Page 61 - Journal of Special Operations Medicine - Spring 2017

were able to have a tourniquet removed or to stop par- Statistical Analysis
ticipating at any time. Numeric time and pressure data were organized in
Microsoft Office Excel 2003 (Microsoft Corp; www
Protocol .microsoft.com). Doppler versus pulse oximeter Signal
1. Recipient age, limb circumference, and blood pres- Gones time and pressure data were analyzed using re-
sure information was collected. peated measures multivariate analysis of variance with
2. Recipients lay down throughout each application, Tukey–Kramer post hoc tests.
with foam support and mid-range flexion of the rel-
evant limb. Contingency data were analyzed using χ tests for Dop-
2
3. Recipients were directed to maintain the relevant pler versus each pulse oximeter at every second from
limb in a completely relaxed state. 1) the first Signal Gone to the last Signal Return and 2)
4. Sensor placements were established for a clear, au- from the first Doppler Signal Gone to tourniquet release
dible Doppler pulse signal and for pulsatile pulse via release of the ratcheting buckle. Contingency data
oximeter waveforms. were also analyzed using χ tests for Doppler versus each
2
5. Tourniquets were applied directly on skin, with the pulse oximeter at every discrete 1mmHg interval from
friction buckle on the lateral aspect of each limb the first Doppler Signal Gone to tourniquet release. The
and the free end of the strap pulled downward time points and pressure points from the first Doppler
through the friction buckle. Signal Gone to tourniquet release were deemed to be
6. The limb order of use was left mid-thigh, left mid- the more relevant for evaluating the potential usefulness
upper arm, right mid-thigh, right mid-upper arm, of a pulse oximeter for field monitoring of tourniquet
with each entire iteration taking approximately 9 effectiveness because release would not be expected to
minutes. occur until definitive care of the injury was occurring.
7. After achieving friction-pressure, the tourniquet was
tightened via advancement of the ratcheting buckle Graphing and statistical analyses were performed with
a single ladder tooth at a time just until the Dop- GraphPad Prism version 5.02 for Windows (GraphPad
pler signal was gone. (This degree of tightening was Software Inc; www.graphpad.com). Statistical signifi-
to increase the probability that the Doppler signal cance was set at p ≤ .05.
would return at least once during most tourniquet
applications.)
8. After a 10-second pause, the pulse oximeter raters Results
were queried for any remaining pulsatile traces. If Tourniquets were applied to seven men and eight
any pulsatile traces were still present, the ratcheting women. None requested any early tourniquet removals.
buckle was advanced an additional ladder tooth. Recipient characteristics are shown in Table 1.
This was to be repeated until all pulsatile traces
were gone.
9. An additional single ladder tooth advance would Table 1 Characteristics of Tourniquet Recipients
occur whenever both the Doppler audible signal
had returned and all pulse oximeters had pulsatile Median (Minimum–
traces. This step remained operative until tourni- Characteristic Maximum)
quet release 205 seconds after the Doppler signal Age (years) 21 (18–56)
was first declared gone. Extremity circumference (cm)
10. The number of ladder teeth advanced to the first Right mid-thigh 50.5 (44.0–59.2)
Doppler Signal Gone was recorded.
11. During the tourniquet release and removal, sensor Right mid-brachium 28.0 (25.0–30.0)*
pressure returns to friction-pressure, the inflated Left mid-thigh 51.0 (44.0–59.2)
bladder pressure, and atmospheric pressure were Left mid-brachium 29.0 (24.5–30.5)*
checked. Blood pressure (mmHg)
12. After sensor return to atmospheric pressure, a “3,
2, 1, stop” countdown was used to assess the time Right arm, systolic 102 (88–118)
synchrony of each pulse oximeter rater stopwatch Right arm, diastolic 64 (54–76)
with the pressure sensor data experiment timeline. Left arm, systolic 102 (86–120)
13. Recipients verbally rated discomfort as None, Lit- Left arm, diastolic 62 (50–78)
tle, Moderate, or Severe. 8
14. Any comments relating to the application were *The median mid-brachium circumference of the arms that received
the Pediatric Ratcheting Medical Tourniquet was 25.7cm and the
recorded. maximum was 27.3cm.

Tourniquet Effectiveness Monitoring 39