Nursing in adult critical care services - safe staffing evidence: A rapid review.

AIM: This rapid review was conducted for the NHS England Safer Staffing Programme (2024) England (2024) [1] to evaluate the evidence base for adult critical care nurse staffing. The review addressed four objectives: 1) identifying current staffing decision-making processes; 2) evaluating the impact of staffing models on patient outcomes and service efficiency; 3) assessing effects on burnout and staff retention; 4) identifying effective staffing responses during the COVID-19 pandemic. METHODS: A rapid systematic review following PRISMA guidelines was conducted across MEDLINE, CINAHL Plus, PsycINFO, and Scopus (2012-2024). Studies examining quantitative, qualitative, and mixed-methods research on registered nurse staffing in adult intensive care were included. FINDINGS: Eighty-six studies met the inclusion criteria. Current staffing guidelines predominantly rely on expert consensus (Level 7 evidence) with day-to-day adaptation by senior nurse managers. Emerging empirical data (Level 4-5) suggest an association between nurse-to-patient ratios of 1:1 or higher and reduced mortality and nosocomial infections, though heterogeneity across studies precludes defining an optimal ratio. Workload intensity may be a more sensitive predictor of outcomes than static ratios. High nursing workloads are associated with increased burnout and turnover. Pandemic responses demonstrated that while "upskilling" non-ICU nurses supported surge capacity, it increased the psychological burden on experienced ICU staff. CONCLUSIONS: While current guidelines rely heavily on expert opinion, there is some evidence from the literature to suggest that moving toward objective, workload-based frameworks might address limitations in current consensus-based models. However, the existing evidence base is largely observational, necessitating further high-quality research to confirm these associations. IMPLICATIONS FOR CLINICAL PRACTICE: Healthcare organisations should consider integrating objective workload measurement tools to supplement the professional judgement of the Nurse in Charge. Such an approach may provide a more defensible basis for workforce planning and help mitigate the impact of rising patient acuity on staff retention.