Sleep apnea is a sleep disorder causing pauses in respiration during sleep, and each episode results in missing of one or more breaths, and such apneas occur recurrently throughout sleep period. The respiratory control mechanism is less effective during sleep and brief periods of apnea occur in normal sleeping adults. During sleep there is decreased sensitivity to low PCO2 (Partial pressure of Carbon dioxide). Because of this decreased sensitivity, PCO2 may fall during sleep which may lead to apnea. Sometimes it produces sleep apnea syndrome, i.e., when it occurs repeatedly the patient wakes up frequently and the loss of sleep causes headache, tiredness, confusion, and poor performance during daytime.
In normal adults, sleep apnea occurs during REM (rapid eye movement) sleep, when muscles are most hypotonic. Resistance against waking is high during this type of sleep. Sleep apnea is said to be present if more than 5 apneic episodes occur per hour of sleep, or more than 30 apneic episodes during night. Sleep apnea is diagnosed by polysomnographic studies during sleep.
Causes of Sleep Apnea
- Old Age
- Hypnotics which produce respiratory depression
Causes are prolapse of enlarged tongue and inspiratory collapse of the hypopharynx. Sleep apnea can be relieved to some extend by advising the subjects not to sleep on their backs. Decrease in PCO2 is the main cause for sleep apnea especially during REM sleep. The respiratory centre is less sensitive to hypercapnia which causes further decrease in PCO2 followed by apnea. Obesity is also a major cause for sleep apnea as it causes rhythm disorders like atrial fibrillation which can ultimately lead to heart failure. Sleep apnea may also be caused by obstruction of airway during inspiration. Two causes are known. Pharyngeal muscles relax during sleep,especially REM sleep, leading to respiratory obstruction. Failure of genioglossus muscle of tongue to contract during inspiration, and tongue falls back and obstructs the airway.
Symptoms of Sleep Apnea
- Loud snoring
- Morning headache
- Daytime sleepiness
- Apneic episodes during sleep
Complications of Sleep Apnea
Sleep Apnea causes pulmonary hypertension which can lead to pulmonary edema resulting in death. It also causes heart failure and myocardial infarction due to excessive clot formation in the arteries supplying the heart. This can result in stroke as an offshoot of heart attack.
Increased incidence of motor vehicle accidents is also a complication. This is primarily due to fatigue and headache. Sleep apnea is also one of the explanations for sudden infant death syndrome (SIDS).
Treatment of Sleep Apnea
To prevent obstruction of the airway, the common problem leading to sleep apnea, there is a treatment which is the best for this disorder. In keeping the upper airway unobstructed, it is necessary to support the airway with a continuous flow of air delivered through a face mask worn while asleep. This most common treatment method is termed as Continuous Positive Airway Pressure or CPAP therapy.
CPAP therapy is the best solution in moderate to severe sleep apnea. However many individuals can’t bear it. In such cases, other treatments might be pursued.
Weight loss is an ideal solution. Surgery to remove excess tissue in the throat opens up the pathway and allows easy sleep. Positional sleep aids such as sleep shirts or wedges also serve the purpose of opening the windpipe for easy breathing. Dental device to move lower jaw forward and oxygen support are some alternatives.