Page 89 - JSOM Fall 2019

Goal of This Study 28,222 (72.8%) of those subjects. Within this dataset, there
We seek to compare outcomes of casualties undergoing crico- were 194 (0.7%) subjects who underwent cricothyrotomy
thyrotomy versus supraglottic airway placement in the prehos- versus 22 (0.1%) who underwent SGA placement as the sole
pital, combat setting. documented means of airway intervention. Subjects in the
cricothyrotomy group compared with the SGA group had a
lower median age, similar sex distribution, similar affiliations,
Methods
similar mechanisms of injury, similar theaters of operations,
Data Acquisition and similar composite injury severity scores (ISSs) but less se-
We identified subjects as part of a larger descriptive study of vere scores for the thorax body region (Table 1). There was a
ED interventions for trauma patients in Iraq and Afghanistan trend toward worse AIS for the face region in the cricothyrot-
using predefined search codes. This is a retrospective review of omy group but a trend toward less severe scores for the abdo-
prospectively collected data within the registry. We searched men. Survival to hospital discharge rates were similar (Table
our dataset for all subjects who had a documented supraglot- 1). When using a binary cutoff of AIS 3 or greater (serious)
tic airway device or cricothyrotomy performed as the sole doc- for the head, the cricothyrotomy group had a higher rate of
umented airway intervention before reaching the emergency serious head injuries (67.5%, n = 131 versus 45.5%, n = 10,
department at a combat support hospital (CSH) or forward p = .0393). When applying the same binary measurement
surgical team (FST). We excluded subjects if they had more to the face, we were unable to detect a significant difference
than one airway intervention documented. (4.6%, n = 9 versus 4.6%, n = 1, p = .984). When documented
in the prehospital setting, median GCS scores were similar for
The US Army Institute of Surgical Research regulatory office the two groups (median 3 [IQR 3–6], n = 95 versus median 3
reviewed protocol H-16-005 and determined it was exempt [IQR 3–7.5], n = 20, p = .591). We also found no difference for
from institutional review board oversight. We obtained only emergency department arrival GCS (3 [3–5.5], n = 188 versus
deidentified data. 3 [3–5.25], n = 21, p = .469).

Department of Defense Trauma Registry Description Regression Analyses
The Department of Defense Trauma Registry (DoDTR), for- On univariable analysis, the OR of survival was similar for
merly known as the Joint Theater Trauma Registry (JTTR), is SGA versus cricothyrotomy (1.20, 95% confidence inter-
the data repository for DoD trauma-related injuries. 12,13 The val 0.49–2.94). We then performed a series of multivariable
DoDTR includes documentation regarding demographics, inju- analyses controlling for confounders comparing SGA versus
ry-producing incidents, diagnoses, treatments, and outcomes of cricothyrotomy. When controlling for injury scores by body
injuries sustained by US/non-US military and US/non-US civilian region, the OR was not significant (OR 1.14, 0.42–3.10).
personnel in wartime and peacetime from the point of injury to When controlling for the presence of a serious head injury
final disposition. The DoDTR comprises all patients admitted to (AISBR1 3 or greater, binary), the OR was not significant (OR
a Role 3 (fixed-facility) or FST with an injury diagnosis using the 1.06, 0.43–2.65). No significant difference was noted when
International Classification of Diseases, Ninth Revision (ICD-9) controlling for the mechanism of injury (OR 1.12, 0.45–2.76),
of 800 to 959.9, near-drowning/drowning with associated injury patient category (OR 1.17, 0.47–2.90), or ED GCS (OR 1.64
(ICD-9 994.1), or inhalational injury (ICD-9 987.9) and trauma 0.62–4.30).
occurring within 72 hours from presentation. We defined the
prehospital setting as any location before reaching an FST or a Discussion
CSH to include the Role 1 (point of injury, casualty collection
point, battalion aid station) and Role 2 (temporary limited-ca- We evaluated combat casualties undergoing either cricothy-
pability forward-positioned hospital inside combat zone without rotomy or SGA for advanced airway management in the pre-
surgical support). The registry categorization scheme considers a hospital setting. We found no difference in survival between
Role 2+ (or variant with surgical support) to be the ED. these two groups. This finding persisted on multiple regression
analyses controlling for several factors, including injury scores
by body region.
Analysis
We performed all statistical analyses using Microsoft Excel Survival among patients undergoing either intervention
(version 10; Redmond, WA) and JMP Statistical Discovery (54.6% for cricothyrotomy and 59.1% for SGA) was higher
from SAS (version 13; Cary, NC). We compared study vari- than previously published data. Studies on military prehospital
ables between subjects undergoing cricothyrotomy versus airway interventions during the recent conflicts that reported
SGA placement using a Student t test for continuous variables mortality outcomes found a combined survival of 38.5% (15
expressed as means with standard deviations, Wilcoxon rank of 39) for cricothyrotomy and 7.1% (1 of 14) for SGA. 14–17
sum test for ordinal variables expressed as medians and inter- The higher survival in our study may reflect exclusion from
2
quartile ranges, and χ test for nominal variables expressed the DoDTR of casualties who died before arrival to an FST or
as numbers and percentages. For binary outcomes, we used a fixed-facility, whereas previous studies included those killed
logistic regression analysis to report ORs. in action. Likewise, subjects in our study may have under-
gone stabilization at a battalion aid station or higher echelon
of care, whereas previous reports primarily analyzed casual-
Results
ties evacuated directly from the point-of-injury to an FST or
Overall Analysis fixed-facility. Additionally, our study captured more expo-
During the study period, there were a total of 38,769 encoun- sures by comparison: 194 versus 39 cricothyrotomies, and 22
ters in the DoDTR. Our predefined ED search codes captured versus 14 SGAs. Our findings suggest clinically appropriate

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