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Patient Flow

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Patient Flow

What is it and how can it help me?

More and more people are using the term ‘patient flow'. This overview describes patient flow and links to theories about flow. Patient flow underpins many improvement tools and techniques.  

'The term flow describes the progressive movement of products, information and people through a sequence of processes. In simple terms, flow is about uninterrupted movement, like driving steadily along the motorway without interruptions, or being stuck in a traffic jam.

In healthcare, flow is the movement of patients, information or equipment between departments, staff groups or organisations as part of a patient's care pathway.

Improving Flow: Improvement Leaders' Guide  

This is an operational or process view of patient flow. A clinician may have a different focus. Their focus could be on the progression of a patient's health status, disease progression and/or the clinical knowledge and understanding of both. The clinical focus naturally allows for appropriate waits, for example ‘watchful waiting'.

 There has to be a close relationship between both the operational and clinical perspectives. What happens to a patient clinically will dictate his or her movement through different steps and settings, as well as the movement of associated information, equipment, samples etc. 

One way to engage and ensure that patient flow incorporates the clinical view is to include clinicians in mapping sessions, i.e. where teams map out patient pathways and associated processes. If you find it difficult to engage clinical staff, you may find it helpful to start from their viewpoint - and then see how processes fit around this.

Reducing delays and making sure that patients receive the right care at the right time will have a significant beneficial effect on the quality of care patients receive. In turn, this will improve patient outcomes and reduce the cost of care.
When does it work best?

Patients referred to and treated in hospitals and systems that ‘keep the flow' and ‘keep things moving' will have quicker referral to treatment times. Any waits that occur will be necessary; either for clinical reasons or due to patients choosing to wait (for example, the time needed to make a decision about whether or not to have a treatment).

How to use it

This guide will help you to structure your overall approach to improving patient flow, and thereby reducing delays. It links up to tools and other guides that provide more detail. The approach is based on two main improvement strategies: the theory of constraints and Lean thinking; and a body of practical knowledge - clinical systems improvement and clinical micro-systems. 

It's useful to start from these theories as they provide health services with proven approaches to improvement, as well as the tools and techniques which we know work. Despite the origins of patient flow being in the manufacturing industry, there are many ideas and concepts that can be borrowed and adapted to help manage health services.

1. Patient flow in context
Improving patient flow is one way of improving health services. Evidence suggests that enhancing patient flow also increases patient safety and is essential to ensuring that patients receive the right care, in the right place, at the right time, all of the time (reliability). However, it is important that patient flow does not improve at the expense of safety or system reliability. 

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There are three aspects of flow:

  • Create flow: provide services to meet demand (real) from patients
  • Flow: reduce variation and improve reliability
  • Increase responsiveness to problems in patient flow.

2. Create flow: provide services to match demand (real) from patients
Start some of your improvement work at the end of a patient's journey (create capacity and pull the backlog through the pathway).

This will allow you to see the impact of improvements in referral to treatment times immediately. It will also prevent a tidal wave of backlog work being shifted along the patient's journey.

You can identify the end of the patient pathway, diagnostic pathway and information pathway through process mapping. Look at the whole pathway, including after patients receive treatment. For example, start with outpatient follow up appointments: the point at which a patient is discharged from the hospital.

Reduce things that do not add value to patients
A lot of our work adds value to patients: right referral, right diagnostic tests, right diagnosis, right information and communication, right advice, right treatment, right aftercare and right handover. Waiting only adds value if there are clinical reasons for the waiting.

Plan ahead: along all parts of a patient's journey
This ensures that each step of the programme is planned for and scheduled so everyone knows what to expect and when to expect it. It helps to co-ordinate and pace work. See enhanced recovery.

3. Pace work to the demand of the patients

Match work rate to the new work that comes in; for example, patient referrals. This means making sure that there is enough capacity to meet demand and in particular, the stage of a patient's journey that is ‘rate limiting'. This is the bottleneck. There are specific ways of managing a bottleneck to make sure that the step works as efficiently as possible (see managing bottlenecks). Ideally, all the other steps along the patient's journey should work in pace with the bottleneck.


Understand sources of variation: reduce artificial variation and manage natural variation

There are two sources of variation: artificial and natural.  Generally speaking, most variation is caused by the way that we work, and is therefore artificial. The key areas of focus to reduce delays in elective care are:


  • Keep the flow: reduce unnecessary waits
    Piles of work to do later, infrequent decision making for groups of patients, batching work and lists all represent a wait in a patient journey or diagnostic pathway. The focus is to have timely decision making.  Increasing the frequency of decision making and acting on the next steps will reduce delay: from monthly to weekly, from two days to daily, from hourly to immediate
  • Pool similar work together and share staff resources
    Pooling works because it reduces the variation in waiting times. This is similar to the system in train stations or post offices where there is one queue for several cashiers. This prevents you getting stuck behind someone who is slow. It's the same as ‘reducing carve out' and ‘reducing the number of queues'. The focus should be to pool at the start, in line with capacity and demand, with slots for Choose and Book made available in line with consultant capacity.
  • See and treat in order / first in first out / clinically prioritise and treat
    If one person jumps the waiting list for non clinical reasons, everyone else behind them waits longer for treatment. Pooling helps patients to be seen and treated in order, between different consultants for example. It is still possible to be seen and treated out of order; for example ‘cherry picking' or when diagnostic tests are stuck at the bottom of the pile.
  • Variation in capacity and resources to do work, for example the way that we manage staff and organise rotas. See a quick introduction to capacity and demand.

4. Organise for patient flow

Look at the whole patient journey and not just the team you work in. The efficiency of the whole patient journey is more important than the individual team's efficiencies. Coordinating and understanding is key to supporting patient flow.

5. Develop systems to monitor and measure patient flow

These should help you to identify operational problems (for example if capacity is not available to meet demand). The unit for measurement needs to include time: see example below.


This example illustrates patient flow around beds.  Beds are sometimes the bottleneck in the system, so understanding flow at this high level is useful.

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 What next?

This is a guide about patient flow. There is evidence that the best approach to improving patient flow is to:

Managing improvement projects can be a challenge. This is because healthcare systems are complex and there are many interactions. Your focus should be to identify high volume activities (see runners, repeaters and strangers) and improve patient flow along the patient pathway for these. At the same time, identify bottlenecks and work with them. Have a flexible, yet strong project management approach and do things on a small scale. 

Additional resources

Improving Flow: Improvement Leaders' Guide 


Patient flow and our current understanding of patient flow in the NHS is mainly built on three theoretical / practical frameworks:

  • The theory of constraints
  • Lean thinking (or the Toyota Model)
  • Clinical systems improvement

Lean is an improvement approach to increase flow and eliminate waste that was developed by Toyota. Lean is basically about getting the right things to the right place, at the right time, in the right quantities, while minimising waste and being flexible and open to change.

Theory of constraints
In a hospital context, the theory of constraints states that there is always a bottleneck setting the pace at which patients travel through a care pathway. It provides an improvement approach that focuses on the bottleneck improvement and management strategies.

Clinical systems improvement
Keep abreast of latest developments on the NHS Institute's website

This is a body of knowledge developed from the Modernisation Agency. Much of the learning is available in the 10 High Impact Changes. It does what it says on the tin - it's all about improving clinical systems.

Acknowledgements / sources

The models developed by ‘ThinkFlow' have influenced our thinking.

© Copyright NHS Institute for Innovation and Improvement 2008