Page 133 - JSOM Winter 2021

strategies for TBI must focus on preventing secondary injury Moore et al. provided the most recent analysis on hypocalcemia
by avoiding hypotension and hypoxia while maintaining ap- by investigating two DoD-funded studies that focused on the use
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propriate cerebral perfusion pressure. The need to maintain a of prehospital plasma in the civilian trauma setting, the Prehos-
normal physiologic arterial blood pressure in TBI is in conflict pital Plasma during Air Medical Transport in Trauma Patients
with the principles of controlled hypotensive resuscitation in at Risk of Hemorrhage (PAMPer) and the Control of Major
hemorrhagic shock. Bleeding After Trauma (COMBAT) trials. They concluded that
prehospital plasma is associated with hypocalcemia, which in
Similar to resuscitation SBP goals in isolated hemorrhagic
shock, there remains an absence of definitive evidence to sup- turn predicts lower survival (adjusted hazard ratio, 1.07; 95%
port specific SBP goals for patients in hemorrhagic shock with CI, 1.02–1.13; p = .01) and need for massive transfusion (ad-
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concurrent TBI. Extrapolating from isolated TBI data, Chi et justed relative risk, 2.70; 95% CI, 1.13–6.46; p = .03).
al. reported 28% mortality when a secondary insult (SPB less Prehospital military experiences regarding hypocalcemia were
than 90mmHg or oxygen saturation less than 92%) was pres- published in a retrospective review of patients transported by
ent in the prehospital setting compared to 20% mortality for the UK Medical Emergency Response Team in Afghanistan
those without such insults. 84 between 2010 and 2014. Their overall incidence of hypocal-
cemia in the group not given prehospital calcium was 70.0%
In a subgroup analysis performed by the authors of the pre- (n=166), compared with 28.3% (n = 17) in the patients treated
viously mentioned meta-analysis for controlled hypotensive with intravenous calcium (p < .001). 99
resuscitation, there appeared to be a mortality benefit for con-
current TBI when SBP goals were at or above 90mmHg. It is While estimates suggest that ionized calcium drops approx-
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important to note that no functional outcomes were reported imately 0.05mmol/L per unit of blood product transfused,
on the TBI patients, and the authors conclude the data is not the literature is in disagreement on specific dosing require-
compelling enough to strongly recommend hypotensive resus- ments. MacKay et al. also noted a 22% incidence of hyper-
citation in traumatic hemorrhagic shock patients with TBI. 82 calcemia in massive transfusion patients in a civilian trauma
center suggesting that care should be taken in redosing cal-
In summary, the consensus opinion of the authors and cur- 101
rently available evidence indicates that fluid resuscitation of cium without laboratory measurements available. It is also
casualties in hemorrhagic shock should be continued to a tar- appropriate to note that slow IV/IO push of calcium salts is
get SBP of 100mmHg, unless the casualty has concurrent TBI, prudent due to the potential risks of adverse cardiovascular
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in which case the target SBP should be 100–110mmHg. effects or extravasation into surrounding tissues.
In summary, the authors believe that the available evidence
supports the administration of 1g of calcium (30mL of 10%
(4) Should empiric calcium be added to the TCCC fluid calcium gluconate or 10mL of 10% calcium chloride) IV/IO
resuscitation guideline? If so, how much and which type given after the first transfused product when blood products
of calcium formulation should be used, and when in the are being administered.
resuscitation sequence should it be given?
Calcium Management in Fluid Resuscitation Conclusions
Ionized calcium is essential to many physiologic functions im-
portant to the trauma patient. It is a cofactor to several com- The conclusions and recommendations of this working group
ponents of the clotting cascade and is essential to platelet include the following answers to the previously posed questions:
adhesion. Ionized calcium has a direct effect on the contractility
of myocardial cells and smooth muscle cells, thus affecting car- (1) Is there a specific blood product that is preferred
diac output, vascular contractility, and thrombus formation. 85,86 over others for resuscitation of casualties in hemorrhagic
shock in TCCC?
Trauma patients at baseline have an increased risk of being The preferred fluids for resuscitation of casualties in hemor-
hy pocalcemic from ischemia, reperfusion, hypothermia, and rhagic shock, in descending order of preference, are:
parathyroid and liver dysfunction. Hypocalcemia on initial
pres entation, prior to resuscitation efforts, has a reported inci- • Cold stored low titer O whole blood
dence between 50% and 75% in major trauma patients. 87–89 • Pre-screened low titer O fresh whole blood
It has also been shown by multiple investigations that blood • Plasma, red blood cells (RBCs), and platelets in a 1:1:1
product resuscitation increases the incidence of hypocalcemia, ratio
especially for patients with massive transfusions. This is likely • Plasma and RBCs in a 1:1 ratio
due to a combination of dilution and binding of calcium by • Plasma or RBCs alone
citrate in the transfused blood products. 90–93 NOTE: *Prescreened low-titer O fresh whole blood and
most platelets obtained in forward deployed locations
Evidence suggests that hypocalcemia has a linear, concentration-
dependent relationship with mortality as Ho et al. reported are not currently FDA compliant.
an odds ratio of 1.25 per 0.1mmol/L decrement (p = .02) in Cold-stored low titer O whole blood is the safest and most
a cohort study of 353 consecutive patients requiring massive beneficial fluid for resuscitation of casualties in hemorrhagic
transfusion. Further studies corroborate these findings and shock due to the hemostatic and oxygen-carrying properties
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suggest ionized calcium <1.0mmol/L increases mortality and of whole blood and the associated FDA compliant testing for
further worsening to levels below 0.9mmol/L increases mor- blood type, antibody titers and transfusion transmittable in-
tality 2- to 3-fold. 93,94,96 Consistent with anecdotal prehospital fections. However, the authors do recognize that cold chain
reporting, Desai et al. reported a direct association between storage requirements limit the use of CS-LTOWB in some
hypocalcemia and hypotension among intensive care unit tactical situations and alternative fluid resuscitation products
patients. 97 may be required.

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