Sleep Apnea

The “Split-Night” Sleep Study

Posted on 06. Dec, 2009 by admin in The Full-Service Sleep Center

The standard way to diagnose and treat sleep apnea requires two full nights in the sleep lab. The first night is for a diagnostic sleep study. If the sleep specialist diagnoses sleep apnea and prescribes the most common treatment, CPAP , the patient spends a second full night in the sleep lab so that the CPAP pressure can be custom-set for him.

In some cases, this two-night procedure is compressed into one night. This is called a “split-night” sleep study. If the patient shows signs of sleep apnea during the first half of the night, CPAP treatment is begun and the CPAP pressure is custom-set during the second half of the night.

Split-night studies have two major advantages: first, one night in the sleep lab is less expensive than two nights; and second, the sleep lab can test more patients by doing split-night studies.

However, a split-night study has several important disadvantages: it can fail to accurately show the severity of the apneas. Sleep apnea usually is worse during REM sleep, most of which occurs during the second half of the night. If a doctor is basing a diagnosis on apneas observed only during the first half of the night, he may underestimate the seriousness of a patient’s sleep apnea. This is especially likely in patients who have split-night studies and are told that they have “moderate” apnea. The split-night study may miss the true severity of their apnea when sleeping in certain positions or during REM. Later, if CPAP fails to treat the patient, the insurer may refuse additional treatment, claiming that the apnea is only mild. Other problems occur when a split-night study results in diagnosing a severe patient as mild or moderate, and after CPAP fails they want to consider surgery. The surgeon may be misled by the findings of mild apnea and make ill-advised surgical recommendations. If you have a split-night study, carefully consider a full diagnostic study before having surgery.

Another possible disadvantage of a split-night study is that, even though the patient may have sleep apnea that needs treatment, the splitnight may not produce enough information to convince an insurance company to pay for treatment.

Finally, there may not be enough time during the second half of the night to obtain an accurate CPAP pressure. For this reason the American Academy of Sleep Medicine does not consider split-night studies appropriate for all patients.

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Tags: Sleep Apnea, Sleep Apnea Treatment, Sleep Study, Split-Night