Sleep staging and respiratory events in refractory epilepsy patients: Is there a first night effect?

Abstract

Purpose: We performed this analysis of possible first night effects (FNEs) on sleep and respiratory parameters in order to evaluate the need for two serial night polysomnograms (PSGs) to diagnose obstructive sleep apnea (OSA) in epilepsy patients.

Methods: As part of a pilot multicenter clinical trial investigating the effects of treating sleep apnea in epilepsy, two nights of PSG recording were performed for 40 patients with refractory epilepsy and OSA symptoms. Sleep architecture was examined in detail, along with respiratory parameters including apnea/hypopnea index (AHI) and minimum oxygen saturation. Analysis included two-tailed t-tests, Wilcox sign rank analysis, and Bland Altman measures of agreement.

Results: Total sleep time differed between the two nights (night 1,363.8 min + 59.4 vs. 386.3 min + 68.6, p = 0.05). Rapid eye movement (REM) sleep and percentage of REM sleep were increased during night two (night 1: 12.3% + 5.9 vs. night 2: 15.5% + 6.2, p = 0.007), and the total minutes of slow-wave sleep (SWS) were increased (night 1: 35.6 + 60.7 vs. night 2: 46.4 + 68.1, p = 0.01). No other sleep or respiratory variables differed between the two nights. Given an AHI inclusion criterion of five apneas per hour, the first PSG identified all but one patient with OSA.

Discussion: Respiratory parameters showed little variability between the first and second nights. Sleep architecture was mildly different between the first and second PSG night. Performing two consecutive baseline PSGs to diagnose OSA may not be routinely necessary in this population.

Conflict of interest statement

Conflict of interest: We confirm that we have read the Journal’s position on issues involved in ethical publication and affirm that this report is consistent with these guidelines. Author disclosures include the following: Ronald Chervin holds a professorship established in part by a contribution from Respironics, Inc. He serves on the scientific advisory board for Pavad Medical, Inc. and has consulted for Alexza Pharmaceuticals, Inc. Dr. Vaughn has research support from GSK, OM, Eisai, and has been a speaker for GSK. Dr. Foldvary-Schafer has grant support from Schwarz pharma, Cepahlon, Inc., UCB, Inc., GSK, and is on the advisory board for GSK. The remaining authors have no conflicts of interest.

Figures

Figure 1

Bland–Altman agreement plot of night 1 and night 2 AHI. The differences of AHI from nights 1 and 2 are plotted against the averages of the two measurements. Horizontal lines are drawn at the mean difference, and at the mean difference plus and minus two times the standard deviation of the differences. The funnel pattern in the plot shows larger AHI values tended to be more variable between the nights. (However, this should not affect results of nights 1 and 2 AHI comparison because the nonparametric Wilcoxon signed-rank test used is robust to this departure from normality.) Epilepsia © ILAE