Monitoring of nociception and awareness during palliative sedation: A systematic review

G. Morawska1, S. Pautex2, N. Elia2, N. Rahm2 (1Collonge-Bellerive ; 2Genève)


Providing unawareness and pain relief are core elements of palliative sedation. In daily practice, the assessment of a patient’s unawareness and comfort under palliative sedation relies on clinical scales, the use of which has limitations. Nociception and electroencephalogram-based depth of sedation monitoring are used to assess the level of consciousness and analgesia during sedation in intensive care units and during procedures.These monitoring could potentially improve the assessment of analgesia and level of unconsciousness during sedation.


The purpose of this review was to systematically identify and examine evidence for the use of depth-of-sedation and nociception monitoring on palliative sedation outcomes and their potential benefit for patients.



Systematic review and narrative synthesis of research published between January 2000 and December 2020. Data sources: Embase, Google Scholar, PubMed, CENTRAL and the Cochrane Library. All reports describing the use of any monitoring device to assess the level of consciousness or analgesia during palliative sedation were screened for inclusion. Data concerning safety and efficacy were extracted. Patient comfort was the primary outcome of interest. Articles reporting sedation but that did not meet guidelines of the European Association for Palliative Care were excluded.


Six reports of five studies were identified. Four of these were case series and two were case reports. Together, these six reports involved a total of 67 sedated adults.

Methodological quality was assessed with the National Institute of Health- Quality Assessment Tool for Observational Cohort and Cross-Sectional Studies for observational studies, fair to good.

Medication regimens were adjusted to bispectral index monitoring values in two studies, which found poor correlation between monitoring values and observational scores. In another study, high nociception index values, representing absence of pain, were used to detect opioid overdosing.

Relatives and caregivers found the procedures feasible and acceptable.


There is no evidence that the use of these monitoring tools provides clinically relevant improvements for patients during sedation. Studies suggest poor correlation between bispectral analysis values and observational clinical scores for deeply sedated patients. Nociception monitoring could help detect opioid overdosing and insufficient analgesia. Next of kin and caregivers reported finding the monitoring useful and without burden.


There is growing concern that the observation-based methods currently used may not be sufficiently effective to optimize outcomes in sedated patients. Given the potential benefits identified in the studies reviewed, the findings indicate that monitoring sedation has the potential for assessing the depth of sedation and the absence of pain. There is, however, no conclusive evidence that depth of sedation and nociception monitoring can improve palliative sedation outcomes and no evidenced-based reasons for palliative care caregivers to change their current practice.These findings support the need for continued - but higher quality - research in this area.