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

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.

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.

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.

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.

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.