June 12, 2014
News Review From Harvard Medical School -- Sleep Apnea Treatments May Protect Heart
Treatments for sleep apnea might help control factors, such as blood pressure, that increase the risk of heart disease, new research finds. The two new studies appeared in the New England Journal of Medicine. One study included 318 adults with sleep apnea. They had either heart disease or a high risk of developing it. Two groups were randomly assigned to use a continuous positive airway pressure (CPAP) machine at night or just receive oxygen. The third group got education on good sleep habits. After 12 weeks blood pressure was 2 to 3 points lower in the CPAP group than in the others. The second study included 181 obese adults with sleep apnea. They were randomly assigned to 6 months of CPAP, weight-loss counseling or both. The group that used CPAP and lost weight had the largest drop in blood pressure. In the 2 groups that lost weight, the loss averaged 15 pounds. These groups also had declines in the blood fats known as LDL ("bad cholesterol") and triglycerides. Their C-reactive protein level, which indicates inflammation of blood vessels, also dropped. These changes could further reduce their risk of heart disease. HealthDay News wrote about both studies June 11.
By Robert H. Shmerling, M.D.
Harvard Medical School
What Is the Doctor's Reaction?
Obstructive sleep apnea is a common condition. Among middle-aged adults, it affects nearly 1 in 10 women and 1 in 4 men. It's a condition in which breathing often stops temporarily during sleep. People with sleep apnea tend to be overweight or obese. They often snore loudly. They may feel sleepy during the day because of the poor quality of their sleep.
Sleep apnea also may cause even bigger problems. In fact, it's a more serious condition than many people realize. For example, sleep apnea has been linked with:
- Reduced levels of oxygen in the blood
- Increased blood pressure
- Increased levels of inflammation in the body
- Changes in insulin that increase the risk of diabetes
- An increased risk of heart disease and related death
- Changes in the blood vessels that impair lung function
A common treatment for sleep apnea is a continuous positive airway pressure (CPAP) device. This machine blows air through a mask worn during sleep. The mask is often uncomfortable and may fall off during sleep. Other steps often recommended include oxygen therapy and loss of excess weight. Surgery to remove excess tissue in the back of the throat can be done in some cases. None of these is always successful. New, more effective and better tolerated treatments are badly needed.
Two studies just published in the New England Journal of Medicine examine the impact of sleep apnea treatments on related health problems.
The first study enrolled 318 people with sleep apnea. All of them also had heart and blood vessel diseases or health factors that increased their risk of these diseases. Each person received information about ways to improve sleep. Some also received CPAP or oxygen during sleep.
This study's main finding was that blood pressure was significantly lower in the group receiving CPAP than in those who received oxygen or only education about sleep. Oxygen treatment did improve the amount of oxygen in the blood. But it did not seem to improve blood pressure.
The second study included 181 people with sleep apnea. They also were obese and had high levels of C-reactive protein (CRP) in the blood. CRP is one measure of inflammation in the body. People were randomly divided into 3 treatment groups: CPAP, a weight-loss program or both. Blood pressure improved in all 3 groups. But the combination of CPAP and weight loss was linked to greater reductions than either treatment alone.
The researchers found that those in the weight-loss program or the combination of weight loss and CPAP also had improvements in:
- Insulin levels
- Blood triglycerides (a fat linked to cardiovascular disease)
These improvements were not seen among those receiving only CPAP.
Based on these studies, it seems that weight loss may be the most effective way to reduce the risk of heart and blood vessel disease for people with sleep apnea. CPAP may be the most important treatment for high blood pressure. Unfortunately, these studies did not look at new treatments for sleep apnea or ways to get the most out of established treatments (such as losing weight or tolerating a CPAP mask).
What Changes Can I Make Now?
Many people with sleep apnea don't know they have it. They may not realize that they stop breathing during sleep if they sleep alone or if their bedmates fall asleep first. Recognize the symptoms of sleep apnea. These include:
- Excessive sleepiness during the day
- Loud snoring
- A headache in the morning
If you already have sleep apnea, avoiding caffeine, alcohol and medicines that make you drowsy can be helpful. Talk to your doctor about treatments. As these studies showed, the options include CPAP, loss of excess weight and oxygen. Some people also benefit from a fitted mouth piece worn during the night or, as a last resort, surgery.
Finally, it's important to change other factors that increase your risk of heart and blood vessel disease. Here's what you can do:
- Don't smoke.
- Keep your blood pressure and cholesterol levels in a good range.
- Keep your blood sugar in an ideal range, especially if you've been diagnosed with diabetes.
What Can I Expect Looking to the Future?
These studies are helpful, but many questions remain. These studies examined moderately severe sleep apnea. Perhaps the results would have been different if milder cases had been included. In addition, they only looked at certain outcomes, such as reductions in blood pressure. Oxygen treatment did not seem to lower blood pressure. But this treatment offers other benefits, especially for those who have low oxygen levels during sleep. More research is needed to sort out the importance of each of these treatments.
Many people cannot tolerate CPAP. Many who try to lose weight are not successful. I hope that in the future we'll have better treatments for sleep apnea and better ways to make the most of current treatments.