Not infrequently, people ask me some variation of the following:
I'm told that I snore every night, and a few times my spouse has heard me stop breathing in my sleep. I've done some research online and I'm pretty sure that I have sleep apnea. Do I really need to do a sleep apnea test or is this just an added expense? Why not just buy an auto-CPAP machine?
In this article I'm going to unpack the rationale behind having a sleep apnea study so that you can fully understand your options. In order to honestly address this issue, I'm going to acknowledge a dirty little secret in sleep medicine: It is possible to buy an auto-CPAP (APAP) machine without a prescription. You may be able to find one on Craigslist, on Amazon, or through some unscrupulous dealers (by law, a prescription is required to dispense CPAP machines, masks, and humidifiers). However, there are risks to sleep apnea self-treatment that you need to know.
Would it change clinical management?
In our medical training, we doctors are taught to constantly question the need for a test before ordering it. The touchstone for making such a determination is, "Will the test change clinical management?" In other words, will the results of the test change how you treat the patient? If not, don't order the test. A sleep apnea test can change clinical management in the following ways:
1. Does the patient have sleep apnea or not?
There are various questionnaires, applications, and algorithms that attempt to predict whether you do or do not have sleep apnea but the bottom line is that you cannot make the diagnosis without a formal sleep apnea test (in-lab or home sleep study). While you might surmise that you have obstructive sleep apnea (OSA) based on symptoms and signs such as chronic snoring, witnessed apneas, and gasp arousals, you won't know with 100% certainty until you have a sleep study showing that your apnea hypopnea index (AHI) - average number of abnormal breathing events per hour - is ≥5. Often patients will ask, "Based on my symptoms, I know that I'm highly likely to have OSA so what's the harm in trying CPAP or another treatment for OSA?" It is true that non-invasive treatments for sleep apnea have very few side effects so there is little risk in trying them. CPAP and Provent Sleep Apnea Therapy have the fewest side effects - with these treatment modalities, probably the worst thing that could happen from experimentally trying them would be wasting your money on unnecessary medical products if you didn't actually have sleep apnea. The hidden danger in this self-treatment approach lies in the potential to under-treat your OSA (and thereby still be at risk for the medical consequences of OSA) and/or not identify and treat other sleep breathing disorders besides OSA (see below). On the other hand, it would be a bad idea to try an oral appliance for sleep apnea or sleep apnea surgery before being formally diagnosed with the disorder because of the potential side effects of these treatments.
2. Determining the phenotype of sleep apnea
While obstructive sleep apnea is by far the most common type of sleep apnea, sleep apnea testing can determine the presence of other forms of sleep breathing disorders such as central sleep apnea (CSA) and sleep related hypoxemia and hypoventilation. If another sleep breathing disorder is identified, clinical management can change dramatically. CSA triggers further inquiry as to whether there may be an underlying, causative medical problem or medication effect at play. Depending on the circumstances, an echocardiogram (ultrasound of the heart), blood work to rule out heart failure (BNP) and kidney failure (creatinine, BUN), or an MRI of the brain may be ordered. If the patient is taking an opiate pain medication, the dose may be adjusted.
APAP may still be used as a first-line treatment for CSA, but there is a higher probability that the patient may have a suboptimal response to it compared to a patient with garden-variety OSA. Recognition of CSA warrants close monitoring by a sleep apnea doctor. In order to get CSA under control, patients may require more advanced forms of positive airway pressure, such as adaptive servo-ventilation (ASV) or BPAP S/T, oxygen therapy, medications, or a combination of the three. Sleep related hypoxemia (low oxygen) and hypoventilation (low oxygen and high carbon dioxide) may require full pulmonary function testing (PFTs), echocardiography, and changes in sedative and/or hypnotic medications, as well as optimizaing treatment of underlying lung problems such as asthma and COPD.
3. Determining the degree of sleep apnea
The degree of sleep apnea can determine what type of treatment will be best suited for you. While PAP is the gold standard for OSA, buying an APAP from Craigslist without having had a sleep apnea study could be a major fail. Here's why: If you have really severe sleep apnea, chances are you are going to need high pressures to keep your airway open. CPAP pressures of about 14-15 cwp and higher are very hard to tolerate. Thus, patients with severe sleep apnea are more likely to find success with bilevel positive airway pressure (BPAP or BiPAP). BiPAP is a more sophisticated medical device than APAP and can sense the difference between inhalation and exhalation. Drilling down into the problem with APAP at higher pressures, it is the exhalation phase of breathing that is the real difficulty. If you are trying to exhale directly into a stiff wind, the two forces are going to meet head on. The usual result is that you will take your mask off and go back to sleep without the treatment that you need to protect your body. BiPAP drops the pressure when you begin to exhale, which facilitates better tolerance and a feeling of more "natural" breathing at higher net pressures. You could end up kicking yourself if you spend the money for an APAP only to find out that you're unable to use it all night and a sleep study would have predicted that you'd be a better candidate for a BiPAP machine.
On the other end of the severity spectrum, if your sleep apnea test determines that your sleep apnea is mild (AHI 5-15) or moderate (AHI 15-30), you might be a candidate for an oral appliance for sleep apnea. Provent is another alternative to PAP that is more likely to be fully effective in patients with mild-moderate degrees of OSA.
If your AHI is just above 5, lifestyle modification alone might be a reasonable treatment plan. Losing some weight, avoiding alcohol and sedating medication before bedtime, and elevating the head of the bed a little might be all that is required to normalize the AHI in borderline cases.
Some patient have positional sleep apnea, with abnormal breathing events only exceeding normal limits during supine sleep. Patients with this subtype of sleep apnea can be effectively treated solely with a positional therapy device to prevent them from moving to their backs during the night. Remember, only a sleep study test can get granular about your abnormal breathing event index in different body positions.
4. Establishing a baseline AHI to assess treatment response
Like determining the degree of sleep apnea, understanding the baseline degree of sleep apnea prior to initiating therapy is crucial. Let me give you an example of why this is important. The following scenario is not uncommon: A patient schedules a consultation with me and wants to review his APAP data. He never had a sleep study but assumed he had sleep apnea and found a way to purchase an APAP machine. His download shows that he has an estimated residual AHI of 9, which is high. Ideally, I like to get the calculated AHI well below 5, to ≤2-3. If the patient's initial AHI was 109, a residual AHI of 9 is a pretty good outcome and I wouldn't make any major changes. If however, the baseline AHI was 10, my assessment would be that the therapy wasn't working well and more investigation and intervention would be needed.
As they say, knowledge is power. Now you're armed with all the facts to make the best decision for you. Before deciding to forego a sleep study, it's best to sleep on it.