Redundancy, Modularity and Degeneracy

by Dr Alan Laverty FRCEM

I stumbled across the above mentioned terms in a newspaper article. It was written by the economist John Kay (he of the UK Kay report post GFC) in regard to the international banking system and his suggestion as I recall was that these were sensible principles upon which to base a new system. Where had he discovered these terms? Engineering interestingly. Where did engineering come up with them from? Evolutionary biology, even more interestingly. Oh for that sort of humility to transplant ideas within the medical fraternity! Now I’ve searched for the article again to try and prove I haven’t created a false memory but alas it’s deep behind a paywall (How we need you now Aaron Swartz).

So what do they mean and while I risk being the proverbial man with a hammer what is their relevance within medicine? Well they’re fairly straightforward individually. Redundancy is probably the most familiar and involves providing back up of functions or components.

In our practice at the Sydney Base we have two helicopters and two road ambulances. This leads to a bit of sitting around from time to time but means that when chance produces a volume of work we can almost invariably respond. We have two engines on the helicopter thankfully. We carry enough fuel to make it to an alternate airfield in the event of bad weather. We have two team members. We have oodles of oxygen within the helo and road ambulance but less moving on foot to a scene. We have multiple redundancies within our primary packs- etCO2 monitoring, pulse oximetry, IV access, PEEP valves (tripping over them), bougies etc. Many of these are the result of feedback from individual cases and clinical governance meetings. This also highlights the benefits of a self regulating system. A state of perpetual beta within a Zeno’s paradox towards unobtainable perfection.

Modularity is a broad concept with differing interpretations in different domains. The general theme is building a system from smaller sub units which function autonomously and can be be recombined as needed. Our organisation is divided up into teams responsible for each facet of of the process – education, simulation, airway registry, M+M, drugs, equipment, operating procedures, blood products, social media etc. Each has its own objectives and a fair degree of autonomy to do the job. In the ED ideally there are a number of smaller teams covering Resus, minors, majors, ambulance reception, ambulatory care, paeds. Working in smaller teams with focused goals is arguably more empowering and helps avoid the negative behavioural aspects of hierarchial bureaucracies. It also reduces management requirements. Consider that the entire Berkshire Hathaway conglomerate is run by 24 people in Omaha.

Degeneracy is where different units can perform distinct functions under regular conditions and similar functions under alternate conditions. This describes the core of our paramedic/ doctor model of prehospital care. Both can assess/ gain IV or IO access/ intubate/ use comms, ventilators, infusers/ give drugs/ give blood/ liaise with local crews and receiving hospitals. Under ideal conditions roles are distinct but then ideal conditions rarely seem to present. In the helicopter, the aircrewman swears he can get the helicopter very close to the ground (but not definitely land it!) in the event of a pilot issue. Some will happily set up the oxylog in preparation for patient transfer. We use a SAM splint for everything but its intended use. We can use a T-pod for airway positioning and holding a hysterotomy wound closed. In an ED, can every doctor and nurse take blood/ apply plaster of paris/ perform an ECG? Can a specialty doctor assist in the ED or see a patient directly? Does everyone know where the spare etCO2 tubing is? Frequently it’s the one nurse who does the ordering who Murphy has decreed to be on leave the day the levee breaks. Sure if the consultant in charge is regularly working as a phlebotomist then there are more fundamental staffing issues but degeneracy within a system provides another form of redundancy to cope with surges in demand.

What are we searching for in our systems? Robustness. I could suggest antifragility but let’s not go there. In classical economics we have the tale of absolute and comparative advantage with the conclusion that the person/organisation/country most efficient at a mode of production should carry it out exclusively. This makes perfect sense in a mathematical sense under ideal conditions or in an operating theatre. Add a little stochastic bedevilment and this model falls apart.

Most of these ideas will be incorporated in some form in healthcare systems but by stress testing each system against each variable from the wider organisation, to specialty, department, training program, operating procedure, care pathway etc. we may build better systems and processes. There will also be trade offs in costs vs benefits to consider but at least we can know where the weak points lie.

Given that these concepts are evident in evolution and have been subjected to the great leveller of time we can be fairly sure there’s something in them and I commend them to you.

As a final corollary, if you’re sitting on an interview panel and the victim has a background in engineering, economics, software design, astrophysics or other real world efforts, sign them up. We need new ideas.

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