Prehospital airway procedures performed in trauma patients by ground forces in Afghanistan

Interventions associated with survival after prehospital intubation in the deployed combat setting

INTRODUCTION

Airway compromise is the second leading cause of potentially preventable death on the battlefield. Prehospital airway management is often unavoidable in a kinetic combat environment and expected to increase in future wars where timely evacuation will be unreliable and air superiority not guaranteed. We compared characteristics of survivors to non-survivors among combat casualties undergoing prehospital airway intubation.

MATERIALS AND METHODS

We requested all Department of Defense Trauma Registry (DODTR) encounters during 2007-2023 with documentation of any airway intervention or assessment within the first 72-h after injury. We conducted a retrospective cohort study of all casualties with intubation documented in the prehospital setting. We used descriptive and inferential statistical analysis to compare survivors through 7 days post injury versus non-survivors. We constructed 3 multivariable logistic regression models to test for associations between interventions and 7-day survival after adjusting for injury severity score, mechanism of injury, and receipt of sedatives, paralytics, and blood products.

RESULTS

There were 1377 of 48,301 patients with documentation of prehospital intubation in a combat setting. Of these, 1028 (75%) survived through 7 days post injury. Higher proportions of survivors received ketamine, paralytic agents, parenteral opioids, and parenteral benzodiazepines; there was no difference in the proportions of survivors versus non-survivors receiving etomidate. The multivariable models consistently demonstrated positive associations between 7-day survival and receipt of non-depolarizing paralytics and opioid analgesics.

CONCLUSIONS

We found an association between non-depolarizing paralytic and opioid receipt with 7-day survival among patients undergoing prehospital intubation. The literature would benefit from future multi-center randomized controlled trials to establish optimal pharmacologic strategies for trauma patients undergoing prehospital intubation.

A prospective, pragmatic non-inferiority study of emergency intubation success with the single-use i-view versus standard reusable video laryngoscope

INTRODUCTION

Video laryngoscope (VL) technology improves first-pass success. The novel i-view VL device is inexpensive and disposable. We sought to determine the first-pass intubation success with the i-view VL device versus the standard reusable VL systems in routine use at each site.

METHODS

We performed a prospective, pragmatic study at two major emergency departments (EDs) when VL was used. We rotated i-view versus reusable VL as the preferred device of the month based on an a priori schedule. An investigator-initiated interim analysis was performed. Our primary outcome was a first-pass success with a non-inferiority margin of 10% based on the per-protocol analysis.

RESULTS

There were 93 intubations using the reusable VL devices and 81 intubations using the i-view. Our study was stopped early due to futility in reaching our predetermined non-inferiority margin. Operator and patient characteristics were similar between the two groups. The first-pass success rate for the i-view group was 69.1% compared to 84.3% for the reusable VL group. A non-inferiority analysis indicated that the difference (-15.1%) and corresponding 90% confidence limits (-25.3% to -5.0%) did not fall within the predetermined 10% non-inferiority margin.

CONCLUSIONS

The i-view device failed to meet our predetermined non-inferiority margin when compared to the reusable VL systems with the study stopping early due to futility. Significant crossover occurred at the discretion of the intubating operator during the i-view month.

A Market Assessment of Introducer Technology to Aid With Endotracheal Intubation

INTRODUCTION

Endotracheal intubation is a potentially lifesaving procedure. Previously, data demonstrated that intubation remains the most performed airway intervention in the Role 1 setting. Additionally, deployed data demonstrate that casualties intubated in the prehospital setting have worse survival than those intubated in the emergency department setting. Technological solutions may improve intubation success in this setting. Certain intubation practices, including the use of endotracheal tube introducer bougies, facilitate intubation success especially in patients with difficult airways. We sought to determine the current state of the market for introducer devices.

MATERIALS AND METHODS

This market review utilized Google searches to find products for intubation. The search criteria aimed to identify any device ideal for intubation in the emergency setting. Device data retrieved included manufacturer, device, cost, and design descriptions.

RESULTS

We identified 12 introducer-variants on the market. Devices varied with regards to composition (latex, silicone, polyethylene, combination of several materials, etc.), tip shape, special features for ease of intubation (markings for depth and visibility, size, etc.), disposability/reuse capability, measurements, and prices. The cost of each device ranged from approximately $5 to $100.

CONCLUSIONS

We identified 12 introducer-variants on the market. Clinical studies are necessary to determine which devices may improve patient outcomes in the Role 1 setting.

Market Analysis of Video Laryngoscopy Equipment for the Role 1 Setting

INTRODUCTION

Airway compromise is the second leading cause of potentially preventable prehospital combat death. Endotracheal intubation (ETI) remains the most common role 1 airway intervention. Video laryngoscopy (VL) is superior to direct laryngoscopy (DL) for first-attempt intubation, especially in less-experienced providers and for trauma patients. The cost has been a major challenge in pushing VL technology far-forward; however, the cost of equipment continues to become more affordable. We conducted a market analysis of VL devices under $10,000 for possible options for role 1.

MATERIALS AND METHODS

We searched Google, PubMed, and the Food and Drug Administration database from August 2022 to January 2023 with a combination of several keywords to identify current VL market options under $10,000. After identifying relevant manufacturers, we then reviewed individual manufacturer or distributor websites for pricing data and system specifications. We noted several characteristics regarding VL device design for comparison. These include monitor features, size, modularity, system durability, battery life, and reusability. When necessary, we requested formal price quotes from respective companies.

RESULTS

We identified 17 VL options under $10,000 available for purchase, 14 of which were priced below $5,000 for individual units. Infium (n = 3) and Vimed Medical (n = 4) provided the largest number of unique models. VL options under $10,000 exist in both reusable and disposable modalities. These modalities included separate monitors as well as monitors attached to the VL handle. Disposable options, on a per-unit basis, cost less than reusable options.

CONCLUSIONS

Several VL options exist within our goal price point in both reusable and disposable options. Clinical studies assessing the technology performance of ETI and deliberate downselection are needed to identify the most cost-effective solution for role 1 dispersion.

Nasopharyngeal Ventilation Compared to Facemask Ventilation: A Prospective, Randomized, Crossover Trial in Two Different Elective Cohorts

BACKGROUND

Facemask ventilation is routinely used to preoxygenate patients before endotracheal intubation during anesthesia induction or to secure ventilation in patients with respiratory insufficiency. Occasionally, facemask ventilation cannot be performed adequately. The placement of a regular endotracheal tube through the nose into the hypopharynx may be a valid alternative to improve ventilation and oxygenation before endotracheal intubation (nasopharyngeal ventilation). We tested the hypothesis that nasopharyngeal ventilation is superior in its efficacy compared to traditional facemask ventilation.

METHODS

In this prospective, randomized, crossover trial, we enrolled surgical patients requiring either nasal intubation (cohort #1, n = 20) or patients who met "difficult to mask ventilate" criteria (cohort #2, n = 20). Patients in each cohort were randomly assigned to receive pressure-controlled facemask ventilation followed by nasopharyngeal ventilation or vice versa. The ventilation settings were kept constant. The primary outcome was tidal volume. The secondary outcome was the difficulty of ventilation, measured using the Warters grading scale.

RESULTS

Tidal volume was significantly increased by nasopharyngeal ventilation in cohort #1 (597 ± 156 ml vs.462 ± 220 ml, p = 0.019) and cohort #2 (525 ± 157 ml vs.259 ± 151 ml, p < 0.01). Warters grading scale for mask ventilation was 0.6 ± 1.4 in cohort #1, and 2.6 ± 1.5 in cohort #2.

CONCLUSION

Patients at risk for difficult facemask ventilation may benefit from nasopharyngeal ventilation to maintain adequate ventilation and oxygenation before endotracheal intubation. This ventilation mode may offer another option for ventilation at induction of anesthesia and during the management of respiratory insufficiency, especially in the setting of "unexpected" ventilation difficulty.

Success rate of prehospital emergency front-of-neck access (FONA): a systematic review and meta-analysis

BACKGROUND

Front-of-neck access (FONA) is an emergency procedure used as a last resort to achieve a patent airway in the prehospital environment. In this systematic review with meta-analysis, we aimed to evaluate the number and success rate of FONA procedures in the prehospital setting, including changes since 2017, when a surgical technique was outlined as the first-line prehospital method.

METHODS

A systematic literature search (PROSPERO CRD42022348975) was performed from inception of databases to July 2022 to identify studies in patients of any age undergoing prehospital FONA, followed by data extraction. Meta-analysis was used to derive pooled success rates. Methodological quality of included studies was interpreted using the Cochrane risk of bias tool, and rated using the Grading of Recommendations Assessment, Development, and Evaluation (GRADE) approach.

RESULTS

From 909 studies, 69 studies were included (33 low quality; 36 very low quality) with 3292 prehospital FONA attempts described (1229 available for analysis). The crude median success rate increased from 99.2% before 2017 to 100.0% after 2017. Meta-analysis revealed a pooled overall FONA success rate of 88.0% (95% confidence interval [CI], 85.0-91.0%). Surgical techniques had the highest success rate at a median of 100.0% (pooled rate=92.0%; 95% CI, 88.0-95.0%) vs 50.0% for needle techniques (pooled rate=52.0%; 95% CI, 28.0-76.0%).

CONCLUSIONS

Despite being a relatively rare procedure in the prehospital setting, the success rate for FONA is high. A surgical technique for FONA appears more successful than needle techniques, and supports existing UK prehospital guidelines.

SYSTEMATIC REVIEW PROTOCOL

PROSPERO CRD42022348975.

Hypothermia in the Combat Trauma Population

BACKGROUND

The MARCH (Massive hemorrhage, Airway, Respirations, Circulation, and Hypothermia/Head injuries) algorithm taught to military medics includes interventions to prevent hypothermia. As possible sequelae from major trauma, hypothermia is associated with coagulopathy and lower survival. This paper sought to define hypothermia within our combat trauma population using an outcomes-based method, and determine clinical variables associated with hypothermia.

METHODS

This is a secondary analysis of a previously described dataset from the Department of Defense Trauma Registry focused on casualties who received prehospital care. A receiver operating curve was constructed and Youden's index was used to define hypothermia within the predetermined population based on mortality risk. A multivariable regression model was used to identify associations.

RESULTS

There were 23,243 encounters that met the inclusion criteria for this study with patients having received prehospital care and documentation of at least one emergency department temperature. An optimal threshold of 36.2° C was found to predict mortality; 3,159 casualties had temperatures below this threshold (14%). Survival to discharge was lower among casualties with hypothermia (91% versus 98%). Hypothermic casualties were less likely to undergo blanket application (38% versus 40%). However, they had higher proportions with Hypothermia Prevention and Management Kit application (11% versus 7%) and radiant warming (2% versus 1%). On multivariable regression modeling, none of the hypothermia interventions were associated with a decreased likelihood of hypothermia. Non-hypothermia interventions associated with hypothermia included prehospital intubation (OR 1.57, 95% CI 1.45-1.69) and blood product administration.

CONCLUSIONS

Hypothermia, including a single recorded low temperature in the patient care record, was associated with worse outcomes in this combat trauma population. Prehospital intubation was most strongly associated with developing hypothermia. Prehospital warming interventions were not associated with a reduction in hypothermia risk. Our dataset suggests that current methods for prehospital warming are inadequate.

Method for Teaching Life-Saving Combat First-Aid Skills With live-actor Patients Using a Wearable Training Apparatus

INTRODUCTION

Training combat personnel in combat first-aid skills has faced many challenges over time, such as the need to combine tactics with medicine and to overcome combat personnel's lack of medical background knowledge. Therefore, many simulation methods are currently being developed, each of which has its advantages and disadvantages. In this study, a combined simulation method involving live-actor patients using a wearable training apparatus was developed, and the effects of this method were observed.

MATERIALS AND METHODS

Focusing on the major causes of preventable deaths among victims killed in action, wearable training apparatuses simulating massive hemorrhage, airway obstruction, and tension pneumothorax were designed and produced. Methods of simulating these three injury types using live-actor patients with these training apparatuses were developed, and medical teachers evaluated the simulation effects. The live-actor patients were incorporated into a tactical scenario to train and test nonmedical and medical students in year 3, respectively. High-fidelity simulator-based training and traditional training without simulation served as the control. A post-training survey using a 7-point Likert scale evaluated the trainees' feelings toward these training approaches.

RESULTS

Three types of training apparatuses were developed to simulate three life-threatening injuries, and the simulation effects of the live-actor patients using these apparatuses were highly recognized by medical teachers. Both live-actor patients and high-fidelity simulator-based training improved performance significantly more than traditional training. However, the improvement due to training with live-actor patients was greater than that due to high-fidelity simulator-based training for nonmedical students, whereas there was no difference between these two simulation methods for medical students. A post-training survey revealed that all the trainees were confident in practicing first-aid skills after training, and they all agreed that live-actor patients could combine tactical situations with first aid better than high-fidelity simulators. The nonmedical students strongly agreed that live-actor patients were more helpful in the training of injury evaluation than high-fidelity simulators.

CONCLUSIONS

The method using wearable training apparatus-based live-actor patients was satisfying and effective for teaching life-saving combat first-aid skills, especially for nonmedical students.

A Market Review of Available Airway Suction Technology

INTRODUCTION

Airway injuries are the second leading cause of potentially survivable battlefield death and often require airway management strategies. Airway suction, the act of using negative pressure in a patient's upper airway, removes debris that can prevent respiration, decreases possible aspiration risks, and allows clearer viewing of the airway for intubation. The most important characteristics for a portable airway suction device for prehospital combat care are portability, strong suction, and ease of use.

METHODS

This market review searched academic papers, military publications, Google searches, and Amazon to identify devices. The search included specific characteristics that would increase the likelihood that the devices would be suitable for battlefield use including weight, size, battery life, noise emission, canister size, tubing, and suction power.

RESULTS

Sixty portable airway suction devices were resulted, 31 of which met inclusion criteria - 11 manually powered devices and 20 battery-operated devices. One type of manual suction pump was a bag-like design with a squeezable suction pump that was extremely lightweight but had limited suction capabilities (vacuum pressure of 100mmHg). Another type of manual suction pump had a trigger-like design which is pulled back to create suction with a firm collection canister that had increased suction capabilities (vacuum pressures of 188-600mmHg), though still less than the battery operated, and was slightly heavier (0.23-0.458kg). Battery-operated devices had increased suction capabilities and were easier to use, but they were larger and weighed more (1.18-11.0kg).

CONCLUSION

Future research should work to lighten and debulk battery-operated suction devices with high suction performance.

Review of Commercially Available Supraglottic Airway Devices for Prehospital Combat Casualty Care

Background

Airway obstruction is the second leading cause of potentially survivable death on the battlefield. The Committee on Tactical Combat Casualty Care lists airway optimization among the top 5 battlefield research and development priorities; however, studies show that combat medics lack access to the recommended supraglottic airway (SGA) devices. SGA devices are an alternative airway management technique to endotracheal tube intubation. Reports have shown SGA devices are easier to use and take fewer attempts to provide patent airflow to the patient when compared to endotracheal tube intubation. Military settings require a higher degree of skill to perform airway management on patients due to the environment, limited availability of equipment, and potential chaos of the battlefield. Finding the optimal SGA device for the military setting is an unmet need. The International Organization for Standardization describes basic functional requirements for SGA devices, as well as patient configurations and size limitations. Beyond that, no SGA device manufacturer states that their devices are intended for military settings.

Materials and Methods

We conducted a market review of 25 SGA devices that may meet inclusion into the medics’ aid bag. The company’s official “Instructions for Use” document, Google Scholar, and FDA reports were reviewed to obtain information for each SGA device.

Results

Twenty-five commercially available SGA devices are explored from manufacturer online sources. A commercially available device list is shown later in this paper, which provides the device’s features, indications, and contraindications based on the manufacturer’s product information documentation.

Conclusions

There are a variety of devices that require further testing to determine whether they should be included in sets, kits, and outfits.

An Analysis of Airway Interventions in the Setting of Smoke Inhalation Injury on the Battlefield

INTRODUCTION

The Committee on Tactical Combat Casualty Care and Capabilities Development and Integration Directorate cite airway burn injuries as an indication for prehospital cricothyrotomy. We sought to build on previously published data by describing for the first time the incidence of prehospital airway interventions in combat casualties who received airway management in the setting of inhalational injuries.15,26 We hypothesized that (1) airway interventions in combat casualties who suffered inhalational injury would have a higher mortality rate than those without airway intervention and (2) prehospital cricothyrotomy was used with greater incidence than endotracheal intubation.

MATERIALS AND METHODS

Using a previously described Department of Defense Trauma Registry dataset from January 2007 to August 2016, unique casualties with documented inhalational injury were identified.

RESULTS

Our predefined search codes captured 28,222 (72.8% of all encounters in the registry) of those subjects. A total of 347 (1.2%) casualties had a documented inhalational injury, 27 (7.8%) of those with at least 1 prehospital airway intervention inhalational injuries (0.09% of our dataset [n = 28,222]). Within the subset of patients with an inhalation injury, 23 underwent intubation, 2 underwent cricothyrotomy, 3 had placement of an airway adjunct not otherwise specifically listed, and 1 casualty had both a cricothyrotomy and intubation documented. No casualties had a supraglottic, nasopharyngeal, or oropharyngeal airway listed. Contrary to our hypotheses, of those with an airway intervention, 74.0% survived to hospital discharge. In multivariable regression models, when adjusting for confounders, there was no difference in survival to discharge in those with an airway intervention compared to those without.

CONCLUSIONS

Casualties undergoing airway intervention for inhalation injuries had similar survival adjusting for injury severity, supporting its role when indicated. Without case-specific data on airway status and interventions, it is challenging to determine if the low rate of cricothyrotomy in this population was a result of rapid transport to a more advanced provider capable of performing intubation or cricothyrotomy may not be meeting the needs of the medics.

An Analysis of 13 Years of Prehospital Combat Casualty Care: Implications for Maintaining a Ready Medical Force

Background: Most potentially preventable deaths occur in the prehospital setting before reaching a military treatment facility with surgical capabilities. Thus, optimizing the care we deliver in the prehospital combat setting represents a ripe target for reducing mortality. We sought to analyze prehospital data within the Department of Defense Trauma Registry (DODTR). Materials and methods: We requested all encounters with any prehospital activity (e.g., interventions, transportation, vital signs) documented within the DODTR from January 2007 to March 2020 along with all hospital-based data that was available. We excluded from our search casualties that had no prehospital activity documented. Results: There were 28,950 encounters that met inclusion criteria. Of these, 25,897 (89.5%) were adults and 3053 were children (10.5%). There was a steady decline in the number of casualties encountered with the most notable decline occurring in 2014. U.S. military casualties comprised the largest proportion (n = 10,182) of subjects followed by host nation civilians (n = 9637). The median age was 24 years (interquartile range/IQR 21-29). Most were battle injuries (78.6%) and part of Operation ENDURING FREEDOM (61.8%) and Operation IRAQI FREEDOM (24.4%). Most sustained injuries from explosives (52.1%) followed by firearms (28.1%), with serious injury to the extremities (24.9%) occurring most frequently. The median injury severity score was 9 (IQR 4-16) with most surviving to discharge (95.0%). A minority had a documented medic or combat lifesaver (27.9%) in their chain of care, nor did they pass through an aid station (3.0%). Air evacuation predominated (77.9%). Conclusions: Within our dataset, the deployed U.S. military medical system provided prehospital medical care to at least 28,950 combat casualties consisting mostly of U.S. military personnel and host nation civilian care. There was a rapid decline in combat casualty volumes since 2014, however, on a per-encounter basis there was no apparent drop in procedural volume.

Outcomes of Casualties Without Airway Trauma Undergoing Prehospital Airway Interventions: A Department of Defense Trauma Registry Study

INTRODUCTION

Airway obstruction is the second leading cause of preventable death on the battlefield. Most airway obstruction occurs secondary to traumatic disruptions of the airway anatomical structures. However, casualties may require airway interventions for other indications (e.g., depressed mental status). We describe casualties undergoing airway intervention in the prehospital, combat setting without apparent upper airway trauma.

MATERIALS AND METHODS

We used a series of emergency department procedure codes to identify patients within the Department of Defense Trauma Registry (DODTR) from January 2007 to August 2016. This is a subgroup analysis of those patients with a documented prehospital airway intervention and no apparent airway trauma as defined by abbreviated injury scale of 0 for body regions 1 (head/neck) and 2 (face).

RESULTS

Our predefined search codes captured 28222 DODTR subjects of whom 409 (1.4%) met criteria for study inclusion. Subjects included members of host nation forces (34%) and civilians (30%). Most subjects sustained injuries in Afghanistan (82%). Explosive (57%) and gunshot wounds (36%) were the most frequent mechanisms of injury. Median injury severity scores were 17. The most common anatomical locations of injuries for included subjects included extremities (53%) and thorax (29%). A majority of subjects underwent intubation (89%); comparatively few casualties underwent placement of a nasopharyngeal airway (2%) or supraglottic airway (2%). The proportion of subjects surviving to hospital discharge was 80% and was highest among subjects undergoing intubation (82%).

CONCLUSIONS

In this subgroup analysis of casualties without apparent upper airway trauma, survival rates were lower when compared to our previous report. Higher quality data are necessary to better understand the resuscitation needs of this critically ill subset of combat casualties.

A Prospective Assessment of a Novel, Disposable Video Laryngoscope With Physician Assistant Trainees Using a Synthetic Cadaver Model

BACKGROUND

Airway obstruction is the second leading cause of preventable death on the battlefield. Video laryngoscopy has improved airway management in the emergency setting for several decades, and technology continues to improve. Current technology in the supply chain is cost-prohibitive to incorporate at Role 1 facilities, which is where many intubations occur by novice intubators. The i-view is a novel video laryngoscopy device that is handheld, inexpensive, and disposable. The aim of this study was to determine if the i-view is suitable based on performance assessments by physician assistant trainees and survey feedback.

MATERIALS AND METHODS

We prospectively enrolled physician assistant students at the Interservice Physician Assistant Program at Joint Base San Antonio-Fort Sam Houston. We provided them structured training on how to use the device, and then, a board-certified emergency medicine physician or certified registered nurse anesthetist assessed their intubations performed on a SynDaver mannequin model. We surveyed the participants afterward.

RESULTS

We enrolled 60 Interservice Physician Assistant Program students. Most participants were male (75%) with a median age of 32 years. Service affiliations included Army (50%), Navy (23%), Air Force (18%), and Coast Guard (8%). Most (70%) had previous deployment experience. All the participants successfully cannulated the mannequins and 98% achieved first-attempt success. Most participants (78%) reported a grade 1 view. On postprocedure survey, 91% strongly agreed with using this device in the deployed setting and 89% strongly agreed with finding it easy to use.

CONCLUSIONS

All physician assistant trainees successfully and rapidly performed endotracheal intubation using the disposable i-view video laryngoscope. Study participants rated the device as easy to use and desirable for deployment. Further research is necessary to validate this novel device in the clinical setting before recommending dissemination to the deployed military medical force sets, kits, and outfits.

Cerebral blood flow changes during palpation of external airway structures in healthy volunteers

Introduction

Previous studies demonstrate increased intracranial pressure (ICP) during direct laryngoscopy in patients with traumatic brain injury (TBI). Worse outcomes in TBI have been associated with increased ICP. It remains unclear if the same effect occurs during cricothyrotomy. We evaluated changes in cerebral blood flow and hemodynamic changes that occurred during preparation for cricothyrotomy in healthy volunteers.

Methods

An emergency medicine trainee performed routine anatomical procedural palpation with simultaneous transcranial doppler (TCD) measurements of cerebral blood flow velocities (CBFV) from bilateral middle cerebral arteries (MCAs). Mean arterial pressure (MAP) and heart rate (HR) were recorded throughout event. Our primary outcome was changes in pulsatility index (PI) and CBFV by TCD during palpation. TCD measurements were used as a surrogate for ICP.

Results

We enrolled 20 healthy volunteers for this study. No significant differences were found in pulsatility index [Right MCA -0.02 (95% confidence interval, -0.09 to 0.06), left MCA -0.02 (95% confidence interval, -0.011 to 0.07)] or mean CBFV [right MCA -0.70 mm/s (95% confidence interval, -10.15 to 8.75) left MCA -1.20 mm/s (95% confidence interval, -10.68 to 8.28)] during palpation. No significant change in HR was found [-1.1 bpm ((95% confidence interval, -2.4 to 0.1)]. A change in MAP was observed [1.3 mmHg (95% confidence interval, -0.1 to 2.4)].

Conclusions

In healthy individuals, no clinically significant change in cerebral blood flow velocities, ICP, or change heart rate was observed during palpation for cricothyrotomy.

Ketamine Administration in Prehospital Combat Injured Patients With Traumatic Brain Injury: A 10-Year Report of Survival

Background

The Tactical Combat Casualty Care (TCCC) guidelines recommend ketamine as the primary battlefield analgesic in the setting of moderate-to-severe pain and hemodynamic compromise. However, despite recent studies failing to support the association between ketamine and worse outcomes in head trauma, TCCC guidelines state that ketamine may worsen severe traumatic brain injury. We compared mortality outcomes following head trauma sustained in a combat setting between ketamine recipients and non-recipients.

Methods

This is a secondary analysis of previously published data in the Department of Defense Trauma Registry from January 2007 to August 2016. We isolated patients with an abbreviated injury scale of 3 or greater for the head body region. We compared mortality between prehospital ketamine recipients and non-recipients.

Results

Our initial search yielded 28,222 patients, of which 4,183 met the inclusion criteria: 209 were ketamine-recipients and 3,974 were non-recipients. The ketamine group had a higher percentage injured by explosives (59.81% vs. 53.57%, p<0.001) and gunshot wounds (28.71% vs. 22.07%, p<0.001) and were more frequently located in Afghanistan (100% vs. 68.0%, p<0.001). The ketamine group had higher rates of tourniquet application (24.4% vs. 8.5%, p<0.001) and had lower survival proportion (75.1% alive vs. 83.0%, p=0.003). All differences were significant. On univariable analysis, the ketamine group had worse odds of survival with (OR: 0.62; 95%CI: 0.45-0.86). When controlling for the presence of an airway intervention and mechanism of injury, the finding was non-significant (OR: 1.09; 95% CI: 0.76-1.55).

Conclusions

In our prehospital combat study, after controlling for confounders, we found no association between administration of prehospital ketamine and worse survival outcomes for casualties with head injuries. However, despite the lack of difference in overall survival noted, those who received ketamine and died had a higher risk ratio for time to death.

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.

Necessity to depict difficult neck anatomy for training of cricothyroidotomy: A pilot study evaluating two surgical devices on a new hybrid training model

BACKGROUND

Everyone dealing with airway emergencies must be able to accomplish cricothyroidotomy, which cannot be trained in real patients. Training models are necessary.

OBJECTIVE

To evaluate the suitability of a hybrid training model combining synthetic and porcine parts to depict variable neck anatomy.

DESIGN

Model-based comparative trial.

SETTING

Armed Forces Hospital Ulm, Germany, August 2018.

INTERVENTION

On four anatomical neck variations (long slim/long obese/short slim/short obese) we performed two surgical approaches to cricothyroidotomy (SurgiCric II vs. ControlCric).

PARTICIPANTS

Forty-eight volunteers divided into two groups based on their personal skill level: beginners group and proficient performers group.

MAIN OUTCOME MEASURES

Time to completion was recorded for each procedure. Once the operator had indicated completion, the correct anatomical tube placement was confirmed by dissection and structures were inspected for complications. Primary outcomes were successful tracheal placement of an airway tube and time needed to achieve a patent airway. Secondary outcome was assessment of complications.

RESULTS

Overall, 384 procedures were performed. Median time to completion was 74 s. In total, 284 procedures (74%) resulted in successful ventilation. Time to completion was longer in short obese than in long slim and the risk of unsuccessful procedures was increased in short obese compared with long slim. Even if ControlCric resulted in faster completion of the procedure, its use was less successful and had an increased risk of complications compared with SurgiCric II. Proficient performers group performed faster but had an increased risk of injuring the tracheal wall compared with beginners group.

CONCLUSION

Participants had difficulties in performing cricothyroidotomy in obese models, but various and difficult anatomical situations must be expected in airway management and therefore must be taught. A new hybrid model combining porcine and synthetic materials offers the necessary conditions for the next step in training of surgical airway procedures.

TRIAL REGISTRATION

The study was performed without human tissue or living animals, and was therefore exempted from ethical review by the University of Ulm Ethical Committee, Germany (Chairperson Prof Dr C. Lenk) on 9 August 2018. Hence a protocol number was not attributed.