Impact of prehospital airway management on combat mortality

Evidence-Based Guideline for Prehospital Airway Management

Airway management is a cornerstone of emergency medical care. This project aimed to create evidence-based guidelines based on the systematic review recently conducted by the Agency for Healthcare Research and Quality (AHRQ). A technical expert panel was assembled to review the evidence using the Grading of Recommendations Assessment, Development, and Evaluation (GRADE) methodology. The panel made specific recommendations on the different PICO (population, intervention, comparison, outcome) questions reviewed in the AHRQ review and created good practice statements that summarize and operationalize these recommendations. The recommendations address the use of ventilation with bag-valve mask ventilation alone vs. supraglottic airways vs. endotracheal intubation for adults and children with cardiac arrest, medical emergencies, and trauma. Additional recommendations address the use of video laryngoscopy and drug-assisted airway management. These recommendations, and the associated good practice statements, offer EMS agencies and clinicians an opportunity to review the available evidence and incorporate it into their airway management strategies.

Prehospital Airway Management: A Systematic Review

Objective: To assess comparative benefits and harms across three airway management approaches (bag valve mask [BVM], supraglottic airway [SGA], and endotracheal intubation [ETI]) used by prehospital emergency medical services (EMS) to treat patients with trauma, cardiac arrest, or medical emergencies, and how they differ based on techniques and devices, EMS personnel and patient characteristics. Data sources: We searched electronic citation databases (Ovid® MEDLINE®, CINAHL®, the Cochrane Central Register of Controlled Trials, the Cochrane Database of Systematic Reviews, and Scopus®) from 1990 to September 2020. Review methods: We followed Agency for Healthcare Research and Quality Effective Health Care Program Methods guidance. Outcomes included mortality, neurological function, return of spontaneous circulation (ROSC), and successful advanced airway insertion. Meta-analyses using profile-likelihood random effects models were conducted, with analyses stratified by study design, emergency type, and age. Results: We included 99 studies involving 630,397 patients. We found few differences in primary outcomes across airway management approaches. For survival, there was no difference for BVM versus ETI or SGA in adult and pediatric patients with cardiac arrest or trauma. For neurological function, there was no difference for BVM versus ETI and SGA versus ETI in pediatric patients with cardiac arrest. There was no difference in BVM versus ETI in adults with cardiac arrest, but improved neurological function with BVM or ETI versus SGA. There was no difference in ROSC for patients with cardiac arrest for BVM versus ETI or SGA in adults and pediatrics, or SGA versus ETI in pediatrics. There was higher frequency of ROSC in adults with SGA versus ETI. For successful advanced airway insertion, there was higher first-pass success with SGA versus ETI for all patients except adult medical patients (no difference), and no difference in overall success using SGA versus ETI in adults. Conclusions: The currently available evidence does not indicate benefits of more invasive airway approaches based on survival, neurological function, ROSC, or successful airway insertion. Strength of evidence was low or moderate; most included studies were observational. This supports the need for high-quality randomized controlled trials to advance clinical practice and EMS education and policy, and improve patient-centered outcomes.

Portable Medical Suction and Aspirator Devices: Are the Design and Performance Standards Relevant?

Airway clearance refers to the clearing of any airway blockage caused due to foreign objects such as mud, gravel, and biomaterials such as blood, vomit, or teeth fragments using the technology of choice, portable suction devices. Currently available devices are either too heavy and bulky to be carried, or insufficiently powered to be useful despite being in accordance with the ISO 10079-1 standards. When applied to portable suction, the design and testing standards lack clinical relevancy, which is evidenced by how available portable suction devices are sparingly used in pre-hospital situations. Lack of clinical relevancy despite being in accordance with design/manufacturing standards arise due to little if any collaboration between those developing clinical standards and the bodies that maintain design and manufacturing standards. An updated set of standards is required that accurately reflects evidence-based requirements and specifications, which should promote valid, rational, and relevant engineering designs and manufacturing standards in consideration of the unique scenarios facing prehospital casualty care. This paper aims to critically review the existing standards for portable suction devices and propose modifications based on the evidence and requirements, especially for civilian prehospital and combat casualty care situations.

Evaluating the Tactical Combat Casualty Care principles in civilian and military settings: systematic review, knowledge gap analysis and recommendations for future research

OBJECTIVES

The Tactical Combat Casualty Care (TCCC) guidelines detail resuscitation practices in prehospital and austere environments. We sought to review the content and quality of the current TCCC and civilian prehospital literature and characterize knowledge gaps to offer recommendations for future research.

METHODS

MEDLINE, EMBASE, CINAHL, and Cochrane Central Register of Controlled Trials were searched for studies assessing intervention techniques and devices used in civilian and military prehospital settings that could be applied to TCCC guidelines. Screening and data extraction were performed according to PRISMA (Preferred Reporting Items for Systematic Reviews and Meta-Analyses) guidelines. Quality appraisal was conducted using appropriate tools.

RESULTS

Ninety-two percent (n=57) of studies were observational. Most randomized trials had low risk of bias, whereas observational studies had higher risk of bias. Interventions of massive hemorrhage control (n=17) were wound dressings and tourniquets, suggesting effective hemodynamic control. Airway management interventions (n=7) had high success rates with improved outcomes. Interventions of respiratory management (n=12) reported low success with needle decompression. Studies assessing circulation (n=18) had higher quality of evidence and suggested improved outcomes with component hemostatic therapy. Hypothermia prevention interventions (n=2) were generally effective. Other studies identified assessed the use of extended focused assessment with sonography in trauma (n=3) and mixed interventions (n=2).

CONCLUSIONS

The evidence was largely non-randomized with heterogeneous populations, interventions, and outcomes, precluding robust conclusions in most subjects addressed in the review. Knowledge gaps identified included the use of blood products and concentrate of clotting factors in the prehospital setting.

LEVEL OF EVIDENCE

Systematic review, level III.

Prehospital Emergency Cricothyrotomy in Dogs Part 1: Experiences With Commercial Cricothyrotomy Kits

The surgical cricothyrotomy (CTT) has been recommended for emergency front of neck airway access (eFONA) during a cannot intubate, cannot oxygenate scenario for military working dogs (MWD) and civilian law enforcement working dogs (operational K9s). In prehospital and austere environments, combat medics and emergency medical service providers are expected to administer emergency medical care to working dogs and may only have emergency airway kits designed for humans at their disposal. The objective of this article is to provide a detailed description of the application of such devices in cadaver dogs and highlight potential alterations to manufacturer guidelines required for successful tube placement. The kits evaluated included the Portex® PCK, Melker universal cricothyrotomy kit and H&H® emergency cricothyrotomy kit. A novel technique for awake cricothyrotomy in the dog is also described, which can also be considered for in-hospital use, together with the open surgical method described for the H&H® kit. To the authors' knowledge, this is the first publication documenting and providing instruction on the application of commercial cricothyrotomy kits in dogs.

Laryngotracheal and pharyngoesophageal traumatic injuries from US military operations in Iraq and Afghanistan, 2003-2017

INTRODUCTION

Laryngotracheal and pharyngo-oesophageal trauma present military providers with especially difficult, life-threatening challenges. Although effective treatment strategies are crucial, there is no clear consensus. This study of combat injuries from Iraq and Afghanistan describes initial treatment outcomes.

METHODS

US service members who sustained 'laryngotracheal' and 'pharyngoesophageal' injuries while deployed in military operations from 2003 to 2017 were identified from the Expeditionary Medical Encounter Database. Those with inhalation or ingestion injuries and an Injury Severity Score (ISS) <16 were excluded. Data on demographics, survival, mechanism and type of injury and diagnostic and therapeutic intervention were recorded.

RESULTS

A total of 111 service members met inclusion criteria. Nearly one-third (32.4%) were killed in action (KIA) or died of wounds (DoW). Fatality was not significantly associated with age, theatre of operation, type of injury or mechanism of injury, but was associated with a higher ISS and those in the Marines. Although survival rates were not significantly different, the frequency of these injuries decreased after the introduction of cervical collar protection in 2007. Of those who DoW or survived, 41.1% required a surgical airway. Tracheobronchoscopy was performed in 25.6%, oesophagoscopy in 20.0% and oesophagram in 6.7%. Of the 85 with penetrating neck injuries, 43 (50.6%) underwent neck exploration, in which 31 (72.1%) required intervention.

CONCLUSIONS

Severe laryngotracheal and pharyngo-oesophageal injuries have a high fatality rate and demand prompt treatment from skilled providers. Further work will elucidate preventive measures and clear management algorithms to optimise outcomes.

Comparison of surgical cricothyroidotomy training: a randomized controlled trial of a swine model versus an animated robotic manikin model

Background

Airway obstruction remains a preventable cause of death on the battlefield. Surgical cricothyroidotomy is an essential skill for immediate airway management in trauma. Training for surgical cricothyroidotomy has been undertaken using simulators, cadavers or animal models. The ideal approach to training for this low volume and high-risk procedure is unknown. We hypothesized that current simulation technology provides an equal or better education for surgical cricothyroidotomy when compared with animal tissue training.

Methods

We performed a prospective randomized controlled study comparing training for surgical cricothyroidotomy using hands-on training on swine versus inanimate manikin. We enrolled medical students who had never performed or had formal instruction on surgical cricothyroidotomy. We randomized their instruction to use either a swine model or the inanimate version of the Operative Experience Inc. advanced surgical manikin. Participants' skills were then evaluated on human cadavers and on an advanced robotic manikin. Tests were scored using checklists modified from Objective Structured Assessment of Technical Skills and Tactical Combat Casualty Care. We compared scores between the groups using Wilcoxon rank sum tests and generalized linear models.

Results

Forty-eight participants were enrolled and trained; 30 participants completed the first testing session; 25 completed the second testing session. The mean time to establish an airway from the incision until the cuff was blown up was 95±52 s. There were no significant differences in any of the outcome measures between the two training groups.

Discussion

Measured performance was not different between subjects trained to perform surgical cricothyroidotomy on an animal model or a high fidelity manikin. The use of an advanced simulator has the potential to replace live tissue for this procedure mitigating concerns over animal rights.

Levels of evidence

I.

Analysis of Casualties That Underwent Airway Management Before Reaching Role 2 Facilities in the Afghanistan Conflict 2008-2014

INTRODUCTION

Airway compromise is the second leading cause of potentially survivable death on the battlefield. The purpose of this study was to better understand wartime prehospital airway patients.

MATERIALS AND METHODS

The Role 2 Database (R2D) was retrospectively reviewed for adult patients injured in Afghanistan between February 2008 and September 2014. Of primary interest were prehospital airway interventions and mortality. Prehospital combat mortality index (CMI-PH), hemodynamic interventions, injury mechanism, and demographic data were also included in various statistical analyses.

RESULTS

A total of 12,780 trauma patients were recorded in the R2D of whom 890 (7.0%) received prehospital airway intervention. Airway intervention was more common in patients who ultimately died (25.3% vs. 5.6%); however, no statistical association was found in a multivariable logistic regression model (OR 1.28, 95% CI 0.98-1.68). Compared with U.S. military personnel, other military patients were more likely to receive airway intervention after adjusting for CMI-PH (OR 1.33, 95% CI 1.07-1.64).

CONCLUSIONS

In the R2D, airway intervention was associated with increased odds of mortality, although this was not statistically significant. Other patients had higher odds of undergoing an airway intervention than U.S. military. Awareness of these findings will facilitate training and equipment for future management of prehospital/prolonged field care airway interventions.