Approach

The patient's bed partner should preferably be present during the interview to establish or confirm sleep and wake symptoms.

Polysomnography is the definitive test for diagnosis, but unattended home sleep tests using fewer parameters may be used to establish the diagnosis.

Clinical evaluation

OSA is a heterogeneous disease; clinical presentation is highly variable.[57]

Typical presenting signs and symptoms may include sleep disturbance, sensation of obstructed breathing, chronic snoring, episodic gasping and breath holding, apneas during sleep, restless sleep, insomnia, breath holding, unrefreshing sleep, and diurnal sleepiness (despite adequate sleep opportunity).[1]​​[58]​ Women commonly present with insomnia and depression.[59][60]

Patients may also report nocturnal heartburn, dry mouth, nocturia, nasal obstruction, and waking with a headache.

Signs commonly observed by the patient's bed partner include chronic snoring, episodic gasping, episodes of apnea, restless sleep, sweating, and excessive daytime sleepiness.

Symptom severity tends to worsen with nasal obstruction, tobacco smoking, alcohol use, and weight gain.[48][61]​​

Diurnal sleepiness and deteriorating neurocognitive function

Daytime sleepiness may adversely affect job performance, mood, and the patient's ability to operate motor vehicles. The patient may report a history of motor vehicle accidents due to sleepiness while driving.[26][27]​​ Mild to moderate Apnea-Hypopnea Index (AHI) elevation in older people may not be associated with diurnal sleepiness.[62]

The patient's level of daytime fatigue can be assessed using the Epworth Sleepiness Scale. [ Epworth Sleepiness Scale (ESS) Opens in new window ] ​ The patient is asked to rate their likelihood of falling asleep during passive or active activities. A score <10 indicates average diurnal sleepiness (compared to the general population); >10 suggests excessive sleepiness depending on the situation. The Epworth Sleepiness Scale alone is insufficient to diagnose, or exclude, OSA. Alerting factors may influence the ESS score.

Patients may present with deteriorating neurocognitive function - including attention, learning, and memory - and personality changes, such as irritability.[24][63]​​ There are some patients who do not admit to having any symptoms, nor dysfunction secondary to OSA, and they are thus more difficult to treat.

History and risk factors

A history of family members who have OSA, or who snore, is common. The patient may have a history of cardiovascular disorders and events, including treatment-resistant hypertension, dysrhythmias, myocardial infarction, stroke, and erectile dysfunction.[64]

Established risk factors for OSA include obesity, maxillomandibular anomalies, polycystic ovary syndrome, hypothyroidism, and mucopolysaccharidoses, among others.[4][13][28][34][43][46][47] 

Patients with macroglossia and/or abnormalities of the mandible are more likely to experience episodes of apnea and may report a history of difficult intubation or airway obstruction with anesthesia. Patients with a history of extraction of noncarious teeth, performed for crowding of dentition in a narrowed mandible and/or maxilla, are at increased risk of experiencing episodes of apnea.[65]​​​

Physical exam

Patients are often overweight or obese and have a large neck circumference (≥40 cm). Some may not be overweight, but have maxillomandibular anomalies. Excessive protrusion of the upper incisors (overjet) and narrowed maxillary and mandibular alveolar arches may be noted in both obese and nonobese patients. Evidence of dental extractions performed for crowding may be present (e.g., missing premolars), associated with a narrow maxilla and crowding.

The exposure of the oropharynx is often limited by a relatively large tongue with lateral crenations (scalloping), resting above the occlusal plane. Increased volume of pharyngeal soft tissue, including increased soft palate length, tonsillar size, uvular length and thickness, and tonsillar pillar width, contributes to narrowing of the oropharynx, as does elongation and webbing of the soft palate to the uvula. The soft palate-to-posterior pharyngeal wall distance may be shortened.

Cardiopulmonary exam is advised given association of OSA with hypertension, dysrhythmias, congestive heart failure, and pulmonary hypertension.[64][66]​​

Awake fiberoptic endoscopy should be performed in the clinic to exclude the presence of hypertrophic lingual tonsils or lesions, such as nasal polyps or tumors (pharyngeal, parapharyngeal, or laryngeal tumors), and to assess structures and sites mediating obstruction. This is particularly relevant for a continuous positive airway pressure (CPAP)-intolerant patient or for preoperative evaluation. The pharyngeal airway is usually narrowest when the patient is in the supine position at end expiration, and hypopharyngeal narrowing is commonly observed when the mouth is open.

Laboratory evaluation

Attended polysomnography at a sleep laboratory is the definitive test, but OSA is more commonly diagnosed at home using unattended studies. An Apnea-Hypopnea Index (AHI) or Respiratory Event Index (REI, index in portable testing) of ≥15 episodes/hour confirms the diagnosis of OSA. However, 5 episodes/hour is considered sufficient for diagnosis in a symptomatic patient or in a patient with hypertension, ischemic cardiac disease, history of stroke, excessive daytime sleepiness, insomnia, mood disorder, or cognitive dysfunction.[67]​​​

Polysomnography commonly includes a number of components:[68]

  • Electroencephalographic (EEG) array: to determine sleep from wake and to stage sleep.

  • Electrooculographic recording: to determine sleep/wake, and especially rapid eye movement (REM) staging.

  • Sensors to assess air flow (expiratory: nasal pressure sensor and/or oronasal thermistor sensor) and respiratory effort (expiratory: thoracic and abdominal piezo sensors): used to determine whether flow cessation is due to obstruction versus absence of effort.

  • Electromyographic recording of limb activity and chin muscle activity: to determine the presence of periodic limb movements and assist with sleep/wake stage determination.

  • Capnography (end tidal or transcutaneous) and esophageal manometry: sometimes used to assess hypoventilation and breathing effort, respectively.

  • ECG and heart rate: to assess for cardiac dysrhythmias and autonomic (sympathetic) activation.

  • Pulse oximetry: to score hypopneas and assess for hypoxemia. The properties of the oximeter and its setting, such as the sampling rate, may significantly affect the sensitivity of the test.

Continuous positive airway pressure (CPAP) titration

If a full night study is performed to diagnose OSA, the patient may return for CPAP titration (or begin treatment using an autoadjusting PAP device).

During a CPAP titration study, the therapeutic CPAP level is determined, and proper interface fitting and troubleshooting is performed. In a split study, the diagnosis and CPAP titration are performed on the same night. This may be more cost effective as it only requires one night of monitoring. However, titration may not be successful if sleep duration is inadequate.

More often and more efficiently, auto-titrating devices may be used at home in lieu of attended CPAP titration. The absence of a sleep technician to exchange different interfaces and troubleshoot problems during sleep may potentially be problematic.[69] Nonetheless, autoadjusting positive airway pressure expedites treatment initiation, may be better tolerated by some, may reduce aerophagia, and can adapt pressure to variable conditions such as weight changes and alcohol intake.[70]

Determining the Apnea-Hypopnea Index (AHI)

To determine the AHI, the number of apneas and hypopneas are scored per hour of sleep. Obstructive apneas are defined by thermistor or nasal pressure sensor signal drop of ≥90% for at least 10 seconds with evidence of continued respiratory effort. Hypopneas are defined by either nasal pressure signal drop for at least 10 seconds of ≥30%, associated with ≥3% oxygen desaturation or arousal (1A, recommended), or by nasal pressure signal drop of ≥30%, associated with ≥4% oxygen desaturation (1B, acceptable).[71] The term REI is the preferred term to signify the AHI per hour of recorded time for portable (home) testing where sleep time is not quantitated. However, some people may still be using the term RDI (Respiratory Disturbance Index), which can cause confusion as the RDI term is technically inclusive of respiratory effort-related arousals (RERAs).

If OSA is suspected but the test is not confirmatory, possible confounding factors include sleep position, shortened sleep time, altered sleep stage percentages (i.e., REM), or other changes from routine sleep conditions. The test may be repeated.

Portable multichannel home sleep apnea tests

Polysomnography is a costly technique for OSA detection, and portable, unattended, home studies that incorporate fewer channels (e.g., pulse oximetry, flow transducers, effort sensors, snore sensors, peripheral arterial tonometry, mandibular movements, respiratory sounds, and position sensors) may be used.[72][73][74]​

When used in high OSA probability patients, portable studies may be combined with home automatic positive airway pressure titration to yield similar adherence and functional improvement results as those obtained in the laboratory.[75] The American Academy of Sleep Medicine recommends that portable studies be used for patients with high pretest probability of OSA when used as part of a comprehensive clinical sleep evaluation in patients without major comorbidities (e.g., cardiopulmonary disease, chronic opioid therapy, or neuromuscular disease).[39][76]​​[Evidence B]​​ The REI may underestimate severity in those portable tests that do not include sleep-wake assessment as the index is diluted by time spent awake during recording.[77]

Peripheral arterial tonometry (PAT)

A method incorporated into a portable sleep test system used to diagnose OSA where sympathetic discharges associated with arousals during sleep are detected in a device worn on a digit.[78] In some devices, PAT measurement is combined with actigraphy, position sensors, chest movement, and oximetry, and can therefore estimate sleep and stage sleep. It has the added advantage of not requiring sensor application on the head. Testing devices using PAT can reliably and comfortably be used to diagnose OSA and objectively assess treatment outcomes as they can be easily used concurrently with positive airway pressure. 

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