Sleep apnea is a common sleep disorder that affects thousands of individuals. With this condition, you have an interruption in your breathing while sleeping that occurs through repetitive pauses, referred to as apneic events. There are several types of sleep apnea, but two prominent types include obstructive sleep apnea (most common) and central sleep apnea.
As a sleep technologist, it's important for you to know the key differences between central and obstructive apnea so you know how to best treat your patients who may have one or the other disorder.
1. Obstructive Sleep Apnea
What is it?
Obstructive Sleep Apnea (OSA) is where your upper airway gets partially or completely blocked while you sleep. This obstruction causes your chest muscles and diaphragm to work harder to open up the blocked airway and draw air into your lungs.
Behavioral and general measures, such as avoiding alcohol for four to six hours before bedtime, weight loss, and sleeping on your side instead of your back or stomach are components of conservative nonsurgical treatment.
Both positional therapy and weight loss were rated as "guidelines" in a 2006 practice parameter, indicating a strategy for patient care with a significant degree of evidence.
Since obesity is a significant predictive aspect for OSA, when you lose weight, you reduce your risk of obstructive sleep apnea. In fact, according to some data, you reduce your respiratory disturbance index (RDI) by 26 percent when you have a 10 percent reduction in weight.
There are other benefits of weight loss in patients with sleep disordered breathing (SDB), including:
- Lowered blood pressure
- Decreased RDI
- Improved snoring and sleep structure
- Improved arterial blood gas values and pulmonary function
- Potential reduction of required optimum continuous positive airway pressure (CPAP) pressure
Weight gain is a prominent source of OSA relapse after surgical treatment. Even though accomplishing and maintaining weight reduction are often tough, the results are very beneficial when you're able to do so. The SBD treatment approach isn't complete if you don't have your obesity addressed with weight reduction.
Treatment depends on how severe your apnea is. If you have a mild apnea, you have a number of options available to you, while if your apnea is moderate-to-severe, it requires treatment with CPAP.
2. Central Sleep Apnea
What is it?
With central sleep apnea (CSA), cessation of respiratory drive results in a lack of respiratory movements. During sleep, your breathing is disrupted regularly because of how your brain functions. It's not that you're not able to breathe (like when you have OSA), but rather your brain doesn't tell your muscles to breathe, and therefore, you don't try to breathe.
CSA is typically associated with severe illness, particularly an illness where your lower brain stem, which is what controls your breathing, is affected. With newborns, CSA produces up to 20-second pauses in breathing.
Hypopneas - Obstructive and Central
As a sleep technologist, you may be very familiar with central apneas, obstructive apneas, and mixed apneas. You may know the proper way of identifying and breaking hypopneas apart into what is recognized by Medicare as the criteria or definition for a hypopnea as well as how other entities recognize them.
But, as of late, the biggest questions seem to be focused on what the difference between central hypopnea and obstructive hypopnea is and why you should know the difference.
Hypopneas aren't necessarily apneas, where you stop breathing completely. They're reductions in your respiratory effort and airflow but without full breath cessation. This means your lungs are still getting some air. So, hypopneas are these reductions.
You can think of obstructive hypopneas as if you're covering a vacuum cleaner's suction nozzle with your hand.
With central hypopneas, however, it's more like you're using less electricity to run the vacuum cleaner. In both cases, although you're getting some air through, it's not enough to do its job properly. Central hypopneas are typically characterized by a reduction in blood oxygen. When you suffer from sleep apnea, you often have hypopneas, and when they happen on their own, it typically means you're developing sleep apnea.
How to Recognize Which One It Is
So how can you tell the difference between obstructive and central hypopneas?
It's an obstructive hypopnea if you experience:
- An increase in PAP flow signal or the flattening of nasal pressure flow
- Snoring during the event
- Paradoxical breathing
It's only central hypopnea if you're experiencing none of the above.
How to Properly Score Each Type of Apnea
The distinction between central and obstructive hypopneas got lost somewhere along the line, and labs started to score and report them as a single entity. This has changed.
The goal of a sleep professional is to treat your patients and ensure their breathing patterns are stabilized. For you to do this, you have to have the proper equipment. Where CPAP works well for obstructive apneas and hypopnea events, other treatment modalities work better for most central events. Central apnea episodes are typically better controlled with either Bi-level pressure support or additional backup support through a Bi-level ST.
But, central hypopneas aren't always controlled by any of these devices. For a more complex case of central hypopnea, you'll have to give your patients Adaptive Servo Ventilation (ASV) which is a more advanced therapy.
If you don't know the difference between central and obstructive hypopneas, you'll find it difficult to determine which device is best suited for the job.
Your patients that have complex breathing patterns might not have central apneas but may have central hypopneas involved in the waxing and waning pattern of breathing. When you don't have enough documentation on central events, it can be difficult to obtain insurance coverage.
When you score and report central and obstructive hypopneas separately instead of together, you'll get the documentation you require to show that the device you use is best for your patient's needs. With some observation and practice, you'll be able to distinguish between the two and determine which pressure and device modality are correct for your patient. You can find information on how to score each type of apnea correctly by reading this blog.
CPAP, or Continuous Positive Airway Pressure is a treatment technique for your patients who have sleep apnea. The CPAP devices keep your patient's airways open using mild air pressure and are used by patients who have problems breathing while they sleep. CPAP therapy, more specifically, helps to ensure that your patient's airway doesn't collapse when they breathe while sleeping.
CPAP therapy uses a CPAP device that includes:
- A mask that covers your patient's mouth and nose, a mask that only covers their nose, or prongs you fit into their nose.
- A tube connecting the mask to the CPAP device's motor.
- A motor for blowing air into the tube.
CPAP therapy is a highly recommended treatment option for your patients who have OSA when they're not getting enough air in their lungs. It's also used for treating newborns whose lungs haven't developed completely. This machine blows air into the newborn's nose, inflating their lungs.
Oral appliances are recommended for patients who have mild to moderate OSA.
This therapy is best for OSA. BPAP (also BiPAPTM) refers to Bilevel Positive Airway Pressure and the device functions similar to a CPAP device.
Both the CPAP and BPAP devices are similar in their design and function as both are noninvasive types of therapy for patients with sleep apnea. BPAP treatments, like CPAP treatments, are created to keep your patient's airway from collapsing and allows them to breathe regularly and easily while they sleep.
The biggest difference between CPAP and BPAP machines is that the BPAP machines have the two pressure settings: a lower pressure for exhalation, or EPAP, and one pressure for inhalation, or IPAP.
The BPAP device is made to increase the pressure when your patients inhale so their airways in their throat and nose don't close while they sleep. It provides EPAP that keeps the airway open. Your patients may find the BPAP device more comfortable than the CPAP devices.
BPAP may be used as well for your patients who need assistance breathing. This machine can also be prescribed for your patients who are suffering from congestive heart failure and other severe illness that affects their lungs and heart.
Patients who have muscle and nerve problems may benefit more from the BPAP device instead of the CPAP device. You can set BPAP devices to ensure your patients breathe a certain number of times each minute.
The CPAP device is typically used for your patients with mild to moderate sleep apnea, however, depending on how severe their sleep apnea is, you may want to use the BPAP device instead.
Adaptive Servo Ventilation (ASV) is a ventilatory treatment option that's non-invasive and made specifically for patients (adults) who have OSA and central sleep apnea. It's good for complex sleep apnea as well. It's a newer PAP unit that continuously monitors your patient's breathing issue. It's also the best option for central apnea.
There are similarities between ASV and CPAP therapy, but substantial differences. You adjust the pressure target of ASV to your patient's input, meaning the target value isn't fixed but instead adapts to the breathing patterns of your patient. Since the device adjusts itself continuously to meet the needs of your patient, your patients experience less discomfort and the pressure subtly changes in a way that keeps them feeling comfortable.
When abnormalities in breathing are detected by the ASV machine, it intervenes to maintain your patient's breathing at 90 percent of what was normal for your patient prior to their sudden breathing change. Once your patient's breathing issue ends, the device adjusts itself again to the normalcy.
Then when your patient's breathing is stable, the device puts out just enough pressure support to give an approximate 50 percent reduction in the patient's efforts to breathe, making the device comfortable for the patient.
Phrenic Nerve Stimulation
Phrenic Nerve Stimulation (brand name remed www.respicardia.com ) is an FDA-approved, implantable, non-mask therapy for moderate to severe central sleep apnea in adult patients. The device activates automatically each night to send signals to the breathing muscle (diaphragm) via the phrenic nerve to restore a normal breathing pattern. It monitors respiratory signals while you sleep and helps restore normal breathing patterns. Because the device is implantable and activates automatically, it does not require wearing a mask; however, as with any implantable device procedure, there is a risk of implant site infection.
- Two main types of sleep apnea include obstructive sleep apnea (most common) and central sleep apnea.
- OSA is where your upper airway gets partially or completely blocked while you sleep.
- Central sleep apnea (CSA), cessation of respiratory drive results in a lack of respiratory movements.
- Treatment options include CPAP, BPAP, ASV, and Phrenic Nerve Stimulation.
- Hypopneas aren't necessarily apneas where you stop breathing completely. They're reductions in your respiratory effort and airflow, but without full breath cessation.
To learn more about telling the difference between obstructive and central apneas, diagnosing them, and treating them properly, you can watch this video titled "Are We Ready to Define Central Hypopneas?"