Palliative sedation: a review of the research literature

The overall aim of this paper is to systematically review the following important aspects of palliative sedation: prevalence, indications, survival, medication, food and fluid intake, decision making, attitudes of physicians, family experiences, and efficacy and safety. A thorough search of different databases was conducted for pertinent research articles published from 1966 to June 2007. The following keywords were used: end of life, sedation, terminal sedation, palliative sedation, refractory symptoms, and palliative care. Language of the articles was limited to English, French, German, and Dutch. Papers reporting solely on the sedatives used in palliative care, without explicitly reporting the prevalence or intensity of sedation, and papers not reporting on primary research (such as reviews or theoretical articles) were excluded. Methodological quality was assessed according to the criteria of Hawker et al. (2002). The search yielded 130 articles, 33.8% of which were peer-reviewed empirical research studies. Thirty-three research papers and one thesis were included in this systematic review. This review reveals that there still are many inconsistencies with regard to the prevalence, the effect of sedation, food and fluid intake, the possible life-shortening effect, and the decision-making process. Further research to clarify all of this should be based on multicenter, prospective, longitudinal, and international studies that use a uniform definition of palliative sedation, and valid and reliable instruments. Only through such research will it be possible to resolve some of the important ethical issues related to palliative sedation.