Ventilator-Assisted Living©

Winter 2001, Vol. 15, No. 4

ISSN 1066-534X

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Read selected articles from this issue ...

Home Mechanical Ventilation: A Brazilian Experience
Luiz Gustavo Ghion, PT, and Ana Maria Cardoso, PT, COOPERFIT, Physiotherapeutic Cooperative for Home Care Assistance, Sao Paulo, Brazil

Ventilators Find Good Home

Sleep Studies: At Home or in the Lab?
Judith R. Fischer, California

More on Oxygen Use
E.A. Oppenheimer, MD, FACP, FCCP, California

Aging with a Ventilator: Independence or Security?

Pearson's Respiratory Outreach Program Moves into Community
Irene Hanley, RRT, Vancouver, British Columbia, Canada

New Interfaces and Equipment

Dr. Alba Honored

Reeve Paralysis Resource Center

Fresh Air Camp

Sleep Studies: At Home or in the Lab?

Judith R. Fischer, Editor, IVUN News, California

Problems with breathing may be noticed first during sleep. In people with neuromuscular disorders, these problems can be due to underventilation, to apnea (obstructive, central, or mixed), or to a combination of both. To establish a definitive diagnosis of obstructive sleep apnea (OSA) – the most common form – the physician usually orders a sleep study or polysomnography (PSG) in a sleep laboratory.

However, in the last several years, home sleep studies to detect OSA have become more common and may decrease the waiting period for sleep lab studies. The home study can provide the correct diagnosis in 70-80% of cases among the general population, but the level of effectiveness in diagnosing OSA in people with neuromuscular conditions has yet to be sufficiently studied.

A sleep study provides information about the quantity and quality of an individual’s sleep in both REM and non-REM sleep by monitoring arousals and leg movements, the number of hypopneas and apneas (known as the apnea/hypopnea index or AHI), the kind of apnea, breathing efforts, air flow, and levels of oxygen saturation in the blood (SaO2).

Generally, standard PSG in a sleep lab measures the different sleep stages with two EEG leads (for brain activity), two electro-oculographic leads (for eye movements), and one electromyogram lead near the chin or throat (for muscle activity). With the information gathered through these leads or channels, an individual’s sleep pattern emerges. In addition, an EKG monitors heart rate, and a pulse oximeter monitors SaO2. Some labs also monitor snoring and body position. The more channels that are used, the more data collected.

The main advantage of sleep lab testing is that a technician is always present to monitor the equipment as well as to handle a medical emergency. The main disadvantages are usually cost, long waiting period, and a strange and unfamiliar sleep environment that does not lend itself to accurately reproducing an individual’s normal sleep.

A sleep study in the home is less expensive and provides a familiar sleep environment, although some people may still have difficulty sleeping with all the wires. A full PSG in the home can supply as many as 20 channels of data. A disadvantage is that, with unattended equipment, data may be lost, requiring another test, which can end up being just as expensive as a sleep lab PSG. However, even though unattended, home studies can be monitored via a modem, so that if a lead falls off, the sleep technician calls the home and asks the individual to put the lead back on. The whole night is not lost, but the disruption is not ideal either. It is important to note that the degree of severity of OSA may not be picked up with a home study, especially if the individual sleeps poorly.

In 1993, the American Sleep Disorders Association (now the American Academy of Sleep Medicine) published a guideline setting minimum standards for home studies. The home recording unit must measure at least four channels: heart rate, SaO2, air flow, and breathing effort. (This may not provide enough data when used for people with neuromuscular disease.) Joint clinical practice guidelines on “Home Testing for the Diagnosis of Sleep-Disordered Breathing” are currently being developed by the American College of Chest Physicians (ACCP), the American Thoracic Society (ATS), and the American Academy of Sleep Medicine (AASM).

During the recent annual meeting of the ACCP, Nancy Collop, MD, and David Hudgel, MD, two sleep and breathing experts, discussed the pros and cons of home sleep studies. They concluded:

The appropriate study for an individual with a neuromuscular disorder may depend on how much data the physician needs and what symptoms the individual is experiencing. If there is a classic presentation of OSA – snoring, daytime sleepiness, high blood pressure, and observed apneas during sleep – then the individual can be studied either at home or in a sleep lab.

People with mild sleep apnea or upper airway resistance syndrome (in which there are arousals during sleep related to inspiratory effort against a narrowed airway, but no clear-cut OSA) would be better evaluated in a sleep lab. Insurance coverage also plays a role in determining whether a home study or a sleep lab is selected. Medicare does not cover home sleep studies.

Special thanks to Nancy Collop, MD, and to The American Sleep Apnea Association, Washington DC.

The American Academy of Sleep Medicine, which accredits sleep disorder facilities, differentiates between those that are full-service sleep disorders centers and those that are specialty laboratories for sleep-related breathing disorders. The centers may see any individual with a sleep disorder, but the laboratories treat only breathing-related disorders. The AASM provides a listing of accredited sleep labs:

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