As the world struggles with the COVID-19 pandemic, health service demands have increased to a point where healthcare resources may prove inadequate to meet demand. Guidelines and tools on how to best allocate intensive care beds and ventilators developed during previous epidemics can assist clinicians and policy-makers to make consistent, objective and ethically sounds decisions about resource allocation when healthcare rationing is inevitable. This scoping review of 62 published guidelines, triage protocols, consensus statements and prognostic tools from crisis and non-crisis situations sought to identify a multiplicity of objective factors to inform healthcare rationing of critical care and ventilator care. It also took ethical considerations into account. Prognostic indicators and other decision tools presented here can be combined to create locally-relevant triage algorithms for clinical services and policy makers deciding about allocation of ICU beds and ventilators during a pandemic. Community awareness of the triage protocol is recommended to build trust and alleviate anxiety among the public. This review provides a unique resource and is intended as a discussion starter for clinical services and policy makers to consider formalising an objective triage consensus document that fits the local context.