Page 90 - JSOM Fall 2019

TABLE 1 Comparison of the Cricothyrotomy Versus the Supraglottic Airway (SGA) Cohort
Cricothyrotomy SGA
(n = 194) (n = 22) p Value
Age (median, IQR) 24 (21–29) 28 (22.75–35) .022
Demographics
Male 98.5% (191) 95.5% (21) .323
US military 30.9% (60) 31.8% (7)
Coalition 6.2% (12) 9.1% (2)
Affiliation Local forces 30.9% (60) 31.8% (7) .915
Humanitarian 28.9% (56) 27.3% (6)
Contractor 3.1% (6) 0% (0)
Explosive 57.7% (112) 63.6% (14)
GSW 28.9% (56) 36.4% (8)
Mechanism of injury .328
MVC 8.8% (17) 0% (0)
Other 4.6% (9) 0% (0)
OEF 73.2% (142) 95.5% (21)
OFS 2.6% (5) 4.6% (1)
Military operation .075
OIF 23.2% (45) 0% (0)
OND 1.0% (2) 0% (0)
Composite 25 (14–33) 27.5 (16.75–41.5) .168
AIS (head) 3 (1–5) 2 (0–4.25) .102
AIS (face) 1 (0–2) 0 (0–1.25) .086
Injury severity scores AIS (thorax) 0 (0–2.25) 3 (0–3) .019
AIS (abdomen) 0 (0–0) 0 (0–3) .077
AIS (extremity) 0 (0–3) 1 (0–3.25) .151
AIS (superficial) 1 (0–1) 1 (0–1) .901
Outcome Survival Rate 54.6% (106) 59.1% (13) .691
GSW, gunshot wound; IQR, interquartile range; MVC, motor vehicle collision; OEF, Operation Enduring Freedom; OFS, Operation Freedoms
Sentinel; OIF, Operation Iraqi Freedom; OND, Operation New Dawn.

cricothyrotomy and SGA may be equally efficacious prehos- evacuation care. It is not clear whether troops are carrying
3
pital advanced airway interventions for the combat trauma different equipment for different phases of care.
population.
Study Limitations
Overall, we found low incidence rates for both airway inter- Our study has several important limitations. First, the obser-
ventions: 0.7% underwent cricothyrotomy, whereas 0.1% had vational nature of our investigation means that we can only
an SGA inserted. These rates, however, are consistent with demonstrate correlation and not causation given the potential
published military data. Multiple studies on US military pre- for confounding. We used logistic regression to control for
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hospital cricothyrotomy describe incidence rates ranging from potential confounders for which we had data, but we could
0.25% to 2.4%. 4,15–20 A military prehospital airway registry not control for unmeasured confounders. Second, for an en-
found an SGA incidence rate of 0.3%. These low incidence counter to be generated within the DoDTR, subjects must
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rates suggest underutilization may be occurring. 19,20 Future re- have arrived at the FST or fixed-facility with signs of life
search might investigate factors contributing to cricothyrot- or with ongoing interventions. Therefore, our analysis does
omy and SGA underuse, to include investigation of alternative not include casualties who died in the prehospital setting or
airway adjuncts in patients requiring ventilation. 21–23 were killed in action. Third, we do not have sufficient data
to calculate procedural success rates or determine if multiple
Our analysis revealed few differences between the interven- attempts were made before the airway intervention was es-
tional groups. The cricothyrotomy group had significantly tablished. Consequently, we are unable to describe the impact
higher AIS for the head when a binary cut-off of 3 or greater of failed procedural attempts on survival outcomes. Further-
(serious injury) was used, while the SGA group had signifi- more, we are unable to characterize the clinical indications
cantly higher AIS for the thorax. There was no difference for both procedures beyond GCS. Fourth, the available data
between groups with respect to AIS for the face and GCS (me- do not indicate time of injury, time of airway establishment,
dian of 3 for both groups). However, prehospital providers and transportation times from point-of-injury to successive
confronted with a comatose trauma casualty with obvious echelons of care. Therefore, it is possible that some subjects
signs of severe head injury may have presumed distorted up- had longer times from injury to definitive surgical care. If true,
per airway anatomy and preferentially performed cricothyrot- prolonged transport times may have increased the need for
omy. Alternatively, the preponderance of cricothyrotomies in airway protection with concomitant increased mortality rates
our study may also be explained by its earlier implementation from delays to surgical intervention. Fifth, we had a relatively
within TCCC. Cricothyrotomy is advocated during tactical small number of subjects included in this study, specifically in
field care for ongoing or impending airway obstruction; SGA, the SGA cohort. A final limitation of note is that the registry
on the other hand, is recommended afterward during tactical includes patients even if their data are incomplete. 25

88 | JSOM Volume 19, Edition 3 / Fall 2019