Background: Terminological problems concerning sedation in palliative care and consequences for research and clinical decision making have been reported frequently. Objectives: To gather data on the application of definitions of sedation practices in palliative care to clinical cases and to analyze implications for high-quality definitions. Design: We conducted an online survey with a convenience sample of international experts involved in the development of guidelines on sedation in palliative care and members of the European Association for Palliative Care (EAPC). Participants were asked to apply four published definitions to four case vignettes. Data were analyzed using descriptive statistics. Results: A total of 32 experts and 271 EAPC members completed the survey. The definitions were applied correctly in n = 2200/4848 cases (45.4%). The mean number of correct applications of the definitions (4 points max.) was 2.2 ± 1.14 for the definition of the SedPall study group, 1.8 ± 1.03 for the EAPC definition, 1.7 ± 0.98 for the definition of the Norwegian Medical Association, and 1.6 ± 1.01 for the definition of the Japanese Society of Palliative Medicine. The rate of correct applications for the 16 vignette-definition pairs varied between 70/303 (23.1%) and 227/303 (74.9%). The content of definitions and vignettes together with free-text comments explains participants' decisions and misunderstandings. Conclusions: Definitions of sedation in palliative care are frequently incorrectly applied to clinical case scenarios under simplified conditions. This suggests that clinical communication and research might be negatively influenced by misunderstandings and inconsistent labeling or reporting of data. Clinical Trial Registration Number: DRKS00015047.
Keywords: cross-sectional survey; deep sedation; palliative care; palliative sedation; terminology; vignette study.