NR 543 Week 6 Bottleneck Brief Example

Bottleneck Brief: The Inpatient MRI Slot Is the Station That Sets the Pace, So Faster Protocols Would Change Nothing, and Every Slot Lost to an Unready Patient Is Throughput the Hospital Cannot Recover

Student Name

College of Nursing, Chamberlain University

NR 543: Information Workflow in Healthcare

Instructor Name

Month Day, Year

Bottleneck Brief: The Inpatient MRI Slot Is the Station That Sets the Pace, So Faster Protocols Would Change Nothing, and Every Slot Lost to an Unready Patient Is Throughput the Hospital Cannot Recover

The Question

One station in any process is slower than the rest, and time saved anywhere else disappears into it without changing the total. This brief identifies that station in the inpatient brain MRI process for our stroke and neuroscience unit, explains how it was identified and argues what should and should not be done about it. The argument matters because the hospital's first instinct, after the mapping work, was to speed up radiology's protocol queue, which is visible and easy to measure. If the protocol queue is not the constraint, making it faster would change nothing that patients experience.

Identifying the Constraint

The theory of constraints, popularized in operations management by Goldratt and Cox (2004), holds that the output of a system is limited by its slowest step, and that improvements elsewhere do not increase output unless they relieve that step. To find it, I compared the capacity of each step with the demand placed on it, using two weeks of data for 38 requests from our unit and the radiology department's figures for all inpatient MRI requests.

Protocol assignment. A neuroradiologist protocols an inpatient request in about two minutes. Even with emergency work taking priority, the department can protocol far more requests each day than it receives. The morning wait is real, but it is a matter of timing, not capacity: requests wait while emergency studies are read, then clear quickly.

Safety screening. Each form takes about ten minutes of nursing time. Capacity is ample in principle, though the wait for information from relatives can be long for patients who cannot answer.

Scanner slots. The hospital has one MRI scanner available for inpatients, shared with outpatients and the emergency department, with six inpatient slots a day, 42 a week. Inpatient demand across all units averaged 47 requests a week over the two weeks. Demand exceeds capacity, so a queue must form, and it does: the median wait from slot assignment to the slot itself was more than four hours, and requests ordered after midday often wait until the next day.

The scanner slot is the constraint. It is the only step where demand exceeds capacity.

Why Speeding Other Steps Would Not Help

If the protocol queue were cleared an hour faster, requests would reach the slot queue an hour earlier and then wait an hour longer for a slot. The number of scans completed each day would not change, because it is fixed by the number of slots. The same is true of faster transport requests or faster report turnaround: they change when individual steps happen but not how many patients are scanned. Lean approaches in health care stress understanding and improving the whole flow of work that reaches the patient rather than tuning separate parts (Mazzocato et al., 2010).

How the Constraint Is Being Wasted

If the slot is the constraint, every slot matters, and the data show that slots are being lost. In 6 of 38 requests from our unit, the patient was not ready when the slot arrived, most often because the screening form was still incomplete or transport was late, and the slot was given to another patient or went unused. Across all inpatient requests, the radiology department estimates that about one inpatient slot a day is lost or partly lost, roughly 15% of inpatient capacity. On a constrained resource, that loss cannot be made up later; it is simply less capacity.

This finding changes the importance of the screening loop. Screening is not the constraint, but incomplete screening is the main reason slots are lost. Professional guidance on MR safety requires screening to be complete before a patient enters the scanner area (Kanal et al., 2013), so an unscreened patient cannot be scanned however long the slot is held. Improving screening therefore matters not because it shortens its own wait but because it protects the constraint.

What Should Be Done

The theory of constraints suggests a sequence: first exploit the constraint, making sure none of its capacity is wasted; then subordinate everything else to it, organizing other steps so the constraint is never starved; and only then consider adding capacity (Goldratt & Cox, 2004). Applied here, that means three steps. Exploit: keep a short standby list of patients who are fully screened and ready, so that a slot is never lost because its assigned patient is not ready. Subordinate: complete screening early, ideally at admission for stroke patients likely to need MRI, and request transport by rule 45 minutes before each slot, so that other steps serve the slot rather than competing with it. Elevate: only if the slots are fully used and demand still exceeds them should the hospital consider adding evening inpatient slots, which would cost technologist time.

What Should Not Be Done

The hospital should not prioritize the protocol queue, report turnaround or transport speed on their own. They may be worth improving for other reasons, but they will not increase the number of inpatients scanned each day. The brief also cautions against adding slots before the lost slots are recovered. Recovering about one slot a day by using the existing ones fully would be cheaper than adding an evening slot and would address most of the gap between demand and capacity.

What to Measure

Two measures will show whether the constraint is being managed: the number of inpatient slots used each day out of six, and the number lost because a patient was not ready. If lost slots fall and used slots rise toward six, the constraint is being exploited. If waits still grow, demand has outrun capacity, and elevating the constraint becomes the right conversation.

References

Goldratt, E. M., & Cox, J. (2004). The goal: A process of ongoing improvement (3rd rev. ed.). North River Press.

Kanal, E., Barkovich, A. J., Bell, C., Borgstede, J. P., Bradley, W. G., Froelich, J. W., Gimbel, J. R., Gosbee, J. W., Kuhni-Kaminski, E., Larson, P. A., Lester, J. W., Nyenhuis, J., Schaefer, D. J., Sebek, E. A., Weinreb, J., Wilkoff, B. L., Woods, T. O., Lucey, L., & Hernandez, D. (2013). ACR guidance document on MR safe practices: 2013. Journal of Magnetic Resonance Imaging, 37(3), 501-530. https://doi.org/10.1002/jmri.24011

Mazzocato, P., Savage, C., Brommels, M., Aronsson, H., & Thor, J. (2010). Lean thinking in healthcare: A realist review of the literature. Quality and Safety in Health Care, 19(5), 376-382. https://doi.org/10.1136/qshc.2009.037986