obstructive sleep apnea

1. Obstructive Sleep Apnea Bruce Tasios, DDS Department of Orthodontics UMDNJ

3. Obstructive Sleep Apnea Leads to partial reductions and complete pauses in breathing that last at least 10 seconds during sleep Most pauses last between 10 and 30 seconds, but some may persist for one minute or longer Can lead to abrupt reductions in blood oxygen saturation, with oxygen levels falling as much as 40 percent or more in severe cases Brain responds to the lack of oxygen by alerting the body, causing a brief arousal from sleep that restores normal breathing

4. Obstructive Sleep Apnea This pattern can occur hundreds of times in one night, resulting in a fragmented quality of sleep that often produces an excessive level of daytime sleepiness Most people with OSA snore loudly and frequently, with periods of silence when airflow is reduced or blocked They then make choking, snorting or gasping sounds when their airway reopens

5. Prevalence Can occur in any age group, but prevalence increases between middle and older age In the United States, 8% of men and 2% of women are affected by OSA OSA occurs in about 2% of children and is most common at preschool ages Estimated that 80-90% of adults with OSA remain undiagnosed Average untreated sleep apnea patient�s health care costs are estimated to be $1336 more than an individual without sleep apnea

6. Significant Health Issue Complications secondary to nocturnal hypoxia and hypercapnia Systemic and pulmonary hypertension Congestive heart failure Ischemic heart disease Myocardial infarction Cardiac arrhythmias Neurological complications Diabetes Motor vehicle accidents Life-threatening problem: untreated moderate to severe OSA has a mortality rate of 37% during a period of 8 years

7. Symptoms Affected individuals are rarely aware of having difficulty breathing during sleep, even upon wakening Often recognized by others witnessing the individual during episodes or suspected because of its effects on the body

8. Etiology General Obesity/elevated BMI Nasal Cavity/Nasopharynx Deviated nasal septum Turbinate hypertrophy Nasal polyps Nasal tumors Sinusitis Enlarged adenoids

9. Etiology Oral Cavity/Oropharynx Macroglossia Enlarged palatine tonsils Enlarged uvula Retroglossal/laryngopharynx Enlarged lingual tonsils Laryngeal abnormalities/masses

10. Etiology Skeletal Maxillary hypoplasia Mandibular hypoplasia

11. Diagnosis Does the patient have sleep apnea? If a diagnosis of sleep apnea is made, should differentiate between obstructive and central sleep apnea Central sleep apnea Breathing is interrupted by a lack of respiratory effort Pathophysiology is related to abnormalities of central control mechanisms and chemoreceptor function rather than to airway obstruction Impervious to treatment modalities used in obstructive sleep apnea, which are aimed towards creating more space in the breathing airway

12. Diagnosis How severe is the patient�s sleep apnea? Does the patient have any health issues secondary to OSA? What is causing the patient to suffer from OSA?

13. Diagnosis Accurate medical history History of respiratory disease May contribute to causing respiratory problems during sleep History of cardiovascular disease and diabetes Possible indication of severity of OSA Epworth Sleepiness Questionnaire Indication of daytime sleepiness Detailed information from patient�s partner

14. Physical Examination Obesity/Body mass index Neck circumference Greater than 17 inches is highly correlated with OSA Soft tissue profile Nasal examination Oral examination Mallampati classification Used to evaluate the oropharyngeal tissues and the potential for airway obstruction Commonly used as an indicator for difficulty of intubation

15. Mallampati Classification

16. Airway Analysis Upper airway imaging is a powerful technique to determine the mechanism underlying the pathophysiology of OSA Imaging Modalities Nasopharyngoscopy Cephalometrics Cone-Beam Computed Tomography Computed Tomography (CT) Magnetic Resonance Imaging (MRI)

17. Endoscopic Pharyngoscopy Used to detect anatomical abnormalities in the upper airway, from the nasal passages to the glottis Sleeping fiberoptic endoscopy Endoscope is present while patient is sleeping Effective method to locate the obstruction site Procedure may cause sleep disturbances and is often refused by patients

18. Endoscopic Pharyngoscopy Mueller�s Maneuver Diagnostic technique to determine the collapsibility of the tissue surrounding the airway Executed by requesting the patient to inhale while the mouth and nose are occluded with a fiberoptic nasopharyngoscope in place The resulting negative pressure may cause the walls of the upper airway to collapse in a narrowed airway Maneuver has been shown to correlate to OSA severity

19. Cephalometrics Lateral cephalogram presents the profile view of the viscerocranium Common abnormalities found in OSA patients: retrognathic maxilla and mandible, short mandibular length, long anterior face height, clockwise rotation of the facial structure, and short cranial base Useful for measuring airway changes in a patient before and after treatment

20. 3-D Imaging Cone-Beam Computed Tomography Computed Tomography Magnetic Resonance Imaging Evaluate the upper airway 3-dimensionally Provide extremely accurate measurements of the airway in all dimensions

21. Polysomnography Commonly used to determine presence and severity of OSA EOG: electro-oculogram REM vs. NREM EEG: electroencephalogram Each sleep stage is associated with a specific wave pattern Arousal EMG: electromyogram Monitor muscle tone ECG: electrocardiogram Detect cardiac abnormalities Oronasal airflow Thoracic and abdominal respiratory effort Differentiate between central vs. obstructive Pulse oximetry Monitor arterial oxygen saturation

22. Apnea-Hypopnea Index Apnea-Hypopnea Index (AHI) The number of apneas and hypopneas per hour of sleep Apnea Cessation of airflow for more than 10 seconds Hypopnea Decrease in airflow by 50% with significant oxygen desaturation Also known as the Respiratory Distress Index (RDI)

23. Non-surgical Treatment Options Weight loss Positional treatment Medication Continuous positive airway pressure (CPAP) Palatal Expansion Oral appliances

24. Weight Loss Many patients who suffer from OSA are overweight Excess weight contributes to upper airway obstruction through an increase in pharyngeal mass, narrowing of the upper airway, and increased work of breathing and oxygen demand Weight loss via dieting and exercising has beneficial effects on the clinical status of OSA in overweight patients

25. Weight Loss However, it may be hard to lose weight when you have OSA, as you may be too tired to exercise and you may eat to stay awake Previous studies have shown that obese patients with OSA are not successful at losing weight when properly counseled and prescribed a weight loss regimen Liposuction may be considered

26. Positional Treatment Sleeping in the supine position tends to promote OSA, as gravity makes it more likely for the tongue to fall back and block the airway Treatment: Raise height of bed Avoid supine position

27. Medications Chemoreceptors detect changes in carbon dioxide, oxygen, and pH in arterial blood Increase in carbon dioxide and decrease in oxygen and pH send signals to the brainstem, calling for an increase in respiration Medications used to treat OSA take advantage of this feedback mechanism Acetazolamide: lowers blood pH to encourage respiration Avoid alcohol and other CNS depressants that may potentially relax the airway

28. Continuous Positive Airway Pressure (CPAP) Continuous Positive Airway Pressure pneumatically splints open the patient�s airway during sleep by delivering pressurized air into the throat Effective at eliminating apneas and hypopneas Considered the gold standard in the treatment of OSA

29. CPAP Side Effects Despite its high efficacy, patients frequently cannot tolerate its usage every night for life and thus long-term acceptance has been found to be low (~50%) Side effects: Oronasal dryness Conjuctivitis from air leak Noise Claustrophobia Mask discomfort Skin abrasions/rash

30. Palatal Expansion OSA patients may have considerable skeletal maxillary constriction, resulting in upper airway narrowing and increased nasal resistance Consequent mouth breathing results in a low tongue posture, provoking a flattening of the retroglossal airway space Growing patients who suffer from OSA with maxillary constriction may benefit from rapid palatal expansion (RPE)

31. Palatal Expansion RPE treatment widens the maxillary bone via distraction osteogenesis at the midpalatal suture Increases the volumetric space of the nasal cavity, which helps reduce nasal resistance Promotes spontaneous repositioning of the tongue to a normal position

32. Palatal Expansion Rapid palatal expansion is successful at treating children with OSA Reduced symptoms of OSA in 71.4% of children Significantly decreased AHI in 78.5 % of children Converted 92.8% of oral breathers to nasal breathers Positive results of RPE treatment has increased the use of surgically assisted rapid palatal expansion in adult patients Successful in adult patients with a transverse deficiency May be coupled with mandibular symphyseal distraction osteogenesis to permit greater transverse expansion without loss of proper occlusal contacts

33. Oral Appliance Therapy Oral appliances used to treat OSA function to increase the size of the upper airway by advancing the mandible, protruding the tongue, and possibly elevating the soft palate Mandibular advancement results in anterior displacement of the soft palate, genioglossus, and suprahyoid muscles Increases the dimensions of the hypopharynx, oropharynx, and velopharyngeal areas Mandibular displacement also stretches the palatoglossal and palatopharyngeal arches Increases upper airway muscle activity, making the airway less likely to collapse

34. Oral Appliance Therapy There are no strict guidelines in the design of oral appliances for OSA management and there is a plethora of them in use There are 1-piece or 2-piece appliances made from soft elastomeric material or hard acrylic 2-piece appliances have the advantage of allowing for titratable mandibular advancement

35. Appliance Design Patients find appliances that encroach the tongue space and open the bite uncomfortable No differences in efficacy between greater or lesser mandibular opening in reducing AHI No difference in treatment success between 1-piece and 2-piece appliances

36. Important Considerations Four factors that influence treatment success of Oral Appliance Therapy Mild to moderate OSA severity (AHI <30) Less effective at treating patients with severe OSA 14-61% of severe OSA cases compared with 57-81% of patients with mild to moderate OSA were successfully treated (AHI<5) Low BMI Obese patients are more resistant to oral appliance therapy

37. Important Considerations Large Mandibular Advancement Many clinicians recommend starting with a mandibular position corresponding to 75% of maximum mandibular protrusion, as this is the most comfortable position Direct relationship between the degree of mandibular advancement and reduction in AHI Supine AHI Patients who have greater supine than lateral AHI readings demonstrate better outcomes with oral appliance use

38. Adverse Effects Transient pain in the upper and lower incisors on wakening Excessive salivation Gingival soreness TMJ discomfort and noises Occlusal changes Reduction of overbite and overjet Retroclination of maxillary incisors (1.9�) and proclination of mandibular incisors (2.8�) Skeletal changes Mandible is relocated downwards and forwards Increase in lower face height

39. Surgical Treatment Options Septoplasty Turbinoplasty Partial turbinectomy Polypectomy Excision of nasal tumours Adenoid tonsils excision Uvulopalatopharyngoplasty Tonsillectomy Uvulectomy Partial glossectomy/tongue base reduction Genioglossal advancement Lingual tonsils excision Hyoid advancement/suspension Maxillomandibular advancement Excision of laryngeal tumours Tracheotomy

40. Risks of Surgical Treatment Surgery in the upper airway results in postoperative edema, which has acute adverse effects on breathing Several medications used during surgery are respiratory depressants and can remain in the body in low amounts for hours/days OSA can be dangerously aggravated by these drugs thus these patients need prolonged monitoring following surgery There is also a concern with postoperative analgesics that are respiratory depressants Other complications: nerve damage, excessive bleeding

41. Which Surgical Treatment Option? When an obvious anatomical abnormality is detected, the appropriate surgical procedure is performed accordingly Unfortunately, even with sound imaging modalities, it is still difficult to ascertain the pathophysiology of OSA It is often a combination of multiple sites affecting the upper airway that contribute to OSA

42. Which Surgical Treatment Option? Retropalatal and retroglossal openings are common areas that are obstructed in the upper airway Maxillomandibular advancement has been shown to be very successful at treating OSA with retropalatal and retroglossal obstructions However, some believe that maxillomandibular advancement is too invasive and should only be performed following a poor response to a procedure involving uvulopalatopharygoplasty, genioglossal advancement, and hyoid suspension These clinicians argue that it would be overly aggressive to submit a patient who would have responded to a less invasive surgery to the risks/complications from maxillomandibular advancement

43. What is Successful Treatment? In surgical studies, the definition of success is mainly based on objective measures Common objective parameters are the apnea-hypopnea index and lowest oxygen saturation Current accepted definition for surgical cure: AHI less than 20 with a reduction greater than 50% Few desaturations less than 90% Reason for setting the success less than 20 is that several studies have found that an index >20 translates to increased morbidity and mortality

44. Genioglossus Advancement Rectangular osteotomy at the chin which contains the genial tubercles Chin is fixated in a more anterior position Technique increase posterior airway space by anteriorly repositioning the genioglossus, geniohyoid, and digastric muscles

45. Uvulopalatopharyngoplasty Strives to increase the dimension of the upper airway by removing tissue in the throat Involved tissues may or may not include the uvula, soft palate, palatine tonsils, adenoids, and pharynx Risk for velopharyngeal insufficiency Results in lack of palatal closure, allowing air to escape during speech and swallowing

46. Hyoid Suspension Hyoid bone is important in determining the position of the tongue Anterior advancement of the hyoid bone may enlarge the airway at the tongue base level Surgical procedure involves repositioning the hyoid bone anteriorly and inferiorly and suturing it to the thyroid cartilage Beneficial effects related to stabilizing the soft tissue, preventing airway collapse, rather than to simple changes in airway diameter

47. Success Rate The success rate of stage 1 surgery involving uvulopalatopharyngoplasty, genioglossal advancement, and hyoid suspension at treating OSA is 60% The success rate of stage 2 surgery involving maxillomandibular advancement at treating OSA is 95% Previous studies have shown that only 25% of stage 1 non-responders went on to stage 2 surgery For this reason, other clinicians recommend using the most efficacious technique from the start and proceeding directly with maxillomandibular advancement

48. Prerequisites for MMA Patient�s AHI must be greater than 15, with a lowest desaturation below 90% and subjective daytime sleepiness Conservative treatments such as weight loss, mandibular repositioning devices, and/or continuous positive airway pressure must have been unsuccessful or intolerable for the patient Upper airway is obstructed at multiple sites or obstruction could not be distinguished, as it was diffuse Patient should present with a dentofacial skeletal deformity, most often a class II relationship

49. MMA Rationale Retro-positioning of the jaws causes the structures that form the anterior and lateral boundaries of the posterior airway such as the tongue, palate, and pharyngeal tissues to be displaced posteriorly The tissues become lax and more liable to collapse in the presence of negative pressure This results in constriction of the posterior airway, increased airway resistance, and obstructions

50. Maxillomandibular Advancement Advancement of the mandible pulls the geniohyoid, genioglossus, mylohyoid, and the digastric muscles anteriorly This brings the base of tongue and hyoid bone forwards and upwards Also creates a larger volume for the tongue and floor of mouth These two effects result in the enlargement of the posterior airway space at the retroglossal and hypopharyngeal region level Technique: Le Fort I level maxillary osteotomy and bilateral sagittal split mandibular osteotomy

51. Maxillomandibular Advancement

52. Preoperative Orthodontics Ideally, pre-surgical orthodontic treatment should be used to ensure a good postoperative occlusion and to correct any pre-existing malalignment of teeth Primary goal would be to maximize the amount of maxillary and mandibular advancement while maintaining a reasonable occlusion For example, in class II patients it is advisable to retract the mandibular incisors and procline the maxillary incisors to maximize the amount of mandibular advancement However, many OSA patients are older and are unwilling to undergo the recommended orthodontic treatment

53. Preoperative Orthodontics Equal maxillary and mandibular advancement is performed in patients who do not undergo preoperative orthodontic treatment However, in those who do receive preoperative orthodontic treatment, the maxilla and mandible may not be advanced in equal amounts, particularly when they do not have a class I occlusion

54. MMA Stability Generally accepted magnitude of advancement was 10mm Large horizontal advancement of the maxilla and mandible is stable without significant relapse Strong evidence in the long-term efficacy of MMA, as previous studies have shown that a 90% success rate was maintained after 4 years

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56. References Bonetti GA et al. 2009. A case report on the efficacy of transverse expansion in severe obstructive sleep apnea syndrome. Sleep Breath; 13: 93-96. Case RC, Schweinfurth J. 2009. Efficacy of a conservative weight loss program in the long-term management of chronic upper airway obstruction. International Journal of Otolaryngology: 1-4. Deatherage RD et al. 2009. Normal Sleep Architecture. Seminars in Orthodontics; 15(2): 86-87. Haskell JA et al. 2009. Effects of Mandibular Advancement on Airway Dimensions Using Cone-Beam Computed Tomography Analysis. Seminars in Orthodontics; 15(2): 99-104. Sittitavornwong S et al. 2009. Evaluation of Obstructive Sleep Apnea Syndrome by Computational Fluid Dynamics. Seminars in Orthodontics; 15(2): 105-131. Villa MP et al. 2007. Rapid expansion in children with obstructive sleep apnea syndrome: 12 month follow-up. Sleep Medicine; 8: 128-134. Weng Lye et al. 2009. Surgical Maxillomandibular Advancement Technique. Seminars in Orthodontics; 15(2): 99-104. Weng Lye et al. 2009. Surgical Procedures for the Treatment of Obstructive Sleep Apnea. Seminars in Orthodontics; 15(2): 94-98. Yow M. 2009. An Overview of Oral Appliances and Managing the Airway in Obstructive Sleep Apnea. Seminars in Orthodontics; 15(2): 88-93.