Page 28 - JSOM Spring 2023

SUPPLEMENTAL TABLE 1 Cont. As expected, when adjusting for ISS on the multivariable re-
2019 a. Conscious casualty with no airway problem identified: gression analysis, we perceive no significant improvement in
• No airway intervention required overall survival across the years (except for 2007–2008 in
b. Unconscious casualty without airway obstruction: which mortality appears to have declined significantly but was
• Place casualty in the recovery position not sustained). The significance of this single-year reduction is
• Chin lift or jaw thrust maneuver or
• Nasopharyngeal airway or unclear and may reflect chance variation or an association with
• Extraglottic airway an unknown variable as it is not sustained. When adjusting for
c. Casualty with airway obstruction or impending airway ISS, there was no difference in year-to-year mortality for crico-
obstruction: thyrotomy or SGA placement. The overwhelming majority of
• Allow a conscious casualty to assume any position
that best protects the airway, to include sitting up airways placed were intubations. This practice pattern is not in
• Use a chin lift or jaw thrust maneuver line with the TCCC guidelines which, over the course of this
• Use suction if available and appropriate study period, solely relied on cricothyrotomy and SGA place-
• Nasopharyngeal airway or ment. Our findings may be attributable to the wide levels of
• Extraglottic airway (if the casualty is unconscious) care and locations that the prehospital Role 1 encompasses. 17
• Place an unconscious casualty in the recovery position
d. If the previous measures are unsuccessful, perform a
surgical cricothyroidotomy using one of the following: The results of our study are qualitatively comparable to prior
• Cric-Key technique (preferred option) findings. In prehospital airway data from the far-forward Reg-
• Bougie-aided open surgical technique using a flanged istry of Emergency Airways Arriving at Combat Hospitals
and cuffed airway cannula of less than 10mm outer
diameter, 6–7mm internal diameter, and 5–8cm of (REACH), endotracheal intubation (ETI) comprised 86% of
intratracheal length airways, while SGA and cricothyrotomy represented 8% and
• Standard open surgical technique using a flanged 6% of cases, respectively. However, failure and complication
18
and cuffed airway cannula of less than 10mm outer rates are high for both ETI and cricothyrotomy in the pre-
diameter, 6–7mm internal diameter, and 58cm of hospital environment. Success rates for ETI can decrease by
intra-tracheal length (least desirable option)
• Use lidocaine if the casualty is conscious 50% when providers do not maintain continuous practice and
2020 a. Conscious casualty with no airway problem identified: training, a need often in excess of the exposure received in
19
• No airway intervention required clinical settings for medics and prehospital physicians. Com-
b. Unconscious casualty without airway obstruction: bat medics already pose a 10–35% failure rate for ETI, with
• Place casualty in the recovery position complication rates remaining high as well. 18,20 Considering
• Chin lift or jaw thrust maneuver or the alternative surgical approach of cricothyrotomies in the
• Nasopharyngeal airway or
• Extraglottic airway combat environment, data do not support favorable outcomes
c. Casualty with airway obstruction or impending airway for combat medic performance on the battlefield, with failure
obstruction: rates ranging from 25% to 33%. 21–23
• Allow a conscious casualty to assume any position
that best protects the airway, to include sitting up
and/or leaning forward There are two potential explanations worth discussing in terms
• Use a chin lift or jaw thrust maneuver of the lack of major improvements in battlefield airway out-
• Use suction if available and appropriate comes: training and technology. First, advanced airway man-
• Nasopharyngeal airway or agement success is heavily dependent upon operator skill.
• Extraglottic airway (if the casualty is unconscious) Adverse combat conditions (e.g., danger, low light, and con-
• Place an unconscious casualty in the recovery
position fined spaces), limited equipment, and innate anatomical varia-
d. If the previous measures are unsuccessful, perform a tion (i.e., short neck, prominent front teeth) may challenge even
surgical cricothyroidotomy using one of the following: experienced operators. Even in the civilian setting, the train-
• Cric-Key technique (preferred option) ing required to attain proficiency in ETI poses a steep learning
• Bougie-aided open surgical technique using a flanged
and cuffed airway cannula of less than 10mm outer curve: the number of intubations performed prior to attaining
diameter, 6–7mm internal diameter, and 5–8cm of a 90% probability of success in a study of physician anesthe-
intratracheal length siology trainees was as high as 47. In the prehospital space,
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• Standard open surgical technique using a flanged paramedic intubation success has been directly correlated to
and cuffed airway cannula of less than 10mm outer the total number of patients that a paramedic has attempted to
diameter, 6–7mm internal diameter, and 5–8cm of 25
intra-tracheal length (least desirable option) intubate and is not correlated with time in service. In the UK’s
landmark NAP4 airway management study, a lack of education
Discussion or training was identified as a factor in airway complications
occurring in the emergency department (ED) and intensive care
During this 13-year time frame, we identified 251 cricothy- unit (ICU) in 40% and 58% of cases, respectively. Despite
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rotomies, 1,147 intubations, and 35 SGA placements that oc- two decades of emphasis in the training of combat medics,
curred in the prehospital setting. Consistent with our previous and 10 years for flight paramedics, there does not appear to
study analyzing prehospital procedures, there was a decline in be evidence of improved outcomes. 27,28 Realistic simulators are
16
the number of all procedures during the study period. This lacking for the difficult airway. The lack of training platforms
decline in airway procedures coincides with a decrease in US for airway skills attainment and sustainment is a major issue
15
casualty deaths over the same period. The Cochran- Armitage for both intubation and cricothyrotomy with multiple previ-
test found a significant difference across the years for the cri- ous studies. A previous study by Blackburn et al. noted that
cothyrotomy procedure. However, that does not adjust for ISS, simulators are notably different in anatomical measurements
which appeared to fluctuate year to year, hence why we ad- from real humans. Moreover, while not the primary aim of
29
justed for ISS in our multivariable model. The low volume of the study, we noted several challenges with using airway sim-
SGA placement was a substantial limitation in assessing trends ulators during a previous study, including simulator failure in
from year to year. unrealistic ways not compatible with real human procedures. 3

26 | JSOM Volume 23, Edition 1 / Spring 2023