Page 33 - Journal of Special Operations Medicine - Spring 2015

While 2 hours is generally considered a safe duration The length of safe use of emergency limb tourniquets
of tourniquet use, the CoTCCC supports conversion is complicated by the observations that many tourni­
of the tourniquet to a hemostatic or pressure dressing quets may not completely occlude arterial inflow and
at the earliest opportunity, rather than routinely wait­ limb cooling may limit damage to ischemic tissue; there­
ing 2 hours; this 2014 revision to the TCCC guidelines fore, actual cases do not replicate laboratory condi­
strengthens and clarifies the recommendation to con­ tions. Functional recovery after prolonged use has also
vert tourniquets as soon as possible during the TFC or been reported. 49,63 Therefore, there is no absolute time
TACEVAC phases of care. at which amputation of an ischemic limb is inevitable.
As a general rule, however, the risks of muscle death,
The CoTCCC has also considered the question of rhabdomyolysis, compartment syndrome, and limb loss
whether to remove a tourniquet that has been used for increase after 3–4 hours of ischemia, and there is a high
prolonged periods during TFC or TACEVAC care. It rate of irreversible limb damage after 6 hours. Due to
should be emphasized that if tourniquet conversion has the risks of rhabdomyolysis, shock, and renal failure
been attempted unsuccessfully within 2 hours of initial with progressive hyperkalemia and acidosis, we suggest
use, then repeated attempts at tourniquet conversion are that tourniquets that have been in place for longer than
not recommended. In some cases, a second attempt to 6 hours should not be removed outside of a closely mon­
convert the tourniquet may be indicated, particularly if itored setting, preferably with laboratory capability.
conditions for wound management have significantly
improved. However, in general, the need to attempt Future reductions in tourniquet­related complications
tourniquet conversion after 2 hours should only arise may be achievable through improved training that
when earlier conversion was neglected or impractical minimizes use of nonindicated tourniquets, recognizes
due to circumstances. and corrects ineffective tourniquets, and minimizes the
duration of ischemia through early conversion of tour­
Prolonged ischemia can result in irreversible damage to niquets to hemostatic or pressure dressings in the TFC
limbs necessitating amputation. Skeletal muscle isch­ or TACEVAC phases of care. In addition, an ongoing
emia­reperfusion injury results in accumulation of lactic commitment to refining tourniquet designs may further
acid and break down of cells with release of myoglobin, minimize tissue damage and more reliably occlude arte­
potassium, and other intracellular products into circula­ rial inflow.
tion. 54,55 Release of tourniquets also causes transient hy­
potension, attributed to vasodilation of the reperfused “High-and-Tight” Placement
limb and blood loss. 47,56 Myoglobinemia may result in The issue of whether to place a tourniquet as proximal
varying degrees of kidney damage beginning at the time as possible on a limb versus clearly proximal to the
of limb reperfusion, with gradual progression of hyper­ identified bleeding site during the CUF phase of TCCC
kalemia and acidosis, which may need to be treated with has not been specifically addressed in the published lit­
renal replacement therapy. erature, although it has been discussed in many forums.
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Tourniquet placement distal to an unseen wound may
The length of time between ischemia­reperfusion and be fatal. Kragh et al. described four of 428 patients with
life­threatening hypotension or renal failure depends, tourniquets placed distal to the most proximal wound;
in part, on the volume of ischemic tissue as well as the two of these four patients died.
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temperature of the limb. A published consensus opin­
ion held that removal of a tourniquet that has been in Arguments in favor of high­and­tight placement are
place longer than 6 hours without successful conversion that it is not advisable to fully expose a wound dur­
should not be removed until the casualty has reached a ing CUF and that placement of the tourniquet as proxi­
surgical facility. 38 mal as possible on the injured limb is the safest method
to avoid placement distal to an unseen wound. On the
Research in animals dating back to the 1910s shows contrary, upper arm and thigh placement tends to be
that irreversible ischemic damage to muscle occurs less effective than more distal placement because of the
when arterial inflow is occluded for longer than 5–6 greater girth compressed compared to the forearm and
hours at room temperature 57–59 ; however, the thresh­ calf, and because proximal tourniquet placement leads
1
old for meaningful functional recovery may actually to a greater volume of ischemic tissue. Some wounds
be shorter. The effects of traumatic injury and blood may be clearly seen as only distal (without any proximal
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loss on ischemic time have been shown to reduce the wound), which may allow more distal tourniquet use
threshold to less than 3 hours for functional recovery in with a lesser physiologic burden.
an animal model. On the contrary, the effect of local
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hypothermia has been shown to have a protective effect As reported in the 2012 Joint Theater Trauma System
on muscles exposed to tourniquet­induced ischemia. 60–62 review of prehospital trauma care in Combined Joint

TCCC Limb Tourniquet Guidelines Change 14-02 23