BackgroundClinical pathways can enhance care quality, promote patient safety and optimize resource utilization. However, they are infrequently utilized in intensive care. This study aimed to explain the implementation process of a clinical pathway based on a bottom-up approach in an intensive care context.MethodsThe setting was an 11-bed general intensive care unit in Sweden. An action research project was conducted to implement a clinical pathway for patients on mechanical ventilation. The project was managed by a local interprofessional core group and was externally facilitated by two researchers. Grounded theory was used by the researchers to explain the implementation process. The sampling in the study was purposeful and theoretical and included registered nurses (n31), assistant nurses (n26), anesthesiologists (n11), a physiotherapist (n1), first- and second-line managers (n2), and health records from patients on mechanical ventilation (n136). Data were collected from 2011 to 2016 through questionnaires, repeated focus groups, individual interviews, logbooks/field notes and health records. Constant comparative analysis was conducted, including both qualitative data and descriptive statistics from the quantitative data.ResultsA conceptual model of the clinical pathway implementation process emerged, and a central phenomenon, which was conceptualized as ‘Struggling for a feasible tool,’ was the core category that linked all categories. The phenomenon evolved from the ‘Triggers’ (‘Perceiving suboptimal practice’ and ‘Receiving external inspiration and support’), pervaded the ‘Implementation process’ (‘Contextual circumstances,’ ‘Processual circumstances’ and ‘Negotiating to achieve progress’), and led to the process ‘Output’ (‘Varying utilization’ and ‘Improvements in understanding and practice’). The categories included both facilitating and impeding factors that made the implementation process tentative and prolonged but also educational.ConclusionsThe findings provide a novel understanding of a bottom-up implementation of a clinical pathway in an intensive care context. Despite resonating well with existing implementation frameworks/theories, the conceptual model further illuminates the complex interaction between different circumstances and negotiations and how this interplay has consequences for the implementation process and output. The findings advocate a bottom-up approach but also emphasize the need for strategic priority, interprofessional participation, skilled facilitators and further collaboration.Electronic supplementary materialThe online version of this article (10.1186/s12913-018-3629-1) contains supplementary material, which is available to authorized users.