Sleep Dallas Blog

Q: Can a MAD improve CSA as opposed to OSA?

Dr. Smith: Yes, there is more and more literature coming out showing that not only can mandibular advancement devices improve obstructive sleep apnea, but they can have a positive effect on central sleep apnea as well.

From articles like this one, it becomes clear that a) Obstructions that create a decrease in respiratory motor output will b) decrease respiratory drive, leading to c) CSA. Therefore, anything that removes obstructions, such as a MAD, can improve CSA.

Additionally, OSA leads to arousals, which leads to hyperventilation, which leads to hypocapnia, which leads to a decreased respiratory drive, which leads to CSA. So, control OSA with a MAD, and you can lessen the likelihood of CSA manifestation.

Q: What does the RDI, AHI and ODI represent on the Watch-PAT report?

Dr. Smith: RDI stands for the respiratory disturbance index, which includes apneas, hypopneas and RERAs. If the RDI is high and the AHI is low, this indicates Upper Airway Resistance Syndrome, and most sleep centers will not report this on studies. Oral appliances are great for this condition.
AHI stands for the Apnea-Hypopnea Index, and contains apneas and hypopneas. Put simply, although not exactly correct, this is the number of times you stop breathing for at least 10 seconds each hour.
ODI is the desaturation index, and it means the number of times each hour your hemoglobin (storage facility and transporter of O2 in your blood) lets go of at least 4% of the O2 it contains. This is what you measure with your pulse oximeters you use when sedating patients.

Q: I was able to get a copy of my sleep study from my doctor, but I don’t understand what I am looking at. Can you tell me what these numbers mean?

Dr. Smith: I read 2 or 3 of these every day, and rarely do they resemble each other. However, I can help with some of the acronyms and numbers even without seeing the study.

AHI: Stands for the Apnea-Hypopnea Index. Very simply, this means the number of times you stop (or significantly hinder) breathing for at least 10 seconds every hour. These “events” can be due to an obstruction or due to your brain’s respiratory center being a bit lazy.

RDI: This stands for Respiratory Disturbance Index. There is some controversy here, but generally this number is derived from adding the RERAs to the AHI. So, the RDI should always be higher than the AHI.

RERA: Respiratory Effort Related Arousal. These do not need to last 10 seconds, but they are related to an obstructed breathing effort that created a sleep arousal. If you have many RERAs but a low AHI, this is called Upper Airway Resistance Syndrome (UARS)

ODI: Oxygen Desaturation Index. This is generally considered to be the number of times per hour that your oxygen became desaturated at least 4%. This usually occurs concurrently with or shortly after a respiratory (breathing) interruption, or apneic event.

If you (or anyone) would like to know more about the numbers or acronyms on your sleep study, just let me know. There are far too many possibilities to list them here.

Q: Can an appliance be used with CPAP successfully?

Dr. Smith: At the same time? Yes, it’s called combination therapy, and
allows a CPAP user to have the pressure reduced to make it easier to
use. They can also be used alternately when they are hunting, on
airplanes, etc.. Of course, the right type of mask would need to be
used, and preferably one of the nasal cone type that does not place
any retrusive forces on the maxilla.

Another use for combination therapy is if you would like to prevent
any potential occlusal (bite) changes with the mandibular advancement
devices. If someone wears a MAD during the week, and CPAP on weekends,
for example, they will get no bite changes.

Q: I wake up a lot of times from dreams, usually around 2 or 3 in the
morning. However, some of my most creative solutions to problems
happen in the wee hours after waking, and there is better mental
clarity. If I didn’t have to keep regular work hours and could nap
during the day, this sleep issue would not be a problem. Have you
heard of this?

Dr. Smith: You may be awaking after you have entered your first REM
stage of sleep, where paralysis sets in, and you are unable to breathe
easily if there are obstructions, such as your tongue. When people
awake during REM, or “dream sleep”, they are more likely to remember
their dreams. Regardless, if this is happening, you should have a
sleep study performed.

You might appreciate a book called “At Day’s Close: Night in Times
Past“, but the meat from the book you would need involves the fact
that centuries ago, we all had a “first sleep” and a “second sleep”,
where we awoke after about 4 hours of sleep and then wrote about
dreams, cleaned house, etc.., then after an hour or two, went back to
sleep. This was routine until we had oil lamps, then street lights,
and the nights became shorter. However, many of us still have this DNA
embedded, and are prone to waking up halfway through the night. They
are now called biphasic sleepers, and they have support groups,
believe it or not. Do some Googling and you may find some buddies.

Q: Hey, been playing some golf with my neighbor, R*** G***, who is an internist and sleep physician, and he doesn’t think much of oral appliance therapy. Can you give me some information that will help him understand what we can do as dentists?

Dr. Smith: I have Dr. ***’s wife in a SomnoDent, if that helps. Is he aware of the protocol from the AASM that was issued 5 years ago?

“Although not as efficacious as CPAP, oral appliances are indicated for use in patients with mild to moderate OSA who prefer OAs to CPAP, or who do not respond to CPAP, are not appropriate candidates for CPAP, or who fail treatment attempts with CPAP or treatment with behavioral measures such as weight loss or positional change.”

That’s from HIS organization!
Ask what his issues are.

If bite changes are his worry, tell them they change with CPAP also, and I can send you photos if needed. There is also a study from 2010 that shows craniofacial changes that occur after 2 years with CPAP. Very convincing.

If TMD is his worry, tell him you are well versed in handling these issues, and you have far fewer issues with the Somnodent, since it has more vertical freedom and you can dial the patient in carefully with .1mm adjustments

If he says they don’t work, see above protocol. There are numerous studies that prove otherwise.

If he says they can’t be titrated in a lab like PAP, that’s true, but we have portable monitoring to assess effectiveness as the appliance is being titrated.

If he says they cost too much, ask him why he doesn’t allow the patient to make that decision. Just send them over and let you handle that.

Follow up everything with “so, what do you do with your patients who do not tolerate CPAP? Most studies show these numbers run close to 50%, with the numbers being higher with mild to moderate patients, which, BTW, is what our appliances are really good at fixing. Do you just tell them to lose weight?” Dr. G: “Yes” You: “Really? How often do you follow them up to make sure they’re losing weight, and what success % are you seeing?”

If he says he sends them for surgery, say “Were you aware that your organization (AASM) says that’s backwards? In October of last year, they said that surgery is to be considered on patients “in whom oral appliances have been considered and found ineffective or undesirable”

One physician at a time, Dr. C. One at a time.

Two-thirds of American adults have slept with their cell phones on or right next to their beds. The number rises to over 90% among people ages 18 to 29. Those are some of the conclusions from the huge Pew Internet & American Life Project called “Cellphones and American Adults.”

What the Pew study did NOT mention is the MIT study from January of 2008, which showed that using a cell phone prior to sleep increases headaches AND negatively affects the timing and amount of slow wave (deep) sleep one gets. This slow wave sleep is important for weight maintenance (leptin levels) and memory functionality. Why don’t you just read a book about cell phones before going to sleep? It would be a more healthful choice.

Carpe Noctum!