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Background
Airway obstruction during sleep is a commonly recognized problem, which may be associated with significant morbidity. Various diagnostic studies and treatment approaches are employed in managing this condition.
Data from the history and physical examination have been shown to be sensitive but not specific for diagnosing OSA. According to available guidelines (ICSI, 2006), the following signs and symptoms may suggest significant risk for OSA: reported apneas by sleep partner; awakening with choking; intense snoring; severe daytime sleepiness, especially with impairment of driving; male gender and postmenopausal females; obesity (BMI greater than or equal to 30); large neck circumference; and hypertension.
Diagnostic tests for OSA can be classified into 4 types. The most comprehensive type is Type I: attended, or in-facility polysomnography (PSG). There are 3 categories of portable monitors (used in both attended and unattended settings). Type II monitors have a minimum of 7 channels (e.g., electroencephalogram (EEG), electrooculogram (EOG), electromyogram (EMG), electrocardiogram (ECG), heart rate, airflow, respiratory effort, oxygen saturation). Type III monitors have a minimum of 4 monitored channels including ventilation or airflow (at least 2 channels of respiratory movement or respiratory movement and airflow), heart rate or ECG, and oxygen saturation. Type IV devices measures 1 or 2 parameters (e.g., oxygen saturation or airflow).
While there is no "gold standard" for the diagnosis of OSA in adults, NPSG performed in a sleep laboratory (Type I) has become the definitive diagnostic tool of choice to confirm the presence and severity of upper airway obstruction. According to the available literature, a minimum 6-hour NPSG is preferred, which allows for the assessment of variability related to sleep stage and position with respect to the frequency of obstructive respiratory events and the occurrence of other types of nocturnal events such as periodic limb movements.
According to the available literature, NPSG performed in a sleep laboratory should include EEG, EOG, EMG, oronasal airflow, chest wall effort, body position, snore microphone, ECG, and oxyhemoglobin saturation. However, diagnostic NPSG may be performed in a healthcare facility, or for appropriate cases, in the patient's home. Based on limited data, the use of unattended home sleep monitoring using a Type II, III, or IV device, may identify AHI suggestive of OSAHS. A technology assessment by the Agency for Healthcare Research and Quality (AHRQ) on Home Diagnosis of Obstructive Sleep Apnea-Hypopnea Syndrome (2007) commissioned by the Centers for Medicare & Medicaid Services (CMS), reported the following: Type II monitors identify AHI suggestive of obstructive sleep apnea-hypopnea syndrome (OSAHA) with high positive ratios (greater than 10) and low negative likelihood ratios (less than 0.1) both when the portable monitors were studied in the sleep laboratory and at home. Type III monitors may have the ability to predict AHI suggestive of OSAHA with high positive likelihood ratios and low negative likelihood ratios for various AHI cutoffs in laboratory-based PSG, especially when manual scoring is used. The ability of type III monitors to predict AHI suggestive of OSAHS appears to be better in studies conducted in sleep laboratories compared to studies in the home setting. Some studies of type IV devices also showed high positive likelihood ratios and low negative likelihood ratios, at least for selected sensitivity and specificity pairs from ROC curve analyses. Similarly to type III devices, the ability of type IV devices to predict AHI suggestive of OSAHS appears to be better in studies conducted in sleep laboratories.
According to the American Sleep Disorders Association (ASDA) (1997 ), split-night study NPSG is indicated for patients with an AHI > 40 events per hour during the first 2 hours of a diagnostic NPSG. Split-night studies may also be considered for patients with an AHI of 20 to 40 events per hour, based on clinical observations, such as the occurrence of obstructive respiratory events with a prolonged duration or in association with severe oxygen desaturation. Split-night studies require the recording and analysis of the same parameters as a standard diagnostic NPSG. Accepted guidelines provide that the diagnostic portion of a split-night study should be at least 2 hours duration. A minimum of 3 hours sleep is preferred to adequately titrate CPAP after this treatment is initiated.
On a subsequent night following a standard diagnostic NPSG, the available literature indicates that OSA patients should receive CPAP titration to specify the lowest CPAP level, which abolishes obstructive apneas, hypopneas, respiratory-effort related arousals, and snoring in all sleep positions and sleep stages. On occasion, an additional full-night CPAP titration NPSG may also be required following split-night study if the split-night NPSG did not allow for the abolishment of the vast majority of obstructive respiratory events or prescribed CPAP treatment does not control clinical symptoms.
According to guidelines from the American Academy of Sleep Medicine (Chesson, et al., 1997), polysomnography with video recording and additional EEG channels in an extended bilateral montage may be indicated to assist with the diagnosis of paroxysmal arousals or other sleep disruptions that are thought to be seizure related when the initial clinical evaluation and results of a standard EEG are inconclusive.
Accepted guidelines indicate that nocturnal pulse oximetry alone is not appropriately used as a case finding or screening method to rule out OSA. Pulse oximetry, when used alone, has not been show to have an adequate negative predictive value to rule out OSA (i.e., all patients with symptoms suggestive of OSA would require polysomnography regardless of whether the pulse oximetry was positive or negative).
The MESAM and the static charge sensitive bed have not been proven to be valid devices for screening or diagnosing OSA. Actigraphy has not been validated as a method of screening or diagnosing OSA although it may be a useful adjunct to other procedures in the evaluation of sleep disorders.
According to available literature, overnight polysomnography has become the definitive diagnostic tool of choice to confirm the presence and severity of the upper airway obstruction in children. OSA is increasingly recognized in the pediatric population. It is characterized by a combination of partial upper airway obstruction and intermittent obstructive apnea that disrupts normal ventilation and sleep. Common symptoms include habitual snoring, difficult breathing during sleep, restlessness, and witnessed apnea. Adenotonsillar hypertrophy is the most common associated condition in otherwise normal children, but craniofacial abnormalities, neuromuscular diseases, and obesity are also predisposing factors. The history and physical examination has been shown to be sensitive but not specific for diagnosing OSAS in children. Treatment depends on the severity of symptoms and the underlying anatomic and physiologic abnormalities. Childhood OSAS is usually associated with adenotonsillar hypertrophy, and the available medical literature suggests that the majority of cases are amenable to and will benefit from tonsillectomy and adenoidectomy. Corrective surgery is possible for rare malformation syndromes. Nocturnal masks for continuous positive airway nasal pressure or procedures for mask respiration are effective in children, but are only used in exceptional cases, such as when adenotonsillectomy is contraindicated or when symptoms of OSAS remain after surgery. The success of pharmacological treatment of OSAS in children has not been evaluated in controlled clinical trials (Erler and Paditz, 2004).
Although the cephalometric x-ray is not necessary for the diagnosis of OSA, it is necessary for certain non-surgical and surgical treatments. A lateral cephalometric x-ray is very helpful if an anterior mandibular osteotomy is being performed for genioglossus advancement, or if maxillomandibular surgery is being planned for surgical correction of OSA. It is also helpful in analyzing hyoid position, posterior airway space, and other cephalometric parameters used in the treatment of OSA. For sleep apnea appliances for obstructive sleep apnea, a pre-treatment lateral cephalometric x-ray and a second cephalometric X-ray with the bite registration or appliance in place may be necessary to visualize the mandibular repositioning and the changes in the airway space.
D'Andrea (2004) stated that sleep-disordered breathing (SDB) is a common condition in children that can have serious complications if left undiagnosed and untreated. Obstructive sleep apnea is the most commonly recognized form of SDB in children. Medical history and physical examination have limitations in their capacity to determine which children have SDB. Abbreviated or screening techniques, such as audio- or video-taping, oximetry studies, nap studies, or home studies, tend to be helpful if the results are positive but have a poor predictive value if the results are negative. Overnight polysomnography is the gold standard for the diagnosis of SDB in children. It is important that children are studied in laboratories that have expertise with children. This is in agreement with the findings of Nixon and Brouillette (2002) who stated that the comprehensive evaluation of children who present with symptoms suggestive of OSA involves the overnight recording and assessment of both sleep and respiration by polysomnography in a sleep laboratory as well as that by the American Academy of Pediatrics (2002), which stated that “history and physical examination are poor at predicting OSAS. Most studies have shown that abbreviated or screening techniques, such as videotaping, nocturnal pulse oximetry, and daytime nap polysomnography tend to be helpful if results are positive but have a poor predictive value if results are negative….The cost efficacy of these screening techniques is unclear and would depend, in part, on how many patients eventually required full polysomnography. In addition, the use of these techniques in evaluating the severity of OSAS (which is important in determining management, such as whether outpatient surgery should be performed) has not been evaluated”.
Uvulopalatopharyngoplasty, jaw realignment surgery, positive airway pressure devices (e.g., CPAP, BiPAP, etc.), tracheostomy, tonsillectomy and adenoidectomy, and orthodontic devices such as the tongue retaining device, may be effective treatments for properly selected patients with obstructive sleep apnea.
The Food and Drug Administration (FDA) has cleared numerous types of CPAP devices under the 510(k) process. These include but are not limited to many devices that allow a patient to wear a device that collects airflow and other patient measurements into a device that records data, while treating OSA with that device. The patient then takes the device to the physician and the physician downloads information that determines whether the patient has apnea sleep-related breathing disorder including OSA or needs further sleep studies or assessment. There are currently many sleep assessment devices on the market cleared by the FDA through the 510(k) process for use in the home.
A variety of oral appliances and prostheses, including tongue retainers and mandibular advancing devices, have been used to treat patients with OSA. These devices modify the airway by changing the posture of the mandible and tongue. A task force of the Standards of Practice Committee of the ASDA concluded that, despite the considerable variation in the design of these devices, their clinical effects in improving OSA have been consistent.
These devices have been shown to be effective in alleviating OSA, and present a useful alternative to CPAP or surgery. Oral appliances, however, have been shown to be less reliable and effective than CPAP, and therefore the literature suggests that their use should be reserved for patients who are intolerant of CPAP.
Patients with OSA suffer from numerous apneic events while sleeping, due to collapse of the upper airway during inspiration. Continuous positive airway pressure, and more recently, BiPAP, DPAP, VPAP, and AutoPAP, have been used in the treatment of OSA as a means of serving as a "pneumatic splint" in order to prop open the airways during inspiration.
Bilevel positive airway pressure, DPAP, VPAP, and AutoPAP have been shown to be effective alternatives to CPAP, but are indicated only as second line measures for patients who are intolerant to CPAP. These alternatives to CPAP may also be indicated for OSA patients with concomitant breathing disorders to include restrictive thoracic disorders, COPD, and nocturnal hypoventilation. Long term adherence to CPAP therapy was initially reported to range from 65-80% (Nino-Murcia, et al., 1989; Waldhorn, et al., 1990; Rolfe, et al., 1991; Hoffstein, et al., 1992) with 8-15% of patients refusing to accept treatment (Waldhorn, 1990; Krieger, 1992) after a single night's use. Other studies have evaluated compliance as regular CPAP use. More recent studies have shown up to 80% of patients falling into the category of regular users (Pepin, et al., 1999).
OPAP® (Oral Pressure Appliance) is a custom fabricated intra-oral device that is used with a positive airway pressure device (e.g., CPAP, BiPAP, etc.) in place of a standard nasal mask. The oral pressure appliance positions the lower jaw forward to maximize the forward movement of the tongue and soft tissues of the back of the throat. In addition, the device has a chamber that, according to the manufacturer, allows air flow and pressure to be delivered into the back of the throat and thereby "splint" the soft tissues of the upper airway and prevent their collapse during sleep. The oral pressure appliance is custom fitted by a dentist specializing in dental appliances for sleep disorders. The OPAP method of treatment is similar to nasal mask delivery of air pressure with CPAP or BiPAP. The oral pressure appliance is connected to the end of the hose coming from the CPAP or BiPAP, and the pressure is adjusted in the same way as through the nose. OPAP differs from nasal masks in that it does not require head gear to hold it in place. It is inserted into the mouth and held in place by the upper and lower teeth. At present, no studies of OPAP have been published in peer-reviewed medical journals. Therefore, one is unable to draw any conclusions about the effectiveness of OPAP compared to a standard nasal mask in treatment of patients with obstructive sleep apnea.
In contrast to fixed CPAP, flexible positive airway pressure (C-Flex, Respironics, Murraysville, PA) (also known as pressure-relief CPAP) is characterized by a pressure reduction at the beginning of expiration. Flexible positive airway pressure is intended to improve patient satisfaction and compliance over standard CPAP. To compare adherence and clinical outcomes between flexible positive airway pressure CPAP, Aloia, et al. (2005) conducted a nonrandomized, open-label controlled trial of CPAP therapy versus therapy using the C-Flex device in persons with moderate-to-severe obstructive sleep apnea. Study participants received either therapy with CPAP (n = 41) or with the C-Flex device (n = 48), depending on the available treatment at the time of recruitment, with those recruited earlier receiving CPAP therapy and those recruited later receiving therapy with the C-Flex device. The mean (+/- SD) treatment adherence over the 3-month follow-up period was higher in the C-Flex group compared to the CPAP group (weeks 2 to 4, 4.2 +/- 2.4 versus 3.5 +/- 2.8, respectively; weeks 9 to 12, 4.8 +/- 2.4 versus 3.1 +/- 2.8, respectively). The investigators reported that change in subjective sleepiness and functional outcomes associated with sleep did not improve more in one group over the other. Self-efficacy showed a trend toward being higher at the follow-up in those patients who had been treated with the C-Flex device compared to CPAP treatment. The investigators concluded that therapy with the C-Flex device may improve overall adherence over 3 months compared to standard therapy with CPAP. The investigators stated that clinical outcomes do not improve consistently, but C-Flex users may be more confident about their ability to adhere to treatment. The investigators concluded that randomized clinical trials are needed to replicate these findings.
A study by Nilius, et al. (2006) found no significant differences between C-Flex and CPAP in effectiveness and compliance. During the first night of treatment, patients receiving C-Flex had less dryness of the mouth, but this difference disappeared over a period of 7 weeks. The investigators conducted a study to compare polysomnographic data and compliance in sleep apnea patients receiving continuous positive airway pressure (CPAP) and C-Flex. Fifty-two persons newly diagnosed with obstructive sleep apnea apnea underwent conventional CPAP titration. Thereafter, polysomnography was performed at the titrated pressure using both the fixed CPAP pressure mode and the C-Flex mode in a randomized crossover approach. The patients were then discharged home for 7 weeks of treatment with the last-applied treatment mode, and compliance data were established at the end of that time. The average apnea-hypopnea index (AHI) was 5.8 per hour with CPAP, and 7.0 per hour with C-Flex. The investigators reported that compliance after 7 weeks was, on average, 9.4 min longer with C-Flex than with CPAP, a difference that was not statistically significant. Evaluation of a 13-item questionnaire (the fewer the complaints, the lower the score) showed no significant difference between scores for C-Flex (16.4) and CPAP (18.1). With regard to oral dryness, the score with C-Flex (1.4) was significantly lower than with CPAP (1.9) (p < 0.05). The investigators reported that this difference in oral dryness score was
no longer detectable after 7 weeks. The investigators concluded that further studies are needed.
Jaw realignment is an aggressive, multi-step procedure requiring a three to six month interval between each step. According to the medical literature, jaw realignment surgery is generally reserved for those patients who fail other treatment approaches for OSA. An NIH Statement (1995) and American Sleep Disorders Association Guidelines (1996) state that jaw realignment surgery is a promising treatment for obstructive sleep apnea. A systematic review of the evidence prepared for the American Sleep Disorders Association by Scher, et al. (1996), concluded that inferior sagittal mandibular osteotomy and genioglossal advancement with or without hyoid myotomy and suspension appears to be the most promising of procedures directed at enlarging the retrolingual region. The ASDA assessment stated that most of the experience with genioglossal advancement with or without hyoid suspension has been in conjunction with or following UPPP. Jaw fixation is necessary for two to three weeks following surgery, and a soft diet is necessary for a total of six weeks. Patients undergoing jaw realignment surgery must usually also undergo orthodontic therapy to correct changes in occlusion associated with the surgery. Jaw realignment surgery is generally reserved for those patients who fail other treatment approaches for OSA. According to the medical literature, patients undergoing jaw realignment surgery must usually also undergo orthodontic therapy to correct changes in occlusion associated with the surgery.
Tracheostomy, which simply bypasses the obstructing lesion of the upper airways, has been shown to be the most effective and predictable surgical approach to OSA. However, the social and medical morbidities of a permanent tracheostomy and the advent of surgical alternatives have made tracheostomy an unpopular solution to OSA, reserved for those patients with the most severe sleep apnea not manageable by other interventions.
Laser-assisted uvulopalatoplasty (LAUP) is an outpatient surgical procedure, which has been used as a treatment for snoring. LAUP has also been used as a treatment for sleep-related breathing disorders, including obstructive sleep apnea. The American Academy of Sleep Medicine Standards of Practice Committee reviewed the evidence supporting the use of LAUP in obstructive sleep apnea, and found that adequate controlled studies on the LAUP procedure for sleep-related breathing disorders were not found in the peer-reviewed literature (Littner, et al., 2001). The AASM concluded that "LAUP is not recommended for treatment of sleep-related breathing disorders."
There is some evidence for the use of uvulectomy or uvuloplasty as a treatment for snoring, but Aetna does not consider treatment of snoring medically necessary because snoring, in itself, is not associated with functional limitations. Most of the published literature on uvulectomy have to do with ritual removal of the uvula at birth in Africa, a practice that is associated with significant complications. Uvulectomy is also performed, again primarily in Africa, as a treatment for recurrent throat infections. However, there is no reliable evidence to support this practice. Acute edema of the uvula causing respiratory distress is an accepted indication for uvulectomy. Hawke and Kwok (1987) reported on uvulectomy in treating a patient with acute inflammatory edema of the uvula (uvulitis) associated with asphyxiation. Waeckerle, et al. (1976) reported on uvulectomy for hereditary angioneurotic edema. There is no evidence to support the use of uvulectomy as a treatment for gagging. Dawodu (2007) reported that gagging may occur as a complication of uvulectomy.
Radiofrequency ablation may be used to reduce and tighten excess tissues of the soft palate, uvula and tongue base (Somnoplasty) or nasal passages and soft palate (Coblation or Coblation channeling). These procedures are performed in an outpatient setting under local anesthesia. Current literature does not support their efficacy and applicability for OSA. Most published studies have been nonrandomized and have enrolled highly selected patients. These studies also fail to report long-term outcomes or recurrence rates. Woodson, et al. (2003) reported on the results of radiofrequency ablation of the turbinates and soft palate in patients with mild to moderate obstructive sleep apnea (AHI of 10 to 30 on screening sleep study). Ninety subjects were randomly assigned to radiofrequency ablation, CPAP, or sham-placebo. Subjects assigned to radiofrequency ablation had a moderate decrease in AHI that did not reach statistical significance. The AHI of subjects assigned to radiofrequency ablation decreased by an average of 4.5 events per hour, whereas the AHI of subjects assigned to sham-placebo decreased by an average of 1.8 events per hour, a difference that did not achieve statistical significance. However, compared with sham-placebo, subjects assigned to radiofrequency ablation reported statistically significant improvements in quality of life, airway volume, apnea index and respiratory arousal index. In addition to the modest impact of radiofrequency ablation on AHI, this study has a number of other important limitations. First, it is a relatively small study, and improvements were not consistently seen among each of the measured parameters. Second, a significant number of subjects were lost to follow up, and data were incomplete on a quarter of study subjects. Third, the study does not report on long-term clinical outcomes or recurrence rates. Fourth, although this study did not involve a direct comparison with UPPP, which is the current surgical standard treatment for obstructive sleep apnea, studies of UPPP have reported much more substantial improvements in AHI, AI and other relevant parameters. Finally, this study involved a single investigator group and is the only published randomized clinical study of radiofrequency ablation for obstructive sleep apnea; this study needs to be replicated by other investigators and in larger numbers of subjects.
A recent study (Garrigue, et al., 2002) reported on the results of an uncontrolled case series examining the impact of atrial overdrive pacing in 15 patients with central or obstructive sleep apnea syndrome who had received permanent atrial-synchronous ventricular pacemakers for symptomatic sinus bradycardia . With atrial overdrive pacing, achieved by increasing the atrial base rate, patients had a significantly reduced the number of episodes of central or obstructive sleep apnea (from an average AHI of 28 with spontaneous rhythm to an average AHI of 11 with atrial overdrive pacing) without a significant reduction in total sleep time. The authors, however, concluded that further studies are needed to elucidate the mechanisms involved in achieving these reductions and to assess the precise role of cardiac pacing in preventing symptoms, disability, and death in patients with sleep apnea syndrome. In a randomized controlled trial, Luthje, et al. (2005) aimed to reproduce the finding of a recent study that atrial overdrive pacing markedly improved SDB. These investigators found that neither the primary endpoint AHI, nor the apnea index, oxygen desaturation, ventilation, biomarkers were affected by the nocturnal atrial overdrive pacing. They concluded that the lack of effect on the AHI means that atrial overdrive pacing is inappropriate for treating SDB. This is in agreement with the findings of a randomized controlled study by Pepin, et al. (2005) who reported that atrial overdrive pacing has no significant effect on OSA.
In a randomized controlled study, Simantirakis et al (2005) reported that atrial over-drive pacing had no significant effect in treating OSA-hypopnea syndrome. In another randomized controlled study Krahn et al (2006) evaluated the impact of prevention of bradycardia with physiologic pacing on the severity of OSA. The authors concluded that temporary atrial pacing does not appear to improve respiratory manifestations of OSA, and that permanent atrial pacing in this patient population does not appear to be justified.
Upper airway resistance syndrome (UARS) is characterized by a normal apnea-hypopnea index, but with sleep fragmentation related to subtle airway resistance. Guilleminault and colleagues (1993) considered UARS clinically significant if it entails greater than 10 episodes of EEG arousals per hour of sleep in patients with a documented history of excessive daytime sleepiness. They described UARS as multiple sleep fragmentations resulting from very short alpha EEG arousals, which in turn are related to an increase in resistance to airflow. According to Guilleminault, et al. (1993), the resistance to airflow is subtle enough that it is not detected by routine sleep analysis, but can be detected with esophageal pressure tracings. In addition, UARS may not be associated with snoring, the classic symptom of OSA. However, there is no consensus on the criteria for diagnosis or indications for treatment of UARS. Neither the American Sleep Disorders Association nor any other professional medical organization has issued guidelines for the diagnosis and treatment of UARS.
Cautery-assisted palatal stiffening operation (CAPSO) is an office-based procedure performed with local anesthesia for the treatment of palatal snoring. A midline strip of soft palate mucosa is removed, and the wound is allowed to heal by secondary intention. The flaccid palate is stiffened, and palatal snoring ceases. Wassmuth, et al. (2000) evaluated the ability of CAPSO to treat obstructive sleep apnea syndrome (OSAS). Twenty-five consecutive patients with OSAS underwent CAPSO. Responders were defined as patients who had a reduction in AHI of 50 % or more and an AHI of 10 or less after surgery. By these strict criteria, 40 % of patients were considered to have responded to CAPSO. Mean AHI improved significantly from 25.1 +/- 12.9 to 16.6 +/- 15.0. The Epworth Sleepiness Scale improved significantly from 12.7 +/- 5.6 to 8.8 +/- 4.6. Mair and Day (2000) analyzed data on CAPSO with regard to extent of surgery, need for repetition of procedure, results, complications, predictors of success. Two hundred and six consecutive patients underwent CAPSO over an 18-month period, followed by office examination and telephone evaluation. The success rate was initially 92 % and dipped to 77 % after 1 year. CAPSO eliminates excessive snoring caused by palatal flutter and has success rates that were comparable with those of traditional palatal surgery. The authors stated that CAPSO is a simple and safe office procedure that avoids the need for multiple-stage operations and does not rely on expensive laser systems or radiofrequency generators and hand pieces. The results of these studies appear to be promising; however their findings need to be verified by randomized controlled studies.
In a prospective, non-randomized study, Pang and Terris (2007) evaluated the effectiveness of CAPSO in treating snoring and mild OSA. A total of 13 patients with simple snoring and mild OSA underwent the modified CAPSO under local anesthesia. Patients had pre-operative polysomnography and at 3 months post-operatively; they were Friedman stage II and III, with tonsil size 0, 1, or 2. All patients had improvement in their snoring; 84 % had improvement in the Epworth Sleepiness Scale, from 12.2 to 8.9. Objective success on the polysomnogram was noted in 75 % of patients (6/8) with mild OSA. The AHI improved from 12.3 % to 5.2 % (p < 0.05), and the lowest oxygen saturation improved from 88.3 % to 92.5 % (p < 0.05). The authors concluded that the modified CAPSO is a simple, low-cost, and effective office-based method to treat snoring and mild OSA. The findings of this small study are promising. Randomized controlled trials with larger sample size and longer follow-up are needed to ascertain the clinical value of CAPSO.
The PillarTM Palatal Implant System (Restore Medical, Inc.) is intended as a treatment option for snoring and obstructive sleep apnea. The System consists of an implant and a delivery tool. The implants are designed to stiffen the tissue of the soft palate reducing the dynamic flutter which causes snoring. According to the manufacturer, the implants reduce the incidence of airway obstruction caused by the soft palate. The implant is a cylindrical shaped segment of braided polyester filaments. The delivery tool is comprised of a handle and needle assembly that allows for positioning and placement of the implant submucosally in the soft palate. The implant is designed to be permanent while the delivery tool is disposable.
Clinical information on Restore's website reported that with the Pillar Procedure, AHI was reduced in 13 of 16 patients (81.3%) with a 53.4% mean decrease for those 13 patients. Six of the 13 patients (46.2%) experienced an AHI decrease of greater than 50% along with a 90 day AHI of less than 10. Ten of the 13 patients (76.9%) decreased to an AHI less than 10. While this data appears promising, larger prospective clinical studies with longer follow up are needed in the peer-reviewed published literature to validate the effectiveness of this procedure for OSA.
In a retrospective review of 125 patients who underwent the Pillar implant for snoring and obstructive sleep apnea/hypopnea syndrome (OSAHS), Friedman and colleagues (2006) found that the Pillar implant is an effective treatment for snoring and OSAHS in selected patients and can be combined with adjunctive procedures to treat OSAHS. The major drawback of this study was that it was a short-term study. Well-designed studies with long-term follow-up are needed to determine the real value of this technique.
A structured assessment of the evidence for the Pillar procedure by Adelaide Health Technology Assessment for the Australian Department of Health and Ageing (Mundy et al, 2006) concluded: "Further investigation is required to establish which patients (mild or moderate obstructive sleep apnoea) would benefit the most from this procedure, and whether greater success would be achieved in conjunction with more invasive surgical procedures. In addition, long term follow-up of obstructive sleep apnoea patients may indicate whether or not the observed reductions in AHI delivered a clinical benefit to these patients".
This is in agreement with the conclusions of an assessment by the Canadian Agency for Drugs and Technologies in Health (CADTH, 2007), which stated that there is currently insufficient published evidence to ascertain if palatal implants (e.g., the Pillar System) are an effective treatment option for patients with mild to moderate OSA due to palatal obstruction. The CADTH report further stated that larger, randomized controlled studies are needed to determine the long-term safety and effectiveness of the implants in a more diverse patient population, including those who are obese or those with co-morbid medical conditions. Comparisons with existing treatments for OSA are also needed.
In a prospective study, Nordgard et al (2007) assessed the long-term effectiveness of palatal implants for treatment of mild-to-moderate OSA. A total of 26 referred patients with a pre-treatment AHI of 10 to 30 and a BMI of less than or equal to 30, representing an extended follow-up of a subset of 41 patients enrolled in previous short-term trials were included. Twenty-one of 26 patients (80.8 %) experienced a decrease in AHI. Fifteen of 26 patients (57.7 %) had a follow-up AHI less than 10 at 1 year, whereas 13 patients (50 %) had a 50 % or greater reduction to an AHI less than 10 at 1 year. Mean AHI was reduced from 16.5 +/- 4.5 at baseline to 12.5 +/- 10.5 at 3 months (p < 0.014) and to 12.3 +/- 12.7 at 1 year (p < 0.019). The authors concluded that patients initially responding to palatal implants with improved AHI maintained improvement through long-term follow-up at 1 year. The main drawback of this study was its small sample size. The authors noted that additional studies with longer follow-up would be appropriate.
In a continuation of a prospective case series, Walker et al (2007) assessed the long-term safety and outcomes of palatal implants for patients with mild-to-moderate OSA. Polysomnography, daytime sleepiness, and snoring intensity were measured at baseline, 90 days, and extended follow-up. A total of 22 (42 %) patients from the previous study were followed for a median of 435.5 days. Thirteen were classified as responders, based on their 90-day evaluation. 76.9 % of initial responders maintained improvements in AHI, daytime sleepiness, and snoring at extended follow-up. Nine patients were initial non-responders for AHI and daytime sleepiness and remained unchanged at extended follow-up. However, snoring for these 9 patients initially improved, and the improvement continued through extended follow-up. The authors concluded that initial response or non-response to palatal implants remains stable over an extended period. However, they noted that the generalizability of these results is unknown because of significant loss to follow-up (31 of 53 or 58 %). Other drawbacks of this study were small sample size, lack of randomization, as well as selection bias that can occur among patients who chose to participate in a follow-up study.
In a Cochrane review, Smith et al (2006) ascertained the effectiveness of drug therapies in the treatment of OSA. The authors concluded that there is insufficient evidence to recommend the use of drug therapy in the treatment of OSA. They noted that small studies have reported positive effects of certain agents on short-term outcome. Certain agents have been shown to reduce the AHI in largely unselected populations with OSA by between 24 and 45 %. For fluticasone, mirtazipine, physostigmine and nasal lubricant, studies of longer duration are needed to establish if this has an impact on daytime symptoms. Individual patients had more complete responses to particular drugs. It is likely that better matching of drugs to patients according to the dominant mechanism of their OSA will lead to better results and this also requires more investigation.
Obstructive sleep apnea has been reported to be common in medically refractory epileptic patients. Chihorek and colleagues (2007) examined if OSA is associated with seizure exacerbation in older adults with epilepsy. Polysomnography was performed in older adult patients with late-onset or worsening seizures (group 1, n = 11) and those who were seizure-free or who had improvement of seizures (group 2, n = 10). Patients in group 1 had a significantly higher AHI than patients in group 2 (p = 0.002). Group 1 patients also had higher Epworth Sleepiness Scale scores (p = 0.009) and higher scores on the Sleep Apnea Scale of the Sleep Disorders Questionnaire (p = 0.04). The two groups were similar in age, BMI, neck circumference, number of anti-epileptic drugs currently used, and frequency of nocturnal seizures. The authors concluded that OSA is associated with seizure exacerbation in older adults with epilepsy, and its treatment may represent an important avenue for improving seizure control in this population. Moreover, they noted that large, prospective, placebo-controlled studies are needed to ascertain if treatment of OSA (e.g., CPAP) improves seizures control in patients with epilepsy.
Appendix
Epworth Sleepiness Scale
Indicate the likelihood of falling asleep in the following commonly encountered situations. Assign the following scores to the patient's responses:
|
Likelihood of dozing
|
Score
|
| None |
0 |
| Low Chance |
1 |
| Moderate Chance |
2 |
| High Chance |
3 |
-
Sitting and reading
-
Watching TV
-
Sitting, inactive, in a public place, i.e., theater
-
As a passenger in a car for an hour without a break
-
Lying down to rest in the afternoon when circumstances permit
-
Sitting and talking to someone
-
In a car, while stopped for a few minutes in traffic.
Sum the scores. A total greater than 10 is considered abnormal.
Multiple Sleep Latency Test (MSLT)
The MSLT, most commonly used in the evaluation of narcolepsy, is also used to document daytime sleepiness in OSA. The MSLT evaluates the rapidity with which a patient falls asleep during daytime nap opportunities at two-hour intervals throughout the day. The test is typically administered after an overnight polysomnogram. Similar to the polysomnogram, the EEG, EOG and EMG are routinely recorded. A sleep latency of less than six minutes is considered clinically significant. Although the polysomnogram is always part of the workup of OAS, the MSLT is considered expensive and time consuming and is infrequently performed. However, with the recent emphasis on excessive daytime sleepiness as an initial symptom of an obstructive sleep disorder, evaluating a patient's daytime sleepiness becomes more important, in order to distinguish true excessive daytime sleepiness from the occasional sleepiness that almost every one experiences.
According to the Standards of Practice Committee of the American Academy of Sleep Medicine (Littner, et al., 2005), the MSLT is indicated as part of the evaluation of patients with suspected narcolepsy and may be useful in the evaluation of patients with suspected idiopathic hypersomnia. The MSLT is not routinely indicated in the initial evaluation and diagnosis of OSAS, or in assessment of change following treatment with nasal CPAP. The MSLT is not routinely indicated for evaluation of sleepiness in medical and neurological disorders (other than narcolepsy), insomnia, or circadian rhythm disorders.
Assessment of Adequacy of Response to CPAP
In an article on the use of oral appliance therapy for OSA, Ferguson (2001) used a conservative definition of treatment success. A complete response is defined as a reduction in AHI to less than 5/h. A partial response was defined as an improvement in symptoms combined with a greater than or equal to 50 % reduction in AHI but the AHI remained greater than 5/h. Treatment failures were defined as having ongoing symptoms and/or a less than 50% reduction in AHI. By this definition, a reduction of 55 events per hour of sleep to 33 events per hour of sleep (40 % reduction in AHI) would not be considered as a good response to CPAP.
Wassmuth et al (2000) evaluated the ability of cautery-assisted palatal stiffening operation (CAPSO) to treat OSA syndrome. Twenty-five consecutive patients with OSA syndrome underwent CAPSO. Responders were defined as patients who had a reduction in AHI of 50% or more and an AHI of 10 or less after surgery.
Furthermore, Heinzer et al (2001) noted that a good response to CPAP treatment is defined as an AHI of less than 10 events/hour.
Javaheri (2000) concluded that an AHI of 4 +/- 3 per hour signifies complete elimination of disordered breathing. The author prospectively studied 29 men with heart failure whose initial polysomnograms showed 15 or more episodes of apnea and hypopnea per hour (AHI). Twenty-one patients had predominately central and 8 patients OSA. All were treated with CPAP during the subsequent night. In 16 patients, CPAP resulted in virtual elimination of disordered breathing. In these patients, the mean AHI (36 +/- 12 [SD] versus 4 +/- 3 per hour, p = 0.0001), arousal index due to disordered breathing (16 +/- 9 versus 2 +/- 2 per hour, p = 0.0001), and percent of total sleep time below saturation of 90 % (20 +/- 23 % to 0.3 +/- 0.7 %, p = 0.0001) decreased, and lowest saturation (76 +/- 8 % versus 90 +/- 3 %, p = 0.0001) increased with CPAP. In 13 patients who did not respond to CPAP, these values did not change significantly. In patients whose sleep apnea responded to CPAP, the number of hourly episodes of nocturnal premature ventricular contractions (66 +/- 117 versus 18 +/- 20, p = 0.055) and couplets (3.2 +/- 6 versus 0.2 +/- 0.21, p = 0.031) decreased. In contrast, in patients whose sleep apnea did not respond to CPAP, ventricular arrhythmias did not change significantly. The author concluded that in 55 % of patients with heart failure and sleep apnea, first-night nasal CPAP eliminates disordered breathing and reduces ventricular irritability. Based on this study, an AHI of 4 +/- 3 per hour signifies complete elimination of disordered breathing.
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