Pros and Cons of Adaptive Servo-Ventilation (ASV) for Sleep Apnea
Sleep apnea is a condition affecting millions of Americans. In fact, the American Sleep Apnea Association reports that sleep apnea is as common, among Americans, as Type 2 Diabetes, affecting some 18 million people.
Adaptive Servo-Ventilation (ASV) is one of the treatments utilized to help people who live with certain types of sleep apnea to get the restful nights of sleep their bodies need to not only survive, but also maintain a better quality of life.
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When left untreated, sleep apnea can lead to a host of medical issues, including:
- Extreme daytime sleepiness
- High blood pressure
- Heart failure, heart attacks, irregular heartbeat
These are just a few of the types of medical issues that sleep apnea can lead to, as each patient can experience different problems based on the level of severity of their sleep apnea. Beyond medical issues, sleep apnea can also affect quality of life by impacting the ability to concentrate at work, and causing moodiness, and lack of energy and drive.
Fast, effective treatment is the best solution for sleep apnea. In order to properly treat this disorder, the first step is reaching a diagnosis during a sleep study. Once the study is complete a sleep physician will evaluate the results to determine what type of sleep apnea patients have and which treatment will be the most effective for them.
As a sleep technologist, it is your role to titrate and monitor the effects of adaptive servo-ventilation for sleep apnea should it be recommended as the treatment for the unique and specific needs of individual patients you work with. Because every person is unique, and every human body has its own individual response to the variety of symptoms sleep apnea causes, an individual patients' needs ar determined by the physician on a case by case basis.
Sometimes a variety of treatments and therapies are attempted before finding the one that works best for an individual patient. Adaptive servo-ventilation is an advanced treatment option for specific patient needs.
What is Adaptive Servo-Ventilation (ASV)?
Used to treat central or complex sleep apnea -- adaptive servo-ventilation is a non-invasive method of treatment that continuously monitors the breathing status of your patients.
ASV is one of the newer forms of positive airway pressure (PAP) therapy on the market today. This machine adjusts pressure delivery based upon the detection of pauses (apneas) in breathing during sleep. ASV is primarily used for the treatment of central sleep apnea, though it is also used to treat patients with complex sleep apnea.
With ASV devices, the pressure window is set to respond to feedback from the patient. Unlike the fixed pressure of a CPAP machine, ASV allows for the pressure to adjust continuously and to trigger breathing when needed according to the patient’s breathing patterns. This makes ASV particularly useful for patients with central sleep apnea.
Often, the continuous positive airway pressure (or CPAP) therapy is the first form of therapy patients receive to treat their sleep apnea symptoms. If patients complain about the continuous pressure of their CPAP machine, bilevel positive airway pressure (BiPAP™) therapy is typically the next form of therapy attempted. This is because BiPAP machines have one pressure setting for inhaling and a different pressure setting for exhaling, so patients who have trouble with CPAP often benefit from the increased comfort that comes with a lower exhalation pressure.
If both CPAP and BPAP have proven ineffective in treating a patient's central sleep apnea symptoms, ASV is typically brought in as a last resort. Because the technology involved in ASV is so advanced, patients who are not adequately treated with the other two therapies can benefit from this treatment option.
Pros of Adaptive Servo-Ventilation for Sleep Apnea
Adaptive Servo-Ventilation has several distinct advantages in treating sleep apnea in comparison to other methods. It's beneficial to central sleep apnea patients, in particular.
One element that sets the ASV apart from other PAP machines is that it adjusts to the patient's individual breathing patterns as they change during the night, providing a breath when central apneas are detected. This helps patients to breathe easier throughout the night and ensure that they are getting an adequate supply of oxygen throughout the night.
An ASV device is ideally suited for patients who have developed complex sleep apnea when using CPAP or BPAP devices, since it offers the variable flow of pressure, and adjusts as needed throughout the night. This technology accommodates to treat both obstructive and central sleep apnea events.
Of course, that doesn’t mean that ASV therapy is the right solution for all sleep apnea patients. In fact, there are very specific considerations to keep in mind when using adaptive servo-ventilation treatment for any sleep apnea patient, despite the benefits this type of treatment may offer.
Cons of Adaptive Servo Ventilation for Sleep Apnea
There are some patients for which ASV therapy simply isn’t recommended for. For instance, patients with severe symptomatic heart failure may experience increased mortality rates by using adaptive servo-ventilation devices.
In addition, some sleep apnea patients who have underlying or pre-existing health conditions shouldn't be using ASV. This includes patients who suffer from the following conditions:
- Profound and chronic hypoventilation
- Moderate to severe chronic obstructive lung disease (COPD)
- Chronically elevated partial pressure of carbon dioxide (PCO2) on ABG (arterial blood gas greater than 45 mm Hg)
- Restrictive thoracic or neuromuscular disease
This is why it is so important for sleep technologists to be aware of contraindications of using ASV to help patients with sleep apnea, and use caution when prescribing this particular type of treatment? It's important to work closely with the patient’s physician to make sure none of the above conditions are of concern before using adaptive servo-ventilation treatment for central sleep apnea patients.
Role of the Sleep Technologist for Mitigating Risk
As a sleep technologist, your role is to help your patients use the most beneficial treatment for their sleep apnea conditions and individual needs. Part of that responsibility involves measuring the potential risks against the potential benefits.
In May of 2015, ResMed, a global maker of CPAP and ASV devices, issued a statement cautioning against the use of ASV treatment in patients who had symptomatic chronic heart failure and reduced left ventricular ejection fraction (LVEF) of less than or equal to 45 percent (normal LVEF is between 55 and 70 percent). Respironics, another manufacturer of sleep technologies, followed up a couple of days later with a statement of their own discouraging use of ASV for at-risk patients while more studies are being conducted.
The American Academy of Sleep Medicine (AASM) also followed up with a statement urging physicians to stop prescribing ASV to patients in symptomatic heart failure with LVEF less than 45%.
AASM went further to recommend that:
- Patients be assessed for heart failure symptoms before prescribing this type of therapy.
- Patients who have have been treated with ASV in this risk group be advised of the risks and urged to seek alternative treatments for their sleep apnea.
Assure that your medical director is aware of the findings of the SERVE-HF study, which precipitated the announcements concerning the safety of using adaptive servo-ventilation therapy for sleep apnea patients with chronic heart failure. Then, work together with your medical director to care appropriately for these patients within your organization.
Your role may include things like:
- Identifying patients who are currently being treated with ASV therapy (you could easily do this by reviewing ASV titrations).
- Communicating with patients about their risks and vulnerabilities according to the instructions and authorization of your medical director.
The next step to take is to review your policies and procedures manual with your medical director to determine if modifications need to be made in order to comply with the most modern and up-to-date recommendations for the use of adaptive servo-ventilation when treating central or complex sleep apnea patients.
Finally, any patient currently authorized for ASV therapy, and those who you are considering authorizing for this potentially beneficial treatment, should be examined and evaluated for heart failure. It is essential that you educate patients about the risks of using this device if they are in certain stages of heart failure and take preventative and precautionary action to avoid treating patients who may not know they are in heart failure.
Ultimately, there are many different treatments available for sleep apnea. Some will offer greater benefits to patients than others. Each one has the potential to offer outstanding benefits to the right patient, whether he or she suffers from obstructive sleep apnea, central sleep apnea, or complex sleep apnea.
It is your role as a sleep technologist to work with your physicians to identify the treatment that will offer the greatest benefit with the least amount of risk to your patients. Because there are many treatments for sleep apnea, it’s important to have all the facts about each patient.
Understanding the fundamentals of adaptive servo-ventilation therapy, including the benefits and risk factors, for treating certain types of sleep apnea is critical to assisting you as you work within your own guidelines to find the most effective and appropriate treatments for each and every patient you serve.
Here at the American Association of Sleep Technologists (AAST), we encourage you to download this helpful Sleep Technology Terms and Definitions eBook. We believe it is a helpful resource for all sleep technologists assisting to improve the health and sleep of their patients. Whether you are an old pro in the sleep technology industry or a relative newcomer, this guide will help you communicate vital messages in a professional manner in all situations.
The 42-page eBook is filled with beneficial terms and definitions that will help you communicate effectively whether talking with other medical professionals or to patients and their families.