question

Dash Ballarta avatar image
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Dash Ballarta asked Matthew Gillespie commented

First available location not reevaluated

HI, just wondering if you could help me troubleshoot my clinic model.

I have three PCIs and they are supposed to go to a waiting area. They leave upon first availabilty of either exam tables or radiology tables.

Two of my PCIs are getting stuck in the waiting area and do no proceed further, although their activity should re-evaluate the availabiilty of tables.

Additionally, my wait times in my dashboard generate an error when i run them - however, this may be related to the above.

fsm is at the following link:

https://utexas.box.com/s/w04d80s2zr7j5pgejouxknekuzkax0gx

Thanks,

Dash

FlexSim HC 5.1.0
healthcaredecisiongridlockfirst available locationreevaluate availability
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1 Answer

Matthew Gillespie avatar image
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Matthew Gillespie answered Matthew Gillespie commented

Dash,

There are a few issues here. I've attached a simplified version of your model to help point them out. When you run the model you'll see that the first set of three patients go through their activities correctly. However, when the next set of three arrive, two of them get stuck in the waiting room. This is because the decide activity starts the ToWaitingRoom activity on the patients if neither area is available at that time. The patients are then stuck forever trying to go to the waiting room because they're already there. Running the model some more shows the other issue. When the group of 5 shows up, 2 of them go to a bed and 2 of them go to a CT. However, they're gridlocked once they finish their processing time. The bed patients are waiting for the CT patients to leave and the CT patients are waiting for the bed patients to leave.

I've attached a modified version of that model that doesn't have these issues. In activity 20, I use the Based on Destination Status pickoption to send the patients to the first available location. The processing time uses the Based on patient's location pickoption so you can have different processing times based on the area. I added a Activity Finished trigger that sets the "nextArea" label on the patient to be the other area (whichever one the patient still needs to go to). Activity 40 then tells the patient to go to the area recorded on that "nextArea" label. Activity 30 is a decide that checks to see if the next area is available and starts activity 40 if it is, otherwise it starts activity 31 that sends the patient to the waiting room and then activity 40 will start.


stuckpatients.fsm (119.0 KiB)
stuckpatientssolution.fsm (125.1 KiB)
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Dash Ballarta avatar image Dash Ballarta commented ·

Matt,

Thanks for this, I wouldn't have thought to structure the logic this way. It works great the way you demonstrated.

As I iterate this model, I do notice that as my queue grows, patients are evaluated on a "last in, first out" basis (e.g., ID8 will end up waiting all day, while ID23 will come in and get throughput). Is there something I can do to have these patients evaluated by priority (that being wait time?).

Dash

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Matthew Gillespie avatar image Matthew Gillespie ♦♦ Dash Ballarta commented ·

This behavior is determined by the Entrance Criteria of the object. The default entrance criteria sorts the patients first by acuity, and then by waiting time, so I doubt you're queue is really LIFO unless you're using a custom entrance criteria.

If you want patients who've been to one of the two areas already to be prioritized above patients who haven't been to one yet (or vice-versa) you can change the entrance criteria of each object to use a custom configurable entrance criteria.

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Dash Ballarta avatar image Dash Ballarta commented ·

Hi Matt, you are correct in that the waiting areas are still evaluating via acuity and total wait time. However, I'm still getting some stragglers that somehow get missed from being evaluated.

mskloiterers.png

The throughput of patients is what i expect it to be for this model, but these folks never get seen - maybe due full beds at the time they get evaluated for rooms?

Dash

msk1.fsm

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mskloiterers.png (625.2 KiB)
msk1.fsm (6.3 MiB)
Matthew Gillespie avatar image Matthew Gillespie ♦♦ Dash Ballarta commented ·

You just need to update your flowchart. There's no connection between the MSKExamTableArea and the WaitingAreaArea. You'll want to make a connection both ways between them.

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Dash Ballarta avatar image Dash Ballarta commented ·

doh! always the flowchart. Thanks matt!

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