Sleep-Disordered Breathing
Tomasz J. Kuz´niar, MD, PhD, and
Kamilla Kasibowska-Kuz´niar, MD, PhD
Introduction
Although descriptions of sleep-disordered breathing (SDB) have been
found in medical and nonmedical literature for centuries, most of our
current knowledge about this condition has been obtained in the past 30
years. SDB—snoring, limited respiratory flow leading to arousals or
oxihemoglobin desaturations (hypopneas), or complete cessation of
airflow (apneas)—are common and occur in up to 20% of the population.
1
If accompanied by symptoms, SDB has been classified into 3 general
categories: obstructive sleep apnea (OSA) syndromes, central sleep apnea
(CSA) syndromes, and sleep-related hypoventilation/hypoxemia syn-
dromes.
2
OSA is the most common of the 3 groups and its prevalence
depends on the diagnostic definition used; using the most conservative
definition of apnea-hypopnea index, AHI, Ͼ5 with excessive daytime
sleepiness, 2%-6% of the population have OSA.
1,3,4
CSA syndromes are less common in the general population and their
exact prevalence is unknown. CSA is more common in patients with
congestive heart failure (CHF) and chronic opioid use. Coexistence of
OSA and central apnea activity, the latter typically revealed on attempts
to correct obstructive events, is termed complex sleep apnea.
5,6
Finally,
obesity-hypoventilation syndrome is a disorder combining obesity (body
mass index Ͼ30 kg/m
2
) with evidence of daytime hypercapnia (PaCO
2
Ͼ
45 mm Hg).
Pathophysiology of Sleep Apnea
Small airway size is the main factor in the pathogenesis of OSA. As
proven in several studies, compared to healthy individuals and snorers,
patients with OSA have smaller airway lumen and larger amounts of
peripharyngeal soft tissue—lateral pharyngeal walls, tongue, and soft
palate.
7
This is reflected by an increased (less negative) airway closing
The authors have no financial support, conflicts of interest, or off-label or investigational use to
disclose.
Dis Mon 2011;57:394-402
0011-5029/2011 $36.00 ϩ 0
doi:10.1016/j.disamonth.2011.06.002
394 DM, August 2011