Page 74 - JSOM Fall 2019

FIGURE 2 Illustration of the TM. (A) The nondominant hand Study Protocol
stabilizes the larynx. (B) The dominant index finger, from a top-
down approach, rests on the CTM. Sample size determination
This study predicted the outcome of 67% success for the
TM, based on the average of the 72% success rate with the
TM found for nonobese male models by Lamb et al. and
10
the 62% success rate with the TM by Bair and Chima. The
5
number of iterations performed in Bair and Chima’s (2015)
study was not clear so the average of the two success rates
(72% and 62%) was used to predict success for this study.
The study by Bair and Chima was the only study that iden-
tified that compared success rates of various CTM palpation
techniques; the authors did not break down success by subject
gender or obesity. However, they noted that 48% of mod-
5
7
els were male and 66% were nonobese. Elliot et al. (2010),
the only other study cited, aside from Lamb et al. (2015),
10
that analyzed the CTM localization success rate on nonobese
males, had a 38% success rate. An absolute difference of 30%
(A) (B) and power of 90% were used by Bair and Chima. Based on
5
this recent research, the authors powered the study to detect a
30% absolute difference between techniques (90% power, α =
of medical professionals of varying levels of training and ex- .05) with an estimated required sample size of 32 participants
perience, and substandard operating conditions—all of which for 64 iterations.
can be obstacles to successful performance of an ESA. Such
3
obstacles, though they cannot be avoided, should be mitigated Selection of participants
to the maximum extent possible through enhanced training, Participants in this study were limited to combat medic train-
techniques, and equipment. This study compares two tech- ees within 1 month of graduation of advanced individual
niques of localizing the CTM, a first and critical step in ESA. training (AIT). This population was selected as by this point
in their training they had completed at least four weeks of
Eight research studies performed between 2010 and 2016 have cricothyroidotomy familiarization including identification of
shown that success rates of identifying the CTM range from the CTM via the TM. It is important to note that the label of
0% to 72%, in a training environment, for physicians and spe- combat medic implies that a soldier has completed AIT, the
cialists of all training levels, including experienced anesthesiol- most basic level of medic training in the Army. Their experi-
ogists and trauma surgeons. 4-11 No published research studies ence and training do not reflect that of the readership Special
were identified that focus on the ability of military medical Operations Forces (SOF) medics.
providers—medics or otherwise—to localize the CTM. This
study was conducted to add to the field of CTM and military Informational sheets were sent to the cadre and presented to
medicine literature. all soldiers in the unit in early September. The following week,
soldiers were asked at a group formation if they were inter-
ested in volunteering. The first 32 trainees who volunteered
Research Question and Hypothesis
were chosen; they were not given any further information until
The research question is: Which method is superior, the LHM the study date.
or the TM, for identifying anatomical landmarks in a timely
manner when performed by US Army combat medics trainees? Study participants with upper extremity amputations, hand
The hypothesis is that there will be a significant difference in sensory deficits, visual defects or those taking any medications
success rates between the two methods. that may cause them to have motor-sensory impairment were
excluded. Those with advanced cricothyrotomy experience,
defined for this study as a procedure performed on a live hu-
Methods
man, human cadaver, or live animal, were also excluded to
Study Design lessen variability in CTM localization familiarity among par-
This was a prospective randomized crossover trial. The study ticipants. Participants who met or possibly met any exclusion
took place at Ft Sam Houston, TX in September 2018. criteria were asked to remove themselves from the study after
the informational brief. Participants were not allowed to serve
as models, and vice versa.
Study Setting and Population
This trial was conducted upon approval from the Depart- Selection of models. Models with limited neck range of mo-
ment of Combat Medic Training (DCMT), the Army Medical tion, gross neck deformities, any prior neck surgery, or his-
Department (AMEDD) Center and Schools, and the Brooke tory of prior cricothyrotomy were excluded. Both models
Army Medical Center (BAMC) Institutional Review Board were male, 18 years of age, and nonobese. Body mass index
(IRB) (C.2018.132e). Volunteers recruited to be assessed were (BMI) was similar with Model 1 at 26.6kg/m and Model 2
2
termed “models” or “subjects,” whereas volunteers recruited at 25.8kg/m . All physical characteristics are listed in Table 1.
2
to test the hypothesis were termed “participants.” Both groups The goal in choosing two male nonobese models with similar
gave verbal consent for participation and no personally identi- body habitus was 2-fold. First, this demographic represents
fiable information was collected in the study. the average warfighter who is most likely to become injured
12

72 | JSOM Volume 19, Edition 3 / Fall 2019