The use of observational scales to monitor symptom control and depth of sedation in patients requiring palliative sedation: A systematic review

Background: Palliative sedation is the intentional lowering of consciousness of a patient in the last phase of life to relieve suffering from refractory symptoms such as pain, delirium and dyspnoea. Aim: In this systematic review, we evaluated the use of monitoring scales to assess the degree of control of refractory symptoms and/or the depth of the sedation. Design: A database search of PubMed and Embase was performed up to January 2010 using the search terms ‘palliative sedation’ OR ‘terminal sedation’. Data sources: Retro- and prospective studies as well as reviews and guidelines containing information about monitoring of palliative sedation, written in the English, German or Dutch language were included. Results: The search yielded 264 articles of which 30 were considered relevant. Most studies focused on monitoring refractory symptoms (pain, fatigue or delirium) or the level of awareness to control the level of sedation. Four prospective and one retrospective study used scales validated in other settings: the Numeric Pain Rating Scale, the Visual Analogue Scale, the Memorial Delirium Assessment Scale, the Communication Capacity Scale and Agitation Distress Scale. Only the Community Capacity Scale was partially validated for use in a palliative sedation setting. One guideline described the use of a scale validated in another setting. Conclusions: A minority of studies reported the use of observational scales to monitor the effect of palliative sedation. Future studies should be focused on establishing proper instruments, most adequate frequency and timing of assessment, and interdisciplinary evaluation of sedation depth and symptom control for palliative sedation.