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sonographic findings of PTX with similar sensitivities as emer- TABLE 5 Medic vs EM Resident Physician Performance in US
gency medicine resident physicians (Table 5) in a similarly de- Detection of PTX in Cadaver Model
signed study by Adhikari et al. A 2009 study assessed the US Army
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ability of a mixed cohort of nonphysicians (including Special combat medics EM Residents
Forces medical sergeants) to detect PTX in a porcine model Meadows et al. Adhikari et al. 10 P Value
with similar results; however, these results may not be trans- B Mode Sensitivity 92% (73/79) 90% (38/42) .739
latable to a human model. Hanlin et al. used a cadaver model Specificity 86% (30/35) 93% (39/42) .454
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to demonstrate that medics can effectively us U/S to confirm Sensitivity 87% (70/79) 83% (35/42) .574
endotracheal tube placement. Several other studies have M Mode Specificity 74% (26/35) 81% (34/42) .586
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demonstrated that U/S can be accurately used by military med-
ics and nonphysician prehospital military personnel, but these
studies evaluated other clinical applications and were con- PTX may allow medics the opportunity to logistically and
ducted in simulated settings using nonhuman models, limiting mentally prepare for execution of eventual needle chest de-
their conclusions and generalizability. 20–23 The use of human compression (NCD). This, in turn, could mitigate procedural
cadavers, as validated by Adhikari et al. and replicated here, stress of urgently performed and invasive NCD, further miti-
may provide anatomical fidelity more comparable to what is gating risk of associated iatrogenic complications. Third, U/S
seen on the battlefield than animal live tissue. Though em- can differentiate PTX from other potential life-threatening
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balming can extend the life of the cadaver model, US Army traumatic injuries such as pericardial tamponade, which may
combat medics in brigade combat teams do not have access to present similarly. Last, accurate detection could ensure proper
resources to lightly embalm cadavers and embalming. The lack allocation of limited medical resources in prolonged field care
of a statistically significant difference in sensitivities between or mass casualty settings and allow clinicians the opportunity
this study and that of Adhikari and colleagues could suggest to mitigate risk of complications emerging during evacua-
that the presence of embalming fluid in the chosen model is tion that could require urgent management under suboptimal
unimportant, but several confounding factors prevent this conditions.
conclusion from being made. The use of cadavers, whether
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fresh or lightly embalmed, appear to provide military medical This study has several important limitations. The small sample
personnel with valuable high-fidelity training in the accurate size from a geographically limited population limits generaliz-
identification of PTX sonographic findings. ability of findings. The study was conducted in a laboratory
setting that did not accurately simulate the austere environ-
Combat casualties are much more likely to receive initial med- ments in which US Army combat medics typically operate. In-
ical care from a combat medic or corpsman, or nonmedical terrogation of the chest, though also achievable laterally, could
personnel than a medical officer, highlighting the important only be performed anteriorly to ensure adequate blinding of
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role nonphysician prehospital personnel play in the survivabil- the participants. Order of mode (B vs M) use during scan-
ity of combat trauma casualties. Logistical constraints limit the ning was not randomized. All participants started in B mode,
medical equipment carried by US Army combat medics, often which could potentially have introduced bias or a carryover
limiting diagnostic capabilities to physical examination only, effect into their scan with M mode. We did not include inter-
which is well demonstrated to be inaccurate in the detection rogation for lung point sign, which has been demonstrated to
of PTX and several other conditions. 15,16 These realities have be highly specific for PTX. Sensitivity of detecting the sono-
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led to renewed focus on expanding the skillset of nonphysi- graphic findings of PTX may not be necessarily translatable
cian prehospital clinicians and exploration of highly portable to detection of actual presence of PTX. We did not assess skill
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technologies that can improve provision of care in the military degradation, an important consideration for this perishable
operational environment. The miniaturization and versatility skill, due to concerns for inadequate longitudinal follow-up.
of U/S make it an attractive option in the provision of pre-
hospital care, but scant literature exists evaluating its poten- Conclusions
tial to be used by those most likely to provide life-saving care
in the operational environment. This study adds to a small This study demonstrated that a small cohort of conventional
but growing body of evidence that US Army combat medics US Army combat medics can use portable U/S to accurately
may be able to effectively use U/S to improve patient care. Ex- identify sonographic findings of PTX in a human cadaver
pansion of U/S training opportunities for US Army combat model after brief didactic and hands-on training. More data
medics may further justify expanded fielding of portable U/S are required to determine if casualties treated by conventional
for the evaluation of PTX on the battlefield or during medical US Army combat medics could potentially benefit from medic
evacuation. use of U/S. Integration of POCUS skills training into US Army
combat and combat paramedic training, and expanded field-
It is important to note that U/S is not currently recommended/ ing of portable or handheld U/S devices at the ROLE I/II levels,
included in the JTS CPG on the assessment and management if not already under way, should be considered. Cadaver mod-
of tension PTX in the tactical combat casualty care setting. els could be integrated into medic training for U/S detection
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Though the authors admit there is arguably no role for U/S in of PTX or other U/S applications when logistically feasible.
the setting of suspected tension PTX, we suggest that there is Further studies assessing the value of medic-performed point-
several potential benefits from the rapid, accurate identifica- of-care U/S with real-world patients, and assessing U/S skill
tion of the presence/absence of PTX in the forward-deployed retention, are needed.
environment. First among these benefits is the prevention of
unnecessary NT of a normal hemithorax and mitigation of Disclosures
the complication risk associated with this procedure. Second, The authors have no financial interests or other conflicts of
early awareness of the presence and localization of nontension interest related to this research to disclose.

74 | JSOM Volume 20, Edition 3 / Fall 2020