Page 41 - JSOM Winter 2017

Tourniquet Recipients that maintained occlusion versus completion pressure minus
The 15 tourniquet recipients were volunteers familiar with pressure at early Doppler signal return. Contingency data were
the study through a research course. They were a convenience analyzed using the Fisher exact test for 2 × 2 contingency tables
sample of students and instructors. Recipient inclusion criteria and using χ test for all other contingency data. The times of
2
were participation in a previous tourniquet study or partici- occlusion losses were analyzed using the logrank test for trend.
pation in the related research course, ability to lie down and Graphing and statistical analyses were performed with Graph-
remain relaxed for two 100-minute sessions, and age 18 years Pad Prism version 5.02 for Windows (GraphPad Software Inc.,
or older. Recipient exclusion criteria were self-reported blood www.graphpad.com). Statistical significance was set at p ≤ .05.
clotting or circulation irregularities, connective tissue disorders, Medians are shown with minimums and maximums. Averages
implants in relevant locations, systolic blood pressure higher are shown ± standard deviation.
than 140mmHg, pain syndromes, or peripheral neuropathies.
Recipients completed an informed consent and were able to Results
have a tourniquet removed or to stop participating at any time.
Tourniquets were applied to eight men and seven women.
Protocol None requested any early tourniquet removals. Recipient char-
1. Recipient age and blood pressure information was collected. acteristics are shown in Table 1.
2. Recipients lay down throughout each application, with
foam support and mid-range flexion of the relevant leg. Table 1 Characteristics of Tourniquet Recipients
3. The locations for placement of each tourniquet were Median (Minimum–Maximum)
marked on the thigh using a template and colored markers. Age (years) 20 (19–56)
4. Recipients were directed to remain completely relaxed. Arms systolic pressures
5. The circumferences of each tourniquet location were (mmHg) 114 (92–128)
recorded. Arms diastolic pressures
6. The Doppler sensor was taped in a location that provided (mmHg) 66 (54–80)
a strong audible Doppler pulse signal. Circumference (cm)
7. Tourniquets were placed in the correct marked locations Tourniquet locations Right Thigh* Left Thigh
(location order previously assigned for each tourniquet Distal 45.0 (35.6–54.7) 44.0 (34.5–54.0)
recipient).
8. Tourniquets were applied directly on skin with the friction 0cm from Distal 49.0 (41.8–58.8) 50.0 (38.1–58.1)
buckle on the lateral aspect of the thigh and the free end of 2cm from Distal 51.7 (42.2–60.5) 52.3 (41.0–60.1)
the strap pulled downward through the friction buckle. 4cm from Distal 54.0 (43.8–63.2) 53.7 (43.2–62.9)
9. After achieving friction pressure, tourniquets were tight- 8cm from Distal 57.2 (46.8–66.7) 55.8 (46.4–67.7)
ened via advancement of the ratcheting buckle a single 12cm from Distal 61.0 (49.8–72.2) 58.6 (48.0–72.7)
ladder tooth at a time with the applier’s hands off the *These thigh circumferences fall within those reported among US mili-
tourniquet at the end of each tooth advance. tary personnel (45.4–78.7cm). 11
10. Data marks were placed at occlusion and at completion.
11. The number of ladder teeth advanced to completion was Order of Application
recorded. There were no order of application effects on friction pressures,
12. Tourniquets were released 125 seconds after the comple- occlusion pressures, or completion pressures (p = .9054, .6342,
tion data mark. and .6255, respectively). There also were no order of application
13. A data mark was placed when the audible Doppler pulse effects on the differences between any of the pressures. There
signal returned. was a small application order effect on discomfort (Table 2).
14. During the tourniquet release and removal, sensor pres-
sure returns to friction pressure, the inflated bladder pres- Discomfort
sure, and atmospheric pressure were checked. The discomfort ratings are shown in Table 2. Most applica-
15. Recipients verbally rated discomfort as None, Little, Mod- tions received discomfort ratings of None or Little. Discom-
erate, or Severe. 10 fort ratings were lowest for pairs and for the last set (pair,
16. Any comments relating to the application were recorded. distal, proximal) of tourniquet applications for each leg.
17. Steps 7 through 16 were repeated until all applications to
that thigh were completed. Friction Pressures
18. At a second session, steps 2 through 17 were repeated for Friction pressures were similar for each tourniquet group. The
the other thigh. group medians, minimums, and maximums were as follows:
distal of pair 122, 109–134mmHg; proximal of pair 122, 109–
Statistical Analysis 140mmHg; single distal 120, 102–134mmHg; single proximal
Numeric pressure data were organized in Microsoft Office 120, 107–135mmHg.
®
Excel 2003 (Microsoft Corp., www.microsoft.com). Most
pressure data were analyzed using one-way repeated measures Occlusion Pressures and Completion Pressures
analysis of variance (ANOVA) with the Tukey multiple com- Occlusion pressures were lower for each tourniquet in the pair
parison test. The exceptions were pressure data analyzed using than each respective single, higher in each distal in the pair than
one-way ANOVA: last tooth advances for the distal and proxi- each respective proximal in the pair, and higher in each single
mal tourniquets in a pair, occlusion pressure minus 120-second distal than each respective single proximal (Figure 2A). Despite
pressure in tourniquets that maintained occlusion versus occlu- increasing circumferences, occlusion pressures were lowest with
sion pressure minus pressure at early Doppler signal return, and the most proximal tourniquet involvement. The same pressure
completion pressure minus 120-second pressure in tourniquets patterns were present with completion pressures (Figure 2B).

Tourniquet Distance Effects | 39