Sleep disordered breathing in heart failure

This section is designed to bring you some basic information on sleep disordered breathing in heart failure.

1. What is sleep disordered breathing?
2. What are the symptoms?
3. Who gets sleep disordered breathing?
4. Why is sleep disordered breathing important in heart failure?
5. Prevalence of sleep disordered breathing in heart failure patients
6. How is it diagnosed?
7. How is it treated?

1. What is sleep disordered breathing? Sleep disordered breathing is a term used to describe several different types of breathing disorders that prevent individuals from getting the good quality sleep that they need to stay healthy. Since these disorders occur during sleep they can go unnoticed for a long time. The disorders are treatable but if they are left untreated they can cause other health problems. The most common form of sleep disordered breathing is known as sleep apnea. It owes its name to a Greek word, apnea, meaning 'want of breath'. People with sleep apnea stop breathing for short periods of time while they are asleep. There are two types of sleep apnea: central and obstructive. Central sleep apnea - this happens when the brain fails to send the correct signals to the breathing muscles and so a breath doesn't happen. This only lasts for a short time (usually only a few breaths are missed) because the body is able to sense the falling level of oxygen and rising level of carbon dioxide in the blood and the brain is alerted, allowing normal breathing to resume. This pattern of breathing and cessation of breathing can repeat continuously during the night, affecting sleep quality. Obstructive sleep apnea - this is the most common form of sleep apnea. Obstructive sleep apnea occurs when air cannot physically flow into or out of the person's nose or mouth although efforts to breathe continue. During sleep, all the body's muscles become more relaxed but in some people the muscles and tissues that hold open the windpipe relax too much and sag, leading to narrowing in this area. This narrowing makes breathing labored and noisy and eventually, as the muscles relax more, the airways become blocked and prevent breathing. Fortunately, the body senses the falling level of oxygen in the blood and increases the effort to breathe until eventually the blockage is overcome and the person can breathe normally again. Usually the unblocking of the airway is quite sudden and the person wakes up, often just for an instant, before falling back to sleep. This blockage or obstruction and waking can become a continuous cycle happening as often as every minute and preventing the individual from getting good quality sleep.

2. What are the symptoms? People with obstructive sleep apnea usually snore loudly, move around a lot during sleep and may wake up suddenly making choking or gasping sounds. This poor quality sleep means they are usually extremely sleepy during the day. For some people this problem is so serious that they cannot keep themselves from falling asleep at work or even while driving a car. Other common symptoms are morning headaches, difficulty concentrating and, in severe cases, impotence and personality changes. People with central sleep apnea tend to experience fewer obvious symptoms, primarily because they tend not to actually wake up during the periods of apnea. The majority of people with central sleep apnea have chronic cardiac or respiratory diseases such as heart failure. It can be difficult to determine if symptoms such as fatigue are caused by their existing disease or by the sleep apnea. So, it is difficult to detect by symptoms alone whether people have central sleep apnea. Interviews with the bed partner can be more useful since the partner may notice that the person stops breathing while they are asleep.

3. Who gets sleep disordered breathing? Obstructive sleep apnea occurs in men and women of all ages but it is most common in overweight, middle-aged men with a large neck (usually taking a size 17 inch collar or more). Being overweight and alcohol abuse are common contributing factors. Certain abnormalities in the nose, throat or upper airways may also cause obstructive sleep apnea. Central sleep apnea is less common in the general population but appears to be more common in people with chronic cardiac or respiratory diseases such as heart failure. The causes of central sleep apnea are less well understood but appear to be related to circulatory or nervous system problems.

4. Why is sleep disordered breathing important in heart failure? Heart failure involves a complicated series of factors that all interact. This interaction is known as the heart failure cycle. Sleep disordered breathing is known to worsen the heart failure cycle. The continual increase and decrease in blood gas levels, fluctuations in blood pressure caused by the frequent awakenings, changes to hormones and the reduced rest that the patient experiences all contribute to this effect. Heart failure patients who have sleep disordered breathing are known to do poorly when compared with heart failure patients without sleep disordered breathing. They have more irregular heart rhythms and there is evidence to suggest that they do not survive as long as heart failure patients who have no sleep disordered breathing. Treatment of the sleep disordered breathing can improve the quality of life of patients and may also increase their life span. Even within the general population, early detection and treatment of sleep apnea is important. Obstructive sleep apnea is associated with an irregular heartbeat, high blood pressure, heart attack and stroke.

5. Prevalence of sleep disordered breathing in heart failure patients An estimated 5 million Americans have heart failure. Recent studies of patients with heart failure have shown that around half of these patients also have a sleep-related breathing disorder. It has also been shown that the majority of heart failure patients who have sleep disordered breathing have central sleep apnea rather than obstructive sleep apnea, making them more difficult to identify.

6. How is it diagnosed? If a doctor suspects that a patient has sleep apnea, they will be referred for a sleep study (known as polysomnography) to confirm the diagnosis. A sleep study is usually done in a sleep laboratory but there are systems available to allow the tests to be carried out at home. The doctor may decide to do a screening test (a simplified sleep study) at home to ensure that the patient has sleep disordered breathing before they are referred on for a full diagnostic sleep test in the clinic. A variety of measurements can be made during a sleep study, with little discomfort. Oxygen levels in the blood are measured continuously from a clip on the finger and breathing is monitored from bands or sensors on the chest and sometimes also on the abdomen. Heart function will be measured and, in a full sleep study, sleep quality itself can be estimated from small sensors stuck to the scalp and to other areas of the body to measure brain and muscle activity.

7. How is it treated? The most common treatment for moderate to severe sleep apnea is nasal continuous positive airway pressure (nasal CPAP). The slightly pressurized air generated by the CPAP machine keeps the person's airways open, maintaining normal breathing throughout the night. The air is delivered via a mask worn over the nose and the mask is connected to a small, quiet pump beside the bed. For people with obstructive sleep apnea, the response to treatment is usually dramatic with greatly improved sleep quality. Although the devices are cumbersome and some people don't like the idea of wearing a mask every night, the benefits far outweigh the disadvantages and the vast majority of people decide to use their CPAP machine every night at home. Additional treatment options include overnight oxygen (also delivered through a mask), surgery, medication and permanent weight loss, depending on the patient's condition and preferences. erences.