What will it take to deliver the recommendations of Lord Darzi's next stage review?

If you ask local NHS leaders why previous policy initiatives have not resulted in anticipated benefits, they are not likely to pinpoint a lack of will or a deficit of ideas. History suggests the implementation strategy is likely to be the weakest link.

A fundamental issue is that the NHS is a complex adaptive system. Any major intervention changes not just aspects of the system, but its very nature. This is made even more complicated by the NHS being mainly a human activity system, which introduces issues of politics and group- or self-interest that are difficult to model or predict. We risk creating a prescriptive change plan at our peril.

So, what might help? The NHS Institute for Innovation and Improvement has developed some "design rules" for these circumstances. Large-scale change experts typically use design rules in complex situations. These rules convey the essence of the factors that make the most difference, based on experience. If we use such principles to guide implementation, we increase the probability of success. I describe just two of the design rules here.

First, build on what already exists. Paradoxically, transformational change is more likely to succeed where it is framed as a continuation of the present, starting from the organisational legacy and what people are used to. Staff are already fatigued by change and leaders are sceptical about the number of different initiatives.

We need to be careful about layering on more new ideas. While politicians and policy makers may push for the "big bang" launch of a major new direction, it will pay to be restrained with NHS staff, focusing on clarifying and integrating efforts.

The NHS has tremendous memory on how to implement radical change. Let's cherish and build on that before engaging the latest external consultants with yet another change methodology and new solutions.

Second, work out where the energy is. We need to identify the nodes of greatest influence. This means natural populations, units or processes that do not necessarily correspond with a linear interpretation of structures in the NHS, but where real change can happen if we focus energy on them. The Productive Ward programme is a great example. It shows that virtually universal take-up can occur without compulsion. Participants also act as facilitators to successor sites.

I have seen numerous doomed pathway redesign projects when more patients would benefit if the change process started from within the groups staff already work in, and build out.

We need to consider not just actions to reform the system but also how to embed the reforms and enhance the potential for breakthrough change. Implementation needs to be managed in a way that has never been done before for results that have never been achieved before. Now is the time to do things differently.