Page 14 - JSOM Spring 2021

simple redirect buckle design allows appliers to reach desir- to have the same amount of tape tension during each measure-
able secured pressures to minimize recipient discomfort. (6) ment. Limb circumference measurements were taken after all
The design is very easy to quickly release by simply pulling the the tourniquet applications.
hook-and-loop apart.
Pressure Measurements
The authors were the recipients and appliers. The tourniquet Pressures were measured using a No. 1 neonatal blood pres-
was buddy-applied on skin with the redirect buckle on the lat- sure cuff (2.2cm × 6.5cm bladder, single tube) at 18mmHg
eral aspect of the limb. Examples are shown in the reference above atmospheric pressure (baseline), secured beneath the
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videos. 8–13 First application sets were to the mid-thigh of the tourniquet with the bladder medially-located and starting
sitting recipient. Second application sets were to the mid- 1cm away from the neoprene sleeve, just past the far end of
8,9
thigh of the laying recipient. 10,11 Third application sets were the toothed ladder from the redirect buckle. The bladder was
to the mid-arm of the sitting recipient 12,13 with only three au- connected to a Vernier Gas Pressure Sensor, Vernier LabPro
thors’ arms used because the circumferences of the other two interface, and Logger Pro Software (Vernier Software and
authors’ arms were too small to allow use of the pressure mea- Technology, www.vernier.com). Pressures were recorded every
suring system (this was known when the study was planned). 6 tenth of a second and marked at the beginning and end of each
5-second position interval.
Application sets were triplicate applications with each of two
different designated starting positions for the involved limb: Pressure Trace Assessment
starting with the adjacent distal joint (knee or elbow) straight Each position interval of every pressure trace was assessed
or starting with the adjacent distal joint bent approximately real-time for the presence of a rhythmically pulsatile pattern
90°. Each application involved tourniquet ratcheting buckle and was also separately assessed later by three authors for the
advancement only to achievement of occlusion, followed by a presence of a rhythmically pulsatile pattern (Figure 2). For the
5-second pause, limb repositioning by the tourniquet applier, later assessments, one author assessed intervals from all of the
a 5-second pause, limb returned to the starting position by the recipients; two authors assessed intervals from three recipi-
applier, a 5-second pause, and tourniquet release. Occlusion ents; and two authors assessed intervals from two recipients.
was defined as hands off following loss of audible distal Dop- The final scores for any interval assessments were determined
pler pulse (Ultrasonic Doppler Flow Detector Model 811 with by the author who was present real-time for all applications
9.5MHz adult flat probe; Parks Medical Electronics, www. and who assessed intervals from all of the recipients. The pres-
parksmed.com). The recipient remained as muscle relaxed as ence of a rhythmically pulsatile pressure trace pattern at any
possible throughout. time during a position interval received a score of 1 (present),
and the absence of such received a score of 0 (absent).
Limb Positions
The order of sitting leg starting positions was randomized, Audible Pulse Assessment
and the same order was then used for laying leg starting po- The loss and return timing of all audible Doppler pulse sig-
sitions. The order of arm starting positions was separately nals was made real-time with any questions answered using
randomized. video of the applications. The presence of an audible Doppler
pulse signal at any time during a position interval received a
In sitting thigh applications, the leg bent position had the in- score of 1 (present). The absence of such received a score of 0
volved thigh horizontal with the knee flexed 90° and the bare (absent).
foot on the floor; the leg straight position had the heel of the
involved bare foot supported on a second chair so that the Statistical Analysis
knee was extended (Figure 1A and B). In laying thigh applica- Pressure data from LoggerPro were organized in Micro-
tions, the leg bent position had hip flexion with the involved soft Office Excel 2003 (Microsoft Corp., www.microsoft
®
thigh 45° from vertical, the knee flexed 90°, and the bare foot .com). Graphing and statistical analyses were performed with
flat (ankle 135° from lower leg); the leg straight position had GraphPad Prism, version 7.04 for Windows (GraphPad Soft-
no hip flexion, the knee extended, and the ankle relaxed with ware Inc., www.graphpad.com). Circumferences and initial
a slightly greater than 90° relationship with the lower leg (Fig- occlusion pressures were compared using paired t-tests. The
ure 1C and D). In sitting arm applications, the arm bent posi- χ test was used for contingency data. Paired t-tests were used
2
tion had the involved hand and distal forearm supported with to compare initial occlusion pressures for each limb position
90° elbow flexion; the arm straight position had the involved when sitting and for leg positions when laying. Two-way anal-
hand and distal forearm hanging unsupported with resulting ysis of variance analysis (ANOVA) with repeated measures
elbow extension (Figure 1E and F). with Tukey’s multiple comparison test was used to compare
pressures for different limb positions. Because pressure under
Changes in limb position were passive for the tourniquet recip- tourniquets decreases over time, the tourniquet pressures of
15
ient. For each position change, the tourniquet applier placed interest to compare were those of the first position interval to
an end-of-position data mark in the pressure trace, placed his those of the second position interval, and those of the second
or her hands on the limb with the tourniquet, supported the position interval to those of the third position interval.
limb while slowly moving it to the next position, took his or
her hands off the limb, and placed a start-of-position data Results
mark in the pressure trace.
Circumferences
Circumference Measurements Sitting thigh circumferences are shown in Figure 3A and B
Limb circumferences were measured with a fabric tape mea- and increased with knee straightening in four of five recipients
sure (sewing tape). The person doing the measuring attempted (p = .297). Laying thigh circumferences are shown in Figure

12 | JSOM Volume 21, Edition 1 / Spring 2021