Limitations of split-night polysomnography for the diagnosis of nocturnal hypoventilation and titration of non-invasive positive pressure ventilation in amyotrophic lateral sclerosis.

Split-night polysomnography is performed at our centre in all patients with ALS who require assessment for nocturnal hypoventilation and their response to non-invasive ventilation. The purpose of this study was to determine how successful this practice has been, reflected by whether a complete assessment was achieved by a single split-night polysomnogram. We undertook a systematic, retrospective review of all consecutive split-night polysomnograms in ALS patients between 2005 and 2012. A total of 47 cases were reviewed. Forty-three percent of patients had an incomplete test, resulting in a recommendation to repeat the polysomnogram. Poor sleep efficiency and absence of REM sleep in the diagnostic portion of the study were strongly associated with incomplete studies. Clinical variables that reflect severity of ALS (FVC, PaCO2, ALSFRS-R) and use of REM-suppressing antidepressants or sedative-hypnotics were not associated with incomplete split-night polysomnogram. In conclusion, a single, split-night polysomnogram is frequently inconclusive for the assessment of nocturnal hypoventilation and complete titration of non-invasive positive pressure ventilation in patients with ALS. Poor sleep efficiency and absence of REM sleep are the main limitations of split-night polysomnography in this patient population.