Sleep Apnea Testing

May 31, 2016

Sleep Apnea Testing

Wondering what levels of testing are available for diagnosing sleep apnea? Wonder no more as we explain them all from in-hospital testing to the tests that you can take home with you. 

Let’s Talk: Sleep Apnea Testing

When sleep seems elusive or daytime fatigue becomes a reality a visit to your GP (General Practitioner) normally leads to further clinical assessment or an at home sleep study (Ambulatory).

With over 88 sleep disorders it is imperative that assessment is done with consistency, accountability and overseen by professionals within the industry. The first step in triaging any of the 88 sleep disorders is to eliminate the obvious and most common sleep disorders. This comes in array of testing from a Level 1 sleep study to a Level 4 sleep study.

First line testing is checking for physiological reasons for your disrupted sleep. Your tongue falling back, your upper airway closing due to muscles relaxing during sleep, this disorder is referred to as obstructive sleep apnea (OSA) and generally makes up over 80% of all diagnosis in the field of sleep medicine. Depending on the region you live in, testing availability and doctor’s preference will determine which test you are referred for.

Level 1

Level 1 is the Gold standard of sleep disorder diagnosis: Completed in a hospital setting, patient spends the night and is “wired up “with electrodes on scalp, chest and leg.

This study has an RPSGT watching and marking events in real time with observed patient behavior.

After this is completed the data is reviewed by a Sleep Specialist Physician.

Being an RPSGT myself, I wish all my patients had this available to them, but the reality is that Sleep Labs in BC are not readily available and can take 12-18 months to get into the lab and then can take a few months after completing the overnight test to have a specialist review the results with you.

When testing became so difficult to access, technology stepped up and created easy at home testing, that in most cases, when used to identify an obstructive disorder correlated closely with Level 1( in hospital ) testing

Level 4 (Oximetry)

Level 4 testing is the least invasive test available and allows for repeating the test with therapy in place so that you can see the changes the treatment has made by using the same scales.

This is the least accurate and least sensitive test to determine if Obstructive Sleep Apnea is present, so a negative result on this test does not necessarily mean that one does not have sleep apnea.

It means that further testing should be done based on patient symptoms.

This test is a simple finger probe that you wear during your sleep. It measures 2 values, oxygenation in your blood and heart rate.

Oxygenation is measured by an oximeter by passing a signal through your finger and determining the amount of oxygen that is attached to hemoglobin in your blood.

When ones airway closes, oxygenation levels drop and the heart has to work harder to compensate for the lack of oxygenation in the blood.

If the oxygen levels drop a certain amount (4% or greater) several times an hour (over 5/hour) then it may qualify as a sleep disorder.

Level 3 

This is a Level 4 test plus measurement of the effort and flow.

A finger probe for checking oxygen and heart rate, plus an effort band worn around your chest to measure the amount of effort required to a take a breath while a nasal cannula monitors how much air is moving during each breath.

The nasal cannula also allows us to measure the snoring and how much restriction there is to airflow.

Level 2

We utilize the Ares by Watermark sleep apnea detections system.

This is a wearable wireless physiological recorder worn on the forehead that acquires and stores up to 3 nights of nocturnal data.

WM ARES™ Unicorder measures blood oxygen saturation (SpO2) and pulse rate (reflectance pulse oximetry), airflow (by nasal cannula connected to a pressure transducer), respiratory effort (a combined signal using pressure transducer sensing forehead venous pressure, venous volume by photoplethysmography, and actigraphy), snoring levels (calibrated acoustic microphone), head movement and head position (accelerometers).

This testing gives the most information available from a home test. This test actually lets technologist know that sleep is reached.

With level 3 and 4 tests it is assumed the patient put it on and went to sleep, yet we have no true idea how much the patient actually slept.

With a level 2 test, sleep is monitored by using an EOG, EEG and EMG lead to determine sleep/wake and NREM versus REM sleep.

This test also monitors the position a patient sleeps in which can also be helpful in treatment.

The type of test utilized is determined by your physician, your sleep tech, and aspects of your health.

Sweet dreams,

The Team at SleepTech
#sleeptech #smartersleep
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