Introduction
Obstructive Sleep Apnea (OSA) is a breathing disorder that occurs during sleep. The muscular relaxation that occurs in the deepest stages of sleep can permit the soft palate and tongue to drop backwards causing a temporary closing of the breathing passage. The dynamic intermittent obstruction to breathing can sometimes be seen at the entrance to the voice box in contrast to the relatively fixed blockage seen within the nose.
The nocturnal obstruction to breathing can be complete or partial. A total blockage to breathing with no air movement for 10 seconds or more is called an apnea. OSA patients can have apneic events which last 45 seconds or even longer and happen multiple times during the night. As you would imagine, when breathing ceases for long periods of time, oxygen levels in the blood will drop. The lowest oxygen saturation (LSAT) recorded during sleep is one feature used as an indicator of disease severity. Partial blockages to breathing that reduce airflow below normal by more than one half for more than 10 seconds are called hypopneas. The average number of apneas and hypopneas per hour is called the respiratory disturbance index (RDI).
The repetitive night-time blockage to breathing interferes with the normal physiology of sleep. Normal sleep architecture is seen as characteristic EEG (electroencephalogram) waveforms and durations at the different levels of sleep. With OSA the normal EEG architecture is altered such that the deepest and most restful levels of sleep are minimized or abolished. How does this happen? While in the depth of sleep, airway occlusion occurs due to poor muscular tone. In response to an obstructive event, the brain partly awakens which is called an arousal. During an arousal muscular tone is increased and the obstruction to breathing is relieved. Multiple arousals from deep sleep occur all night long in response to the repetitive apneic and hypopneic events. Perhaps this is a natural defense mechanism which prevents suffocation, but at the expense of high quality sleep. Repetitive nocturnal obstruction to breathing results in poor quality sleep with visible symptoms of sleep deprivation.
Many factors may predispose to OSA. The character of the skeletal and soft tissues supporting the throat are important. A small lower jaw, large tongue, intrusive tonsils, enlarged adenoids and long floppy soft palate can be contributing features. Male gender, excess weight or obesity and aging are typical risk factors for OSA. The use of alcohol, sedatives, tranquilizers or antihistamines around bedtime can precipitate snoring and OSA.
The diagnosis of OSA is made by a test commonly called a sleep study or polysomnogram. This is preferably done in a facility accredited by the American Sleep Disorders Association (www.asda.org) and requires an overnight stay. The study measures multiple body functions which includes your efforts at breathing, oxygen levels, heart rhythms and EEG while you are asleep.
OSA is often treated by non-surgical methods. The standard non-surgical treatment is called continuous positive airway pressure (CPAP). Through a mask, the CPAP device pushes room air into the breathing passage which temporarily prevents the collapse of the airway. CPAP is not a cure, but a support measure. As such, when CPAP is not used nocturnal obstruction to breathing will occur again.
Surgery can successfully treat obstructive sleep apnea. Hence, one can avoid or eliminate the need for CPAP usage and provide satisfaction for those people who can not tolerate the treatment. The basic surgical strategy is to open the one or more sites of obstruction to breathing typically at the nose, palate or tongue base. Some of the procedures are well known such as removal of the tonsils, trimming of the soft palate or straightening the crooked septum. Other less known techniques enlarge the breathing passage behind the tongue. This may entail operation directly on the tongue tendons or indirectly on the jaw. The type of OSA surgery that you are offered is designed specifically for your particular problem since the blockage to breathing does not always occur in the same location. Various combinations of procedures are sometimes required in order to open the multiple areas of blockage. Snoring can also be eliminated allowing restful sleep for spouses and other family members. A brief overview of the current surgical options for treatment of OSA can be found on this web site.The material on this site should not be used to diagnose or treat sleep apnea or any other medical problem. If you feel you may have the disorder, please consult your physician.
