202
Endothelial Dysfunction
Research has supported a relationship between OSA and endothelial dysfunction as
measured by forearm vascular flow, carotid intima-media thickness, carotid-femoral
pulse-wave velocity and number of circulating endothelial progenitor cells, and lev-
els of vascular endothelial growth factor (VEGF).
Metabolic Factors
Obesity is common to both HTN and OSA; studies have shown that obese individu-
als (BMI > 40) are five times as likely to require three antihypertensive medications
as compared with patients whose body mass index is normal [ 41 ]. It is therefore
crucial that any examination of the relationship between OSA and hypertension
attempt to control for the presence and degree of obesity. OSA has also been linked
to impaired glucose tolerance and prediabetes [ 42 ].
Other Consequences of OSA
Aside from its contribution to hypertension, OSA has been linked with other long-
term health consequences and impairments in quality of life. Patients with OSA are
also at increased risk of pulmonary arterial hypertension, coronary artery disease,
cardiac arrhythmias, heart failure, stroke, insulin resistance, type 2 diabetes, and
nonalcoholic fatty liver disease. Motor vehicle crashes are two to three times more
common among patients with OSA than those without the disorder.
Diagnosis of OSA
The diagnosis of OSAS is based on a constellation of symptoms, clinical findings,
and overnight sleep testing, as shown in Table 13.2. In adults, a diagnosis of OSA is
made when either of the following is present:
- Five or more obstructive respiratory events per hour of sleep in a patient with
appropriate clinical symptoms or medical comorbidities - Fifteen or more obstructive respiratory events per hour of sleep regardless of
associated symptoms or comorbidities
Qualifying clinical symptoms in the above diagnosis include excessive sleepiness,
non-restorative sleep, fatigue, insomnia, habitual snoring, subjective nocturnal respira-
tory disturbance, and observed apneas, while comorbidities include HTN, mood disor-
der, cognitive dysfunction, coronary artery disease, stroke, congestive heart failure, atrial
fibrillation, and type 2 diabetes.
L.A. Tobias and F. Roux