Our baseline process studies, based on an average demand of 500 slides per day (62 cases,) revealed a takt time of 2.61 minutes. However, measurement of the capability of each process step demonstrated an inability of the status quo methods to meet this demand in the areas of gross dissection, microtomy and H&E staining. (Figure ) As is evident from the graph, the biggest bottleneck was in the H&E staining step. While reducing non-value adding steps could bring the other processes below the takt time threshold, this alone would not work in the H&E production workcell. This workcell used a semi-automated batch stainer, an automated coverslipping device, in addition to traditional embedding stations with integrated paraffin dispenser and cold plate, and manual microtomes. Different case types were embedded in batches as they came from the tissue processor, then moved in batches to the microtomy stations where batches of slides were prepared, and the sections made. Baking and staining then ensued, also in batches. Case assembly happened as groups of finished slides came off the coverslipping device and were matched with blocks and paperwork for assembly and delivery to the pathologist.
Baseline process performance and threshold tatk time needed to match demand.
Following an implementation of the floorplan and process changes described here (Figures and ), and installation of the Symphony integrated staining/coverslipping machines, including elimination of multiple process steps that were considered non-value-adding, the cycle time for this workcell was projected to be reduced such that the overall takt time could be sustained. Total process and floorplan redesign projects substantial movement savings as detailed in Figure , with a breakdown of potential savings by process step.
Baseline floorplans and process flow diagram.
Floorplan and process diagram following change.
Summary of movement savings following implementation.
Raw measurements of productivity showed improvement in productivity data immediately following implementation of the H&E workcell modification. These results show statistical significance (Table and Figure ).
Comparison of monthly productivity following H&E workcell process change
Productivity gains from Lean implementation in H&E workcell.
The distance-travelled graphics in the baseline state and in the redesigned state are presented in Figure . Specimen movement distances were decreased within the H&E workcell from 92 to 53 feet, a reduction of 42%. These reconfigurations of workcell instrumentation and organization represented a collaborative effort of consultants, lab team members and leadership.
Time to first available slides decreased from a minimum of 12 hours to four hours. The primary intent of this was to provide added time for resident review of slides prior to sign-out, and was accomplished by use of a short sequence processor run for biopsy specimens arriving in the laboratory in the morning and a second large section run for tissues fixed overnight before cutting the following morning. By introducing these modifications 17% of the total workflow was shifted from a night-shift time to an afternoon time, and this contributed greatly to the overall change in average time from gross station to finished slides of 2.9 hours. This change however, also meant that the average time at which the last case was presented for diagnosis also improved from 9:59 to 8:55, an improvement of one hour and four minutes. The number of days in which new slides/cases were arriving on the pathologist's desk for diagnosis after 10 am was reduced 50%.
The process evaluation identified several significant wait times between steps, in addition to the bottlenecks noted above in actual process capability, some of which were eliminated or reduced by the changes implemented to date. (Table ) These were noted to be significant barriers, and an opportunity for large gains in TAT, even if we were only able to reduce them by half. This portion of the project, focused on the last two of these pauses, was successful in reducing the measured times by 11%. Through altering the work flow and manner of work, and adding additional processor runs, the waiting times at gross dissection, case assembly and the microtome were decreased. We encountered resistance to the changed work methods calling for single piece flow embedding and cutting steps, as evidenced by persistence of a 2.5 hour wait observed between embedding and microtomy. Future anticipated process accountability changes are expected to overcome this. By using the Symphony stainer to allow continuous case flow, generally assigning a single case to a single tray, we further facilitated the process.
Inventory or wait times for specimens between process steps
Process simplification and worker efficiency gains from installation of the Symphony automated platform appear significant. Both the Microtomy and H&E Staining workbenches were positively impacted as illustrated in green (Figures and ). At the microtomy bench, a total of seven manual and highly variable steps are replaced by a simple single step leading to loading Symphony (Figure ). At the H&E Staining bench, thirteen steps are now automated. A total of 23 minutes of manual and semi-automated work are absorbed by Symphony (Figures and ). Coupled with eliminating a queue area for slides that needed to go to the oven prior to staining and to the coverslipper after staining, a total of 30 minutes was saved as a result of converting the H&E staining process from a semi-automated platform to a fully automated platform. We did not capture the amount of time spent draining and changing stains in the baseline state, though we retrospectively estimate this to be just over 1 hour per week with the slide volume in our lab. With a direct waste line in the Symphony however, no manual draining of waste is needed. Additionally, over 32 feet (47%) of travel distance was removed from the Microtomy and H&E Staining processes (Figure ) - a total of 106 miles of transport distance saved per year.
Pre- and Post-Symphony Impacted Process Steps (in green) at the Microtomy Workbench.
Pre- and Post-Symphony Impacted Process Steps (in green) at the H&E Staining Workbench.
Case assembly at the tail end of the sequence had previously been a task for only the most meticulous of technologists, as the chaos introduced between grossing, processing trays, embedding stations, cutting areas, and batch strainers often meant that a case was scattered over several runs. Errors in assembly were common, despite meticulous care. Delays due to the need to hunt down an errant slide in another run were the norm. Although not measured in the baseline state, the post-change anecdotal impression is that an increased number come off the Symphony stainer complete and ready to be presented to the pathologist. Cases with delayed blocks (some case types, e.g. gynaecologic tumor debulking and staging procedures, often had smaller component specimens along with large specimens that were processed on separate processor runs from the major resection) were however still easier to reassemble because secondary portions arrive together at the end of the staining process.
The results of our cost analysis show an actual increase in our fully loaded operating cost per slide of 3.2% over baseline at our interim state, inclusive of capital costs, service contracts, renovation and reagents as well as labor. We project, based on historical volume growth rates of 2.8%, to defer the need for additional staff in the H&E workcell at least 11.6 years due to the improved productivity observed from the implemented changes to date. Another way of stating that would be that the H&E work cell has the capacity for over 32% more work before exceeding the takt threshold for any of the process steps in this work cell. We also project to defer the need for space expansion and additional instrumentation, based similarly on historic growth rates exclusive of known projects or added contracts/clients, for at least 10 years. Inclusive of these avoided costs (in 2009 dollars) and a reduction in liability costs, our cost/slide is reduced by 8.8%. The payback period from operational savings for just the improvements included in this portion of our project then becomes 3.6 years.