Page 92 - Journal of Special Operations Medicine - Spring 2017

Figure 4 PRBCs (330mL) on a concrete surface. Limitations
The blood product we used for illustrative purposes was
PRBCs only. Given that this is a fractionated product
without plasma and other constituents, it is possible
whole blood might interact differently with the environ-
ment and change the visual appearance of the bleeding.
In addition, during actual wounding, there is likely to be
absorption of blood by the injured soldier’s uniform and
equipment, which was not pictured in the figures in this
article. Regardless, we believe the use of PRBCs allows
the reader to gain a rough idea of the amount of blood
loss based on visual estimation.

Conclusion
Accurate visual estimation of blood loss is problematic
for the reasons listed in this article. However, given lim-
ited objective data in the military prehospital environ-
there is evidence of hemorrhagic shock, defined as al-
tered mental status and a weak radial pulse. Although ment, it is unrealistic to think that the visual impression
9
not always accurate, classical teaching maintains that of blood loss will not affect patient-management deci-
750–1,500mL of blood loss causes class II hemorrhagic sions. Because of this, it is important to understand in-
shock, which corresponds to hypotension and changes herent biases such as overestimating small volumes of
in mental status. Despite the visual impression of a sig- hemorrhage and overestimating large volumes of hem-
8
nificant amount of blood loss, the amount of blood pic- orrhage. We hope that the clinical images in this article
tured in Figures 1–4 (330mL) would not be expected give some perspective on this topic and illustrate that a
to cause hemorrhagic shock. Approximately four to six relatively small amount of bleeding, which would not be
times the amount of bleeding pictured would be required expected to cause hemorrhagic shock, can appear very
before the blood loss would be so significant that hem- large.
orrhagic shock might develop, warranting blood prod-
uct and tranexamic acid administration. Of note, Figure Disclosures
5 shows 990mL of blood loss, which is slightly below
the aforementioned threshold where the probability of The authors have nothing to disclose.
developing hemorrhagic shock increases significantly.
However, a 70kg patient could develop shock physiol- References
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70 Journal of Special Operations Medicine Volume 17, Edition 1/Spring 2017