Introduction

Introduction

Sleep apnea is a disorder in which a person stops breathing during the night, perhaps hundreds of times, usually for periods of 10 seconds or longer and sometimes for as long as a minute. These gaps in breathing are called apneas. Apnea literally meaning absence of breath.

Sleep apnea is usually accompanied by snoring. People might not even know they have the condition. It inevitably causes daytime sleepiness.

Sleep apnea is grouped into three categories:

• Obstructive
• Central
• Mixed

There is also another, less severe form of obstructed breathing called upper airway resistance syndrome (UARS).

Obstructive Sleep Apnea

Obstructive sleep apnea (OSA) is the most common form of apnea. It occurs when tissues in the upper throat collapse at different times during sleep, thereby blocking the passage of air. In general, OSA occurs as follows:

• On its way to the lungs, air passes through the nose, mouth, and throat (the upper airway).
• Under normal conditions, the back of the throat is soft and tends to collapse inward as a person breathes.
• Dilator (widening) muscles work against this collapse to keep the airway open. Interference or abnormalities in this process cause air turbulence.
• If the tissues at the back of the throat collapse and become momentarily blocked, apnea occurs. Breath is temporarily stopped. In most cases the person is unaware of it, although sometimes they awaken and gasp for breath.
• In some cases, the interference is incomplete (called obstructive hypopnea) and causes continuous but slow and shallow breathing. In response, the throat vibrates and makes the sound of snoring. Snoring can occur whether a person breathes through the mouth or the nose. (Snoring also occurs without sleep apnea.)
• Apnea decreases the amount of oxygen in the blood, and eventually this lack of oxygen triggers the lungs to suck in air.
• At this point, the patient may make a gasping or snorting sound but does not usually fully wake up.

Obstructive sleep apnea is defined as five or more episodes of apnea or hypopnea per hour of sleep that occur in individuals who have excessive daytime sleepiness.