FROM THE BLOGOSPHERE
THE DEVIL’S ADVOCATE IS BACK; Blood Loss
Estimations in Trauma
Anne Hayes, MD
I
find myself regularly fascinated by the
accuracies (and frequent inaccuracies) of
our subjective findings concerning trauma.
Consider how often we hear about details;
mechanism, intrusion, extrication time to
name a few, and how heavily they guide both
pre-hospital and ED workups. I have come
across some interesting studies regarding
blood loss estimation. Next time you hear
a report about blood loss at a scene, contemplate (and feel free to
cackle and wisely reference) the following studies:
The first, published in Prehospital Emergency Care, tested a cohort
of EMTs and paramedics on estimating blood volumes spilled on
carpet and vinyl surfaces. Blood product was poured onto these
surfaces and participants estimated total volume demonstrated
at six different spill sites. Mean percent errors of 74 percent and
56 percent were observed for initial estimations! A similar study
published in The Journal of Trauma: Injury, Infection, and Critical
Care produced similar results, where only eight percent of the 99
providers tested were within 20 percent of the actual volume, and
only 24 percent were within 50 percent of actual volume.
Perhaps the more interesting feature of the first study is the
post-estimation training that occurred afterwards. One arm of the
cohort returned to the initial scene where actual blood loss was
revealed followed by some education on making volume estimates.
The second arm had similar education, however, this was performed
in a classroom using slides instead of returning to the original scene.
Both groups were retested with new scenarios and both demon-
strated improvement in mean percent errors to 59 percent (return
to scene) and 45 percent (slides in classroom), suggesting this may
be learnable skill with further education.
It turns out, emergency physicians are not much better than
our pre-hospital colleagues at blood estimation. A study from the
Western Journal of Emergency Medicine examined a cohort of 56
emergency physicians (mixed residents and attendings). Participants
were tested with four different scenarios in which specific amounts
of blood were poured onto a bedsheet, gauze, a t-shirt and into a
commode. The mean standard error for all estimates was 116 percent
with a range of zero to 1,233 percent. Only eight percent tested were
28
LOUISVILLE MEDICINE
within 20 percent of the true value. Sound familiar?
The next question I arrived at, which you may be thinking your-
self, was that these studies do not include scenario details or vital
signs. One would expect more data would result in more accurate
estimates. Unfortunately, the rabbit hole of my literature search
revealed that, even equipped with additional information, both
pre-hospital providers and emergency room physicians continued
to be poor estimators of blood loss. A study from The Journal of
Trauma tested estimations in set blood loss amounts (300 mL,
800 mL and 1,500 mL) in a “stable” patient and in an “unstable”
patient. Researchers found that in the stable patient (i.e. normal
blood pressure and heart rate) blood loss was underestimated in
the 800 mL and 1,500 mL patients and overestimated in the 300 mL
patient. Remarkably, in the unstable patient, blood loss in both 800
and 1,500 mL scenarios were underestimated. Of the 870 estimates
made, 51 percent were underestimated (less than 10 percent from
true value), 39 percent were overestimated (greater than 10 percent
of true value) and only 10 percent were exact.
Is visually estimated blood loss of any pre-clinical value and
worth being mentioned during handover in the emergency unit?
Perhaps not, but there may be hope with additional training...
Dr. Hayes is a PGY-3 Resident at University of Louisville Hospital prac-
ticing Emergency Medicine.
References:
1. Patton K., Funk DL., McErlean M., Bartfield JM. (2001) Accuracy of
estimation of external blood loss by EMS personnel. The Journal of
Trauma: Injury, Infection, and Critical Care. 50(5):914-916.
2. Moscati, R., Billittier, AJ, Marshall, B., Fincher, M., Jehle, D., Braen, GR.
(1999) Blood loss estimation by out-of-hospital emergency care providers.
Prehospital Emergency Care, Jul-Sep;3(3): 239-42.
3. Ashburn, J. C., Harrison, T., Ham, J. J., & Strote, J. (2012). Emergency
physician estimation of blood loss. The western journal of emergency
medicine, 13(4), 376-9.
4. Frank M., Schmucker U, Stengel D, Fischer L, Lange J, Grossjohann R,
Ekkernkamp A, Matthes G. (2010) Proper estimation of blood loss on
scene of trauma: tool or tale? The Journal of Trauma. Nov;69(5):1191-5.
This blog entry was featured on Room 9 Blogs, a blog for UofL ER
Residents. You can view other entries at www.room9er.com