Page 73 - JSOM Fall 2020

US Army Combat Medic Performance With Portable Ultrasound to Detect
Sonographic Findings of Pneumothorax in a Cadaveric Model

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Robert M. Meadows, PA-C ; Jonathan D. Monti, DSc, PA-C, RDMS *;
Mohamad A. Umar, DSc, PA-C ; Kerri A. Van Arnem, DSc, PA-C ; Eric J. Chin, MD, MBA, FAAEM ;
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Christopher A. Mitchell, MD, NRP, RDMS ; Sue Love, DSc, PA-C 7
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ABSTRACT
Background: Ultrasound, due to recent advances in portabil- unreliable, often present very late in disease course, can mimic
ity and versatility, has become a valuable clinical adjunct in other life-threatening conditions, and can be compromised by
austere, resource-limited settings and is well demonstrated to chaotic and noisy environments during combat. Addition-
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be an accurate/efficient means to detect pneumothorax. The ally, the loud and persistent noisy environment in military and
purpose of this study was to evaluate the impact of hands-on rotary-wing aircraft represents a significant challenge as it ren-
ultrasound training on ultrasound-naive US Army combat ders the auditory element of a reliable physical exam imprac-
medics’ ability to detect sonographic findings of pneumotho- tical. A suboptimal physical examination may, therefore, lead
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rax with portable ultrasound in a cadaver model. Methods: to delays in detection and proper management of tension PTX,
Ultrasound-naive US Army combat medics assigned to con- and inaccurate differentiation of thoracic injuries that share
ventional military units were recruited from a single US Army similar signs/symptoms (i.e., pericardial tamponade).
installation and randomized to receive either didactic training
only, or “blended” (didactic and hands-on) training on ultra- Field management of tension PTX requires tube or needle
sound detection of pneumothorax. Blinded participants were thoracostomy (NT). Needle decompression of a tension PTX
asked to perform a thoracic ultrasound exam on ventilated is a life-saving intervention that all conventional US Army
human cadaver models. Primary outcome measured was sensi- combat medics received training on during their advanced
tivity and specificity of detecting sonographic findings of pneu- initial training. This life-saving intervention is relatively inva-
mothorax between cohorts. Results: Forty-three participants sive, however, and is not without risk of potential complica-
examined a total of 258 hemithoraces. The didactic-only co- tions, which may include cardiac tamponade, life-threatening
hort (n = 24) detected sonographic findings of pneumothorax bleeding from damage to pulmonary and intercostal vessels,
with a sensitivity of 68% and specificity of 57%. The blended nerve injury, and iatrogenic PTX due to incorrect hemithorax
cohort (n = 19) detected sonographic findings of pneumotho- placement, complications that the medic may not be trained/
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rax with an overall sensitivity of 91% and specificity of 80%. equipped to manage. Data suggest that over 25% of patients
Detection sensitivities were similar between B-mode versus who receive needle thoracostomy in the prehospital setting for
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M-mode use. Conclusion: US Army combat medics can use suspected PTX do not have a PTX, highlighting the risks of
portable U/S to detect sonographic findings of pneumothorax inaccurate assessment of the presence of PTX.
in a human cadaver model with high sensitivity after a brief,
blended (didactic and hands-on) training intervention. Ultrasound (U/S) has emerged as a rapid and reliable diagnostic
adjunct to detect PTX. Technological advances have increased
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Keywords: combat medics; utrasound; military; POCUS; pneu- the versatility of U/S and allowed for significant miniaturiza-
mothorax; cadaver tion of machines. These advances have led to the commercial-
ization of inexpensive handheld devices, which allow trained
users to perform a myriad of diagnostic and procedural appli-
cations, even in unconventional, austere environments. De-
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Introduction spite these advances, U/S employment remains limited on the
Tension pneumothorax (PTX), resulting from undiagnosed battlefield, specifically forward of Role III (combat support
and/or untreated PTX, is the second leading preventable cause hospital level), where the potential for life- saving intervention
of death and the third leading cause of mortality overall in is greatest. The Joint Trauma System’s (JTS) Clinical Practice
combat-related injury. US Army combat medic training and Guideline (CPG) titled “Wartime Thoracic Injury,” specifically
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equipment constraints have historically dictated that detection states “where available, ultrasound and chest X-ray are useful
of PTX, and decisions to decompress a tension PTX, be ac- diagnostic adjuncts.” Additionally, the guideline states in a pa-
complished based on physical examination findings, which are tient with normal hemodynamics and adequate oxygenation
*Correspondence to jmonti@hjfresearch.org
1 MAJ Meadows is affiliated with the US Army/Baylor University Doctor of Science Emergency Medicine Physician Assistant Program. MAJ
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(Ret) Monti is affiliated with the US Army/Baylor University Doctor of Science Emergency Medicine Physician Assistant Program; and the De-
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partment of Clinical Investigation, Madigan Army Medical Center, Joint Base Lewis-McChord, WA. LTC Umar is affiliated with the US Army/
Baylor University Doctor of Science Emergency Medicine Physician Assistant Program; and the Department of Emergency Medicine, Brooke
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Army Medical Center, Ft. Sam Houston, TX. MAJ Van Arnem is affiliated with the Interservice Physician Assistant Program AMEDD C&S
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HRCoE, Ft Sam Houston, TX. LTC Chin is affiliated with the Department of Emergency Medicine, Brooke Army Medical Center, Ft. Sam
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Houston, TX. LTC Mitchell is affiliated with the Department of Emergency Medicine, Carl R. Darnall Army Medical Center, Ft Hood, TX.
7 MAJ (Ret) Love is affiliated with the Department of Emergency Medicine, Brooke Army Medical Center, Ft. Sam Houston, TX.
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