“Why am I using that this thing?” they asked me. This ‘thing’ they were referring to is also known as CPAP.
Many people find themselves having had a sleep test and they are not sure why. They have a CPAP machine (Constant Positive Airway Pressure machine). Yet, they tell me, “I don’t know why.” Yes, they’ve been told they have apnea (Obstructive Sleep Apnea or OSA), but why do they need to do this? It is a question that they should be able to answer. Why do we use CPAP? Why do we treat OSA?
Why do we treat OSA?
When a sleep evaluation or sleep testing was considered for you, your physician felt it might explain some of your sleep related symptoms or medical problems. It might have been for snoring that you were not even aware had been occurring. Maybe you were sleepier than you wanted to be or more sleepy than your family or friends thought you should be. It could have been for another non-related issue. Your doctor was concerned that your problem with glaucoma, asthma or hypertension may have been made worse by or possibly even caused by a sleep condition. The test was ordered. Obstructive Sleep Apnea was found and now you have a CPAP machine.
Obstructive Sleep Apnea may cause symptoms. Excessive sleepiness, poor quality nocturnal sleep and waking up with headaches are just a few of these symptoms. Your snoring could be waking your spouse. Certainly, you would prefer not to have the symptoms. You want to sleep better and to feel better during the day.
One of the major goals of therapy for OSA, including CPAP, is to improve or eliminate symptoms. When the obstructive apnea is corrected, many of its symptoms resolve or improve, sometimes dramatically. If you had symptoms when your apnea was diagnosed, one goal of therapy is to improve or correct those symptoms.
Most symptoms of OSA are not specific.
Most symptoms of OSA are not specific. A wide range of medical conditions, some common and others not so common, can cause these symptoms. It is unfortunate, but our sleepiness or headaches do not come with labels telling us what is causing them to occur. Often, sleep apnea treated with CPAP will totally correct the obstructive events, but the symptoms that led to the evaluation and testing do not go away.
Many patients at the time they are diagnosed with significant obstructive apnea will have few or no symptoms. These individuals have varying degrees of OSA severity on their sleep testing. Surprisingly, significant OSA can be seen with minimal symptoms or even no symptoms. While the number of obstructive events per hour will generally be related to the severity of the symptoms, is it not unusual to see patients with both moderate and severe apnea with few symptoms. Even without symptoms, our current knowledge strongly supports the need for their treatment.
Many patients at the time they are diagnosed with significant obstructive apnea will have few or no symptom.
Understanding the reason for treating individuals with few or no symptoms requires a little more information. Obstructive Sleep Apnea is the repeated interruption of someone’s breathing while asleep. The obstructions result in a blood oxygen drop and an arousal to light sleep or brief awaking. These arousals are not usually associated with full awakenings. Most individuals are not aware that the obstructions have occurred.
There are two types of obstructions. The first is a total blockage of the airway with a drop in blood oxygen level while breathing efforts from the chest continues. The technical term for complete obstruction is Apnea. The second is a partial blockage of the airway while the breathing continues. These partial blockages cause the same problems as seen with an apnea. The technical term for the partial obstruction is Hypopnea. The two types of obstruction are measured during a night or portion of a night of sleep testing. The numbers of each are added together. When divided by the duration of the sleep where the measurements were made, the results represent the number during an average hour of sleep. The resulting number is the Apnea-Hypopnea Index or AHI. The AHI is the average number of apneas and hypopneas in one hour of sleep.
The AHI is considered a measurement of the severity of Obstructive Sleep Apnea. Other factors enter into the measurement of severity. The most common would be the degree of oxygen drop that occurs with these obstructive events. It is generally accepted that an AHI of less than 5 is not considered to be diagnostic of OSA. An AHI of 5 to 15 events per hour is considered mild OSA. An AHI of 15 to 30 is moderate and above 30 is severe Obstructive Sleep Apnea.
The AHI is considered a measurement of the severity of Obstructive Sleep Apnea.
In the past 40 years, thousands of research studies on Obstructive Sleep Apnea have been performed. The vast majority utilize the severity scale noted above. Those studies strongly support the current concept of the role of apnea in causing and aggravating other medical conditions.
The higher a person’s AHI on their diagnostic sleep test, the more likely they will die from a stroke or heart attack. The risk is far higher than those who have no obstructive sleep apnea. And, they die younger. When the AHI is greater than 15 per hour the risk is significant. An increased risk is measurable at an AHI of five but it is relatively small. It is very small at an AHI of less than five. It is generally accepted the long-term treatment of patients with an AHI greater than 15 at the time of diagnosis will improve secondary medical conditions and prolong life.
The second goal of therapy is obvious. It is to reduce or eliminate as many apnea and hypopnea events as possible. A person with OSA cannot know what their AHI is on any given day, night, week or month. As noted above, the symptoms do not always reflect the success of OSA treatments. However, with modern CPAP machines, technology can measure those events (AHIs) while you use the machine. Reports are now available on most machines, on most machine manufacturer’s websites, or through your physician. You and your physician can know how well your therapy is controlling your AHI.
What have we covered.
1. Obstructive Sleep Apnea can occur with minimal or no symptoms.
2. Obstructive Sleep Apnea is treated for two reasons
3. Obstructive Sleep Apnea treatment may only improve one of the reasons it is being treated.
4. The Apnea Hypopnea Index (AHI) is the number of obstruction events per hour of sleep.The AHI while on therapy demonstrate how well the therapy is controlling the Obstructive Sleep Apnea.
Three questions follow naturally from this brief review. These topics will be addressed in future post.
1. Why do I still have symptoms on treatment for OSA?
2. If I have mild OSA when diagnosed, do I need treatment?
3. What is the definition of apnea?
Why is OSA treated? The two reasons are: to improve symptoms and control the obstructive events. When we treat OSA, the treatment may be successful treating both, or just one of the two. One or both may be the reason CPAP, or another treatment, was recommended for you.
Goals of treatment for Obstructive Sleep Apnea
2. Control the obstructive events