Sleep Apnea
During
sleep, all body functions slow down and body muscles relax. This
relaxation involves the muscles of the upper airway which help in
keeping our airway patent and hence facilitates movement of air
from and to the lungs. This relaxation in the muscles of the upper
airway does not affect the patency of the upper airway in most
people. However, certain people are prone to obstruct their upper
airway during sleep either partially or completely. In that group
of people, the upper airway repeatedly collapses, causing
cessation of breathing or inadequate breathing which result in
sleep fragmentation. Sleep fragmentation in turn, results in
chronic excessive daytime sleepiness. Complete airway obstruction
during sleep is known as Obstructive Sleep Apnea (OSA) and its
milder form is known as the Upper Airway Resistance Syndrome.
OSA is a known medical problem that requires medical attention. If
left untreated it results in a number of medical complications
some of them are potentially life threatening. It affects 2-4% of
middle age people. It has been estimated that 18 million Americans
have sleep apnea.
Identification:
The key features that indicate a high probability of
OSA are; excessive daytime sleepiness, snoring, pauses in
breathing during sleep and gasping or choking during sleep.
Patients with OSA are usually middle-aged males who are
overweight. However, this disorder occurs in all age groups and
both sexes and can affect thin people. Some patients may have
physical abnormality in the nose, throat, or other parts of the
upper airway. Ingestion of alcohol and sleeping pills increases
the frequency and duration of breathing pauses in people with
sleep apnea.
How does airway obstruction affect sleep?
During airway obstruction, the patient is unable to breathe in
oxygen and to exhale carbon dioxide, resulting in low levels of
oxygen and increased levels of carbon dioxide in the blood. The
reduction in oxygen and increase in carbon dioxide alert the brain
to resume breathing and cause arousal. With each arousal a signal
is sent from the brain to the upper airway muscles to open the
airway; breathing is resumed, often with loud snort or gasp.
Frequent arousals, although necessary for breathing to restart,
prevent the patient from getting enough restorative deep sleep.
The arousals are very short and most patients do not recall them.
What are the consequences of airway
obstruction during sleep?
Due to the serious disturbances in their normal sleep patterns,
people with airway obstruction during sleep often feel very sleepy
during the day and their concentration and daytime performance
suffer. The consequences of this sleep disorder range from
annoying to life threatening. They include symptoms suggesting
depression, irritability, sexual dysfunction, learning and memory
difficulties, and falling asleep when the patient does not want
to. It has been estimated that up to 50% of patient with
obstructive sleep apnea have high blood pressure. Fifty to sixty
percent of patients with impaired heart function suffer from sleep
related breathing disorders. If left untreated, obstructive sleep
apnea can cause hypertension, irregular heart beat, heart attack,
stroke, motor vehicle and work related accidents due to sleepiness
(the risk of motor vehicle accident is three times higher in
patients with sleep apnea compared to normal), and poor quality of
life.
How is airway obstruction during sleep
diagnosed?
Diagnosis of sleep apnea is not simple because there can be many
different reasons for disturbed sleep. Overnight sleep study (polysomnography)
is the test used to both diagnose the disorder and determine its
severity.
How is airway obstruction during sleep
treated?
Treatment is tailored to each individual patient based on medical
history, physical examination and the results of the sleep study.
The basic problem in patients with these disorders is airway
obstruction, which prevents air from moving in to the lungs.
Therefore, oxygen usually does not help in these patients as it
does not overcome the mechanical obstruction. Medications are
generally not effective in obstructive sleep apnea patients.
The approach to the management of airway obstruction has two
components; general measures and specific measures.
General Measures: there are few things that are known to enhance
the chance of airway obstruction during sleep like; sleeping
pills, alcohol and smoking. Therefore, they should be avoided. In
some patients with mild forms of airway obstruction, snoring and
airway obstruction happens when they sleep on their back. In those
patients sleeping on the side may help eliminating the problem.
Such task can be achieved by using some techniques like sewing a
pocket in the back of the pijama and putting a tennis ball in it.
That will make it uncomfortable to sleep on the back and will
gradually train the patient to adopt sleeping on the side.
Overweight people are at an increased risk of airway obstruction
during sleep. Therefore, losing weight may help. Losing 10% of
body weight may result in significant reduction in the obstructing
events.
In most cases, general measures do not result in complete cure and
need to be supplemented with specific measures.
Specific Measures:
Positive airway pressure (CPAP): this
is the gold standard treatment for patients with airway
obstruction during sleep. Basically, the patient wears a nasal
mask that is connected to a machine that pushes air under positive
pressure. This positive pressure air acts as a splint to prevent
airway collapse. The machine pressure is adjusted during the
overnight sleep study and the minimal pressure required to
eliminate airway collapse is used. The patient has to wear it each
time he/she goes to sleep. The machine is small and light (≈1.5
kg). It is not noisy and most patients get used to it after some
time.
Dental appliances: Plastic devices
that is designed by the dentist and put inside the mouth during
sleep to reposition the lower jaw in order to increase the airway
size. They have been shown to be helpful in some patients with
mild airway obstruction and those who snore but do not have airway
obstruction. It may cause soreness of the jaw in some patients.
Surgery: Several surgical techniques have been developed to
increase the size of the airway and hence treat airway
obstruction. In children with airway obstruction, surgery is
generally the treatment of choice in most of them. However, in
adults, the success rate is variable and depends on the experience
of the medical center and the surgeon. The long-term side effects
and benefits of most surgical procedures are not known yet and it
is difficult to predict which patients will do well. It is
important for patients to realize that surgery may eliminate
snoring but not necessarily airway obstruction. Therefore, all
patients should have a follow up overnight sleep study after
surgery.
Ahmed BaHammam, FRCP, FCCP
Professor of Medicine
Director, Sleep Disorders Center
College of Medicine, King Saud University
Associate Editor, Ann Thoracic Med
