Bispectral index monitoring of sleep in palliative care patients

Abstract

In patients receiving palliative care (PC), sleep is often negatively influenced by pain, anxiety and medication. Because these patients are often too sick to be investigated in a sleep laboratory, it is difficult to obtain objective information concerning their sleep. This study investigates whether bispectral index (BIS) monitoring reflects wakefulness, sleep and the effect of medication and whether it is tolerable for patients. In all, 10 patients from an inpatient PC unit participated in the study. They were monitored using a BIS system for one night, while each event was carefully documented by patient care attendants. In addition, participants completed a questionnaire on the evening prior to and on the morning following the recording about their subjective wellbeing and sleep. On a scale from 0 to 100, BIS measurements covered values ranging from a minimum of 29–40 to a maximum of 74–98. Individual differences between minimum and maximum ranged between 38 and 68. High BIS values are associated with wakefulness, low BIS values with sleep. The administration of sedative and analgesic medication was followed by a long-lasting decrease in BIS measurements. In 3 patients, the measurements were discontinued due to the patient being disturbed or irritation of the skin. BIS monitoring was well tolerated by most but not all patients. It can be useful in complementing patients’ reports in questionable cases. This might be of special interest in outpatient settings where continuous objective professional observation is not available.