Saturday, June 1, 2013

Focus and Leverage Part 216

For the past dozen or so postings we have been discussing the Theory of Constraints Thinking Processes with readers coming in record numbers.  In this posting I’m going to shift gears to the Healthcare field and discuss a recently completed Process Value Stream Analysis (PVSA) project at a hospital located in the Mid-Western part of the US.  The focus of this PVSA was in this facility’s Emergency and Cardiology Departments where they wanted to improve one of their key performance metrics, Door to Balloon Time (D2B).  For those of you (like me before I started this engagement) who don’t have a clue as to what D2B s, let me fill you in.  Door-to-balloon is a time measurement in emergency cardiac care (ECC), specifically in the treatment of ST segment elevation myocardial infarction (or STEMI). The interval starts with the patient's arrival in the Emergency Department and ends when a catheter guide-wire crosses the culprit lesion in the Cardiac Cath lab.  In everyday language, this just means that a balloon is inflated inside one of the heart's primary blood vessels to allow unimpeded blood flow through the heart    The clock starts ticking either as a walk-in to the Emergency Department or in the field where a patient is being attended to by medical personnel.  This metric is enormously important to patients simply because the longer this procedure is delayed, the more damage occurs to the heart muscle due to a lack of oxygen to the heart muscle.  It’s damaged because the cause of this problem is typically due to a blockage within the heart that prevents oxygen from being supplied to the heart and without proper amounts of oxygen, muscle damage results.  The inflated balloon "unclogs" the blood vessel.
We started this event with a training session for the team members focusing on how to use an integrated Lean, Six Sigma and Constraints Management.  I have seen a lot of PVSA’s where waste is identified throughout the process and then the team works to either reduce it or eliminate it.  It has been my experience that when attempting to reduce the time it takes to process something through a process, such as this one, by attacking the entire process for waste reduction, teams frequently miss the opportunity to reduce the cycle time much more quickly than they could.  This is where Constraints Management and its five focusing steps offers a much quicker solution to this type of project.  If you’ve a regular follower of my blog, then you are quite familiar with these steps.  But if you’re new to this blog, TOC’s five focusing steps, first introduced by the late Dr. Eli Goldratt, are:

1.  Identify the system constraint – In a physical process with numerous processing steps, the constraint is the step with the least amount of capacity. Or another way of stating this is the step with the longest processing time.

2.  Decide how to exploit the system constraint – Once the constraint has been identified, this step instructs you to focus your efforts on it and use improvement tools of Lean and Six Sigma to reduce waste and variation, but focus your efforts mostly on the constraint.  This does not mean that you can ignore non-constraints, but your primary focus should be on the constraint.

3.  Subordinate everything else to the constraint – In laymen’s terms this simply means don’t over-produce on non-constraints and never let the constraint be starved.  In a process like the Door to Balloon time, it would make no sense to push patients into this process since they would be forced to wait excessively.  But of course the hospital cannot predict when patients with heart attacks will show up needing medical attention.  But by constantly trying to reduce the constraint’s time, the wait time should be continuously reduced.

4.  If necessary, elevate the constraint – This simply means that if you have done everything you can to increase the capacity of the constraint in Step 2 and it’s still not enough to satisfy the demand placed on it, then you might have to spend money by hiring additional people, purchasing additional equipment, etc.

5.  Return to Step 1, but don’t let inertia create a new constraint – Once the constraint’s required capacity has been achieved, the constraint could move to a new location within the process.  When this happens, it is necessary to move your improvement efforts to the new constraint if further improvement is needed.  What is thing about inertia?  What Goldratt meant by that was to make sure things you have put in place to break the original constraint (e.g. procedures, policies, etc.) are not limiting the throughput of the process.  If necessary, you may need to remove them.

For whatever reason, the agency who developed this metric used the median rather than the mean.  The current median standard for Door to Balloon Time was  set at 90 minutes and this hospital was actually doing quite well against this standard with a median score of 66 minutes.  However, because this hospital is anticipating the standard will be changing to 60 minutes in the future, they decided to be proactive by putting together a team of subject matter experts to look for ways to achieve this future target before it is mandated to do so.  In addition to this new time benefitting the patient (i.e. much less heart muscle damage), there is also a financial incentive for the hospital in that reimbursement rates for Medicare and Medicaid patients are tied to completing the D2B time below the standard median time.

After completing the training session, the team was instructed to “Walk the Gemba” by going to both the Emergency Department and Cardiology to observe what happens during this process and to have conversations with employees from both departments about problems they might encounter.  This was a fact-finding mission aimed at understanding how patients are managed through this treatment process.  The team collected many observations during this walk, most of which would be used to construct their current state process map, which unfortunately is too large to post here.  The team also had access to DTB time data that has been collected on previous patients passing through this process.  The team then analyzed the data to better understand what was happening on previous D2B events.  The figure below is a summary of this analysis.

The time data that had been collected was broken down into three separate phases of the D2B process:  Door to EKG, EKG to Table and Table to Balloon.  This was extremely helpful for the team in their efforts to identify the system constraint.  As you can see in the above figure, the EKG to Table Phase, with a Mean value of 36.7 minutes, is clearly that part of the process requiring the most time and was designated by the team to be the system constraint.  Table to Balloon time, at 21.2 minutes on average, also consumed a significant amount of time while Door to EKG only required 4.75 minutes to complete.  It is important to remember that this metric (D2B) was developed to capture median times rather than mean times, so hospitals are judged (and reimbursed) by a median time and is reported as such.  The difference between the median and mean times for EKG to Table (i.e. median = 32 minutes and mean = 36.7 minutes) indicates that the data might be skewed and not perfectly normally distributed.  This, of course, means that there are outliers which must be investigated for cause.

After collecting and analyzing this data, the team was instructed to create two Interference Diagrams (ID’s), one for Phase 2 (EKG to Table) and one for Phase 3 (Table to Balloon).  You may recall from earlier posts on this blog that the purpose of the ID is to identify any barriers or obstacles (i.e. interferences) that stand in the way of achieving a goal or objective.  In the cases for Phase 2 and 3, the goal was identified as reducing the time required to complete each phase.  The following photo was of the ID created for the EKG to Table phase and is presented here only to depict what an Interference Diagram looks like for those of you who may never have used one before.  The post-it-notes contain a description of the interference with an estimate of how much time the interference might negatively impact the goal of reducing cycle time.

The team then used their fact-finding “walks” (i.e. observations and conversations) and the Interference Diagrams to create both an Ideal State and a Future State Map.  The image below compares the Current State Map and Future State Map after completion of the standard value analysis and as can be seen, the number of total steps was dramatically reduced as were the number of decision points, swim lanes and hand-offs.  You will also notice when comparing the current state to the future state, a dramatic reduction in the number of non-value-added (i.e. red) steps (i.e. 27 to 2).  The team also developed an Ideal State Map which is included in the figure below.
This team did an excellent job of analyzing this important process and was able to remove much of the waste contained within it.  But the real improvement came in the overall potential time to complete this procedure which should have a significantly positive impact on damage to patient’s heart muscles when their recommendations are implemented and this was the overriding premise and objective of this event.  The following is a summary of before and after for this PVSA.  The numbers in parenthesis in this table is a sub-process that the team also looked at.
Although a reduction in Door to Balloon time of 13 minutes might not seem like much of an improvement to some of you, consider how much less damage to a patient’s heart muscle might be avoided.  In the healthcare field for procedures such as Door to Balloon Time, every minute counts…..
Bob Sproull


No comments: