ConqueringSleepApnea

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A Sleep Study - What to Expect

When sleep apnea is suspected a sleep study is recommended in most cases. It is a very good tool to collect comprehensive information about someone's sleep pattern. You will need to get an appointment for a sleep study.

The study usually takes place in a specially equipped room called a sleep lab in a hospital or a sleep clinic. Today's modern sleep study clinics are less like a hospital and more like a nice hotel or motel room although probably smaller. Many have a television and magazines or you can bring a book or your knitting. You will also need to bring pajamas or something that covers you while you sleep because you will be monitored by an unobtrusive camera while you sleep. You will be asked to bring your regular sleeping supplies.

A number of electrodes and other sensors will be attached to your head and chest, such as during a routine EKG. Multiple data channels will record certain physiological parameters taken from your sleeping body. These are: blood oxygen saturation, airflow through your nose, chest effort, muscle tension, eye movement, and brain activity.

When you show up in the lab you will learn all you need to know about the study, you will also have a chance to ask all the questions you may have. The whole procedure is rather relaxing, there is no pain or risk involved. The technician that will work with you wants you to feel comfortable and relaxed so you can have as good a sleep as possible.

The only complication being that, as mentioned before, there will be several electrodes and sensors attached to various places on your body that may be slightly uncomfortable and may limit your freedom of movement. Once you are in bed all the wires and tubings will be connected to the recording equipment. Usually it is located across the wall in the neighboring room so you are not disturbed by its operation.

At any time if you need to leave the bed the study will be stopped and you will be allowed to leave the room to use the bathroom or get a drink of water, etc., it will just take a minute to disconnect you from the equipment. Even if you are not able to sleep through the night they will usually collect enough data to come up with a diagnosis.

Most people who have sleep apnea are sleep deprived and fall asleep easily. There will also be a camera and a microphone in the room so the position, movements, and sounds of your body during sleep can be correlated with the recorded data.

Once the study is over all sensors and electrodes will be detached and you will be free to go home. Within a day or two your study will be scored and the results reviewed by a doctor specializing in sleep disorders. If the study reveals that you have sleep apnea your doctor will choose the best treatment option based on the severity of your disease and other factors including medical insurance and personal preference.

The photographs on this page illustrate the proceedures of a sleep study. First the patient is wired with various electrodes. while the patient sleeps he/she is monitored
in two ways. Bodily functions are monitored in graphs and if necessary, the technician can monitor the patient through a camera. The patient can signal the tech if he or she needs to get up during the night.

Streamlining Sleep Apnea Diagnoses with a Split-Night Study

Doctors perform sleep studies or to diagnose sleep related illness or symptoms. Traditionally, patients have a diagnostic study performed for an entire night to diagnose obstructive sleep apnea (OSA). Once the doctor confirms OSA, he sets up a separate therapeutic study.

During this second study the doctor adjusts a continuous or bilevel positive airway pressure (CPAP or BiPAP) to levels that eliminate or significantly reduce the number of respiratory abnormalities (apneas). Doctors perform therapeutic PSG with CPAP if patients have a diagnostic study demonstrating an apnea-hypopnea index (AHI).

They may also perform it if the patient’s respiratory disturbance index (RDI) of at least 20 events per hour regardless of symptoms or an AHI/RDI of 10 events per hour associated with excessive daytime somnolence (sleepiness). To reduce costs and improve efficiency many centers now combine the diagnostic and therapeutic studies into a single night, called a split-night study.

Split-night polysomnography (PSG) divides the patients testing into two phases in one night. During the first part of the night, sleep specialists diagnose obstructive sleep apnea (OSA) and the second half determine the appropriate level of positive airway pressure (CPAP or BiPAP).

Split night testing has shown to be less dependable in patients with AHI/RDI measurements less than 20 events per hour. Some doctors have been successful utilizing a split night strategy in patients with AHI/RDI as low as 10 events per hour if associated with EDS, impaired cognition, mood disorders, or documented hypertension, heart disease, or a history of stroke. There is good evidence that split-night studies can be used under these guidelines. The challenge is that the patient must fall asleep promptly and demonstrate an elevated RDI early in the evening. Only about 25-30 percent of patients have successful split-night studies.

The patient must have at least two hours of sleep documented in the diagnostic phase of the study with the documented increase in AHI/RDI. At least three hours of time is necessary for the therapeutic phase. If the RDI is elevated early in the sleep cycle, then the patient is awakened. The specialist places a pre-fitted CPAP mask on the patient and then patient resumes sleep for another three hours as the pressure is adjusted to eliminate the respiratory events.

That is, the first part of the split study is diagnostic, and the second is therapeutic. When a split-night study cannot be accomplished, then a therapeutic study is indicated. There is no specific time frame for the performance of a therapeutic study after a diagnostic study. It should be done as soon as is practical.

Requesting a split-night study is a very cost effective strategy. Up to seventy to 75 percent of studies may require two separate nights.