Page 65 - JSOM Fall 2025

findings of the 75th Ranger Regiment study by Meledeo and col- Finally, while the OG method among experts had a slightly
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leagues. Meledeo et al. concluded that the 6.5" BC was supe- lower correct fill rate compared to the PC strategy (70% vs.
rior to other constriction methods (ties cord, zip tie, tourniquet, 80%), the OG method was less likely to have low fill volume
hemostat clamping, 6.25" and 6.75" BC) in meeting the 450mL (10% vs. 20%). It is not known if an overfill or an underfill
target. However, it is important to note that the Meledeo et al. would portend worse outcomes for a patient. This concern
participants filled donor bags with saline via gravity from a 1L highlights the importance of further research to assess the im-
bag suspended 18” above the donor bag, which took less than pact of transfusing blood from a donor bag that is overfilled,
2 minutes, roughly 1/6 the time to fill blood bags from human underfilled, or appropriately filled.
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donors in a previous study using Valkyrie novices. Further,
comparisons of results between studies are also difficult because Implications
Meledeo et al. conducted a benchtop laboratory study without The most important implication of the present study is that
situational duress, while the novices in the present study were none of the tested techniques (as taught in a Valkyrie course)
using live donors in a field environment under time pressure appear to be adequate for reliably estimating accurate blood
and formal evaluation duress. Further, the expert group in the bag fills, given that the overall study-wide correct fill success
present study, who were not under formal evaluation duress, rate was only 55%. The highest-performing technique for ex-
demonstrated a 50% underfill rate with BC, reasonably similar perts was PC, which still demonstrated a 20% failure rate in
to the novice group, suggesting that the use of live donors in a hitting the target volume. Further, study data were collected in
field environment may explain the differences between the pres- relatively calm and well-controlled conditions, and it is likely
ent findings and the findings of Meledeo et al. that performance would degrade under battlefield conditions.
We therefore need to revisit both the instruction and method-
The reason for the high rate of underfills with BC is unclear. ology currently being employed at Valkyrie towards increasing
However, some participants in the present study perceived rates of correct bag fills.
that the constriction of the BC progressively slowed flow
rates, while others found it difficult to visualize whether the BC performed poorly in all objective and subjective metrics and
bag was full. It is therefore possible that the high rate of BC should therefore be avoided as currently taught at Valkyrie.
underfills was due, at least in part, to these two factors, with Further, underfills comprised 41% of all attempts study-wide,
many participants prematurely concluding that the bag was and greater than 50% when using BC. Given the success of
full compared to the other methods tested in the present study. Meledeo et al., dedicated efforts at Valkyrie (and perhaps else-
Regardless of the reason, the poor overall performance in all where) are warranted towards finding effective ways to reduce
objective and subjective assessments demonstrates that the the rate of underfills, particularly when using the BC method.
BC method, as currently taught within the Valkyrie course,
resulted in unacceptable outcomes for our novice and expert Lastly, while experts were somewhat higher than novices in
participants. Evaluating alternative instruction methods and correct fills (as might be expected), novices and experts were
adjusting the length of the beaded cable towards determining generally more similar than dissimilar in patterns between BC,
the viability of the BC method within the Valkyrie program are PC, and OG in objective and subjective assessments. The im-
therefore important areas for future research. plications here are two-fold. First, practice repetitions may be
valuable towards hitting the target volume. Second, the gen-
The PC technique conferred mixed results in the present study. eral patterns of differences between BC, PC, and OG might
PC correct fill rates were roughly half for the novices and be more dependent on the methods themselves rather than on
somewhat higher than OG for the experts. PC was rated be- experience.
tween BC and OG for all subjective assessments and novices
and experts agreed that they would use PC in a combat envi- Limitations
ronment willingly. Some novices indicated that they verified The present study was limited by the sample. All study partici-
PC using OG. pants were Valkyrie students (Novices) or Valkyrie instructors
(experts). The expert group included a modest sample size (be-
The OG technique generally performed better than BC or PC, cause of operational commitments within the Division), which
but there remains room for improvement. For novices, OG limited statistical power. Further, the Valkyrie program is a
demonstrated significantly higher rates of correct fills than BC highly specialized training, so its results should be generalized
and PC, though marginally lower than PC for experts. OG to other professionals with appropriate caution.
had significantly higher subjective ratings than BC and PC for
novices and experts. Participants liked that OG requires no Some novice cases (38%) were eliminated from the analyses
additional equipment, but proficiency may require practice because the participant did not complete all three techniques
repetitions. Novices and experts generally agreed that they due to issues unrelated to BC, PC, and OG (e.g., failed IV
would use OG in a combat environment eagerly. However, it access or blown lines). This strategy of dropping incomplete
is important to note that the study-wide failure rate of OG cases was employed because we sought to determine relative
to achieve the target volume was roughly 30%, which is un- differences between BC, PC, and OG within participants.
acceptable in the context of methods to preserve the life of a However, it is theoretically possible that our choice to only
wounded warfighter in need of a safe WBB transfusion. So, include complete cases could have biased our results. Further,
while OG performed well relative to BC and PC in the present it is possible that the expert group participants, who each had
study, the high failure rates suggest that the OG technique can- extensive experience with BC, PC, and OG, may have formed
not be endorsed as the principal strategy for blood collection, opinions prior to the study onset. While this identifies a poten-
and further investigation will be necessary to determine the tial source of bias, it is important to note that the expert and
optimal strategy for determining accurate blood bag fills in novice group participants were more similar than different in
field environments. subjective assessments of BC. PC, and OG techniques.

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