Chapter 2: Obstructive Sleep Apnea

Introduction

Obstructive sleep apnea (OSA) is a highly prevalent disorder typified by repeated episodes of complete or partial pharyngeal collapse and airway obstruction occurring during sleep. It is estimated by the seminal Wisconsin Sleep Cohort that OSA affects 3% of middle-aged women and 9% of middle-aged men, with incidence increasing in parallel with society’s worsening obesity rates. OSA is among the most common problems seen by Otolaryngologists and a recent NEJM (New England Journal of Medicine) editorial has described OSA as a “perioperative epidemic.”

Sleep Disordered Breathing

The term sleep disordered breathing (SDB) refers to a large number of sleep-related breathing problems, of which OSA is just one, the others being beyond the scope of this chapter. In regards to obstructive diseases specifically, the severity can range from simple snoring to life-threatening obstruction. The more commonly employed terms are stated below.

Primary Snoring

Primary snoring is defined as snoring without concomitant arousals or sleep fragmentation. All patients with OSA will snore, but not all snorers have OSA. Although not pathological in and of itself, snoring can be associated with altered sleep habits (because of bed partner dissatisfaction). Additionally, there is emerging evidence that the physical trauma of the snoring vibrations on neck structures can be independently associated with carotid artery stenosis and stroke.

Upper Airway Resistance

Upper airway resistance remains poorly defined in the literature. It is generally accepted to consist of respiratory events during sleep that are not severe enough to qualify as apneas or hypopneas, but still lead to sleep fragmentation and daytime symptoms.

Obstructive Sleep Apnea

OSA is formally defined as repetitive episodes of airway obstruction consisting of either hypopneas (partial obstruction associated with hypoxia and brief sleep arousal) or apneas (complete obstruction for minimum of 10 seconds associated with hypoxia and brief arousal). In OSA evidence must also exist of respiratory effort being made in association with the decreased or absent airflow, in order to differentiate this from central sleep apnea (in which no respiratory efforts are made). Respiratory events in OSA are more common during stage 2 or rapid-eye-movement (REM) sleep, which in the adult are the largest proportional sleep stages.

Impact of OSA on Personal Health

• Snoring

• Witnessed choking or gasping

• Frequent body moments

• Disproportionate fatigue

• Daytime somnolence

• Morning headaches

• Sensation of unrefreshing sleep

• Memory loss

• Sexual dysfunction

• Personality changes

Impact of OSA on Society

• Increased odds-ratio of motor vehicle accidents (MVAs)

• Loss of economic productivity

• Workplace accidents

• Patients with OSA are known to use more health-care resources

Medical Consequences of Untreated OSA

Hypertension

OSA is an independent risk factor for hypertension (HTN) ...