Untreated Obstructive Sleep Apnea (OSA)
9/10/18 in Blog Posts
Untreated Obstructive Sleep Apnea (OSA) can impact one’s health and wellness. Untreated moderate and severe OSA are independent risk factors for hypertension, diabetes, heart attacks, strokes and premature death.
OSA also impacts everyday life. People with untreated OSA have a higher incidence of car and work-related accidents due to excessive sleepiness. Depression and reduced productivity at work are also common. The bedpartner’s sleep is also disrupted, often leading to separate sleep arrangements. It does not have to be this way as OSA is treatable.
To determine whether or not someone has OSA, and to what degree, a sleep study is needed. Sleep studies can be performed in the sleep lab or at home.
A sleep study will report the degree of OSA as determined by the Apnea Hypopnea Index (AHI), otherwise reported in home sleep studies as the Respiratory Event Index or Respiratory Disturbance Index (RDI or REI). Scoring criteria can vary with vastly different results, thus the criteria for diagnosing hypopneas should be reported and noted. A more reliable index is the Oxygen Desaturation Index (ODI) but even ODI can be scored using 3% or 4% minimal desaturation. There is much more to a sleep study’s interpretation than a summary index value. A sleep study should be examined for the positionality of OSA, the extent of oxygen desaturations during the night and the overall pattern of obstructions in sleep.
The three mainstays of treatment for OSA are Positive Airway Pressure (PAP) therapy, oral appliance therapy and surgical intervention. The treatment, for each patient, should be individualized to the patient’s particular preferences and needs.
The most common treatment for OSA in the US, particularly for moderate and severe cases, is PAP therapy. PAP acts as a pneumatic splint, or stent, to maintain airway patency. The device is an air compressor that can be placed on the night stand, delivering air pressure through tubing to an interface, or mask. The interface is what couples the air pressure to the patient’s airway.
There are 3 main types of interfaces. A nasal mask covers the nose. Nasal pillows sit underneath, and at times just inside the nostrils. A full-face mask covers the nose and mouth. Which one a patient uses is dependent upon comfort, as well as their ability to breathe through their nose and/or keep the mouth closed at night. Usually full-interfaces are least preferred. At times, a chin strap will be added to a nasal interface to prevent the mouth from opening when asleep. Some patients adapt to nasal breathing while using PAP, thus mouth breathers don’t always require a full interface.
There are several different types of PAP machines that each deliver the air pressure in slightly different ways. CPAP is continuous PAP, set at one constant pressure. This pressure is usually determined by a CPAP titration study in the sleep lab.
When using APAP, or auto-adjustable PAP machines, a set pressure is not used, but rather a range of pressures. This can be more economical for patients who undergo a home study, who can then forgo a subsequent in-lab PAP titration. In addition, if a patient undergoes an in-lab PAP titration, but optimal pressure is not determined, he/she can also be treated immediately with APAP. There are several advantages of APAP over CPAP. First, one’s pressure requirement is not fixed during the course of a night and can vary for patients with positional apnea that is worse in the supine position compared to the non-supine position. Thus, less pressure is used when not needed. Second, if a patient, after an in-lab titration study, is having difficulty tolerating a CPAP setting, options include going back to the lab to re-titrate the pressure or to empirically reset the pressure. With APAP, there is data on a compliance report that tells us how much pressure is being delivered each night to open the airway. This will allow adjustment of the range. An APAP device will also adjust treatment pressure as patients lose weight or when patients imbibe alcohol. Finally, all APAP machines have a CPAP mode and so if preferred, a constant level pressure may be set after determining the optimal pressure from the downloaded device data.
BPAP, or bi-level PAP, machines use two set pressures for each breath, a higher inspiratory pressure and a lower expiratory pressure. In general, the differential between these 2 pressures, also called pressure support, is at least 4 cm H2O. BPAP is frequently helpful for patients who are obese, have severe OSA and a high pressure requirement. It is easy breathing in at a high pressure, such as 18 cm H2O, but it may be difficult to exhale against that amount of pressure. BPAP lessens the work of exhalation. BPAP settings are determined in the sleep lab. Not everyone accommodates to BPAP and studies have not proven it superior to CPAP.
It is imperative to follow-up with patients long term for PAP therapy. OSA is an entity with potential cardiovascular consequences if untreated or treated improperly. The critical issue is long term adherence, which may be 50% or lower. In the SAVE study where PAP usage was low, at 3.3 hours mean per night, cardiovascular protection was not present. After beginning PAP treatment, as dictated by insurance entities such as Medicare (CMMS), patients require a face-to-face evaluation with the physician within 30-90 days. Assuming they are doing well, they should be seen once a year, or sooner if there are issues to address.
At the follow-up visit, it should be ascertained how the patient is doing clinically with their machine. That is, do they feel more rested? Is snoring treated? Any difficulties, such as interface difficulties, “too much pressure”, “too little pressure”, etc., should be addressed.
A compliance report should be checked. In the past, the only way to check a compliance report was to get it from the Durable Medical Equipment (DME) company that supplied the patient with the PAP machine and supplies or by downloading a chip from the machine if you had the “chip reader”. Most new machines have a modem to supply that information to the ordering physician. The physician only needs an ID and password on the machine manufacturer’s site and to be linked by the DME company to the patient.
The compliance report gives details about the patient’s usage of his/her machine and its’ efficacy, via an estimated “AHI”. Most insurance companies require usage of >4 hours per night at least 70% of the nights (5 nights a week) to continue to pay for the machine and supplies.
In general, our goal with PAP therapy is to attain an AHI of <5/hour. More important than the AHI number on a compliance report, though, is the patient’s clinical response to treatment. That is, treat the patient, not a number. However, this can be helpful to see that the PAP machine is doing what we expect it to do. In fact, showing the number to the patient, and comparing to their original sleep study’s AHI, at times, can be very motivating.
There are other parameters on a compliance report that help us trouble shoot issues patients may be having with PAP therapy, including the median and 95th percentile pressures on an APAP machine, as well as interface leak. Detailed data reports can be used for troubleshooting problems with PAP use.
Oral Appliance Therapy
Oral appliances that advance the mandible are an alternative to PAP therapy in patients who do not tolerate PAP or as primary therapy for patients who prefer them over PAP. Though PAP is more efficacious at reducing the sleep study indices of OSA, the clinical effectiveness of PAP and oral appliances is similar. Patients are twice as likely to adhere to oral appliance therapy than to PAP treatment, and this may explain the similar clinical effectiveness.
Oral appliances maintain the mandible in a protruded position in sleep. By doing so, they stabilize and expand the pharynx. The main mechanism of action is expansion of the upper pharynx at the palate level, not at the tongue base. An ENT endoscopic examination of the pharynx may be used to help assess potential for efficacy, by assessing the degree of expansion of the pharyngeal with jaw protrusion. Otherwise, if available, titration of mandibular protrusion during sleep using a MATRX device may be performed in a sleep center prior to appliance production, in order to assess potential efficacy.
Not all patients are good candidates for oral appliance. Clinical examination is needed to assess the number and condition of the dentition that will support the appliance and oral health. Particular features on exam may be used to select a specific appliance for a given patient. A doctor’s prescription is required to have an appliance made by a qualified MD or dentist. Oral appliances are a covered DME under most commercial carriers and medicare, and thus can be quite affordable with a participating doctor or dentist.
Custom-made appliances, produced in a dental lab from impressions or scan, are preferred to those made in office for comfort, durability and efficacy. Appliance should be titratable as optimal treatment position is not known apriori and slow adjustment allows accommodation to advancement. Once a patient is fitted with a titratable oral appliance, further advancement is usually performed at home to resolve the clinical symptoms and signs of OSA, usually by snoring abatement. Side effects include intolerance due to discomfort, bite changes and rarely dental or gum problems.
Clinical follow-up is needed to assess outcome, side effects and adherence, as long-term adherence rate is approximately 50%. Dental follow up is also needed to assess dental health. For patients with moderate to severe OSA, follow up sleep testing is needed to assess effectiveness of the appliance at reducing the indices of OSA and to assess the need for further titration or concurrent treatment, such as non-supine sleep positioning.
Recent advances in oral appliance therapy include the development of embedded temperature sensors for adherence monitoring and production of thinner, lighter appliances via 3-D printing techniques.
Upper Airway Surgery
Sleep surgery is simply not “less than 50% effective” as some have been told. Many patients are counseled against surgery, due to misinformation, and this leave many patients untreated (Russell et al 2015). Upper airway surgery has an important role in treating OSA for its most important clinical outcomes: Reduction of risk of risk of death, cardiovascular morbidity and improvement of quality of life. Research in large populations including the US Veterans database and the Korean National health database (Weaver et al 2004, Lee et al 2018), shows clear and substantial benefit of sleep surgery for survival and cardiovascular risk. Upper airway surgery has been shown to reduce the rate of motor vehicle accidents (Haraldsson 1995), regardless of the AHI, and also to improve quality of life in numerous studies.
Sleep surgery usually does not normalize the AHI but can reduce it significantly. How important is AHI normalization? The AHI is a surrogate parameter of OSA, not the disease. The AHI is a parameter whose measurement can vary greatly, has multiple definitions, and is insufficient to diagnose OSA when < 15/hour, where symptoms are required. The AHI does not convey critical data such as degree, duration and time spent with oxygen desaturations. The AHI may portend medical major risk when >30, when scored by 4% desaturations, and associated with hypoxemia.
Surgery is beneficial in that it does not require adherence, as compared to PAP and oral appliance therapy, where a large percentage of patients do not adhere long term. Nonetheless, pharyngeal surgery has risk and thus it should be considered carefully and applied to selected patients. Patients with very large tonsils are usually good candidates, and surgery may be considered first line for them (Browaldh et al 2013). Surgery should also be offered to those who have not responded to medical therapies, as surgery can often salvage these patients, reducing risk and improving quality of life.
UPPP or upper pharyngeal surgery has changed since introduction in the 80s. Lateral pharyngoplasty (LP) and its variants, such as expansion sphincter pharyngoplasty (ESP) have become powerful techniques to widen and stabilize the lateral pharyngeal walls. They have been shown to reduce the AHI, lower blood pressure and improve quality of life alone, even in patients that appear to have a tongue base collapse in addition (Cahali et al 2004, Pang & Woodson 2007, Hsu & Jacobowitz 2017). Thus newer techniques may be able to open the upper bottleneck of the pharynx and reduce the need for additional procedures. These advanced sleep surgery techniques have become the staple of sleep surgeons worldwide.
Maxilomandibular Advancement (MMA) , jaw surgery, can widen and stabilize the lateral pharyngeal walls effectively and more reliably lower the AHI. For the skeletally deficient patient, MMA can treat OSA and improve cosmesis. However, the patient must accept a long post-op oral rehabilitation and risk of lower facial sensory problems. For these reasons, not many patients accept this approach.
Implantable Hypoglossal Neurostimulation (HGN),
The new treatment frontier, implantable hypoglossal neurostimulation (HGN), combines the medical and surgical approaches. A pacemaker-like device is implanted under the skin and is used to active the hypoglossal nerve on one side of the neck. A cuff, connected to the pacemaker, is surgically placed around the hypoglossal nerve or its branches for stimulation. There is one HGN system approved in the US presently, from Inspire Medical, whose system consists of an implanted pacemaker, nerve cuff and respiratory chest wall sensor. There is another system by ImThera Medical which is investigational in the United States, presently in pivotal trial testing. Dr Jacobowitz from ENT and Allergy Associates is a primary investigator for this system and notes that it does not use a chest wall sensor, thus only having 2 components.
HGN systems are targeted for patients with moderate to severe OSA who are intolerant of other treatments. In clinical trials, these devices have shown significant AHI reduction and improved quality of sleep and of life, though not for all.
The mechanism of action is most likely pharyngeal wall and palatal stabilization rather than tongue movement. Stimulation is carefully adjusted to not interfere with sleep. A remote control, if used to activate the device after a delay. The pacemaker devices require surgical replacement but this can be performed under local anesthesia.
HGN is a new treatment. It is not accepted by all but may increase with our dependence on technology and with further device miniaturization. System cost may decrease over time and hopefully insurance carrier acceptance will become less challenging. Optimal features for successful outcome are still not well known. Inspire Medical uses sleep endoscopy to identify severe collapsibility as an exclusion. ImThera’s pivotal trial criteria exclude severe hypoxemia and high apnea index, possibly also to limit extreme collapsibility. More reliable criteria are still needed.
Additional experimental systems are in preliminary testing phase. For example, Nyxoah SA, for which Dr Jacobowitz consults, has developed an HGN system with an external power source, eliminating the need implant a power source. The system uses bilateral stimulation of the hypoglossal nerve branches to the genioglossus muscle. A button-like power source is applied on a patch under the chin at bedtime and is removed and charged after sleep. Clinical trial has completed enrollment in European and Australian centers. There are more systems in development, and this new frontier is very promising.
OSA is a serious disease with potential reduced survival, great morbidity, and functional impairment. Treatments, though imperfect, are readily available and should be offered using a personalized approach to achieve long term success.