Page 26 - Journal of Special Operations Medicine - Fall 2014

hemorrhage—and were resuscitated with Hextend or should produce 100% survival if his or her hemorrhage
LR. Shed blood was replaced with an equal volume of has been effectively controlled and that the Hextend
Hextend. (Note that, in a human, a 60% loss of blood volume currently recommended should be sufficient to
volume would equate to 3L; 3L of Hextend would be achieve this target SBP. The authors found no clinical
a much larger resuscitation volume than the currently studies that confirm this, but a recent unpublished case
recommended 500mL with one repeat dose as needed.) report described a casualty with an isolated extremity
All 14 study animals survived the 6-hour study period. wound. Tourniquet placement was delayed due to an
The 6-hour observation period in this report is relevant ongoing firefight and the casualty became unconscious
to military operations, in which prolonged evacuation from hemorrhagic shock. The treating medic subse-
times may not be the norm, but are always a possibil- quently placed a tourniquet to control the bleeding and
ity. Six hours may not, however, be long enough to ob- then administered 500mL of Hextend. The casualty re-
serve some potential complications of fluid resuscitation gained consciousness and had a Glasgow Coma Scale
such as ARDS, extremity compartment syndrome or score of 15 by the time he was evacuated. There was no
ACS, or acute kidney injury. The animals resuscitated evidence of acute kidney injury during his subsequent
with LR also all survived but required 118 ± 3mL/kg stays at several hospitals in the continuum of care.
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of fluid for resuscitation—almost 3 times as much
fluid—to maintain their hemodynamic status as did the Casualties with isolated hemorrhage that has been
Hextend animals (42mL/kg), reinforcing the point that controlled with certainty (ie, shock due to an isolated
Hextend achieves equal volume expansion with much extremity gunshot wound now controlled with a tour-
less equipment weight for combat medics, corpsmen, niquet) can be resuscitated to a higher BP (greater than
and pararescuemen (PJs). In addition, the mean lactate 90mmHg).
levels in the LR group at the end of the 6-hour period
were twice that of the Hextend group, indicating that However, on the battlefield, the number of casualties
resuscitation was more effective with Hextend, although with hemorrhagic shock in whom ongoing uncontrolled
the lactate infused with the LR might also contribute to hemorrhage can be definitively ruled out is limited.
the increased lactate level. The Hextend animals were Thus, in casualties with penetrating torso trauma, blunt
more coagulopathic than the LR animals, but that did trauma, or blast trauma who may still have noncom-
not result in decreased survival in this controlled hem- pressible hemorrhage, once external hemorrhage is ade-
orrhage model. The relevance of this model to combat quately controlled, they should still have a target SBP of
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casualties must be tempered with the understanding that 80 to 90mmHg. A weakly palpable radial pulse or im-
the polytrauma often seen on the battlefield makes it dif- proved level of consciousness may be used as end points
ficult to establish with certainty that noncompressible for resuscitation if BP monitoring is not available. This
hemorrhage is not also present. will provide adequate resuscitation for these casualties
while reducing the risk of dilutional coagulopathy and
In another study by Burns and colleagues, male minia- disturbing clot formation at noncompressible bleeding
ture swine were hemorrhaged 60% of their estimated sites.
blood volume and then resuscitated with 1mL/kg/min
of Hextend to an SBP of either 65mmHg or 80mmHg.
The animals were then observed for 180 minutes. The Prehospital Resuscitation Fluid Options
mean survival time for the control (unresuscitated) an- Early in the conflicts in Afghanistan and Iraq, military
imals was 64 minutes; the survival rate in this group trauma surgeons observed that the large-volume crystal-
at 180 minutes was 6%. Survival at 180 minutes was loid resuscitation and low volumes of plasma used for
86% for the animals resuscitated to 65mmHg and initial in-hospital resuscitation might be exacerbating
100% for those resuscitated to 80mmHg. The mean the coagulopathy of trauma and causing excess deaths
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replacement volume of Hextend needed to maintain from uncontrolled hemorrhage. 46–48 The principles of
an SBP of 65mmHg was 265mL; for 80mmHg, the re- DCR emphasize a balanced transfusion strategy in which
quired volume was 640mL. (The shed blood volume plasma (with its clotting factors) was transfused in an
in this swine model was approximately 1700mL.) Re- equal ratio to the number of RBC units administered.
placing a 3000mL blood loss volume for volume in a The use of crystalloids during resuscitation was mini-
human would mean infusing 3L of Hextend, while the mized. DCR is now the standard of care in deployed
equivalent volumes suggested by the Burns et al. study medical facilities. 38,47,49 Platelets have been shown to im-
to achieve the lower SBPs of 65mmHg and 80mmHg prove outcomes when available.
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would be 467mL and 1129mL, respectively.
Prehospital fluid resuscitation options are typically more
The Burns et al. study suggests that resuscitating a ca- limited based on the logistics of blood component avail-
sualty with hemorrhagic shock to an SBP of 80mmHg able on the battlefield and the training level of combat

18 Journal of Special Operations Medicine Volume 14, Edition 3/Fall 2014