Page 44 - Journal of Special Operations Medicine - Spring 2015

Figure 2 Touchpad screen for setting conditions of tourniquet Figure 3 Results screen on touchpad. A close-up photograph
performance. A close-up photograph shows touchpad buttons shows results of user performance in tourniquet use.
to set the conditions of tourniquet performance.

under the tourniquet, and the blood loss volume. The blood loss volume as calculated using a linear equation
time to effectiveness was from when the iteration began from the arterial flow and number of pulses before hem­
to when effectiveness was determined. Routinely, this orrhage was controlled or test termination.
was when the manikin sensed that the thigh was losing
no more blood, but in the event of ongoing ineffective­ Tourniquet devices, users, test iterations, and outcomes
ness despite multiple attempts to correct, the time to were uniquely identified. The order of testing was first
effectiveness determination was when the user stopped for the no­heat exposure group and then the heat­
the test iteration by pressing the touchpad button. Ef­ exposure group. The physician assistant went before the
fectiveness was defined by the stoppage of blood loss; clinician­scientist. The users and team members were
ineffectiveness was defined as either any ongoing hem­ not blinded to the users’ performance.
orrhage at the time of determination of effectiveness
or completed exsanguination. Iterations began with a Results were summarized as percentages of outcome by
tourniquet device laid out flat undone (strap not routed group. The critical outcome was damage (yes or no: One
through the buckle) on the benchtop and not yet ap­ or more device components mechanically broke apart
plied to the thigh. Users tightened the tourniquets until or separated before or during testing). An important
they perceived that simulated bleeding stopped. Itera­ outcome was effectiveness (yes or no: Hemorrhage was
tions ended when the user touched the touchpad but­ controlled). Minor outcomes included time to effective­
ton, having assessed that the hemorrhage was stopped. ness (seconds), pulse stoppage (yes or no), and pressure
A custom scenario was used in which the casualty had a under the tourniquet (mmHg). Effectiveness, time to ef­
medium build and the setting was “Care Under Fire,” a fectiveness, and pressure were measured by the manikin;
setting resembling emergency care when under gunfire damage and pulse stoppage were measured by the user.
or similar danger. Overt structural damage was looked for between tests
when examining devices for structural and functional
The manikin settings also included a constant hemor­ integrity. For example, a label to record time of appli­
rhage rate (635mL/min); the resulting bleed­out time in cation coming off a strap would represent very minor
this scenario was 4 minutes, giving the user 240 seconds damage. Occult structural damage was to be evidenced
to successfully apply the tourniquet. The system reported by the functional tests conducted.

34 Journal of Special Operations Medicine Volume 15, Edition 1/Spring 2015