Background. In case of untreatable suffering at the end of life, palliative sedation may be chosen to assure comfort by reducing the patient's level of consciousness. An important question here is whether such sedated patients are certainly completely free of pain. Because these patients cannot communicate anymore, caregivers have to rely on observation to assess the patient's comfort. Recently however, more sophisticated techniques from the neurosciences (fMRI, EEG) have shown that sometimes consciousness and pain is undetectable with these traditional behavioral methods.

Therefore there is an urgent need for a more reliable way of assessment by combining existing observational scales, subjective assessments of caregivers and family and neuroimaging techniques.

Aim. The aim of this study is to better understand how unconscious palliative sedated patients experience the last days of their life and to find out if they are really free of pain.

Methods In this study the investigators will observe 40 patients starting with initiation of palliative sedation until death.

Assessment of comfort based on behavioural observations will be related with the results from a NeuroSense monitor, an EEG-based brain monitor used for evaluation of the adequacy of anesthesia and sedation in the operating room and an ECG-based Analgesia Nociception Index (ANI) monitor, which informs about the comfort or discomfort condition of the organism, based on the parasympathetic tone (including calculation of ANI). Additionally, the researchers will investigate whether changes of these measures can be linked to changes in the patients' experience as observed by caregivers and relatives, especially in the last moments of life. An innovative and challenging aspect of this study is its qualitative approach, implying all the different types of data will be used to link "objective" and "subjective" data to achieve a holistic understanding of the study topics.

The following data will be collected:

• assessment of pain/comfort by the patients themselves before loss of consciousness due to deep continuous sedation (if possible) by scoring a Visual Analogue Scale (VAS)
• brain function monitoring (NeuroSense monitor)
• monitoring of parasympathetic tone (ANI monitor)
• assessment by caregivers on 3 VAS scales (different scales or 3 different caregivers?)
• relatives' perception of the quality of the dying process on 3 VAS scales (idem)
• assessment by 2 trained investigators using observational scales
• observation: video and audio registration

Inclusion Criteria:

Patients may be included if they are considered by their treating physician as:

1. in their last week of life
2. in conditions that might, when not treated, cause high levels of distress
3. sedated
4. unable to communicate

Exclusion Criteria:

-

All patients older than 18 years where palliative sedation is expected to be initiated, regardless of underlying diseases.