Continuous Deep Sedation: A Proposal for Performing More Rigorous Empirical Research.

Continuous deep sedation until death (CDS) is a type of palliative sedation therapy, and it has recently become a focus of intense debate. Marked inconsistencies in intervention procedures (i.e., what is CDS?) and unstandardized descriptions of patient backgrounds lead to difficulty in comparing the results in the literature. The primary aim of this article was to propose a conceptual framework to perform empirical studies on CDS. We propose the definition of CDS using the intervention protocol. As there are two types of CDS proposed in world-wide literature, we recommend to prepare two types of intervention protocol for CDS: "continuous deep sedation as a result of proportional sedation" (gradual CDS) and "continuous deep sedation to rapidly induce unconsciousness" (rapid CDS). In addition, we recommend that researchers characterize study patients' general condition using a validated prognostic tool, Prognosis in Palliative Care Study predictor model-A. Using this conceptual framework, we can compare the outcomes following the same exposures among homogenous patients throughout the world. This article proposes a provisional definition of two types of CDS. Defining CDS using the intervention protocol and describing patient backgrounds using validated prognostic tools enable comparisons and interpretations of empirical research about CDS. More empirical studies are urgently needed.