Page 48 - JSOM Fall 2019

Both users were experienced in tourniquet research. One was (N = 60 tourniquet applications for the study). Users collected
proficient and the other was an expert who acted as coach. their own data: use number, ease of use (scored on a Likert
scale: 1–very difficult, 2–difficult, 3–neutral, 4–easy, 5–very
The deliberate practice sessions were in a research laboratory. easy), time to apply the tourniquet, girth, gap (i.e., wound to
The practice focused on developing a specific motor skill un- tourniquet), and notes of interest. Girth was measured as a cir-
der ideal circumstances. Users were given their choice to wear cumference around the limb using a tape measure with mark-
eye protection or reading glasses. The sessions included an ori- ings to one-sixteenth of an inch. Two girths were measured
entation to the study and its skill, repeated performances of from each of the two edges of the tourniquet band. The aver-
the skill, collection of data, and periodic coaching. age of the two girths was compared to the baseline as a girth
of the limb while the tourniquet was applied but untightened
The medical device used was the Combat Application Tour- to derive a calculated squeeze or indentation of the limb due to
niquet (C-A-T, generation 7). Each participant used their own a tightening effect. The minimum wound–tourniquet distance
practice tourniquet. was visually chosen for measurement with a caliper.

The simulated limb was a thigh-like cylinder with wounds Descriptive statistics were used to analyze the data and report
(Z-Medica Hemorrhage Control Trainer, https://www.z results. Paired t tests were performed to determine the signifi-
-medica.com). The thigh-sized limb was on a benchtop, and cance of girth change. Analyses were performed by using Excel
the simulated case was first aid, or as military services say, 2003 (Microsoft, www.microsoft.com).
tactical field care (Figure 1).

FIGURE 1 Information about the case practiced. Results
Deliberate Practice in Tourniquet Use
In deliberate practice of tourniquet use, the two participants
showed little interuser difference (Table 1). For example, ease-
of-use results were similar between users when represented as
summary parameters. These parameters provided a snapshot
of performance, so they gave a basic assessment. However,
summary parameters did not tell a developing story of learn-
ing over time for the individuals.

TABLE 1 Summary Parameters of Performance
Time Ease of Use Squeeze Gap
User Set Parameter (seconds) (scale 1–5) (%) (inches)
Mean 104 4 −16 2.4
Minimum 59 4 −26 1.8
Expert Maximum 146 5 −9 2.8
user
Standard 21.3 0.5 3.5 0.3
deviation
Mean 91 4 −15 2.5
Minimum 76 3 −18 1.6
Proficient
user Maximum 113 5 −8 2.8
Standard 10.1 0.7 2.2 0.3
deviation
Mean 97 4 −15 2.4
Minimum 59 3 −26 1.6
Both
users Maximum 146 5 −8 2.8
Standard 17.8 0.6 3.0 0.3
deviation
The information about the case used for practice in this study is de-
picted in a simulated rendering of a caregiving record. Two red Xs Application Time
mark a wound track (tunnel), with its entrance and its exit at the When charting the times to apply the tourniquet as a mean
skin surface, respectively. The thick black marks that transverse the
thigh indicate that the tourniquet band is looped circumferentially 2–3 of the data from both users, a radial polar plot was used to
inches above each externally visible wound. demonstrate if performance was seen as a spiral (Figure 2).
As users accrued experience by use number, times lessened,
Each use comprised a sequence of actions. The user started the on average, as the users became faster and more proficient.
timer function on a smartphone, grasped a configured tourni- In the charted data, the users plainly showed spiral learning
quet, opened its looped band, passed the open loop around the of the skill. The performance pattern looked like an outline
end of the limb, placed the tourniquet on the skin 2–3 inches drawing of a spiral-shaped seashell. In the first uses (uses 1–4
above the wound, pulled the band to remove its slack, turned of block 1), the means were maximal, and in the last uses (uses
the rod three times forming a 540° arc, put the rod into a clip, 3–6 of block 5), the means were minimal. The large difference
pulled the time strap to fasten it to the opposite clip in secur- between the last use and the first use was seen as a big step
ing the rod, taped over the strap, wrote the time of day on the up, and the height of that step was the change in the amount
1-inch cloth tape, and stopped the timer. learned. By this metric, in these practices by these users, the
average quantity of individual learning was 49 seconds (119
Both users applied the tourniquet six times per day (one block seconds [use 1] – 70 seconds [use 30]). The users improved
of six performances) over 5 days to accrue 30 uses individually 41% (49/119).

46 | JSOM Volume 19, Edition 3 / Fall 2019