Analyze patient flow and systems constraints
Trace how patients move through an ER and find the constraint that slows the whole system down.
- A process is an ordered set of steps: Analyzing patient flow requires seeing the ER as a sequence of steps, each taking time, rather than one event.
- Rate and time basics: Finding a bottleneck means comparing how fast each step can handle people, so you need to reason about rate (people per hour) and waiting time.
Prerequisites are inferred: pending teacher review.
Re-learn the skill with worked practice and clear examples.
The constraint (bottleneck) is the step with the lowest capacity. It sets the throughput of the whole ER, so it is the step to fix first.
An ER's four steps have these capacities (patients per hour): triage 20, registration 18, treatment 8, discharge 25 (see the table). What is the ER's throughput, and which step is the constraint?
Approved| Step | Capacity (patients/hour) |
|---|---|
| Triage | 20 |
| Registration | 18 |
| Treatment | 8 |
| Discharge | 25 |
- A.Throughput 25/hour; the constraint is discharge
- B.Throughput 8/hour; the constraint is treatment
- C.Throughput 18/hour; the constraint is registration
- D.Throughput 71/hour; there is no single constraint
Show the worked solution ▾
Answer: B. Throughput 8/hour; the constraint is treatment
- Step 1: Find the smallest capacity: The four capacities are 20, 18, 8, and 25. The smallest is 8, at the treatment step.
- Step 2: Set throughput to the bottleneck: The whole system can only finish patients as fast as its slowest step, so the throughput is 8 per hour and treatment is the constraint.
Why it's right: Treatment has the lowest capacity (8/hour), so it caps the entire ER at 8 patients per hour and is the constraint.
- A: Discharge is the fastest step, so it cannot be the bottleneck.
- C: Registration (18) is faster than treatment (8), so it is not the limiting step.
- D: You do not add the capacities; the slowest single step sets the throughput.
Aligned to Systems thinking: bottleneck and throughput · reading level ~grade 9
- A flow study where staff time each ER step for a week, then circle the slowest step as the one renovation dollars should target.
Fill these in as you work through the lesson.
- Patient flow (the path a patient takes through the ER):
- Triage (the sorting step near the entrance):
- Constraint (the step that limits the whole system):
- Throughput (how many patients move through per hour):
The of a whole system is set by its slowest step; that slowest step is called the , and fixing it raises the system's .
- List the steps a walk-in patient passes through, in order, from door to discharge.
- If one step can handle far fewer patients per hour than the others, what happens to the people upstream of it?
- Why does speeding up a step that was never the slow one fail to fix the backup?
An ER has four steps with these capacities per hour: arrival/triage 20, registration 18, treatment 8, discharge 25. Find the bottleneck, state the system's throughput, and explain which step to fix first.