Polysomnogram (PSG)______________________________________________________

A Sleep Study or Polysomnogram (PSG) is a multiple-component test, which electronically transmits and records specific physical activities while you sleep. This is the first test you will have done. The recordings become data, which will be "read" or analyzed by a qualified physician to determine whether or not you have a sleep disorder.

What happens when I get to the Sleep Lab?
You will be escorted to your private bedroom. Along the way, you may see the central monitoring area, where the technicians monitor as many as four sleeping patients. It is done by means of computers and video. The technicians will be able to react quickly if you need help or have a question while in your room.

Setup can take 45 minutes or more in order to get everything connected properly. There are a large number of supplies that are used in the process. The two blue belts are placed around your chest and abdomen to measure your respiratory efforts, and the band-aid like oximeter probe on your finger measures the amount of oxygen in your blood. The electrodes are temporarily "glued" to your skin and scalp or we may use adhesive electrodes. Don't worry, the glue comes off easily the next morning.

The key part of a sleep study is understanding what is happening while you sleep. By attaching the electrodes to your body, the recorded electrical signals generated by your brain and muscle activity are sent back through the wires and recorded digitally. The pattern of this activity can be recognized by a sleep specialist who "reads" or interprets the study. These valuable clues reveal whether or not you have a sleep disorder, and if present, how severe it is.

Before the electrodes can be glued onto the scalp, cranial dimensions are taken with a tape measure to ensure their precise placement. During placement the patient usually sits in a comfortable chair.

The EEG or electroencephalogram, is a major part of a sleep study. It measures and records four forms of brain wave activity - alpha, beta, delta and theta waves. Alpha waves are usually found during relaxed wakefulness, particularly when your eyes are closed. Theta waves are seen during the lighter sleep stages 1 and 2, while delta waves occur chiefly in deep sleep, the so-called "slow wave sleep" found in sleep stages 3 and 4.

The EMG or electromyogram, records muscle activity such as face twitches, teeth grinding, and leg movements. It also helps in determining the presence of REM stage sleep. The amount and duration of these activities provides the doctor important information about your sleep.

The EOG or electro-oculogram, records eye movements. These movements are important in determining the different sleep stages, particularly REM stage sleep. The electrodes are usually placed on the outer aspect of your right eyebrow and along the outer aspect below or beneath your left eye.

EKG or electrocardiogram, records heart activities, such as rate and rhythm. Electrodes are placed on your chest.

Nasal Airflow Sensor: Records breath temperature, airflow, apnea and hypopnea events. A sensor is placed near your nose and mouth.

Chest/Abdomen Belts: Records breathing depth, apnea and hypopnea events. Elastic belts are placed around your chest and abdomen.

Oximeter: Records blood oxygen saturation. A band-aid like clip is placed on a finger.

Video: Records body positioning and movements.

Snore Microphone: Records snoring. An electrode is placed over your trachea, on your lower neck.

Sleeping is a complex activity that must occur for a successful polysomnographic study. During sleep, our brain and body cycle between NREM and REM sleep approximately every 90 minutes.

During these transitions, major changes occur in our EEG, EOG, EMG, heartrate and respiration that are necessary for healthy sleep. If abnormal changes are observed during a particular sleep stage, then we are able to define this problem as it occurs during the night.

The hookup is complete! The electrodes and all other components are in place. The data they collect and record is what makes a polysomnographic study. Once the sleep specialist reads the "book" of data, they will know if you have a sleep problem or a sleep disorder. Following a diagnosis, the sleep specialist will work with you and your doctor to plan appropriate treatment

CPAP Titration______________________________________________________________

A CPAP Titration is required if sleep apnea is diagnosed or strongly suspected. Typically, this is a full night of study performed during a second night, but is sometimes performed during the last few hours of a split-night study.

CPAP (Continuous Positive Airway Pressure) therapy is the first line of treatment for sleep apnea. The CPAP device delivers pressurized air through tubing to a nasal mask or nasal pillows, which are fitted around the head. The pressurized air acts as an airway splint. It gently opens the patient's throat and breathing passages, allowing them to breathe normally while asleep, but only through their nose!

To properly treat sleep apnea, the correct CPAP air pressure setting must be determined by titration. Titration is done for each patient - there is no "one size fits all" solution.

During a titration study, the patient will sleep all wired up, just like a normal sleep study, but they will also wear a nasal mask which is connected to a CPAP machine. Since the pressurized air can be irritating to a nose that hasn't been used much at night, many sleep labs also connect the CPAP device to a heated humidifier during the titration procedure. This adds moisture to the air after it leaves the CPAP and before it enters the patient's nose, easing the drying effect of the pressurized air

During the titration study, the technician will set the air pressure on the CPAP at a certain level and then watch the resulting measurements. If that pressure does not reduce the number of apnea and hypopnea events, or eliminate the snoring, the technician will adjust the air pressure and continue observation. This process continues throughout the night until the optimum pressure is reached.

The physician then reviews the study and will order a CPAP machine and mask for you to use at home while you sleep. The machine and mask will be provided to you by a DME (durable medical equipment) company that is contracted with your insurance. Depending on how your insurance benefit is for DME, you may or may not have a co-pay, deductable or co-insurance for the equipment.

BiPap______________________________________________________________________

Some patients cannot tolerate the CPAP and may be ordered a BiPAP instead. BiPAP stands for Bi-level Positive Airway Pressure. It is a breathing apparatus that helps people get more air into their lungs. It was developed in the 1990s as a development from the C-PAP, which stands for Continuous Positive Airway Pressure. The extra pressure from C-PAP allowed users to sleep by keeping the airways open. The problem with C-PAP was that the person had to exhale against the extra pressure. This made it unsuitable for people suffering from neuromuscular diseases.

With the development of BiPAP, air delivered through a mask can be set at one pressure for inhaling and another for exhaling. This makes BiPAP much easier for users to adapt to and also allows neuromuscular disease sufferers to use the device. Because of these dual settings, BiPAP allows people to get more air in and out of the lungs without the natural muscular effort needed to do so.

Split Night Study____________________________________________________________

A Split Night Study is done when you come in for your initial PSG but you then meet the criteria to have a CPAP device put on the same night. Each sleep lab will have it’s own criteria for a Split Night Study. The criteria is a specific number of respiratory events seen during the first two hours of sleep. If you meet this criteria the technician will wake you up and let you know you have met the criteria for CPAP. You will then have the CPAP mask put on and you will be titrated throughout the rest of your study.

MSLT_______________________________________________________________________

A Multiple Sleep Latency Test or MSLT, is designed to measure the degree of sleep tendency or sleepiness in a given patient. This test is conducted during the day following a routine PSG and features a series of up to 5 naps, each lasting usually less than 30 minutes that are timed to start every two hours during the day. For example, 10 am, 12(noon), 2 pm, 4 pm and 6 pm represent a possible nap schedule.

It is important prior to having an MSLT study that a 1-2 week sleep diary be completed and your doctor be aware of any medications (OTC or otherwise) that you are taking, since many medications can effect the results of this test.

The purpose of the MSLT is two fold: first, to average the number of minutes that it takes to fall asleep (sleep onset latency) during all the naps and second, to record if REM stage sleep occurs during any of these scheduled napping periods.

The testing procedure includes essentially the same PSG leads as for a diagnostic overnight study. During the periods between naps, the patient must stay awake and not fall asleep.

This test is particularly useful in helping people with Narcolepsy adjust their medication, diagnose Narcolepsy, objectively quantify the degree of sleepiness in a particular patient, such as an OSA (obstructive sleep apnea) patient who is still sleepy despite CPAP treatment and in diagnosing Idiopathic Hypersomnolence.

MWT_______________________________________________________________________

The MWT is a test that consists of a series of four, twenty-minute “non-nap” periods scheduled approximately two hours apart. MWT stands for “Mean Wakefullness Test”.

The patient is given four opportunities to document that excessive daytime sleepiness has been eliminated by treatment for their sleep/breathing disorder. Measurements of the interval from the start of the “non-nap” period to the first sign of sleep are measured for each “non-nap”.  

The main reason for having an MWT is to document that a sleep/breathing disorder treatment is effective. This test is required by the FAA in order to give pilots the approval they need to return to flying after treatment for a sleeping disorder has been under way.