluation techniques, including the Friedman Stage, awake fiberoscopic endoscopy with Müller maneuver, and the lateral cephalogram.
This study was a first step in showing that DISE provides different information compared with other techniques. The next step is to determine whether the information is useful, Dr. Kezirian said. This preliminary work may determine whether DISE should be part of routine surgical evaluation, but instead it may be that the main role for DISE is for patients who do not have ideal results with surgery.
Another active area of research is the use of MRI and CT scans in planning surgery. Different groups around the country are studying whether this will turn out to be useful.
Major Shift in Thinking
One of the most important advances in the field of obstructive sleep apnea is the recognition that it is often a multilevel disease, even in patients with mild sleep apnea, explained Michael Friedman, MD, Professor of Otolaryngology and Chairman of the Section of Head and Neck Surgery at Rush University Medical Center and Chairman of Otolaryngology at Advocate Illinois Masonic Medical Center in Chicago.
New thinking about this disorder is that patients with mild to moderate obstructive sleep apnea can be helped with a multilevel, minimally invasive approach that treats the areas responsible for obstruction. The nose, palate, and tongue base can all be treated with minimally invasive surgery, he said.
Basic criteria for minimally invasive procedures include mild to moderate obstructive sleep apnea and anatomy that is easily correctable, Dr. Friedman said. We don't use these procedures on patients with severe apnea. The choice of technique depends on the level of obstruction. The palate is easy to treat, the tongue base is a little more difficult, and if tonsils are blocking the airway, they need to be removed, he said.
Dr. Friedman pointed out that classic thinking was that only patients with mild sleep apnea could be helped. Now we know that if you choose the right technique for the individual patient depending on the sites of obstruction, you can help patients with mild and moderate sleep apnea using minimally invasive surgery, he stated.
In my experience, 75 percent of patients have some involvement of the palate and tongue base, and these include patients with mild and moderate sleep apnea. In these patients, I combine minimally invasive techniques to reduce the tongue base and to stiffen the palate, Dr. Friedman said.
The Pillar implant is Dr. Friedman's technique of choice for palatal obstruction. At the recent AAO-HNS meeting, he presented results of a randomized, double-blind study in 55 consecutive adults with a history of snoring, daytime sleepiness, and mild to moderate sleep apnea comparing the Pillar implant to a sham procedure. Objective cure rate was higher with the Pillar procedure (37.9% vs 0%), subjective improvement in symptoms was greater (62.1% vs 0%, respectively), and quality of life was improved compared with the control arm. This study provided level 1 evidence favoring the Pillar procedure for improvement of sleep apnea, quality of life, snoring intensity, and daytime sleepiness.
Dr. Friedman commented that at least eight studies to date have shown good outcomes with the Pillar implant at six months, and a recent study suggests that good results are maintained for at least one year.
Dr. Catalano agreed that the Pillar implant is an excellent procedure, with the caveat that that its success depends on appropriate patient selection. He said that success rates with the Pillar implant range from 70% to 75% in patients who are treated for snoring alone and for mild to moderate sleep apnea (respiratory disturbance index [RDI] ≤30).
FDA approval states that up to three Pillar implants can be used to treat snoring and obstructive sleep apnea. Every patient's anatomy is different. We are not always hitting the threshold with three implants, he said.
At the recent AAO-HNS meeting, Dr. Catalano presented a study showing that patients with refractory snoring who failed on three Pillar implants were successfully treated with up to five implants. The study included 31 patients; of these, 26 were considered cured and five remained failures. There is no FDA indication for more than three implants yet, he said.
A multicenter prospective study with an investigational device exemption (IDE) has been approved by the FDA to look at the benefit of additional Pillar implants in 50 patients who are snorers without obstructive sleep apnea. After this study is completed, Dr. Catalano and colleagues plan to apply for another IDE study in patients with obstructive sleep apnea.
Patients with sleep apnea often have obstruction at several sites, and surgical procedures used in combination to address the involved sites may provide improved outcomes.
The safety and efficacy of combining Pillar implants with nasal surgery was assessed in a preliminary study reported by Dr. Catalano at the AAO meeting. The study enrolled 11 patients with nasal and palatal obstruction who were treated with combined nasal and Pillar surgery. Six patients were cured, and of the remaining five patients, only two had mild elevations of obstructive sleep apnea.
If those five patients received additional Pillar implants, they might have gotten better, Dr. Catalano said. He noted that concern has been raised that nasal surgery may make some patients worse. In his experience using nasal surgery alone, 50% of 15 patients had cured apnea and only 15% had worsened apnea.
In summary, he said, The potential for the Pillar implant is just beginning to be explored. We are now learning how to use them.
The tongue base, Dr. Friedman said, can be reduced using a new technique called submucosal glossectomy. This procedure, still under development, entails a tiny incision and a radiofrequency device that utilizes cool energy to disrupt the tissue at the tongue base and aspirate out the debris. Thus far, Dr. Friedman has treated more than 50 patients with the glossectomy and says it is a bloodless procedure with minimal pain that should be widely applicable for patients with obstructive sleep apnea.
A larger study of about 90 patients will be initiated to compare the Pillar procedure with submucosal glossectomy and with the combination of both procedures. Although glossectomy can be an outpatient procedure, for the time being, Dr. Friedman admits patients for an overnight stay in the hospital.
Safety is the most important consideration. We need wider experience to assess the risk of complications, Dr. Friedman said. If additional studies support preliminary findings, this procedure will improve treatment results dramatically, he added.
Another tongue-based procedure under development is suspension of tongue tissue with sutures, called tongue-based suspension. Several companies are studying modifications of this procedure, developed originally by Influent. These promising techniques are under FDA review, Dr. Friedman noted.
Outpatient or Inpatient Procedure?
Opinions on UPPP vary, with some physicians considering it a high-risk procedure and others who think it is safe if patients are appropriately selected. General anesthesia is required for UPPP, and the anesthesiology literature advocates performing the procedure in an inpatient setting with an overnight stay for subsequent monitoring, while the ENT literature suggests the procedure is safe with a low incidence of complications.
A study presented at the AAO-HNS meeting found that UPPP could be safely performed in an outpatient setting, freeing up hospital beds for longer more complicated procedures and reducing resource use. Forty consecutive patients with moderate to severe obstructive sleep apnea and median RDI of 40 underwent UPPP and 80% had tonsillectomy at the same time, said senior author of the study Marilene Wang, MD, who is Professor of the Division of Head and Neck Surgery at the David Geffen School Medicine at UCLA in Los Angeles. All patients were adults, up to 77 years old, and median body mass index was 27.1. Dr. Wang performed all the surgeries. Thirty-six patients did very well as outpatients. One patient was already an inpatient, hospitalized for other comorbidities related to obesity. Only three patients were admitted to the hospital overnight, and these were mainly for social reasons, such as not having a ride home or wanting a full night's sleep undisturbed by young children, Dr. Wang said. No postoperative complications occurred in any of these patients-specifically, no bleeding, postoperative pulmonary edema, or respiratory difficulties.
Complications may occur with aggressive procedures. Dr. Wang explained that she favors a conservative technique, removing the tonsils and the uvula, and then placing sutures on the uvula and lateral walls. Scar tissue and fibrosis around the sutures mitigates the obstruction.
Dr. Wang emphasized that comorbidities are an important consideration in selecting patients for UPPP, as well as for inpatient or outpatient hospital stay. Morbid obesity, cardiac problems, and respiratory illness are contraindications to UPPP. Patients with these conditions are probably best treated with CPAP, she said. She believes that the decision about whether to hospitalize patients undergoing UPPP should be made jointly by the anesthesiologist and surgeon on a case-by-case basis.
We [surgeons] would like to make that judgment ourselves, but often we are not given that option. The vast majority of patients with obstructive sleep apnea can have UPPP on an outpatient basis, she said.
©2007 The Triological Society