Sleep Apnea and Relevant Sleep Disorders

The most common sleep disorder is insomnia. Insomnia represents difficulty in initiating and/or maintaining sleep along with daytime tiredness and impairment. Of note to the dentist, sleep bruxism would fall under the umbrella of a sleep movement disorder.

The topic at hand is sleep apnea. Sleep apnea is classified under sleep breathing disorders (SBD). These disorders range from basic snoring to sleep apnea-hypopnea syndrome (SAHS). While snoring may not always present with adverse effects, SAHS is associated with daytime sleepiness and cognitive issues and an increased risk of developing health issues. Central sleep apnea is a form of SAHS which features a diminished central nervous system drive to breathe. Conversely, obstructive sleep apnea (OSA) implies a mechanical impedance to upper airway airflow. It is in this OSA arena that the dental profession has expanded its service line. While there are several ways to manage OSA, one of the management strategies involves use of a specialized oral appliance.

OSA is a result of recurrent episodes of complete or partial blockage of the upper airway despite respiratory effort. Apnea is a cessation of breathing attributed to complete airway obstruction during sleep. Hypopnea involves episodes of labored breathing or a low respiratory rate that does not meet metabolic needs and is attributed to partial obstruction of the airway.

An obstructive apnea or hypopnea event, by definition, lasts at least 10 seconds and meets one of the two following features (AASM Task Force, 1999):

1. Substantial reduction in airflow (> 50%) relative to a baseline of the preceding two minutes.

2. Moderate reduction in airflow (< 50%) with blood oxygen desaturation (> 3%) relative to a baseline of the preceding two minutes or an electroencephalographic evidence of cortical arousal.

Per the American Academy of Dental Sleep Medicine (www.aasm.org), apnea and hypopnea can be further defined:

• Apnea is reported when there is ≥90% reduction in airflow for >10 seconds.

• Hypopnea is scored when all of the following criteria are met:

1. The peak signal excursions drop by ≥30% of pre-event baseline using nasal pressure (diagnostic study), PAP device flow (titration study), or an alternative hypopnea sensor (diagnostic study).

2. The duration of the ≥30% drop in signal excursion is ≥10 seconds.

3. There is a ≥3% oxygen desaturation from pre-event baseline and/or the event is associated with an arousal.

# A complete scoring of a polysomnogram is beyond the scope of this presentation. Interested readers are encouraged to review resources available at the AASM website.

## MEDICARE scores OSA differently.

The AASM Scoring Manual recommended definition requires that changes in flow be associated with a 3% oxygen desaturation or a cortical arousal, but allows an alternative definition that requires association with a 4% oxygen desaturation without consideration of cortical arousals.