Page 52 - JSOM Winter 2024

benefits of more invasive airway approaches based on Why was the extraglottic airway deemed unsuitable
survival, neurological function, ROSC, or successful airway for the battlefield environment?
insertion.
The EGA has multiple characteristics that deem it unsuit-
able for the battlefield environment. The device is unable
Additionally, there was insufficient evidence to support a con-
clusion regarding adult trauma patients. to protect against upper airway burns below the epiglottis
and is likely not effective in many of the fatal airway inju-
ries that cause airway anatomy disruption. Environmental
4
• A bias-adjusted OHCA systematic review analyzed 17 stud-
ies (n=388,878) comparing advanced airway interventions factors are a concern for gel-filled EGAs, and there are aero-
37
(AAI) to basic airway interventions (BAI). The short-term medical evacuation concerns for air-filled cuffs. Finally, pre-
survival for AAI compared to BAI were overall odds ratio hospital trauma patients that receive an advanced airway
(OR) 0.84 (95% CI 0.62–1.13), and for supraglottic air- without significant sedation or relaxants have remarkably poor
ways (SGA), OR 0.59 (95% CI 0.39–0.89). Long-term sur- outcomes:
vival for AAI were overall OR 0.49 (95% CI 0.37–0.65),
and specifically for SGA, OR 0.35 (95% CI 0.28–0.44). Casualties that tolerate invasive airway management without
The authors concluded that AAIs decreased patient survival sedation in the context of trauma prognosticates a very high
but are likely biased: mortality. Airway management algorithms for military provid-
ers should reflect the casualties encountered on the battlefield
not patients in cardiac arrest which predominate in the civilian
The results of this systematic review concur with Gausche 9
et al., Egly et al., and Mitchell et al.; three studies that did EMS airway management practice.
not meet our inclusion criteria but investigated AAI versus Level of Evidence: B-NR and C-LD (Nonrandomized and Lim-
BAI in cardiac arrest and showed either decreased or no ited Data)
difference in survival for patients managed with AAI.
What are the recommendations regarding the use of
• A civilian trauma-focused review comparing advanced and bag valve masks in combat situations?
basic airway interventions, found that:
BVMs should provide regulated positive pressure ventilations
between 6–8mL/kg of ideal body weight, as recommended by
Of 5,773 patients, 316 had ETI and 217 had BVM. Patients
receiving ETI were significantly more likely to die. When the European Resuscitation Council Guidelines 2021, equal-
corrected for Injury Severity Score, Revised Trauma Score, ing 490–650mL of tidal volume for a 180-pound ideal-weight
41
and mechanism of injury, ETI was associated with similar or patient. Current AHA Guidelines recommend 500–600mL
42
greater mortality than BVM. 38 tidal volume for adults undergoing CPR.
The tidal volumes delivered by most commercially available
• A Japanese nationwide study evaluating prehospital airway
management assessed 649,359 patients with OHCA, of adult BVMs can dramatically exceed recommendations and
whom 367,837 (57%) underwent bag valve mask (BVM) cause lung injury in a patient already suffering from other in-
ventilation and 281,522 (43%) advanced airway manage- juries. Smaller tidal volumes have shown to decrease mortality
ment, including 41,972 (6%) with endotracheal intubation in acute lung injury patients and reduce gastric inflation is-
and 239,550 (37%) with use of supraglottic airways. sues. In a study comparing the then-traditional tidal volume of
39
In the full cohort, the advanced airway group incurred a 12mL/kg of predicted body weight with a smaller tidal volume
lower rate of favorable neurological outcome compared of 6mL/kg of body weight, the study was stopped early be-
with the BVM group (1.1% vs. 2.9%). Conclusion: Among cause of increased mortality in the higher tidal volume group
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adult patients with OHCA, any type of advanced airway (39.8% vs. 31.0%; P=.007).
management was independently associated with decreased
odds of neurologically favorable survival compared with In a study by Dafilou et al., adult BVMs with a resuscitator
conventional bag-valve-mask ventilation. bag volume of 1,900mL provide an expended mean tidal vol-
ume of 807.7mL while pediatric BVMs with a 1,000mL vol-
ume provide a mean expended volume of 630.7mL. While
44
• A retrospective review of 1,267 MEDEVAC U.S. Military
patients during Operation Enduring Freedom, comparing both the adult and pediatric BVMs have the capability to pro-
BVM to cricothyrotomy and SGA placement determined vide appropriate tidal volume to patients, 93% of providers
that SGA patients incurred fewer vent-free, ICU-free, and exceeded the maximum threshold for tidal volumes using the
hospital-free days compared to BVM patients and found no adult BVM compared with 82.3% who exceeded it with the
difference in survival between groups. Notable limitations pediatric BVM. The authors concluded that the pediatric-sized
of this study include a small sample size and statistically BVM provided far more consistent and appropriate ventila-
significant differences in ISS scoring. 40 tion for adults compared to an adult BVM. The Pocket BVM,
a generally popular device in the prehospital battlefield setting,
has a bag reservoir volume of 1600mL. 45
While there are limitations to the strength of evidence compar-
ing EGA to BVM use and the evidence’s applicability to bat-
tlefield trauma patients, the overwhelming majority of civilian Wenzel et al. demonstrated that patients ventilated with a
studies alongside limited combat studies indicate that EGA is 500-mL pediatric BVM received 365mL of tidal volume as
not superior and could be considered inferior to the BVM with compared to 779mL with a 1,000-mL BVM and developed
46
respect to patient survival. less peak airway pressure. Additional studies have also shown
Level of Evidence: Level A and B-NR (Multiple Randomized that smaller BVM sizes achieve adequate ventilation and are
47,48
Trials or Meta-Analyses and Nonrandomized) less likely to cause pulmonary barotrauma.
50 | JSOM Volume 24, Edition 4 / Winter 2024