What can we learn about ED Capacity and Patient Flow from Funnels?

This is part of the support material for the ER Overcrowding Solutions Presentation at the bottom of this Post...


As it has been shown time and time again, an Emergency Department that doubles its bed capacity never ends up seeing double the amount of patients before it requires another expansion. Why is that? The reason is simple. When a Hospital doubles ED physical capacity, it never doubles inpatient capacity nor doubles the number of radiologists, consultants, lab techs, analyzers, transporters, etc. As such, even a modest increase in ED volumes puts significant strain on all the ancillary departments we need to help us service demand and the inpatient units we need to unload admitted ED patients to. This markedly increases variability in system interfaces and increases the time patients actually spend idle in ED beds.

To illustrate this, close your eyes and imagine we are pouring sand into a three-dimensional funnel. As we pour sand on the top of the funnel some sand makes it to the bottom opening and exits the funnel but, if we pour sand more briskly, the funnel will eventually fill up as sand is being poured in faster than it can exit. The sand that spills over the top (because it does no longer fits in the funnel), represents patients accumulating in the ED waiting room and hallways.

Now, let’s imagine we obtain a much larger funnel but this funnel has an even smaller opening to let the sand out. We will now be able to pour more sand initially into the funnel entrance and pack more sand within the inside of the funnel. Nevertheless sand is getting out more slowly. As we pour more sand, each individual grain of sand has a far longer and congested distance to travel from the top to the bottom and is also competing with far more grains of sand to get through the bottom opening. When this funnel eventually spills, the mess will be far greater. That is what happens to Emergency Departments that just expand…

By contrast, eliminating variability is the equivalent of widening the bottom exit of the funnel. The more variability we eliminate, the wider we make that exit. Now, when we pour sand on the top, it travels much faster towards the bottom exit and the funnel is less likely to spill.

If we were able to eliminate all variability, the bottom opening would widen to the same diameter that the top opening making in effect an open cylinder. In such a perfect system, the same amount of sand being poured at the top would swiftly exit the bottom no matter how much is poured into it and could never be saturated even if the overall size of the cylinder was very small indeed.

Unfortunately, such a perfect non-variable system is unattainable when we talk about patient flow. All we can do is to strive to open the bottom of the funnel as much as possible by decreasing and eliminating as much variability in the system as we can. The take home message is that decreasing variability is by far, the most significant, cost-effective, logical and fastest thing we can do to increase ED efficiency, improve asset utilization and free-up functional capacity. Anything else…including ED expansion, is doomed to fail…