Table 1.

Selected implementation science frameworks and theories used within the FICUS implementation study

Framework/theory	Type and description	Relevance to the FICUS implementation study
NPT	The NPT is a middle-range sociological theory that conceptualises implementation, embedding and integration of complex interventions in healthcare settings.49 It focuses on the work required to embed and normalise an intervention in routine practice. NPT consists of 4 key constructs (coherence, cognitive participation, collective action and reflexive monitoring) and 16 subconstructs.80	NPT provides a flexible framework to evaluate integration and embedding of the FSI. NPT will help to first, better understand the way implementation processes and context shape each other, and second, to explore the collaborative work people do to make sense of the FSI and to integrate it in ICU clinicians’ daily routine.63 NPT will be used to investigate and to describe the integration and normalisation of the FSI in ICU teams.
CFIR*	The CFIR is a meta-theoretical determinant framework which provides a pragmatic structure to guide process evaluations. CFIR provides an overarching typology to promote implementation theory development and verification about what works where and why across multiple contexts.50 It includes five domains (inner setting, outer setting, intervention characteristics, characteristics of individuals involved and processes of implementation).50 Within the five domains are 37 constructs that can each act as a barrier and/or facilitator to the implementation of an intervention.	The CFIR framework includes a wide range of constructs that relate not only to individual characteristics, but also to structural characteristics of the healthcare system, as well as on characteristics of the intervention itself. CFIR provides a degree of flexibility where constructs can be selected that are the most relevant to understand individual and system barriers and facilitators associated with the implementation50 and to assess key contextual determinants to consider within the outer setting and the intervention characteristics domains, which are outside of the NPT scope.51 CFIR will be used to describe potential influencing determinants (barriers and facilitators) during implementation.

*We will use the first version of CFIR⁵⁰ because our contextual analysis to adjust the implementation was conducted before the publication of CFIR version 2.0.⁸¹

CFIR, Consolidated Framework for Implementation Research; FICUS, family intensive care units; FSI, family support intervention; ICU, intensive care unit; NPT, Normalisation Process Theory.