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FIGURE 1 Results of field tourniquet trials for blood loss by group. Donning Delays
The pattern of results among groups for field tourniquet trial
time (Figure 2) did not match the corresponding pattern of
blood loss seen in Figure 1. Also, the results pattern for test
time (i.e., sum trial time, of a field tourniquet trial and its
conversion trial time, Figure 3) did not align with either field
tourniquet trial blood loss or field tourniquet trial time in Fig-
ures 1 and 2, respectively. The field tourniquet trial blood loss
correlated moderately with test time (Figure 4).

FIGURE 2 Trial time results of field tourniquet use by group.

The vertical boxplot graphically depicts blood loss results of 30 field
tourniquet trials among three groups of personal protective equipment
(PPE). The control group with no PPE (PPE0) resulted in less mean
blood loss than both PPE1 and PPE2 by differences of 805mL and
1004mL, respectively (P < .05, both). The PPE2 – PPE1 mean differ-
ence of 199mL was not statistically significant (P > .05). The box top
is the third quartile (Q3 or 75th percentile), the box bottom is the Q1
(25th percentile), the up whisker is the 95th, and the down whisker is
the 5th. The central line is the median (Q2 or 50th percentile), and the
diamond is the mean. The circle is a maximum.

applied too loosely. In PPE1, median pressure and blood loss The boxplot depicts field tourniquet trial time results among PPE
were 267mmHg and 553mL, respectively. Ease of conversion groups. The pattern of time results nearly matched that of blood loss
ranged from 3 to 5, with a median of 4. in Figure 1. PPE0 took less trial time than both PPE1 and PPE2 by
differences of 1.5 and 1.9 minutes, respectively (P = .0002, both). The
PPE2 – PPE1 mean difference of 0.34min was not statistically signifi-
PPE2 cant (P = .053). The maximums are circles, and the labels are the test
The field tourniquet trial status results for PPE2 showed that number.
all tourniquet uses stabilized the patient. In each case, the
tourniquet was placed at the correct site with sufficient pres-
sure, with satisfactory results. Median tourniquet pressure and FIGURE 3 Sum trial time results in sum of a field tourniquet trial
blood loss were 421mmHg and 1305mL, respectively. Ease of and its conversion trial by group.
use in tourniquet trials was either 4 or 5, with a median of 4.

For PPE2, conversion status results showed that all conver-
sions to pneumatic tourniquet use stabilized the patient.
However, in 4 of 10 cases, the tourniquet was placed incor-
rectly, and the results were unsatisfactory. Among these four
instances, two tourniquets were applied too loosely. Median
pneumatic tourniquet pressure and blood loss were 291mmHg
and 289mL, respectively. Ease of conversion ranged from 3 to
5, with a median of 4.

Intergroup Comparisons: PPE1 – PPE0, PPE2 – PPE0,
and PPE2 − PPE1
Comparing the control group, PPE0, to PPE1, the differences
(PPE1 − PPE0) in mean blood loss for a field tourniquet trial, a
conversion trial, and a test were 805mL, 233mL, and 1038mL,
respectively. All were more for PPE1.
The boxplot depicts the sum trial time results being a summing of
Comparing PPE0 to PPE2 (PPE2 − PPE0), the differences in paired trials (field tourniquet trial and its conversion trial) among PPE
mean blood loss for a field tourniquet trial, a conversion trial, groups. The pattern here was significant (P = .0008 by ANOVA), but
and a test were 1004mL, −84mL, and 920mL, respectively. it did not match the pattern of blood loss or of trial time in Figures 1
and 2. The PPE0 − PPE2 mean difference of 1.69 minutes was signif-
Comparing PPE1 to PPE2 (PPE2 − PPE1), the differences in icant (P = .0001; 95% CI, −2.70 to –0.68 minute). Likewise, PPE1 −
PPE2 difference of 1.10 minutes was significant (P = .02; 95% CI,
mean blood loss for a field tourniquet trial, a conversion trial, −2.11 to –0.09 minute). The PP0 – PPE1 mean difference of −0.60
and a test were 199mL, −318mL, and −118mL, respectively. minute was not significant (P = .17; 95% CI, −1.61 to –0.42 minute).

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