Flow Lab: Patient Flow Interactive Module

Introduction 101 · interactive companion

Why is the emergency department full when everyone is working hard?

Follow Emre, the new patient flow manager of a public hospital, through his first month. Each station pairs his question with an exercise you can run yourself.

Built on a Web of Science search: 666 records screened, 655 included (1980 to 2026). Companion to Patient Flow: An Introduction (101) by Prof. Dr. Mehmet Nurullah Kurutkan.

EMRE
Monday, 10 a.m. Twelve admitted patients are on trolleys in the emergency department. The wards say they are full. Theatres just cancelled a hip operation. The director wants the emergency department to “work faster”. Is that really the problem?
655
Web of Science records on patient flow
248
records on the emergency department, the most studied setting
19 min
longer ED stay for every 10% rise in bed occupancy (25 hospitals)
3
records with an author address in Türkiye
THE SHORT ANSWER
Patient flow is the movement of patients through and between care settings. A crowded emergency department is usually a symptom: the queue forms where patients wait, but the cause often sits downstream, in full wards and late discharges.
Station 1

Demand, capacity and variability

EMRE
On average we discharge enough patients to make room for the ones who arrive. So why do we still get a queue every day? Let me simulate one day.
Variability:
utilisation (arrivals / capacity)
longest queue (patients waiting)
average wait for a bed (Little’s law)

Teaching simulation: arrivals follow a typical daily pattern (quiet nights, a late-morning peak); capacity is constant. Queue = waiting patients carried forward hour by hour.

EMRE’S NOTEBOOK
Average capacity can exceed average demand and a queue still forms, because demand is uneven. Variability, not only volume, creates waiting (de Bruin et al., 2005).
Station 2

Find the bottleneck

EMRE
The board gave me four extra resource units. Each adds 2 patients per hour to one step. Where should they go?

Seven patients per hour arrive. Throughput can never be higher than the slowest step. Units left: 4

throughput (patients per hour)
queue growth per hour
current bottleneck
EMRE’S NOTEBOOK
Speeding up triage does nothing if the constraint is bed allocation. Improvements must start at the step with the least spare capacity, then move to the next one.
Station 3

Occupancy and the emergency department

EMRE
Finance says a full hospital is an efficient hospital. What happens to the emergency department when the wards run hotter?
relative waiting, compared with 85% (queueing curve)
change in ED stay vs 85% (average association)

The curve uses the simple queueing ratio occupancy / (1 − occupancy) to show the shape of the relationship. The ED estimate applies the average association reported across 25 Queensland hospitals, 19 minutes per 10 points of occupancy (Riahi et al., 2026); the critical threshold differed from hospital to hospital, so treat both numbers as illustrations, not forecasts.

Station 4

Words that get mixed up

EMRE
In meetings people use flow, throughput, crowding and length of stay as if they were the same. Flip the cards.
Station 5

What works

EMRE
Every vendor promises a solution. What does the evidence say?
Station 6

Diagnose the problem

EMRE
Six situations from my first month. For each, which lever matters most?
Station 7

Flow scorecard for your hospital

EMRE
Before my report to the board, I rate our hospital on eight questions drawn from the research. Rate yours and copy the report.

Result

0/ 100

Report





EMRE, A MONTH LATER
We stopped asking the emergency department to work faster. A daily bed meeting at 8 a.m., discharge planning from admission and a fast track for minor cases cut the trolley count by half. The queue moved to where it could be fixed.





Key sources


Full reference list, method box and figures are in Patient Flow: An Introduction (101).