Page 63 - JSOM Fall 2019

turn, and failure to achieve adult-thigh arterial occlusion Appliers should be taught that after the strap is secured, the me-
with one windlass turn. When using limb models rather chanical advantage tightening system should be used to achieve
than actual limbs, the amount of indentation that occurs a tourniquet pressure that visibly indents the limb (Figures 1D
under the tourniquet varies for a set pressure according to and 2D), stops visible bleeding, and stops limb arterial blood
the give of the material: Firmer materials show less inden- flow. Ideally, appliers should have an indicator of arterial flow
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tation per unit of applied pressure. and its occlusion. Doppler monitoring is the current gold stan-
(5) Rotate the windlass rod with the slot in the rod main- dard, but pulse oximeters with visible plethysmographic wave-
tained parallel to the stabilization plate (Figure 1C). 7 forms are existing tools that can be used to ballpark completed
(6) Secure the windlass rod in the securing bracket at a degree application effectiveness on live humans. The continued pres-
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of rotation beyond the cessation of bleeding and of the ence of a pulsatile plethysmographic waveform from a sensor
distal pulse. This is ideally only one 180° windlass turn distal to the tourniquet indicates inadequate tourniquet pres-
from a windlass starting location parallel to the tourni- sure; the absence of a pulsatile plethysmographic waveform
quet strap (Figure 1D). 7,8 suggests the tourniquet might be sufficiently tight. 63
(7) When the windlass rod is in the securing bracket, the
strap pressure on the limb or a material with similar give SWATTs are a different style of effective tourniquet design that
to that of a limb should exceed 250mmHg and should can be present in Bleeding Control kits. SWATTs depend on
more probably be in the 300 to 400mmHg range for an elastic recoil from correct stretch throughout multiple wraps
adult thigh application. 24,60–63 to achieve thigh arterial occlusion. Optimal SWATT applica-
tions require different motor skills than those involved with
Stop the Bleed courses and associated information involve nonelastic tourniquets; therefore, training for optimal SWATT
tourniquet training. We believe teaching medical and non- application is different (Figure 3A–3D; and see SWATT appli-
medical persons optimal limb tourniquet application concepts cation video ). Optimal SWATT applications involve a mini-
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and techniques is desirable and possible. Optimal applications mally stretched first wrap directly and smoothly overlaid with
involve conceptual knowledge, motor skills, physical effort, subsequent wraps that are all fully stretched throughout the
and attention to several details. Conceptual knowledge should circumference of each wrap (doubled material length, correct
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include the importance of arterial occlusion/the hazards of visual indicators on tourniquet; Figure 3B and 3C, and see
tourniquet looseness, placement proximal to limb injuries, SWATT application video ). Appliers need to develop good
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and placement on skin as optimal. If a tourniquet is placed foresight regarding when and where to establish a “last-wrap
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over clothing, appliers should be taught why this is not op- securing location” under which to securely tuck the end of the
timal: because applications over clothing are associated with SWATT to complete the application. Thigh arterially occlusive
tourniquet looseness and have the potential to be put on distal SWATT applications will visibly indent the limb (Figure 3D;
to hidden injuries. 6,74 and see SWATT application video ).
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Appliers should be taught that the strap of nonelastic tourni- Limitations
quets should be pulled as tight as possible (maximum physical This review involved publications from a limited set of sources,
effort; see C-A-T and Tactical RMT application videos 75,76 ) and only pictures, text, and videos that clearly involved sub-
and should visibly indent human limb tissue before use of the optimal application techniques or knowledge were included.
mechanical advantage system (Figures 1B and 2B). Ideally, ap- Also, this review is weighted toward optimal C-A-T applica-
pliers should have real-time pressure data, but this is currently tion techniques because the preponderance of pictures, text,
not widely available. Late knowledge (after application com- and videos involved C-A-Ts. Other effective tourniquet de-
pletion) concerning strap-pressure adequacy can be gained signs exist, and they, too, are more likely to be effective when
from how many windlass turns or ratchet clicks are required applied using optimal application techniques.
to achieve arterial occlusion: for thigh applications on normo-
tensive adults, more than one or possibly two windlass turns Regarding the pressure values presented in this review, the system
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or more than six or seven ratchet clicks with a Tactical RMT used to obtain the pressures matters. Placing a sensing system un-
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indicate suboptimal strap tightness before use of the mechani- der a tourniquet can change tissue pressure isobars; the location
cal advantage system. of the sensor matters relative to tourniquet structures (strap or
stabilization plate) and to limb structures (surface, medial, lateral,
To help appliers achieve visible limb indentation, they should etc.); and the linear response range of sensing systems is finite.
be taught motor skills that take advantage of physics; namely,
appliers should be taught to pull the strap at a 0° angle rel- Conclusions
ative to the strap entering the redirect buckle, and appliers
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should be taught to use their body weight to advantage when Pictures and videos showing limb tourniquet-application tech-
possible (Figures 1A and 2A; and see C-A-T and Tactical RMT niques that are suboptimal and completed applications that
application videos 75,76 ). Many appliers find a bit of end-of-pull are clearly not tight enough to be arterially occlusive are un-
strap wiggling helpful in obtaining maximum strap pressure. desirable in publications and instructional videos purporting
Appliers should be taught to keep the tourniquet from slip- to show correct tourniquet applications. Publications and in-
ping around the limb while pulling on the strap; the holding structional videos showing staged limb-tourniquet use should
location to prevent tourniquet slipping should be on the side show optimal application technique and properly applied
of the redirect buckle away from the direction of pull and tourniquets: The tourniquet straps should be pulled appro-
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should not be the windlass rod (Figures 1A and 2A; and see priately tight before engagement of the mechanical advantage
C-A-T and Tactical RMT application videos 75,76 ). The securing system, optimal technique should be used with the mechanical
clip is an uncomfortable but acceptable holding location on advantage system, and the completed tourniquet application
C-A-Ts. 56 should be sufficiently tight to be arterially occlusive.

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