NR 720 Week 4 Bottleneck Analysis Example

Bottleneck Analysis: Where the Two Hours Between a Central Line and Its First Use Are Spent, Split Into Work and Waiting

Student Name

College of Nursing, Chamberlain University

NR 720: Topics in Healthcare Systems Leadership I

Instructor Name

Month Day, Year

Bottleneck Analysis: Where the Two Hours Between a Central Line and Its First Use Are Spent, Split Into Work and Waiting

The Candidate and the Data

The candidate constraint is the step between a confirmation chest film being taken and its read being posted: the radiologist's reading queue. It was chosen because observation of 22 daytime placements put most of the waiting there, but observation cannot show whether the pattern holds at night, on weekends or over a longer period. This analysis therefore uses the record for every central line placed in the medical unit's 20 beds from January to March 2027: 64 placements, at all hours. For each, the record gives the time the film was ordered and its priority, the time the technologist marked the exam complete, the time the read was posted, the time of the clearance note and the time of the first infusion through the line.

What Counts as Arrived

A film arrives in the radiologist's queue when the technologist marks the exam complete; that timestamp, not the order time, starts the reading interval. A clearance arrives at the bedside when the first infusion through the line is documented, which is a slightly late proxy for when the nurse learned of it, since observation found a median of six minutes between the two. Fixing these definitions before counting matters, because a reading interval measured from the order would charge the radiologist for the technologist's time.

Work Time Against Wait Time

Table 1

Work and Waiting at Each Step, 64 Central Line Placements, January to March 2027

Note. Note. Elapsed times from the record. Work times are stopwatch medians: technologist work from 10 observed films, reading time from 12 films timed in the reading room with the radiologists' permission, clearance and infusion work from observation.

Of a median 122 minutes from line to first use, about 14 minutes are work. The reading step is the extreme case: a line film takes a radiologist about two minutes to read and waits a median of 64 minutes to be opened. A step whose work takes two minutes and whose waiting takes an hour is not short of skill or effort; it is short of priority (Goldratt & Cox, 2004).

A Figure Needs a Neighbor

A 66-minute reading interval means little alone, so it is compared three ways. By priority: the 11 films ordered urgent were read in a median of 13 minutes; the 53 ordered routine waited 74 minutes. By time of day: routine films taken between 22:00 and 07:00, 19 of them, were read in a median of 41 minutes, faster than daytime routine films, even though one radiologist covers the whole hospital overnight, because the overnight queue is shorter. By step: reading is the longest single interval, but the read-to-clearance gap, a median of 21 minutes, is the second, and it contains even less work as a share of its length than technologist time does.

Arrivals and Capacity

Line films are a small part of the reading queue. The unit produces about 0.7 central line films a day, while the daytime inpatient and emergency department queue that the three daytime radiologists share runs at roughly 38 studies an hour. A routine film enters behind every urgent and emergency study and moves up only as those clear. Adding a radiologist would shorten the queue for everything; changing the line film's priority would move one study, a few times a day, to the front, at a cost of about two minutes of reading time each.

The Rival Explanation

The rival explanation is that radiology is understaffed and the delay is a capacity problem. It deserves a hearing, because the daytime queue is long and the department has one vacancy. But the evidence points away from capacity as the cause for this study type. The same radiologists read urgent line films in 13 minutes, and nights, with one radiologist instead of three, read routine line films faster than days. A capacity shortage would slow urgent films too and would make nights slower, not faster. Capacity is a real problem for the department as a whole; it is not what holds line films.

The Second Constraint

Once the reading interval shortens, the read-to-clearance gap becomes the next constraint. It has no owner, a median of 21 minutes and a range up to an hour. Fixing the reading queue alone would move the waiting downstream to a crossing nobody watches, which is the usual result of relieving one constraint in a chain (Goldratt & Cox, 2004). Any proposal therefore has to address both: the priority of the order and the ownership of notification. In work system terms, one fix changes a tool, the order set, and the other changes the organization of roles; both are needed because the delay sits where tools and roles meet (Carayon et al., 2006).

What the Analysis Does Not Show

The analysis shows where time is spent and how much of it is work. It does not show harm. Of the 64 placements, 41 were made to start or move a vasopressor, so for those patients the waiting meant more time with a vasopressor running through a peripheral vein, but the record does not show whether any peripheral site was damaged, and none of the 64 had a documented extravasation. The analysis also does not show the cost of the nurse time spent checking for results, which observation put at about five checks per placement but which no system records. Both belong in the case for acting; neither changes the location of the constraint.

Hand Counts, and Their Limits

The work times come from stopwatch counts on small samples: 10 technologist exams, 12 radiologist reads and the 22 observed clearances. Hand counts are a legitimate way to measure work content that no system records, and a lean analysis routinely relies on them (Graban, 2016). They are also small, and a radiologist reading a complicated film might take longer than two minutes. The conclusion does not depend on precision here: even if reading took five times as long, work would still be under a sixth of the reading interval.

References

Carayon, P., Schoofs Hundt, A., Karsh, B. T., Gurses, A. P., Alvarado, C. J., Smith, M., & Flatley Brennan, P. (2006). Work system design for patient safety: The SEIPS model. Quality and Safety in Health Care, 15(Suppl. 1), i50-i58. https://doi.org/10.1136/qshc.2005.015842

Goldratt, E. M., & Cox, J. (2004). The goal: A process of ongoing improvement (3rd rev. ed.). North River Press.

Graban, M. (2016). Lean hospitals: Improving quality, patient safety, and employee engagement (3rd ed.). CRC Press.