Sleep

I have been treating snoring and sleep apnea patients for more than three decades. As a surgeon I try to do operate on these patients, but those who are unable to undergo surgery or unwilling for surgery I prescribe CPAP machine (Continuous Positive Airway Pressure).I must say CPAP is a wonderful machine having its advantages and disadvantages.

If you think that starting CPAP for obstructive sleep apnea would help you to lose weight, then read the recent study published in the Journal of Clinical Sleep Medicine find that this is not the case. In fact, using CPAP is found to cause statistically significant mild weight gain compared to sham CPAP users in this prospective randomized study.

After treating OSA patients over these years by CPAP therapy, I have heard many patients complaining of gaining weight and some say losing weight. Initially I thought patient who gets good sleep should lose weight and poor sleep should promote weight gain.

I read conflicting results on CPAP use and weight status. There are a number of possible reasons why this can happen, but no one is absolutely sure. Of course, I’ve also had many patients who did lose significant weight after CPAP, which only adds to my confusion.

So I thought write this article based on my experience, but I stress that more studies need to be done in this subject. Physicians should stress an active weight loss plan and not assume CPAP alone will lead to weight loss. A larger, prospective study may help clarify these findings.

Obesity and Sleep Apnea

Obesity is causally linked to OSA. Why weight change after treatment with CPAP is not yet clear. Although hormonal changes would predict weight gain or loss, decreasing energy expenditure by reducing work of breathing would predict weight gain.

Metabolic Response in OSA

Sleep Apnea and Insulin Resistance

Obstructive sleep apnea (OSA) is characterized by sleep-related airway obstructions that produce apnea. These events provoke arousals and cause oxygen desaturations and heightened sympathetic activity during sleep and waking hours that may play a role in the development of insulin resistance. Obesity is a strong risk factor for OSA and both obesity and OSA are associated with increased insulin resistance and diabetes.

Obstructive sleep apnea (OSA) is associated with obesity, insulin resistance (IR) and diabetes. Continuous positive airway pressure (CPAP) rapidly mitigates OSA in obese subjects but its metabolic effects are not well recognized.

CPAP effectively improved hypoxia. However, subjects had increased insulin and IR. Fasting ghrelin decreased significantly while leptin, adiponectin and resistin remained unchanged. Changes in body weight directly correlated with changes in insulin and IR. Ghrelin changes inversely correlated with changes in IR but did not change as a function of weight.

Hormonal Changes

Hormones involved in the regulation of body weight and glucose metabolism include ghrelin, leptin, adiponectin and resistin. Ghrelin is an orexigenic hormone and it has been proposed as a cause of increased appetite and obesity .

Ghrelin is an appetite-increasing hormone postulated as a contributor to OSA-associated obesity as ghrelin levels were elevated .Leptin is secreted by adipocytes in proportion to body fat, being elevated in obese individuals and decreasing with weight loss. Adiponectin is decreased in obese individuals and in those with type 2 diabetes. It is thought to play a role in many of the metabolic complications suffered by these patients including metabolic syndrome and cardiovascular disease. However, its role in patients with OSA remains controversial.

CPAP treatment induced a decrease in fasting ghrelin levels, although body weight increased in most subjects. Adipokines such as leptin, adiponectin and resistin also appear to be influenced much more by adiposity rather than hypoxia. The fact that these adipokines remain unchanged after 6 months of CPAP treatment suggests that they are unlikely to play an important role in the development of the metabolic complications seen in the setting of OSA.

CPAP and Body Weight

CPAP alone may not reduce body weight and that in the face of weight gain CPAP treatment may not reduce insulin resistance and leptin or increase adiponectin in obese subjects. It is possible that CPAP use has only a transient effect on insulin sensitivity and that changes in body weight are a much more important factor in the long-term regulation of insulin sensitivity.

Hypothyroidism and Sleep Apnea

Hypothyroidism is a condition where the body produces insufficient amounts of thyroid hormones, the most important of which is Thyroxine. Hypothyroidism produces many complications in the body including fatigue, loss of muscle tone, weight gain and sleep apnea, among others. It is thought that the symptoms of Hypothyroidism (swollen tongue and soft tissue in the mouth and throat) are responsible for the Sleep Apnea. As stated earlier, another frequent symptom of hypothyroidism is obesity, which can also cause sleep apnea.

This similarity in presenting symptoms raises a question on how patients with suspected OSA should be evaluated.

 Fluid retention may lead to pulmonary edema and cardiac failure

Complications of sleep apnea may lead to cardiac failure in some patients. Patients with hypertension are already at risk of developing cardiac failure and it is thought sleep apnea may increase the likelihood of this occurring. This in turn may result in gain in weight in some CPAP users.

Conclusion

It’s all may be confusing to patients. I would recommend CPAP users must monitor their weight regularly and if there is substantial gain, then they should consult the physician. They also should start workout programmes to burn excess calories they saved overnight by decreased energy expenditure during work of breathing which is taken over by CPAP machine.

What is Sleep Apnea?

Sleep apnea is a condition in which one stops breathing while asleep. During sleep, your breathing is interrupted by repeated pauses known as apneic events.

How we breathe while sleeping?

With normal respiratory drive, after exhalation, the blood level of oxygen decreases and that of carbon dioxide increases. Exchange of gases with a lungful of fresh air is necessary to replenish oxygen and rid the bloodstream of built-up carbon dioxide. Oxygen and carbon dioxide receptors in the blood stream (chemo receptors) send nerve impulses to the brain, which then signals reflex opening of the larynx and movements of the rib cage muscles. These muscles expand the chest cavity so that a partial vacuum is made within the lungs and air rushes in to fill it.

Types of Sleep Apnea

The types of sleep apnea include: obstructive sleep apnea, which is the most common form of sleep apnea; central sleep apnea; and mixed (or complex) sleep apnea, which combines the two other types.

Sleep apnea is a killer disease and can cause many serious health problems. It can increase the risk for stroke, obesity, diabetes, heart attack, heart failure, irregular heartbeat, and high blood pressure. It may also increase the risk for accidents while working or driving, as some people with sleep apnea may fall asleep during those activities.

What Is Central Sleep Apnea?

In central sleep apnea, breathing is disrupted regularly during sleep because of the way the brain functions. It is not that you cannot breathe (which is true in obstructive sleep apnea); rather, you do not try to breathe at all. The brain does not tell your muscles to breathe. This type of sleep apnea is usually associated with serious illness, especially an illness in which the lower brainstem — which controls breathing — is affected.

In central sleep apnea, the basic neurological controls for breathing rate malfunction and fail to give the signal to inhale, causing the individual to miss one or more cycles of breathing.

In general, the main risk factors for sleep apnea are male, being overweight, and being over 40 years of age. However, anyone can have any of the types of sleep apnea.

Central sleep apnea is often associated with other conditions. One form of central sleep apnea, however, has no known cause and is not associated with any other disease. In addition, central sleep apnea can occur with obstructive sleep apnea, or it can occur alone.

Conditions that may be associated with central sleep apnea include the following:

• Congestive heart failure

• Hypothyroid Disease

• Kidney failure

• Neurological diseases, such as Parkinson’s disease, Alzheimer’s disease, and amyotrophic lateral sclerosis.

• Damage to the brainstem caused by encephalitis, stroke, injury, or other factors

What happens to breathing in Sleep Apnea?

During central apneas, the central respiratory drive is absent, and the brain does not respond to changing blood levels of the respiratory gases. No breath is taken despite the normal signals to inhale. The immediate effects of central sleep apnea on the body depend on how long the failure to breathe endures. At worst, central sleep apnea may cause sudden death.

Symptoms of Central Sleep apnea

The main symptom of central sleep apnea is temporary stoppages of breathing while asleep. Although snoring is a very strong symptom of obstructive sleep apnea, snoring is usually not found with central sleep apnea. The central sleep apnea is rare when compared to obstructive sleep apnea. The symptoms of central sleep apnea are for the most part the same as those of obstructive sleep apnea. They include chronic fatigue, daytime sleepiness, morning headaches and restless sleep. But if the cause is a neurological disease, the CSA sufferer may also experience difficulty swallowing, voice changes, and an overall sense of weakness and numbness.

If the pause in breathing is long enough, the percentage of oxygen in the circulation will drop to a lower than normal level and the concentration of carbon dioxide will build to a higher than normal level. Brain cells need constant oxygen to live, and if the level of blood oxygen goes low enough for long enough, the consequences of brain damage and even death will occur. Fortunately, central sleep apnea is more often a chronic condition that causes much milder effects than sudden death.

In any person, hypoxia and hypercapnia have certain common effects on the body. The heart rate will increase, unless there are such severe co-existing problems with the heart muscle itself or the autonomic nervous system that makes this compensatory increase impossible. The more translucent areas of the body will show a bluish or dusky, which is the change in hue that occurs owing to lack of oxygen in the blood (“turning blue”).

DIAGNOISIS

After taking a sleep history, overnight sleep study called a polysomnogram is conducted. This test is performed in a sleep lab or home under the direct supervision of a trained technologist. During the test, the following body functions may be monitored:

• Electrical activity of the brain

• Eye movements

• Muscle activity

• Heart rate

• Breathing patterns

• Air flow

• Blood oxygen levels

After the study is completed, the technologist will tally the number of times that breathing is impaired during sleep and then grade the severity of sleep apnea. In some cases, a multiple sleep latency test is performed on the day after the overnight test to measure how quickly you fall asleep. In this test, patients are given several opportunities to fall asleep during the course of a day when they normally would be awake.

Any individual, no matter how healthy, who is given enough of a central respiratory depressant drug, will develop apnea on a central basis. Generally, drugs that are sedative effects, alcohol, opiates can make central apnea worse.

Should these individuals have general anesthesia, for example, they require prolonged monitoring after initial recovery, as compared to a person with no history of sleep apnea, because apnea is likely to occur with even low levels of the drugs in their system.

Premature babies with immature brains and reflex systems are at high risk for central sleep apnea syndrome, even if these babies are otherwise healthy. Fortunately, those premature babies who have the syndrome will generally outgrow it as they mature, providing they receive careful enough monitoring and supportive care during infancy to survive. Because of the propensity toward apnea, medications that can cause respiratory drive depression are either not given to premature infants, or given under careful monitoring, with equipment for resuscitation immediately . Cot death or sudden deaths in infants are sometimes attributable to sleep apnea.

Central Apnea and Heart Diseases

Adults suffering from congestive heart failure are at risk for a form of central sleep apnea called Cheyne-Stokes respiration. This is periodic breathing with recurrent episodes of apnea alternating with episodes of rapid breathing. In those who have it, Cheyne-Stokes respirations occur while both awake and asleep. There is good evidence that replacement of the failed heart cures central apnea in these patients. The uses of some medications that are respiratory stimulants decrease the severity of apnea in some patients. There is an association between atrial fibrillation and central sleep apnea.

How Is Central Sleep Apnea Treated?

If central sleep apnea is associated with some other condition, such as congestive heart failure, that condition is treated.

Some of the more conservative treatments for obstructive sleep apnea would likely benefit people with central sleep apnea as well. Some of these conservative treatments include:

• Losing weight if necessary, and then maintaining a healthy weight

• Avoiding the use of alcohol and sleeping pills, as these items make the airway more likely to collapse during sleep

• Sleeping on your side if you have apneic events when sleeping on your back, possibly using pillows or other devices to keep you in place

• Using nasal sprays or breathing strips to keep air flowing if you have sinus problems or nasal congestion

• Avoiding sleep deprivation

Another treatment is continuous positive airway pressure (CPAP), which is the preferred initial treatment for most people with obstructive sleep apnea. The treatment has been beneficial in people with central sleep apnea, as well. This is especially true of people who have central sleep apnea associated with heart failure.

With CPAP, patients wear a mask over their nose and/or mouth. An air blower forces air through the nose and/or mouth. The air pressure is adjusted so that it is just enough to prevent the upper airway tissues from collapsing during sleep. The pressure is constant and continuous. CPAP prevents airway closure while it is being used, but apnea episodes return when CPAP is stopped or is used improperly. Other styles and types of positive airway pressure devices are available for people who have difficulty tolerating CPAP.

Treatment for central sleep apnea differs slightly in that the device is not set at one optimal constant pressure as with CPAP, but at two different settings for inhalation (IPAP) and for exhalation (EPAP), therefore aiding respiration. Other specifications, for instance the breathing rate and the duration of a single breath, can also be programmed. This device is called BiPAP (bi-level positive airway pressure, meaning it is set at two different pressures). Both CPAP and BiPAP devices can be connected to a humidifier to humidify and heat the inhaled air, thus reducing unpleasant symptoms such as a sore throat or blocked nose that can result from inhaling cold, dry air.