Page 15 - JSOM Summer 2023

Descriptive Analysis of
Combat-Associated Aspiration Pneumonia

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Steven G. Schauer, DO, MS *; Thomas Damrow, DO ;
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Silver M. Martin, DO, MS ; Ian L. Hudson, DO, MPH ; Robert A. De Lorenzo, MD ;
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Megan Blackburn, PhD ; Luke Hofmann, DO ; Michael D. April, MD, DPhil 8

ABSTRACT
Background: Airway obstruction is the second leading cause over half of all battle wounds sustained in the field. Many of
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of potentially preventable death on the battlefield. The treat- these blast wounds resulted in polytrauma, subsequent airway
ment for airway obstruction is intubation or advanced airway obstruction, or disordered breathing as a result of brain injury,
adjunct, which has a known risk of aspiration. We sought to increasing the risk of aspiration. Assuredly, airway compro-
describe the variables associated with aspiration pneumo- mise is a leading cause of mortality in combat, second only to
nia after prehospital airway intervention. Methods: This is a hemorrhage in the military population at large. A recent study
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sub-analysis of previously described data from the Department by Mazuchowski et al. evaluating potentially survivable death
of Defense Trauma Registry (DoDTR) from 2007 to 2020. We in Special Operations Forces (SOF) found that 14 of the 95
included casualties that had at least one prehospital airway in- had airway injury as a primary or contributing cause of death. 3
tervention with documentation of subsequent aspiration pneu-
monia or pneumonia within three days of the intervention. We Addressing airway injuries is a high-priority in prehospital
used a generalized linear model with Firth bias estimates to care, as securing the airway quickly and efficiently decreases
test for associations. Results: There were 1,509 casualties that the time to definitive and potential lifesaving procedures.
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underwent prehospital airway device placement. Of these, 41 However, airway interventions in the prehospital setting are
(2.7%) met inclusion criteria into the aspiration pneumonia not without complications, including aspiration pneumonia.
cohort. The demographics had no statistical difference be- The definition of aspiration pneumonia is pneumonia occur-
tween the groups. The non-aspiration cohort had fewer me- ring within 48 hours of intubation. Aspiration pneumonia
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dian ventilator days (2 versus 6, p < 0.001), intensive care unit accounts for 5% to 15% of all community-acquired pneu-
days (2 versus 7, p < 0.001, and hospital days [3 versus 8, monias, and diagnosis is generally based on clinical presenta-
p < 0.001]). Survival was lower in the non-aspiration cohort tion in conjunction with chest radiograph findings. The exact
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(74.2% versus 90.2%, p = 0.017). The administration of suc- cause and acuity of aspiration pneumonia is multifactorial.
cinylcholine was higher in the non-aspiration cohort (28.0% However, it is thought that the large bacterial load of from
versus 12.2%, p = 0.031). In our multivariable model, only macro-aspiration events along with the high pH of upper gas-
the administration of succinylcholine was significant and was trointestinal fluids leads to infection of the lung parenchyma
associated with lower probability of aspiration pneumonia and subsequent disease. Micro-aspiration of oropharyngeal se-
(odds ratio 0.56). Conclusion: Overall, the incidence of aspira- cretions also account for a growing percentage of pneumonias
tion pneumonia was low in our cohort. The administration of after intubation. 7
succinylcholine was associated with a lower odds of develop-
ing aspiration pneumonia. Controversy persists regarding association of prehospital intu-
bation versus emergency department intubation and the sub-
Keywords: airway; combat; aspiration; vomit; intubation; sequent development of pneumonia. However, we must note
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prehospital that comparing the civilian literature to the military setting is
challenging as protocols are quite different. Military medics
are not routinely trained to intubate prehospital, whereas ci-
vilian medics often do. 9,10 Conversely, military medics perform
Introduction
substantially more cricothyrotomies than the civilian sector.
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Operation Enduring Freedom (OEF) and Operation Iraqi Free- This makes direct comparisons challenging. Given these chal-
dom (OIF) began shortly after the terrorist attacks of Septem- lenges, applying data from the civilian setting may not be ap-
ber 11, 2001. These operations brought with them complex propriate to the battlefield setting. Combat-specific data are
wounds inflicted by improvised explosive devices that included needed.
*Correspondence to steven.g.schauer.mil@health.mil
1 Dr Steven G. Schauer is a physician affiliated with the US Army Institute of Surgical Research and Brooke Army Medical Center, JBSA Fort Sam
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Houston, TX, and the Uniformed Services University of the Health Sciences, Bethesda, MD. Thomas Damrow is affiliated with University of the
Incarnate Word – School of Osteopathic Medicine, San Antonio, TX. Silver M. Martin is affiliated with the University of the Incarnate Word –
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School of Osteopathic Medicine, San Antonio, TX. Dr Ian L. Hudson is a physician affiliated with the US Army Institute of Surgical Research
and Brooke Army Medical Center, JBSA Fort Sam Houston, TX. Dr Robert A. De Lorenzo is a physician affiliated with the University of Texas
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Health Science Center at San Antonio, San Antonio, TX. Dr Megan Blackburn is a scientist affiliated with the US Army Institute of Surgical Re-
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search, JBSA Fort Sam Houston, TX. Dr Luke Hofmann is a physician affiliated with the Brooke Army Medical Center, JBSA Fort Sam Houston,
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TX, and Uniformed Services University of the Health Sciences, Bethesda, MD. Dr Michael D. April is a physician affiliated with the 14th Field
Hospital, Fort Stewart, GA and Uniformed Services University of the Health Sciences, Bethesda, MD.
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