Question 1

Polysomnography (PSG)

Accepted Answer

The definitive diagnosis to establish the presence of sleep apnea relies on a clinical evaluation during a sleep test and a polysomnography (PSG). This standardized test is reproducible and validated in research and clinically, and is the gold standard for diagnosing sleep apnea. Nocturnal polysomnography is the most comprehensive examination and remains the preferred choice for evaluating sleep-related breathing disorders. However, it requires a technician and must be performed in a laboratory or a sleep specialized clinic using heavy equipment. PSG consists of a night of recordings of various parameters for a duration of at least 6 hours. This comprehensive test allows for the diagnosis of several types of sleep disorders, including obstructive sleep apnea syndrome (OSAS), restless legs syndrome, and narcolepsy.

Question 2

Causes

Accepted Answer

Two main causes can explain sleep apnea: Obstruction • Apnea can be "obstructive" if it is accompanied by an obstruction or associated with metabolic syndrome. This is then referred to as obstructive sleep apnea syndrome (OSAS, or OSA). This is the most common type of sleep apnea. • Other factors that can contribute to obstructive sleep apnea include the presence of: • enlarged tonsils obstructing the airway, • excess fatty tissue in the throat in obese individuals, • an overly long soft palate, • a lower jaw that is too short or set back (mandibular retrognathia). • Obstructive apnea requires respiratory effort to overcome an obstruction in the upper airway (nose, mouth, pharynx, and larynx). • Obstruction can vary in severity and may be due to age (aging), malocclusion, hormonal imbalance, diabetes, enlarged adenoid tissues (tonsils, adenoids), or excess weight.

Question 3

Symptoms

Accepted Answer

The main symptoms of obstructive sleep apnea are: • unexplained daytime fatigue and drowsiness; • frequent and uncontrolled falling asleep; • snoring and breathing interruptions during sleep. Other signs and symptoms may include: • elevated blood pressure; • irritability; • sensation of choking or gasping at night; • extreme fatigue; • depression; • difficulty concentrating; • decline in academic performance (children); • morning headaches; • memory problems; • erectile dysfunction (impotence) • The severity of OSAHS includes 2 elements: the severity of daytime sleepiness and that of nocturnal respiratory abnormalities. (5)

Question 4

Cardiorespiratory sleep polygraphy (CRSP)

Accepted Answer

There is a simpler version of a sleep test that measures fewer signals, called cardiorespiratory polygraphy. This simplified polysomnography does not evaluate physiological parameters and is primarily used to investigate sleep-related breathing disorders. It is not a screening test but a simplified diagnostic test. • It cannot distinguish between obstructive sleep apnea and central sleep apnea. • It cannot diagnose other sleep-related disorders such as lower limb movements, central sleep apnea, REM sleep behavior disorder, etc. Furthermore, insomnia can interfere with the results. (2) Using various sensors, this test measures and records, but is not limited to: • Oxygen saturation and heart rate; • Respiratory flow; • Thoracic effort; • Abdominal effort; • Body position.

Question 5

Consequences

Accepted Answer

Not only do individuals with OSAS experience a reduced quality of life, but so does their entourage. Sleep apnea affects sleep quality, which can: • decrease deep and REM sleep and cause micro-arousals, • cause excessive daytime sleepiness, cause irritability, decreased libido, or a depressive state, • decrease the partial pressure of oxygen in the blood, causing oxygen desaturation. This leads to chronic hypoxia which can result in high blood pressure and other cardiovascular disorders. • worsen pre-existing conditions such as endocrine disorders like diabetes or cardiovascular conditions.

Question 6

Nocturnal oximetry (nocturnal saturometry)

Accepted Answer

Several diseases, such as chronic obstructive pulmonary disease, decompensated heart failure, and sleep apnea-hypopnea syndrome (SAHS), can cause nocturnal oxygen desaturations. (1) Nocturnal pulse oximetry uses a simple device placed on a fingertip that allows for the assessment of functional blood oxygen saturation through a painless optical measurement. The measurement of blood oxygen saturation indicates the percentage of oxygen-carrying hemoglobin in the blood. The device is worn for one night, and the data is recorded in the device to be subsequently interpreted by computer. This allows for easy screening which can lead, depending on the results obtained, to a more complete evaluation if necessary.

Question 7

Diagnosis

Accepted Answer

The best way to diagnose sleep apnea and other sleep problems is with a test called a "polysomnography" (PSG). This test can be performed in a "sleep lab," which is a clinic where one can spend the night. Some partial tests can be done using a portable device that the patient can use at home for home monitoring. This allows for the evaluation of oxygen levels, airflow through the nose and mouth, respiratory variations, and snoring. Diagnosis is based on the presence of an excessive number of events (apneas and hypopneas) observed during the polysomnographic recording. This test can measure the following: • brain activity • sleep stages (duration, awakenings, etc.) • eye movements • muscle tone • pulse • leg movements • respiration • airflow • chest and abdominal movements • blood oxygen level.

Question 8

Apnea-Hypopnea Index (AHI)

Accepted Answer

Polysomnography quantifies respiratory events per hour and establishes an Apnea-Hypopnea Index (AHI). • Apnea is defined as a complete cessation of breathing or naso-buccal airflow for 10 seconds or more. • Hypopnea is a partial interruption (a 30% reduction in airflow). It corresponds to a decrease in blood oxygen saturation of at least 3-4% on a polysomnography, but there is no consensus on the duration of this event. However, many accept a duration of 10 seconds as a reference for hypopnea, just as for apnea. Note: Currently, there is no consensus among sleep-disordered breathing specialists regarding the definition of hypopnea.

Question 9

Self-assessment

Accepted Answer

Some quick screening tests and questionnaires can give you an idea of your risk factor for sleep apnea by allowing you to assess your level of daytime sleepiness and indicate whether you should consult a clinic for further evaluation. Click here to take the Epworth Sleepiness Scale test.

Question 10

Lab Report for a Sleep Study

Accepted Answer

Private laboratories or those associated with a hospital or CLSC have the results of sleep studies interpreted by a respirologist. The reports produced generally use the following respiratory event criteria: • Episode lasting at least 10 seconds with: • a reduction in airflow or respiratory amplitude: • ≥90% (apnea), • ≥50% or + (hypopnea), • or associated with a ≥4% drop in oxygen saturation, • or the presence of a micro-arousal (measured by EEG (electroencephalogram) or autonomic (increase in pulse by 5 bpm or beats per minute)), • UARS (Upper Airway Resistance Syndrome); this indicates an increase in respiratory effort (inspiratory flow limitation) without significant reduction, and whose normalization is associated with the presence of an EEG or anatomical micro-arousal (increase in pulse by 5 bpm).

Question 11

How to get a polysomnography or sleep study?

Accepted Answer

A medical prescription or order is required to undergo a polysomnography. It can be written by your family doctor, a respirologist, ENT, etc. Some dentists, orthodontists, and other dental specialists can also write such an order. This examination, which will identify respiratory sleep disorders (mainly sleep apneas or hypopneas), requires recording certain parameters during a night of sleep (at least 6 hours). The test can be done in a hospital, in some private clinics, or on an outpatient basis at your home for simpler tests (polygraphies). In Quebec: • Tests performed in a hospital setting are covered by the Régie de l’assurance maladie du Québec (RAMQ), but waiting periods can be very long, sometimes more than a year depending on the location. The degree of urgency will be determined by the physician, respirologist, etc.

Question 12

MAD and CPAP

Accepted Answer

Mandibular Advancement Devices (MAD) and CPAP are both effective ways to manage sleep apnea. However, they work differently. CPAP, which stands for Continuous Positive Airway Pressure, delivers pressurized air through a mask to overcome the mechanical blockage caused by the closure of the upper airways when apnea occurs. A CPAP consists of a mask connected by a tube to a small machine that delivers pressurized air. It is an effective way to manage sleep apnea. However, not everyone adapts to it due to the bulkiness or noise of the machine, the mask shifting during the night and potentially leaking, or the unattractive appearance of the device, for example. The MAD, for mandibular advancement device, operates differently. It passively holds the lower jaw in an advanced position.

Question 13

Treatment and Solutions

Accepted Answer

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Sleep Test

How does a sleep test work?

Polysomnography and Respiratory Polygraphy

Sleep Tests

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Sleep Test

How does a sleep test work?

Polysomnography and Respiratory Polygraphy

Sleep Tests

Polysomnography (PSG)+

Cardiorespiratory sleep polygraphy (CRSP)+

Nocturnal oximetry (nocturnal saturometry)+

Apnea-Hypopnea Index (AHI)+

Lab Report for a Sleep Study+

How to get a polysomnography or sleep study?+

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