Commercial risk will be a critical catalyst of progress – it’s complicated, but is it possible? We think so.


Case Study

Criteria-based mid-acuity segmentation

5 Minute Read


The challenge

Many emergency departments have effective pathways for treating high-acuity patients, while also quickly moving low-acuity patients to fast tracks. But when a significant portion of emergency department patients are mid-acuity patients, this straightforward system is challenged. These patients are often more difficult and time-consuming to diagnose and their care strategy is less obvious than low-and high-acuity patients.

The organization

PeaceHealth Southwest Medical Center is a 450-bed hospital located in Vancouver, Washington, US, with 110,000 emergency department (ED) visits annually. Almost two-thirds of their ED population were mid-acuity patients.

The approach

PeaceHealth partnered with frontline nurses to create a track for mid-acuity patients, segmenting them by acuity and diagnostic needs to optimize throughput for these difficult-to-classify patients.

The result

PeaceHealth’s collaborative process helped proactively manage bottlenecks associated with mid-acuity patients, leading to overall improvements in ED LOS and left without being seen rates.



A triage nurse separates mid-acuity patients entering the ED who have an Emergency Severity Index (ESI) score of three 3 into three paths—low acuity, stable and noncomplex, and sick and complex.

To identify the needs of each patient track, PeaceHealth examined typical arrival times and volumes. This helped them determine staffing levels, number of beds, and hours of operation for each treatment segment. These criteria now help staff direct a third of all ESI-3s to dedicated pods to expedite care.

PeaceHealth’s three patient tracks

“Pod A”: Low-acuity ESI level 3s

  • Typical conditions: lacerations, fever, flank pain

  • Hours of operation: 8am –1am

  • Staffing: one PA, two nurses, one technician

  • Number of beds: six beds, one swing bed shared with fast track

“Pod B”: Stable, noncomplex ESI level 3s

  • Typical conditions: those too severe for “Pod A,” but not severe enough for main ED

  • Hours of operation: 9am –3am

  • Staffing: one doctor, two nurses, one technician

  • Number of beds: nine beds

Main ED: Sick, complex ESI level 3s

  • Typical conditions: abdominal pain, sepsis

  • Hours of operation: 24/7

  • Staffing: two doctors, seven nurses, three technicians, two unit secretaries

  • Number of beds: 23 beds

The four pillars of PeaceHealth’s mid-acuity track staffing model

This new model was built on four important pillars, each reinforcing the others and making the entire system functional and adaptable.

  1. Built-in flexibility: Clinical staff can be moved across pods to respond to changing patient volumes. Doctor supports physician assistant in neighboring pod.

  2. Most capable staff in the lead: Project leaders selected staff who were hardworking, worked well with others, and were willing to speak up. Selected members served as mentors and leaders for the rest of staff.

  3. Well-supported transition to new model: Facilitator present in the area for three months after implementation to ensure sustainability and to support staff. Facilitator able to answer any questions and ensure staff did not revert to old model.

  4. Resources matched to demand: Operating hours and number of staff determined based on data from patient volumes and acuity levels during the day.

Building in flexibility and matching the resources to demand meant that only the appropriate resources were used at all times. Putting the most capable staff in the lead of a gradual and sustainable change ensured that the quality of service improved as well.


Keeping less-sick patients vertical

One noteworthy aspect of PeaceHealth’s model is keeping less-acute patients vertical. This principle recognizes that not all patients need an emergency department bed, which is a scarce resource. Staying vertical reinforces to patients and staff that these patients are not going to be in the emergency department for long.

PeaceHealth’s criteria are critical to this model of care, as they give the triage nurse enough information to make this decision up-front.

This change underscores a key lesson on optimizing emergency department throughput: utilize beds only for the sickest patients. Many emergency department patients do not necessarily need a bed, and if they do, they may need it only for a certain period of time. This represents a big shift in thinking for some emergency departments, but if patients are well enough and conditions are appropriate, placing them in a bed should no longer be an automatic step.



In large part due to PeaceHealth’s criteria, ESI-3s are not only assessed in less time, but their care plans and tests are also initiated more quickly, yielding impressive results. A drop in emergency department length of stay and left without being seen rates reveals that relieving bottlenecks for the largest, most ambiguous emergency department population has impacted flow for all patients.

PeaceHealth did this all without adding staff, creating any new construction or redesigns, or implementing an EMR system. PeaceHealth cited flexibility to respond to patient volumes and acuity in real time as the key to success. Doctors and physician assistants can be pulled from one pod to another for a quick consult, and patients can be shifted to a pod with more capacity if one track is falling behind.

Have a Question?


Ask our experts a question on any topic in health care by visiting our member portal, AskAdvisory.