Signs and Symptoms
Snoring
Excessive daytime sleepiness is a highly subjective symptom
History and physical examination
Polysomnography
The cardinal symptoms are loud snoring and excessive daytime sleepiness. Since snoring is much more prevalent than OSA, your challenge as a clinician is to distinguish patients in whom snoring is a marker for pathology from those who have "benign" snoring. is a marker of turbulent airflow through a narrowed posterior pharynx . Apnea occurs when the pharynx closes completely. An history of observed apneas during sleep is strongly linked to a subsequent diagnosis of OSA. The greater the frequency of reported snoring and breathing pauses, the greater the likelihood that the patient has OSA.
Excessive daytime sleepiness is a highly subjective symptom and may not be a particularly useful discriminator, since it is neither sensitive nor specific for sleep apnea. Also, it may be denied by patients with chronic OSA, who come to believe that their daytime drowsiness is "normal." Various surveys have been designed to measure this symptom. The most noteworthy are the Stanford Sleepiness Scale and the Epworth Sleepiness scale.
Diagnosis
The initial evaluation of a patient presenting symptoms and signs of OSA should include an history and physical examination that are targeted toward the assessment of sleep-disordered breathing. If possible, as part of the clinical history, ask the bed partner whether the patient snores, chokes or gasps for breath, displays restlessness during sleep, or stops breathing. You should also ask the patient about excessive daytime sleepiness; although acknowledgment of sleepiness is neither necessary nor sufficient to establish the diagnosis of OSA, you should be suspicious if the patient describes a series of automobile accidents that may have been related to daytime fatigue.
The physical examination should focus on blood pressure (BP) measurements, assessment of any nasal obstruction and oropharyngeal narrowing, measurement of BMI and/or neck circumference, examination for signs of cor pulmonale -- loud pulmonic second heart sound (P2), right ventricular heave, pedal oedema -- and general assessment of level of alertness.
Patients in whom you suspect OSA should undergo overnight polysomnography (PSG) to confirm the diagnosis of a sleep-related breathing disorder. The full PSG study should include electroencephalography, electrooculography, chin electromyography, airflow, arterial oxygen saturation, respiratory effort, and electrocardiography. You can use PSG data to calculate the AHI and to separate central from mixed and obstructive apneic events. PSG can also indicate the severity of sleep disturbance, oxygen desaturation, cardiac rhythm status, and the presence of other sleep disorders such as periodic limb movements of sleep, circadian rythm disturbances, parasomnias, nocturnal seizures, and changes in sleep structure suggestive of narcolepsy. Patients with OSA who are candidates for nasal continuous positive airway pressure (CPAP) therapy can also undergo in-laboratory "split-night" titration to determine optimal CPAP treatment.
