use in lab sleep testing instead of home for complicated sleep apnea

  • Home sleep apnea testing (HSAT) can often be used for simple sleep apnea
  • HSAT has lower sensitivity and higher specificity (high sensitivity rules out, high specificity rules in) compared to in lab testing
  • The two types of HSAT are WatchPAT and Alice One
  • Send patients to sleep labs for complicated sleep apnea:
    • hx of seizure, stroke
    • hypoxemia
    • daily narcotics
    • lung disorders: moderate COPD, pHTN, ILD
    • severe obesity BMI > 45

Alice

  • flow based

WatchPAP

  • no nose part
  • pulse telemetry

SEEK

Home sleep apnea testing (HSAT) is a relatively new diagnostic modality for OSA, which is increasingly being used as a more convenient and less expensive alternative to in-lab polysomnography (PSG). Many patients prefer this technique, as they can be studied in their own home environment and the data can be collected over several consecutive nights. However, because there is no technician directly supervising the test, artifacts and lost physiologic signals are more common than with PSG. Because of the paucity of physiologic parameters measured, it is generally not possible to identify nonrespiratory pathologies, and reliable distinction between obstructive and central respiratory events is difficult. In addition, as most devices do not measure electroencephalography, it is difficult to accurately determine total sleep time. As a result, it is technically not possible to measure apnea-hypopnea index (AHI), which is calculated on PSG by dividing the total number of respiratory events by total sleep time. Instead, most HSATs report a respiratory event index (REI), which is the total number of detected events divided by the total recording time. Since recording time is necessarily greater than total sleep time, REI is reliably smaller than AHI. This difference is more marked in patients who have significant sleep-onset insomnia or elevated wake time after sleep onset.

Because HSAT can underestimate the degree of sleep apnea, an initial negative study should not preclude further evaluation in a patient with a moderate-to-high pretest probability of OSA, as with the patient in this question. Either PSG or repeat HSAT should be performed (choice B is correct); in the absence of reported insomnia, there is no indication to add a hypnotic during the reevaluation, particularly as some of these agents can lead to an artificial worsening of sleep-disordered breathing (choice A is incorrect). Because the initial evaluation did not demonstrate clinically significant sleep-disordered breathing (total event index < 5 / hour), there is no indication for therapy at this time (choices C and D are incorrect).

In summary, HSAT is recommended as a diagnostic modality of OSA in patients with a high pretest probability of moderate to severe obstructive disease. HSAT should not be used in the context of significant cardiovascular disease (as the risk for central sleep apnea is higher in this population), suspected hypoventilation, or suspected nonrespiratory sleep pathology. In the case of a low pretest probability for OSA, a good case can be made for proceeding directly to PSG and foregoing HSAT entirely, as a negative HSAT will not be particularly helpful in ruling out disease. 1

Footnotes

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