ReSC: What does a good mass casualty plan look like?

Mass casualty incidents are rare, which makes learning from them difficult, and their wider consequences for health and social care can be very different. This left us asking what, exactly, we should be planning for.

NHS Highland and IHRR approached the problem from different perspectives. As resilience practitioners, we tend to think about what an incident will require organisations and people to do, while Professors Bruce Malamud and Alex Densmore brought a hazard science perspective which encouraged us to consider what a hazard could plausibly do and the consequences that might follow.

We combined a literature review and interviews with practitioners and subject matter experts with workshops involving people from health and social care, emergency planning, resilience, policy and academia. We also used the UNDRR-ISC Hazard Information Profiles to consider indirect, cascading and compounding consequences. Together, these different sources of knowledge allowed us to consider what happened when those consequences met a real health and social care system, with its existing pressures, workforce, capacity and dependencies.

We developed Reasonable Worst Case Scenarios ranging from natural hazards and transport incidents to infrastructure failures and deliberate threats. These were not predictions, but plausible situations through which we could explore system effects and test our thinking. Increasingly, the cause became less important than the consequences health and social care would actually have to manage.

Recommendation 9 of the UK Covid-19 Inquiry’s Module 1 report called for regular use of external red teams to challenge preparations for whole-system civil emergencies. Although directed at government, it prompted us to consider what Red Teaming might look like in health and social care.

Using the Ministry of Defence Red Teaming Handbook as our starting point, we explored what might be useful, what needed adapting and what could make effective challenge difficult in health and social care. We became interested in both the techniques and the Red Team mindset: remaining curious, making room for different perspectives, questioning assumptions and being willing to stay with uncertainty. We then used some of these approaches with the ReSC scenarios, exploring how constructive challenge might become part of planning itself.

Mass casualty planning understandably gives considerable attention to the early response, including ambulance services, Emergency Departments, critical care and hospital capacity. Working through the scenarios made it increasingly difficult to consider these in isolation. Creating capacity through early discharge may relieve one problem while increasing demand on primary and community care, social care and families, while disruption to infrastructure can affect both the response and the workforce needed to sustain it.

As we worked through this together, our understanding of how pressure moves through the system became better defined. The underlying idea was familiar to practitioners: relieving pressure in one place can create or increase it somewhere else. Working together allowed us to identify the pattern more clearly, find ways to explain it and, importantly, visualise what we were describing.

Developing the visualisation became part of the thinking rather than simply a way of presenting it afterwards. Putting pressures from different parts of health and social care into one picture helped us see their different timescales, where they overlap and how apparent stabilisation in one part of the system may coincide with increasing pressure elsewhere.

This changes how we think about whether a response is succeeding. If pressure has reduced, where has it gone, who is carrying it now and for how long? What makes sense in one part of the system may create pressure or risk elsewhere.

By our final workshop, we had returned to the mass casualty plan, although we found ourselves talking as much about planning as about the document. Planning brings people together to share knowledge, understand dependencies, question assumptions and work through choices that become much harder once an incident is under way.

ReSC was a relatively small exploratory project and has not produced a definitive answer to mass casualty planning. It has, however, changed how we think about the original question. Perhaps a good mass casualty plan is not one that predicts the incident that eventually happens, but one that comes from a good planning process, where people have explored what could happen, followed the consequences through the system, challenged what they think they know and understood enough about their dependencies and limits to adapt when reality does something different.

IMAGE FIGURE: The Migration of Pressure: A Systemic View of Mass Casualty Response

The Migration of Pressure developed through that shared process of identifying, explaining and visualising what happens across the system. It is not a predictive model or fixed timeline, and we do not regard it as finished. We expect it to develop as we continue to explore how health and social care plans for mass casualty incidents and improve our understanding of how pressure moves, overlaps and changes over time.