AIM: To determine activities and outcomes of intensive care unit Liaison Nurse/Outreach services. The review comprised two stages: (1) integrative review of qualitative and quantitative studies examining intensive care liaison/outreach services in the UK and Australia and (2) meta-synthesis using the Nursing Role Effectiveness Model as an a priori model. BACKGROUND: Acute ward patients are at risk of adverse events and patients recovering from critical illness are vulnerable to deterioration. Proactive and reactive strategies have been implemented to facilitate timely identification of patients at risk. DESIGN: Systematic review. METHODS: A range of data bases was searched from 2000-2008. Studies were eligible for review if they included adults in any setting where intensive care unit Liaison Nurse or Outreach services were provided. From 1423 citations and 65 abstracts, 20 studies met the inclusion criteria. RESULTS: Intensive care liaison/outreach services had a beneficial impact on intensive care mortality, hospital mortality, unplanned intensive care admissions/re-admissions, discharge delay and rates of adverse events. A range of research methods were used; however, it was not possible to conclude unequivocally that the intensive care liaison/outreach service had resulted in improved outcomes. The major unmeasured benefit across all studies was improved communication pathways between critical care and ward staff. Outcomes for nurses in the form of improved confidence, knowledge and critical care skills were identified in qualitative studies but not measured. CONCLUSION: The varied nature of the intensive care liaison/outreach services reviewed in these studies suggests that they should be treated as bundled interventions, delivering a treatment package of care. Further studies should examine the impact of critical care support on the confidence and skills of ward nurses. RELEVANCE TO CLINICAL PRACTICE: Advanced nursing roles can improve outcomes for patients who are vulnerable to deterioration. The Nursing Role Effectiveness Model provides a useful framework for evaluating the impact of these roles.