Palliative sedation : assessment of pain awareness and perception can be improved

In Research

A recent doctoral study lead by Stefaan Six, PhD in Social Sciences of Health (VUB), PhD in Public Health (ULiège / GIGA), Postdoctoral Researcher, Mental Health and Wellbeing Research Group, Vrije Universiteit Brussel, shows that the clinical assessment of the depth of sedation and the presence of pain during palliative sedation could be improved by the use of medical monitors.


uring palliative sedation, carers must assess whether the (unconscious) patient is sufficiently comfortable. This is done by checking whether the patient shows signs of pain (clinical observation). New PhD research conducted by Stefaan Six at the VUB and ULiège now shows that observational estimates of consciousness and pain do not always correspond to their neurophysiological indicators. The traditional method of clinical assessment can therefore be unreliable and the patient's suffering may remain unnoticed or underestimated. As a result of this study, Dr Six concludes that current standard methods of assessing patient comfort during palliative sedation can at least be questioned and that consideration should be given to how more objective monitoring can be implemented in palliative care.

The gold standard for detecting pain and discomfort is patient self-assessment. However, with continuous palliative sedation, patients are no longer able to communicate. Dr. Six's study examined how the clinical estimates of caregivers matched the assessment provided by two monitors used in surgery. In addition, the researcher also made assessments using four "classic" observation scales. The results of the study - which were published in the scientific journal Pain and Therapy - show that there appears to be little correspondence between the subjective clinical estimates of the caregivers and the objective estimates of the monitors.

The monitors used were the Neurosense monitor and the Analgesia Nociception Index (ANI) monitor. The Neurosense shows how sedated the person is. The ANI monitor gives an indication of possible pain. This monitor can also detect a possible overdose of analgesic. A total of 108 assessments were studied in detail in a group of 12 patients. In addition, the researcher also carried out assessments using four "classic" observation scales.

Dr. Stefaan Six: "One of the most striking conclusions is that while, according to the monitor, there was still a possibility of consciousness, this was only recognised by the carers in 24% of cases, which means that it was missed in about 3/4 of the cases! There also seems to be little correlation between the classic observation scales and the monitoring values."

In addition, doctors, nurses and family members who participated in the study with the monitors were also interviewed as part of the study. This showed that such objective monitoring was feasible and acceptable to all parties concerned and that its use was considered to be an added value. The results of these interviews were published earlier this year in the Journal of Pain and Symptom Management.

Dr. Stefaan Six: "These studies show that clinical estimates of the depth of sedation and the possible presence of pain can be improved by using monitoring devices during palliative sedation. In addition, the use of monitors was deemed acceptable by all parties concerned. We therefore need to think about how we can implement this approach in healthcare."

This PhD thesis was co-supervised by the Mental Health and Wellbeing Research Group of the Vrije Universiteit Brussel (promoter Prof. Reginald Deschepper, co-supervisor Prof. Johan Bilsen) and the Coma Science Group / GIGA Consciousness of the University of Liège (promoter Prof. Steven Laureys).


  • Six, S., Laureys, S., Poelaert, J. et al. Neurophysiological Assessments During Continuous Sedation Until Death Put Validity of Observational Assessments Into Question: A Prospective Observational Study. Pain and Theraoy (2020). DOI:
  • Six, S., Van Overmeire, R. et al. Attitudes of Professional Caregivers and Family Members Regarding the Use of Monitoring Devices to Improve Assessments of Pain and Discomfort During Continuous Sedation Until Death. Journal of Pain and Symptom Management (2020). DOI:
  • Towards a better understanding of what palliative sedated patients experience. Linking numbers to experiences, VUBpress 2020.

Share this news