Page 25 - JSOM Summer 2023

FIGURE S5 Example of the blast pressure Friedlander Waveform denotes the least important test. Further, we calculated the
the supraglottic airway devices were subjected to for assessing their weights of each test method by taking the reciprocal of the
capability of withstanding an open-field blast. mean ranking.

Each device, after each test, received a score of between 1 and
10 (Table 4) based on the results of the visual examination and
operational check (Tables S2 through S10). A score of 10 rep-
resents a pristine device that has not been damaged in any way,
while a score of 1 represents a device that cannot operate in
any capacity. We calculated the score for each model of SGAs
by averaging the score of the devices within a model for each
MIL-STD-810H test method. We continued to use devices that
For this test, the devices were subjected to a custom-built were damaged unless the device was unable to provide any
shock tube (Applied Research Associates), a compressed-air- airflow, which did not occur throughout the study. We deter-
driven device operated by mounting one or more burst disks mined additional damages resulting from subsequent tests by
of 6061-t6 aluminum between the driver and driven sections comparing the operational check values from the previous test.
of the tube. We used a peak pressure value of 200kPa and a Additionally, we used visual examinations to determine any
positive phase duration in the range of 4ms to 10ms. These additional damage.
values are based on IED (improvised explosive device) pres-
sure profiles. 11 Results

The purpose of the vibration test was to determine whether We calculated the final score for each SGA model by the summa-
the devices will function in and withstand the vibration expo- tion of the averaged model score multiplied by the test weight
sures of a life cycle. For this test, we kept the devices within for each test (Table 5). Here, we list the results for SGA models
their packaging and mounted the devices to a VWR Incubat- in the order by which they scored, from highest to lowest.
ing Mini Shaker vibration exciter. We applied a frequency of
1000Hz for a 30-minute duration. We then removed the de- LMA Classic
vice from its packaging and applied the same frequency for a The LMA Classic had the highest total score across the nine
15-minute duration. 11 MIL-STD-810H tests. The devices sustained only small aes-
thetic damages during the sand and dust test as well as the shock
The purpose of the acceleration test is to assure that materiel test.
can structurally withstand the steady-state inertia loads that
are induced by platform acceleration, deceleration, and ma- Ambu AuraGain
neuver in the service environment and function without deg- The AuraGain had the second highest score and performed
radation during and following exposure to these forces. For poorly only during the sand and dust test, during which the
the test, we installed the devices in a Thermo Fisher Scientific non-return valve of the inflatable cuff was damaged.
Sorvall Legend XTR centrifuge and brought the devices to
the required speed to induce a force between 2g and 3g. Once i-gel
the centrifuge speed stabilized, the g-level was maintained for The i-gel had the third highest score and performed poorly
1 minute. only during the sand and dust test. All the i-gel devices con-
11
tained significant amounts of particulate in the airway tube
Scoring Method after the 10-second cleaning period.
Each MIL-STD-810H test method was rank ordered based on
how critical it was that an SGA device perform well during Solus
that test (Table 3). Five military (four active duty, one retired) The operational check after the low-temperature test showed
and emergency medicine SMEs ranked the test methods; an inability to provide the appropriate ventilation level. Addi-
we used the mean values as the final rankings. A rank of 1 tionally, the airway tubes became rigid during the freeze/thaw
denotes the most important test method, while a rank of 9 test, making insertion into the mannequin difficult.

TABLE 3 Weights of Each MIL-STD-810H Test Method Based on SME Rankings
SME #1 SME #2 SME #3 SME #4 SME #5
Test Ranking Mean Weight
Contamination by Fluids 1 1 1 — 1 1.0 1.0
High Temperature 4 3 7 1 — 3.8 0.3
Low Temperature 5 4 5 2 5 4.2 0.2
Sand and Dust 3 6 6 5 2 4.4 0.2
Freeze/Thaw 2 2 9 3 6 4.4 0.2
Humidity 8 8 2 4 3 5.0 0.2
Solar Radiation (Sunshine) 6 7 4 — 8 6.3 0.2
Shock 9 5 8 — 4 6.5 0.2
Low Pressure (Altitude) 7 9 3 — 7 6.5 0.2
SME, subject matter expert

Testing SGA Devices in Military Combat | 23