Page 81 - JSOM Summer 2020

FIGURE 3 Time-course study of blood loss. FIGURE 4 Cumulative blood loss by step among five strata of
performances.

The graph depicts gradual blood loss over time. Cumulative blood
loss is shown among five strata of performances, with minimum times The graph depicts cumulative blood loss. The 14 steps are on the hor-
connoting fastest speed of first aid and maximum times connoting izontal axis and are preceded by indication. Indication is a prestep as
slowest speed. All strata originate at the bottom left at the point of onset point of clinical need after which task steps are to be performed.
indication: 177mL of blood loss was the clinical need for tourniquet All performance strata originate at the bottom left at the point of in-
use in first aid. The graphed simulation results allowed its total blood dication at 177mL of blood loss. Cumulative blood loss including that
loss to be seen as the height of the plateau. Each path had a differ- 177mL is plotted on the vertical axis among strata with minimum
ent, scalable height (loss) and length (time). By framing cumulative times as the fastest speed and maximum times as the slowest speed.
bleeding by time, the explanatory power is clear that benefits among Steps are ordinal, not time scaled.
performance strata for time and blood are by both their amounts and
when they occur. Notably, a user with minimum times finishes 10- TABLE 3 Time Results Among Performance Strata by Step Order
fold earlier than one with maximum times. The chart shows benefits Time (s)
by increments of speed but also implies that acquired increments of
speed may have consumed user time and effort in practice to acquire Step Name Minimum Short Moderate Long Maximum
it beforehand. A return on investment looks promising. By respective Detect bleed 1 3 5 8 10
stratum in a path metaphor, the differences between sprint, run, trot, Assess 1 3 5 8 10
hike, or walk made five different mesas to climb. Tracing one’s eye
backward along the paths, one imagines watching a movie in reverse Decide 1 3 5 8 10
to see regression to the trailhead at the edge of the pool of blood Call 9-1-1 15 18 75 113 150
(177mL), the indication. If the down climb was to be made in forward Talk with
direction and forward time, the return trip would end in a bloody dispatcher 30 75 150 225 300
puddle (420mL to 2,460mL).
End call 2 5 10 15 20
Find tourniquet 3 8 15 23 30
The largest accrual of blood loss in this stepwise plot occurred Unwrap
during the talk with the dispatcher (Figure 4). tourniquet 9 23 45 68 90
Table
Results of time and blood loss by step name showed propor- tourniquet 1 3 5 8 10
tionate results for each stratum of performance as set by the Get gloves 8 20 40 60 80
math (Tables 3 and 4). The 10-fold differences in duration and Don gloves 12 30 60 90 120
blood loss ranged widely, and the maximum blood loss was Grab
2,434mL. When a 2,434mL loss was added to the prestep in- tourniquet 1 3 5 8 10
dication of 177mL, the sum was 2,611mL. Apply
tourniquet 27 67 134 201 267
Next, the results of task manipulation showed potential value Secure 51 126 253 379 505
by redesigning the task. Users may unwrap tourniquets before- Total 161 403 806 1,209 1,612
hand to save time by deleting that step from first aid. If one
unwrapped a tourniquet beforehand, the deletion of that step
shortened trial time by 6% and prevented 9% of blood loss. in a bloody scene, moving or positioning the patient, or per-
Because the deleted step preceded putting the tourniquet down forming other lifesaving interventions. Reordering the steps of
to table it, the deletion now makes that tabling step nonsense. getting gloves (5% of time) and donning gloves (7% of time)
An added value of the deletion was that its consequence natu- to when no bleeding occurs results in faster control of bleed-
rally made some following steps less relevant or superfluous. ing by moving 12% (5% + 7%) of task duration from before
In manipulating the task by reordering steps, if one moves the bleeding control to after secure. Such reordering necessarily
step of “find tourniquet” to after donning gloves, then another prolongs postcontrol time by that 12%. Such a reordering
two steps, table tourniquet and grab tourniquet, may also be eliminates blood losses of those two steps (with their losses
deleted. The deletion of these two steps sum to 1% of time and of 8% and 12%, respectively), thereby additionally lessening
2% of blood loss, after rounding. The net savings of deleting task blood loss by 21%, after rounding. The net savings of
all three steps in trialing this redesigned task are 7% of time deleting all the three steps and moving two in trialing this re-
and 11% of blood loss. designed task are 21% plus the 11% saved previously, to yield
32% blood saved.
If one not only deletes the step of unwrapping the tourniquet
but also moves the step of don gloves to after the moment Taking redesigns further may improve results more if, alto-
bleeding is controlled, another reordering of steps may fur- gether, one unwraps a tourniquet beforehand, dons gloves af-
ther improve results; donning gloves may benefit a tourniquet ter secure, and moves the call to dispatch to postcontrol time.
user during other first-aid actions like splinting or handling Those manipulations additionally reorder the steps of “call
the limb to which the tourniquet has been applied, working 9-1-1,” “talk with dispatcher,” and “end call” (9%, 19%, and

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