Page 26 - JSOM Spring 2023

The limited changes in airway management associated with Analysis
guideline changes and incremental technology solutions con- We extracted data from the DoDTR on those casualties with
trast sharply with the advances made with regards to hem- documented placement of an endotracheal tube, cricothyrot-
orrhage control and hemorrhage resuscitation. Tourniquets omy, tracheostomy, or SGA in the prehospital or emergency
revolutionized extremity hemorrhage control in the prehos- department setting. We defined mortality as death that occurs
6
pital setting. Blood products are available far forward near during the initial hospitalization period.
the point of injury with increasing data demonstrating the
7
lifesaving benefit of this intervention. Other technologies, in- We performed all statistical analyses using Excel version 10
cluding junctional tourniquets and resuscitative endovascular ( Microsoft, www.microsoft.com/en-us/microsoft-365/excel) and
balloon occlusion of aorta (REBOA), are also now available in JMP Statistical Discovery version 13 (SAS, https://www.jmp.
the far-forward combat setting. Despite identification as the com/en_us/home.html). We present continuous variables as
8,9
second leading potentially preventable cause of death in the means and 95% confidence intervals, non-parametric con-
prehospital setting, comparable advancements in airway man- tinuous variables and ordinal variables as medians and in-
agement technology have not been achieved, and it is unclear terquartile ranges, and nominal variables as percentages and
if the incremental changes are associated with significant im- numbers. We analyzed the data under the assumption of ac-
provements in the clinical outcomes of casualties undergoing curate documentation of all care rendered. We applied the
airway management. Cochran- Armitage trend test to assess trends in unadjusted
models. We used multivariable regression models to control
for confounders, which are described in the results section. We
Goal of this Study
treated years as an ordinal variable. Given the low incidence of
We sought to assess mortality trends among casualties under- procedures during several of our study years and subsequent
going prehospital airway intervention over the course of 12 model dissociation using logistic regression models, we used a
years of combat operations (2007–2019). Assessing outcomes generalized linear model with Firth bias-adjusted estimates to
associated with airway interventions and temporal trends can search for associations with death with an odds ratio >1 repre-
reflect the influence of training, technology, the system of care, senting increased risk of death. 13,14 We present 95% confidence
and other factors. (CI) intervals and p-values so that the reader can interpret the
strength of the statistical finding.
Methods
We excluded all encounters from 2020, since that represented a
Data Acquisition partial year in our dataset. We included only casualties that had
This is a pre-planned analysis using a previously described documented placement of an endotracheal tube and/or crico-
dataset from the DoDTR for casualties that underwent at least thyrotomy prehospital setting. We excluded supraglottic device
one prehospital assessment or intervention recorded from 1 placement due to the exceedingly low volume. If casualties had
January 2007 to 17 March 2020. This analysis excluded all documentation of both an intubation and a cricothyrotomy,
10
casualties from partial calendar year 2020. The US Army Insti- we included them in analyses, which we conducted separately.
tute of Surgical Research (USAISR) regulatory office reviewed
protocol H-20-015nh and determined it was exempt from
Institutional Review Board oversight. We obtained and used Results
only de-identified data. Within the DoDTR from January 2007 to December 2019,
there were 25,849 adult encounters with documentation of
Department of Defense Trauma Registry (DoDTR) any prehospital activity. Within that group, there were 251
Description documented cricothyrotomies, 1,147 documented intubations,
The DoDTR, formerly known as the Joint Theater Trauma and 35 documented SGAs placed.
Registry (JTTR), is the data repository for DoD trauma-
related injuries. 11,12 The DoDTR includes documentation re- Cricothyrotomy recipients had a median age of 25, of which the
garding demographics, injury-producing incidents, diagnoses, largest proportion were non-NATO military (35%), were injured
treatments, and outcomes of injuries sustained by US/non-US by explosives (54%), and had a median ISS of 24. Within that
military and US/non-US civilian personnel in wartime and group, 60% survived to hospital discharge. Intubation recipients
peacetime (including host nation civilians) from the point of had a median age of 24, of which the largest proportion were
injury to final disposition. Short-term outcome data are avail- non-NATO military (37%), were injured by explosives (57%),
able for non-US casualties. The DoDTR comprises all patients and had a median ISS of 18. Within that group, 76% survived
admitted to a Role 3 (fixed-facility) or forward resuscitative to hospital discharge. SGA recipients had a median age of 28, of
surgical detachment (FRSD) with an injury diagnosis using which the largest proportion were non-NATO military (37%),
the International Classification of Disease 9th Edition (ICD- were injured by firearm (48%), and had a median ISS of 25.
9) between 800–959.9, near-drowning/drowning with as- Within that group, 54% survived to hospital discharge (Table 1).
sociated injury (ICD-9 994.1) or inhalational injury (ICD-9
987.9), and trauma occurring within 72 hours from presen- There was a general downward trend in all procedures with
tation. We defined the prehospital setting as any location the most prominent spike in 2010, except for SGA placement,
prior to reaching surgical capabilities at an FRSD, field hos- which remained low throughout (Figure 1, Supplemental Ta-
pital (FH), or a combat support hospital (CSH) to include the ble 1). This corresponds to the year with the greatest num-
Role 1 (point of injury, casualty collection point, battalion aid ber of US casualty deaths in the war. Placement and survival
station) and Role 2 without surgical capabilities (temporary rates were variable throughout the study period (Figures 2–4,
limited-capability forward-positioned hospital inside combat supplemental Table 2). In the unadjusted and adjusted mod-
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zone). els, we noted a decrease in mortality for the 2007–2008 and

24 | JSOM Volume 23, Edition 1 / Spring 2023