Determination of sleep state in infants using respiratory variability

Area of Science:

• Neonatal Physiology
• Sleep Medicine
• Biomedical Engineering

Background:

• Conventional sleep staging relies on neurophysiologic and behavioral criteria, which are not always accessible.
• Cardiorespiratory variables differ between rapid eye movement (REM) sleep and quiet sleep.

Purpose of the Study:

• To investigate if cardiorespiratory variables can be used for sleep state determination in infants.
• To develop a method for classifying sleep states using these variables.

Main Methods:

• Studied nine infants at 1 and 4 months of age.
• Measured ventilation and RR interval, alongside standard sleep monitoring (EEG, EOG, EMG).
• Analyzed means and coefficients of variation of cardiorespiratory variables in 30-second intervals.

Main Results:

• Coefficients of variation showed greater differences between REM and quiet sleep than means for all variables.
• The coefficient of variation of respiratory cycle time provided the largest separation between sleep states.
• A decision rule based on this variable correctly classified 93% of quiet sleep epochs and 99% of REM sleep epochs.

Conclusions:

• Cardiorespiratory variables, particularly the coefficient of variation of respiratory cycle time, can reliably differentiate between REM and quiet sleep in infants.
• This offers a potential non-neurophysiologic method for sleep staging.