The Sleep Apnea Test

Now that you have understood what side effects sleep apnea could lead to, you are probably wondering how you can get it tested.

The general term for a sleep test is also known as a “Polysomnography Test”, or in short term, a PSG study. These tests, or studies, use many different parameters as a diagnostic tool for sleep apnea. They are conducted overnight, and generally, one nights’ worth of data will be enough to determine if you are diagnosed positive for sleep apnea or not.

There are actually many different ways to get tested for sleep apnea on the market, so which one is better? How and why are they different? Are there any preparations we need to be aware of?

1. Simple Oximeter Home Sleep Test 

This is the simplest of all sleep studies, and it only uses 2 parameters to determine if you have sleep apnea:

• Finger Pulse Oximeter – To monitor the level of oxygen in your blood
• Heart Rate Monitor –To look out for elevated heart rate

This type of test kit could be picked up from any good pharmacy or chemist (make sure you call and make an appointment first!).

Who is best suited for this kind of study?

Patients who suspect they are most likely positive for sleep apnea, or have very obvious signs and symptoms such as constant daytime sleepiness and snoring could benefit from this study. This test is also better for candidates with a Body Mass Index (BMI) of more than 25.

This test kit is usually comprised of a small machine that straps onto your wrist, with a clip that’s going to be attached to one of your fingers. It monitors for a drop in blood oxygen level, and a rise in heart rate during the night. It is not the most accurate test kit available for patients who have mild symptoms of sleep apnea.

Preparations for this study

There really is not a lot you have to be aware of before commencing this study. You will be given a pre-sleep questionnaire to complete. Remember to sleep enough so there is sufficient data to generate a report. Remove all nail polishes, and do not over indulge in alcohol before doing this test. Stick to your normal sleep/ wake time as close as possible. After waking up in the morning, remove the device and return it to the chemist for analysis. The turnaround time for this test is generally 8-10 days. We will talk about interpreting test reports in the next article.

2. Home-Based Sleep Study / Ambulatory Home Sleep Study

This is also a sleep test that can be done at home. It is usually a machine that’s attached to the center of your chest, with wires and electrodes coming out of it. Compared to the Simple Oximeter home Sleep Test, this is a bit more extensive. It uses a few more parameters:

• Electroencephalography (EEG)/ Electrooculography (EOG) – Measures brain waves and eye movements
  • These electrodes are usually situated on the lateral corner of your eyes, the center of your forehead, and on the bony structure behind your ear. They are used to see what stage of sleep you are in.
• Respiratory Belts – Measures breathing movements
• Nasal Cannula – Detects for nasal breathing
• Oral Thermistor – Detects for mouth breathing
• Finger Pulse Oximeter – Monitors the level of oxygen in your blood
• Body Positioning Sensor – Records if you are a side or back sleeper

Who is best suited for this kind of study?

This study is usually recommended for people who are able to follow simple instructions at home. This is also suitable for all patients who suspect they may have sleep apnea.

Preparations for this study

This study requires you to attach all the gadgets onto yourself. Prior to setting up the sleep study kit, complete the pre-sleep questionnaire provided for you. I would highly recommend you start attaching the sleep kit 30 minutes before bedtime. An instruction card in words and pictures will be provided. 

The whole set up generally takes about 15 minutes to put on, but make sure you give yourself some time to relax so you are nice and comfortable before heading to bed, it’s not a bad idea to put the machine on first, then relax and watch TV/ read before bed. Remember to remove all nail polish and stick to your normal sleep/wake up time. 

Return the sleep study kit the next morning for analysis. Generating reports for these kinds of studies are generally longer, about 2 weeks turnover time.

3. In-Lab Polysomnographic Sleep Study 

This is the most extensive sleep test one can pick from. The chances of this sleep study failing is pretty much close to zero, unless the patient has trouble falling asleep. In this sleep study, you will be admitted into the hospital for one night, a sleep technician will be working with you to ensure all signals and electrodes are in the correct position. During the night, an infrared night vision camera will also be used to monitor your sleeping patterns.

• Finger Pulse Oximeter – Monitors the level of oxygen in your blood
• Nasal Cannula – Detects for nasal breathing
• Electroencephalography (EEG)/ Electrooculography (EOG) – Measures brain waves and eye movements (In this study, there will be 2 pairs of each electrode)
• Oral Thermistor – Detects for mouth breathing
• Respiratory Belts – Measures breathing movements, one on the upper chest, one on the level of your belly button
• Electrocardiogram (ECG) – Monitors heart rate and checks for irregular heart rhythm
• Body Positioning Sensor – Records if you are a side, back, or stomach sleeper
• Electromyography (EMG) – Electrodes placed at your jaw muscles to detect teeth clenching and grinding
• LegEMG – Similar to the electrodes placed at your jaw muscles, except these are placed on your leg muscles to detect restless leg/muscle twitch
• Snoring Sensor – A small microphone placed on the neck to detect for vibrations and snoring
• Infrared Night Vision Camera – Camera used by the sleep technician to oversee the study

Who is best suited for this kind of study?

This study is suited for everybody suspected with sleep apnea, it is extremely accurate and especially good for people who require additional assistance in the middle of the night such as bathroom breaks, it is also good for the elderly who are unable to conduct home sleep studies themselves.

Preparation for this study

Prior to arriving at the hospital, have dinner and make sure all nail polish is removed. Remember to bring pajamas, toothbrush, shampoo, soap, and all your amenities required for cleaning up the next morning. Most hospitals will provide you with your own private room and a bathroom attached to it, towels and water are usually provided too.

Admission time is usually around 8-9pm. After settling in your room, you will be greeted by a nurse, who will double confirm your details and the reason you are admitted into hospital. The nurse will also take clinical observations such as blood pressure and body temperature. After the nurse has completed all the administrative tasks, they will pass you onto the sleep technician. From here on, you will be under the care of the sleep technician until the morning.

The sleep technician will introduce themselves to you, you will then be asked to complete a pre-sleep questionnaire, after completion of the questionnaire, brush your teeth and then change into your pajamas, you are welcome to relax on the bed, read (if you brought a book), or watch TV while the sleep technician prepares their equipment.

After a while, the sleep technician will enter your room and proceed to attach all the electrodes for you. This will take approximately 45min-1 hours. You will be seated on a chair, you are definitely welcome to read a book, watch TV, or just have a casual chat with the sleep technician while he/she is hooking you up. A well-experienced sleep technician will not be disturbed and they do not mind at all.

After the sleep technician is done hooking you up, he or she will move you into bed and work with you to complete some final calibrations to make sure all the signals are recording properly. You may be asked to do some simple exercises such as blinking a couple of times, roll your eyes to the left and right, do a few breathing exercises, and flexing your foot a few times. Bedtime will approximately be 10pm, you are allowed to watch TV or read before sleeping, and there should be a light switch within arms’ reach for when you are ready to sleep.

I would highly recommend you using the bathroom prior to the hook up, but if you need the bathroom in the middle of the night, you will need to be unhooked from the machine with the assistance of the sleep technician. If you require the bathroom, simply click on the bell provided or raise your arm to gain attention.

During the night, if any electrodes fall off, the sleep technician will enter the room. They will attempt to fix it without waking you up, feel free to ignore them if you are accidentally disturbed/ woken up.

Wake up time is usually 6am-6:30am, the sleep technician will take about 20 minutes to unhook all the electrodes. You are then asked to complete a post sleep questionnaire. Breakfast may be provided, and you will have an option to stay and shower or go straight home.

Your report should be ready in approximately 2 weeks time for a review with your doctor.

4. In-Lab Titration Polysomnographic Sleep Study 

This study is very similar to the previous in-lab study we talked about, and this study is usually offered to people who are already diagnosed positive to sleep apnea, and are wanting to use a CPAP (Continuous Positive Airway Pressure) machine (we will discuss about CPAP in the next few articles). The purpose of this study is to help find out the settings needed to treat sleep apnea.

All the parameters recorded will be exactly the same as the In-Lab PSG Study. The only difference is you will lose the nasal cannula and oral thermistor, in exchange for a CPAP mask. The sleep therapist will help you try on a few masks to ensure you are fitted with the most comfortable one for you.

During the night, the sleep therapist will remotely adjust the amount of CPAP pressure needed to eliminate all apnea events.

By the end of this study, the sleep technician would have found out the perfect and most suitable pressure in order to alleviate your apnea events.