CleveMed Blogs

For most of us, when we think of carbon dioxide (CO2), we think of words like waste, danger, toxic, poison; but in reality CO₂ is not only a natural part of our existence but an essential one. We know we need to breathe oxygen to live. So many of us naturally assume that when we hold our breath, that it is the lack of oxygen that our body is reacting to and forcing us to breathe again. . . wrong. In reality, it is the accumulation of CO₂ that our body is reacting to and forcing us to breathe again, trying to reduce and remove the CO₂ from our lungs (You say: Ah ha, see, CO₂ is bad! Our body is fighting to get rid of it). Well, yes, too much of anything is a bad thing, even oxygen (Oxygen toxicity or oxygen poisoning, causes disorientation, breathing problems, and even seizures, but that’s not the point of this article). Back to CO₂, the needed concentrations of carbon dioxide we are talking about are well below the toxic levels, and most importantly without CO₂, you don’t have as much drive to breathe.

There are tens of millions of people with sleep apnea (that is, the failure to breathe while you sleep). Sleep apnea is typically further broken down into obstructive sleep apnea (OSA), where by the patient is trying to breath but air can’t get in due to an obstruction or collapse in the airway, and central sleep apnea (CSA), where by the patient just stops trying to breathe for short periods of time. The most prominent and successful treatment of OSA is using a constant positive airway pressure (CPAP) device or a variation there of. However some of these OSA patients do not get better, do not tolerate the CPAP, or even get worse. One reason is that a portion of the OSA population actually has a complex sleep apnea (CSA) condition that is masked by the OSA. In these cases the CPAP will prevent the obstructions, but then it becomes apparent that the patient is exhibiting CSA characteristics as well. The complex sleep apnea symptoms are unmasked or amplified because of a lack of respiratory drive due to insufficient levels of CO₂. Normally when we sleep, our CO₂ levels increase just slightly. Think about it, you are sleeping in a relatively stationary position creating a slight cloud of CO₂ around you. A CPAP device, however, reverses that effect since it is drawing air from an area a few feet away and pumping it into your airway. To add to that, the increased pressure and flow also acts to ‘blow off’ more of the CO₂ that is normally inside your lungs, so it is very conceivable that the CO₂ levels on CPAP can be even lower than normal (as opposed to slightly elevated in normal sleep). So this complex sleep apnea (CSA) population would appear to have a CO₂ ‘critical threshold’ right at that point between the CO₂ levels experienced with and without CPAP. There are multiple studies that have now shown that adding just a small amount of CO₂ actually treats these patients.

So yes, these patients do say, “give me CO₂ or give me bad sleep!”

Immediately after a lunch meeting, David Sullivan (CleveMed Software Quality Engineer) tweeted: Interesting presentation on sleep science during lunch by Dr. Robert Thomas. Ilya Gotfryd (Software Engineer), from a nearby cubicle, promptly echoed: Came back from an exciting sleep science presentation. Starting to view sleep as a window. The CleveMed Twitter page announced: “Fascinating lunch meeting presentation by Dr. Robert Thomas (BIDMC, a Harvard Medical School affiliate) on ‘Sleep as Window’”. Although the lunch-time talk was much-tweeted about by the CleveMed team, it was not the main focus of Dr. Thomas’ visit.

Dr. Robert Thomas of Beth Israel Deaconess Medical Center was in Cleveland this week to partner with CleveMed in developing and commercializing a new therapeutic technology for sleep apnea. Sleep apnea has many forms, like Obstructive (OSA), Central (CSA), and Complex (CompSA). OSA is the only form with an effective treatment - Continuous Positive Airway Pressure – CPAP. However, CSA and CompSA, which are strongly linked to serious heart and lung diseases remain largely untreated. It is suspected that more than 25% of Congestive Heart Failure (CHF) patients have CSA or CompSA. Furthermore, Central or Complex apnea events often coexist with OSA, which can compromise the effectiveness of the popular CPAP therapy.

The technology, which was created by Dr. Robert Thomas at BIDMC, Boston and Mr. Robert W. Daly of Wellesley, Massachusetts, is based on injecting small amounts of CO₂ levels into the patient while applying CPAP. A major contributor to CSA and CompSA is thought to be an increased sensitivity to CO₂ levels, which causes central apneas readily when the patients fall asleep. This is especially true during CPAP since the increase in breathing lowers CO₂ in those patients; thus, triggering central apnea. “By introducing 0.5% to 1% of CO₂ during CPAP, we have found that the patient′s normal breathing is restored“, said Dr. Thomas. “The key is to prevent a drop in CO₂; there is no need to increase CO₂ above wake levels. The implications are huge. Not only will such technology bring relief of symptoms to CSA and CompSA patients, but may also improve cardiac function itself, as the restoration of normal breathing may relieve stresses on the heart. The project with CleveMed will test the benefit on patients with and without CHF and both CSA and CompSA.”

Technology completion and clinical validation on more than 100 patients will be supported by a recent NIH SBIR Fast Track grant awarded to CleveMed with BIDMC and Wayne State University as the two clinical sites.

This post is an adaptation from CleveMed News Release: CleveMed to Collaborate with Robert Thomas MD on New Sleep Apnea Therapy

A sleep study (also called a polysomnogram) is a test that records your physical state during various stages of sleep and wakefulness. It provides data that are essential in evaluating sleep and sleep-related complaints, such as identifying sleep stages, body position, blood oxygen levels, respiratory events, muscle tone, heart rate, amount of snoring and general sleep behavior.

Arriving at the sleep lab and initial paperwork:

If your physician feels you need a sleep study you will make an appointment for a test that will take place at night in the sleep center. After your arrive at the sleep center, you will be asked to complete questionnaires on your sleep the night before and a brief sleep history. Many sleep centers offer a video or other information about the sleep study or specific disorders such as sleep apnea, since a significant percentage of those who have sleep tests are suspected to have sleep apnea. The video may also address what you should expect during the sleep test to ease any concerns that you may have. Then you will be asked to change into nightclothes.

Applying electrodes:

After changing, the polysomnographic technologist will connect you to the electrodes that will record your brain waves and muscle movements throughout the night. This will not hurt or break the skin. The electrodes are placed in specific areas and applied with water-soluble gel and tape. The electrodes record brain waves, muscle movement, rapid eye movement (REM), air intake, and periodic limb movement. A microphone attached to your neck records snoring, and two belt-like straps around the chest and lower abdomen monitor muscle movement during breathing. Despite all of the equipment, most people say it doesn’t disrupt their sleep.

Testing electrodes and Monitoring:

After settling into bed, your technician may go to a monitoring room and ask you over an intercom to perform certain tasks that will show the electrodes are recording properly. You will be observed on a television monitor during the night, but that is to allow the technician to note your body movements during sleep.

Follow up:

A follow up appointment with your referring physician may occur after your initial sleep study. If your physician feels you have symptoms requiring a second night in the sleep lab; this may be scheduled prior to your follow up. During the follow up, the physician will discuss results, and may prescribe treatment for a sleep disorder.

List of things to do the day of your test:
• Do not drink alcohol or caffeine.
• Arrive on time, since setup takes some time.
• Bring a pair of comfortable bedclothes. Some patients like to bring their own pillows or blankets as well.
• Bring any medications you are being prescribed or will need to take during the hours you will be at the sleep center.
• Generally, you are asked to obtain a normal nights sleep the night before the test. Do not take naps on this day.