Page 17 - JSOM Spring 2024

FIGURE 4 Forearm and thigh occlusion pressures or peak pressures.
(A) 300 (B) 1400
1st gones 1st gones
280 1st returns 1300 1st returns
(mmHg) 260 2nd returns (mmHg) 1100 2nd gones
2nd gones
1200
2nd returns
240
not occluded
1000
Pressure 220 Pressure 900
200
800
700
180
Tourniquet 160 Tourniquet 600 2nd gones vs 2nd returns
p<.0001
500
1st gones vs 1st returns
140
p<.0001
1st gones vs 2nd gones
120 1st gones vs 1st returns 400 1st returns vs 2nd returns
300
2nd gones vs 2nd returns 2nd gones vs not occludeds
100 200
14.5 15.0 15.5 16.0 16.5 17.0 17.5 18.0 18.5 19.0 19.5 20.0 20.5 21.0 21.5 22.0 22.5 23.0 23.5 42 44 Mid-Thigh Circumference (cm) 68 70 72
62
66
64
60
52
54
56
46
48
50
58
Distal Forearm Circumference (cm)
(C) 1400
1300
1200
(mmHg) 1100 (A) Forearm pressures for the first and second sets of paired pulse
gones and pulse returns. The data is shown as box and whisker plots
with all data points shown. The p<.0001 is for first pulse gones versus
1000
first pulse returns and also for second pulse gones versus second pulse
Pressure 900 p<.0001 returns. (B) Mid-thigh pressures for the first and second sets of paired
800
pulse gones and pulse returns or for the peak pressure reached without
700
occlusion. The data is shown as box and whisker plots with all data
points shown. The p<.0001 is for first pulse gones versus first pulse re-
600
Tourniquet 500 turns, second pulse gones versus second pulse returns, first pulse gones
versus second pulse gones, first pulse returns versus second pulse re-
400
turns, and second pulse gones versus peak pressures without occlu-
300
sion. (C) Medians of each set of second pulse gones for each subject or
200
for the comparison between thigh occlusion pressures and thigh peak
100 the peak pressure reached without mid-thigh occlusion. The p value is
0 n=68 n=55 n=13 pressures without occlusion.
Forearm Thigh Thigh not
occluded occluded occluded
occluded occluded occluded
Forearm Thigh not
Thigh
secondary influence from the associated difficulties of forcing TABLE 1 TPT2 Thigh Impression Widths According to
more air into the TPT2 at higher pressures. Circumferences and Pulse Gone Pressures
Thigh Median Pulse Width of Red, Slightly Patterned
To roughly ascertain the width of the TPT2 pressure applica- Circumference Gone Pressure Surface Portion of Thigh
tion (which was not preplanned and was only done on five 41.6cm 274mmHg 3.5cm
subjects), we measured the width of the red, slightly patterned 50.9cm 348mmHg 2.8cm
portion of the surface of the thigh that had been under the 54.6cm 500mmHg 2.9cm
TPT2 during the occlusive pressure applications (Table 1). 56.6cm 782mmHg 2.8cm
Larger circumference thighs required higher pressures for oc-
clusion, and higher TPT2 pressures resulted in TPT2 rounding 59.6cm 1114mmHg 2.7cm
with narrower TPT2 impression patterns, so the functional
width of the TPT2 decreases as the TPT2 pressure increases. 420 applications of 3.8cm-wide Ratcheting Medical Tourni-
®
quets [m2 inc., www.m2inc.biz] to thighs ranging from 34.5–
Discussion 72.7cm in circumference 4,6–9 ).
There were two concerning key findings. First, arterial occlu- Interestingly, forearm arterial occlusion pressures with the
sion was not reached on all thighs. Second, even when thigh TPT2 (135–216mmHg 5th to 95th percentile with a median
arterial occlusion was reached, the required TPT2 pressures of 176mmHg) were more similar to 3.8cm-wide Ratcheting
(373–1118mmHg 5th to 95th percentile with a median of Medical Tourniquet forearm arterial occlusion pressures re-
574mmHg) were much higher than the occlusive pressures ported in the literature (225–415mmHg 5th to 95th percen-
reported for 3.8cm-wide non-pneumatic tourniquets (250– tile with a median of 274mmHg and a coefficient of variation
428mmHg 5th to 95th percentile with a median of 332mmHg of 21% for arterial occlusion for 14 subjects with forearms
and a coefficient of variation of 17% for arterial occlusion for ranging from 19.8–30.2cm in circumference at the tourniquet
TPT2 Pressures | 15