Sleep apnea syndrome
The analysis of multiple physiological variables recorded during sleep, known as polysomonography, is an important method for research into the control of breathing that has had increasing using in clinical evaluation of sleep disturbances. In normal sleep, reduced dilatory upper-airway muscle tone may be accompanied with brief intervals with no breathing movements. Some people, typically overweight and predominantly men, exhibit more severe disruption of breathing, referred to as sleep apnea syndrome. Sleep apnea is classified into two broad groups.
- Obstructive
- Central
In central sleep apnea, breathing movements cease for a longer than normal interval .In obstructive sleep apnea; the fault seems to lie in a failure of the pharyngeal muscle to open the airway during inspiration. This may be the result of decreased muscle activity, but the obstruction is worsened by an excessive amount of neck fat with which the muscle must contend. With obstructive sleep apnea, progressively larger inspiratory efforts eventually overcome the obstructive and airflow is temporarily resumed, usually accompanied by loud snoring.
Some people exhibit both central and obstructive sleep apneas. In both types, hypoxemia and hypercapnia develop progressively during the apnea intervals. Frequent episodes of repeated hypoxia may lead to pulmonary and systemic hypertension and to myocardial distress; the accompanying hypercapnia is thought to be a cause of the morning headache these patients often experience. There may be partial arousal at the end of periods of apnea, leading to disrupted sleep and resulting in drowsiness during the day.
Daytime sleepiness, often leading to dangerous situations, is probably the most and most debilitating symptoms. The cause of this disorder is multivariate and often obscure, but mechanically assisted ventilation during sleep result in significant symptomatic improvement.
Reference:
- Medical physiology, Lippincott Williams & Wilkins 3rd edi.
- mayoclinic.com
- medicinenet.com
- nhlbi.nih.gov
- health.nytimes.com
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