Temporal Characteristics of the Sleep EEG Power Spectrum in Critically Ill Children

Abstract

Study objectives: Although empirical evidence is limited, critical illness in children is associated with disruption of the normal sleep-wake rhythm. The objective of the current study was to examine the temporal characteristics of the sleep electroencephalogram (EEG) in a sample of children with critical illness.

Methods: Limited montage EEG recordings were collected for at least 24 hours from 8 critically ill children on mechanical ventilation for respiratory failure in a pediatric intensive care unit (PICU) of a tertiary-care hospital. Each PICU patient was age- and gender-matched to a healthy subject from the community. Power spectral analysis with the fast Fourier transform (FFT) was used to characterize EEG spectral power and categorized into 4 frequency bands: δ (0.8 to 4.0 Hz), θ (4.1 to 8.0 Hz), α (8.1 to 13.0 Hz), and β1/β2 (13.1 to 20.0 Hz).

Results: PICU patients did not manifest the ultradian variability in EEG power spectra including the typical increase in δ-power during the first third of the night that was observed in healthy children. Differences noted included significantly lower mean nighttime δ and θ power in the PICU patients compared to healthy children (p < 0.001). Moreover, in the PICU patients, mean δ and θ power were higher during daytime hours than nighttime hours (p < 0.001).

Conclusions: The results presented herein challenge the assumption that children experience restorative sleep during critical illness, highlighting the need for interventional studies to determine whether sleep promotion improves outcomes in critically ill children undergoing active neurocognitive development.

Keywords: children; circadian rhythm; critical illness; electroencephalogram; intensive care unit; mechanical ventilation; pediatric critical care; sedation; sleep.

© 2015 American Academy of Sleep Medicine.

Figures

Figure 1. Nocturnal EEG δ power in PICU patients and age and gender-matched healthy children.

Values plotted were derived using a Lowess smoothing function.

Figure 2. Nocturnal EEG θ power in PICU patients and age and gender-matched healthy children.

Values plotted were derived using a Lowess smoothing function.

Figure 3. Twenty-four-hour EEG δ power in PICU patients.

Values plotted were derived using a Lowess smoothing function.

Figure 4. Twenty-four-hour EEG θ power in PICU patients.

Values plotted were derived using a Lowess smoothing function.