Page 29 - Journal of Special Operations Medicine - Summer 2016

Figure 1 Plot of mean blood loss by user order. Disclaimer
The opinions or assertions contained herein are the pri-
vate views of the authors and are not to be construed
as official or reflecting the views of the Department of
Defense or US Government. The authors are employees
of the US Government. This work was prepared as part
of their official duties and, as such, there is no copyright
to be transferred.

Disclosures

The technique of plotting mean blood loss volumes is shown. With The authors declare no conflicts of interest.
30 sequential users, the plot shows that the individual user’s mean
blood loss trended down as the instructor gained experience with each
newly instructed user. However, no obvious turning point (cusp) was Reference
reached in that the data looked variable and there was no obvious
step or change. The linear regression line showed that about 9% of 1. Kragh JF, Lunati MP, Kharod CU, et al. Assessment of groin
the variability (the R value) of the blood loss was explained by gained application of junctional tourniquets in a manikin model. Pre-
2
experience (i.e., increases in user order). The power curve had similar hosp Disaster Med. 2016;31:1–6.
results. Together, the line and curve indicate that mild learning was
evident. The trend is unclear for determining how long it took for the
instructor to learn.
Dr Kragh is a researcher of bleeding control at the US Army
Figure 2 CUSUM of mean blood loss by user order. Institute of Surgical Research (USAISR), Joint Base San An-
tonio Fort Sam Houston, Texas, and Department of Sur-
gery, Uniformed Services University of the Health Sciences,
Bethesda, Maryland. He is an orthopedic surgeon who was
the 3d Ranger Battalion Surgeon from 1990 to 1993. E-mail:
john.f.kragh.civ@mail.mil.
Dr Aden is a statistician at the USAISR, Joint Base San Anto-
nio Fort Sam Houston, Texas. He has published many papers
in operational medicine.

Dr Shackelford is a trauma surgeon in the Joint Trauma Sys-
The technique of CUSUM is shown for blood loss. With 30 sequential tem at the USAISR, Joint Base San Antonio Fort Sam Houston,
users, the plot shows that the trend had a turning point at the seventh
user. The prior portion (users 1–7) of the trend indicated that the in- Texas. She is a member of the Committee on Tactical Combat
structor improved much with the first seven users and less afterward: Casualty Care and has published many papers in operational
the instructor’s trend in improvement changed with the seventh in- medicine.
struction episode.
Dr Dubick is a resuscitation researcher at the USAISR, Joint
Base San Antonio Fort Sam Houston, Texas. He is the task
of student caregivers acquiring medical skills are seldom area manager of the Department of Damage Control Resusci-
empirically studied. Evidence is unavailable to decide if tation. He has published many papers in operational medicine.
early learners should be retaught because their instruc-
tion was less effective; after instruction improved, rep-
etition of the instruction may be useful for those early
learners. Future directions include broader and deeper
analyses of learning, using such metrics.
See related article, “Preliminary Comparison of
Pneumatic Models of Tourniquet for Prehospital
Funding Control of Limb Bleeding in a Manikin,” by Gibson
This project was funded by the Defense Health Program et al. on page 21.
(Proposal 201105: Operational system management and
post-market surveillance of hemorrhage control devices
used in medical care of US Servicepersons in the current
war).

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