Swiss cheese

Most controls to prevent hazards have some gaps.  That’s why you have multiple controls to prevent a hazard.

One of the models used in risk assessment and hazard prevention is the Swiss cheese model.  Imagine several slices of Swiss cheese; each one of those is one of the controls you have in place to prevent a hazard from occurring. Line those slices up on edge and shifting them so that there are limited lines of sight from the left hand side to the right hand side.  This is a fair model of how hazard control processes are designed and implemented.  Now, imagine that, when the slices are lined up, the holes in the Swiss cheese nonetheless allow the hazard to occur.

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The recent Ebola story out of Dallas brought this to mind.  How many pieces of Swiss cheese were there?  How many failed? Would more Swiss cheese have prevented this?

Patient Zero shouldn’t have been allowed on a plane out of Liberia had he honestly answered the question “Have you been in contact with a person with Ebola?”  He’d carried an infected person into their home, where they died the next day.  Maybe he answered honestly, and the airline screener screwed up.

When he went to the hospital the first time, and he told the nurse that he had a fever and had recently been to Liberia (as it appears he did), did the nurse use the checklist for potential Ebola exposure?  If so, why didn’t that information get passed on to the doctor before he/she prescribed antibiotics and sent Patient Zero home?  Or, worse, did the information get passed on, in which case, why didn’t the doctor quarantine Patient Zero immediately?

“Ebola Patient’s Contacts Pursued,” Wall Street Journal, October 2, 2014 A1. The number of people with whom he can into contact after he displayed symptoms, both before he went to the hospital the first time and when he went to the hospital the second time, and the number of people that those contacts then came into contact with, continue to grow.

How many times does the correct collection, management, and use of information come into play with this scenario? What about the preparation for the hospital spokespeople and the Texas Governor before and after their various speeches? What other processes would you put in place, and how could those processes fail?