Page 70 - JSOM Spring 2021

in identifying instruments, and ease in suturing. We also ob- FIGURE 1 Tomahawk MC tactical flashlight with Tactical Retention
tained the tactical lighting preferences of the users. System mount (LEFT), shown chest-mounted for field use (RIGHT).
Photographs courtesy of First Light-USA, Seymour, IL.
Methods
Setting
This laboratory study was conducted at Naval Medical Center
Portsmouth (NMCP). All procedures were approved by the
NMCP Institutional Review Board (IRB) prior to the start of
any study activities. This manuscript was approved for sub-
mission for publication by Naval Medical Center Portsmouth’s
Public Affairs Officer, Publication Officer, as well as the Navy
Bureau of Medicine and Surgery. darkened vestibule in a windowless laboratory that was made
as dark as possible using opaque drapes.
Participants
Participants were 24 resident physicians at NMCP who vol- Following dark adaptation, a randomly assigned light color
unteered without compensation. Participants held the rank was activated and participants were instructed that they would
of Lieutenant or Lieutenant Commander in the United States be placing two deep, interrupted sutures using 4-0 Vicryl
®
Navy, including 17 men (71%) and 7 women (29%). Roughly (Ethicon, https://www.jnjmedicaldevices.com) and three su-
half (54%) had corrected vision and none reported being perficial, interrupted sutures using 4-0 Prolene (Ethicon,
®
color blind. All participants had extensive prior suturing https://www.jnjmedicaldevices.com) into a 6cm long, 3cm
experience, whether on live humans (100% of participants, full-thickness laceration on the hind leg of a swine cadaver.
M = 47, range: 1–200), live animals, (78%, M = 24, range: Full-thickness in this context indicated that the laceration was
0–100), human cadavers (91%, M = 10, range: 0–30), ani- deep to the dermis, thus requiring two-layer suturing to pro-
mal cadavers (43%, M = 10, range: 0–100), or mannequins vide adequate closure while relieving tension on the wound.
(83%, M = 13, range: 0–50). All but one (96%) reported The sutures were placed a minimum of 5mm apart with four
lifetime experience suturing full-thickness lacerations on live throws each. Participants were informed that the task would
humans, and 92% performed this procedure during the pre- be timed by stopwatch, beginning when they first touched
vious year, including 29% who performed this procedure an instrument and ending when the task was completed and
4–7 times and 42% who performed this procedure eight or they verbally stated “done.” After task completion, the room
more times during the previous year. Participants were there- lights were turned on and participants completed a post-test
fore considered to be adept at performing a basic two-layered survey. Each participant returned for a second and third ses-
wound closure using simple interrupted sutures. Five partic- sion on sequential days to complete the suturing task under
ipants (21%) had previous experience performing medical all three lighting conditions. Examples of the procedure being
procedures under low light conditions, including four un- completed under the three lighting conditions are displayed in
der red light conditions and two using night vision goggles. Figure 2.
All participants provided informed consent prior to data
collection. Measures
Outcome measures included time to task completion (in sec-
Tests of power using G*Power software (version 3.1.9.4, Faul onds) and suture quality. Suture quality was operationally de-
et al., 2007) revealed that, assuming a 95% confidence inter- fined as the number of attempts to successfully complete the
val, statistically significant results would be realized on 80% five sutures. Each attempted placement of a suture was counted
of opportunities (power = 0.80), with as few as 20 participants regardless of whether it resulted in a successful (scored as “1”)
for an omnibus repeated measures ANOVA with an effect size or a failed (scored as “0”; e.g., improper placement, broken
of f = 0.30, and with as few as 24 participants for localizing sutures, sutures torn through) stitch. Broken sutures and su-
pairwise comparisons with an effect size of 0.60 (Cohen’s d tures that tore through tissue were each independently counted
= 0.60). Therefore, to ensure adequate power, this study in- for separate analyses. Participants rated the ease in identifying
cluded 24 participants. blood, identifying instruments, and suturing for each lighting
condition using a 1 (strongly disagree) to 5 (strongly agree)
Materials scale. User preference data were obtained using a three-alter-
The Tomahawk MC (First Light-USA, https://firstlight-usa native forced-choice paradigm.
®
.com) is a relatively compact (3.35" H × 2.38" L × 1.48" W)
and lightweight (5.6 ounces) tactical flashlight that provides Design and Analysis
red-only, green-only or mixed red-green wavelengths (Figure This experiment employed a within-subjects design, such that
1). Powered by two CR123 batteries, this device was chest- each participant was tested under each lighting condition. By
mounted for the present study and used at the highest power randomizing participants to mirrored Latin squares sequences,
setting, in which the three lighting modes confer similar lu- each lighting condition was represented in the first, second,
mens of light quantity. and third order position and each lighting condition had an
equal probability of being proceeded by the other lighting con-
Procedures ditions. Continuous variables were analyzed using repeated
Participants provided written informed consent and then com- measures ANOVA with localizing pairwise comparison, each
pleted a pretest survey regarding their background and level of confirmed with nonparametric Friedman and Wilcoxon signed
experience. The Tomahawk MC was then chest mounted and rank tests. Categorical variables were analyzed using χ sta-
2
®
the participants were dark adapted for 10 minutes within a tistics. All hypotheses were tested at the p < .05 threshold for
66 | JSOM Volume 21, Edition 1 / Spring 2021