Triple Modular Redundancy – From Planes to Patients

Two years ago I was sitting in airplane on the tarmac of Manchester airport. Doors had been closed for some time, but we had not moved much since. Something was obviously no right. The calming voice of the crew came through the tannoy: “We have got a problem with an electronic module. We have got another two functioning modules on board, but we think it is safer to return to the stand to change the module. This will take probably 20 minutes.”

I was slightly nervous. Obviously better to find a fault before setting up then after. But also clearly a sign that planes can have problems, and we were about to lift up into the sky. My palms were getting sweaty. And why were they not confident to fly with the remaining two modules: did they not trust them either?

It was only about a year later when being educated by colleagues from RAF Valley that I understood the importance of what I had just witnessed. This was ‘triple modular redundancy’ (https://en.wikipedia.org/wiki/Triple_modular_redundancy) in action!

Triple modular redundancy is a way of doubling (em: tripling)  up on safety critical technology in planes, the Apollo mission, satellites etc. In order to avoid system failure planes will have most electronic and hydraulic systems in triplicate (and even in quadruplicate). as a result the risk of a crash is dramatically reduced.

How does this compare to healthcare? Which safety critical parts of the system are there in triplicate or quadruplicate? Some of the documentation is: staff might be asked to answer the same questions over 20 times in different parts of a documentation system. But safety critical parts? Such as …. doctors? Nurses?

The standard chain of escalation has often got a number of elements that are consecutively activated (https://www2.rcn.org.uk/__data/assets/pdf_file/0004/435586/Competencies_for_Recognising_and_Responding_to_Acutely_Ill_Patients_in_Hospital_2009.pdf). And given that each chain is as strong as its weakest link it if obvious that the longer the chain, the more unreliable the response.

We have untaken research in the last few years to evaluate the effects of technology to create this redundancy (https://www.ncbi.nlm.nih.gov/pubmed/28288655) with promising results. But thinking more about it I am convinced that there is a role for patients and their friends to support a more stable system but being health-literate, coached to know what might go wrong, able to escalate even if those at the bed-side are unsure. Patients know if something is not right, if they have a fever, started passing urine of a strange colour, are feeling faint.

Could patients be one element for triple modular redundancy?  What training would they need? What role would technology play in training and escalation?

 

 

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