Short-term outcomes of US Air Force Critical Care Air Transport Team (CCATT) patients evacuated from a combat setting

A Novel Continuous Real-Time Vital Signs Viewer for Intensive Care Units: Design and Evaluation Study

BACKGROUND

Clinicians working in intensive care units (ICUs) are immersed in a cacophony of alarms and a relentless onslaught of data. Within this frenetic environment, clinicians make high-stakes decisions using many data sources and are often oversaturated with information of varying quality. Traditional bedside monitors only depict static vital signs data, and these data are not easily viewable remotely. Clinicians must rely on separate nursing charts-handwritten or electric-to review physiological patterns, including signs of potential clinical deterioration. An automated physiological data viewer has been developed to provide at-a-glance summaries and to assist with prioritizing care for multiple patients who are critically ill.

OBJECTIVE

This study aims to evaluate a novel vital signs viewer system in a level 1 trauma center by subjectively assessing the viewer's utility in a high-volume ICU setting.

METHODS

ICU attendings were surveyed during morning rounds. Physicians were asked to conduct rounds normally, using data reported from nurse charts and briefs from fellows to inform their clinical decisions. After the physician finished their assessment and plan for the patient, they were asked to complete a questionnaire. Following completion of the questionnaire, the viewer was presented to ICU physicians on a tablet personal computer that displayed the patient's physiologic data (ie, shock index, blood pressure, heart rate, temperature, respiratory rate, and pulse oximetry), summarized for up to 72 hours. After examining the viewer, ICU physicians completed a postview questionnaire. In both questionnaires, the physicians were asked questions regarding the patient's stability, status, and need for a higher or lower level of care. A hierarchical clustering analysis was used to group participating ICU physicians and assess their general reception of the viewer.

RESULTS

A total of 908 anonymous surveys were collected from 28 ICU physicians from February 2015 to June 2017. Regarding physicians' perception of whether the viewer enhanced the ability to assess multiple patients in the ICU, 5% (45/908) strongly agreed, 56.6% (514/908) agreed, 35.3% (321/908) were neutral, 2.9% (26/908) disagreed, and 0.2% (2/908) strongly disagreed.

CONCLUSIONS

Morning rounds in a trauma center ICU are conducted in a busy environment with many data sources. This study demonstrates that organized physiologic data and visual assessment can improve situation awareness, assist clinicians with recognizing changes in patient status, and prioritize care.

Early Enteral Nutrition in Aeromedically Evacuated Critically Ill/Injured Patients With a Resultant Validation Algorithm for the Theater Validating Flight Surgeon

INTRODUCTION

Early enteral feeding in critically ill/injured patients promotes gut integrity and immunocompetence and reduces infections and intensive care unit/hospital stays. Aeromedical evacuation (AE) often takes place concurrently. As a result, AE and early enteral feeding should be inseparable.

MATERIALS AND METHODS

This retrospective descriptive study employed AE enteral nutrition (EN) data (2007-2019) collected from patients who were U.S. citizens and mechanically ventilated. The dataset was created from the En Route Critical Care, Transportation Command Regulating and Command and Control Evacuation System, and Theater Medical Data Store databases. Comparisons were performed between patients extracted and patients not extracted, patients treated with EN and patients treated without EN, and within the EN group, between AE Fed and AE Withheld. The impact of the nutrition support in the Joint Trauma System Clinical Practice Guidelines (CPG) was assessed using the 'before' and 'after' methodology.

RESULTS

An uptick in feeding rates was found after the 2010 CPG, 15% → 17%. With the next two CPG iterations, rates rose significantly, 17% → 48%. Concurrently, AE feeding holds rose significantly, 10% → 24%, later dropping to 17%. In addition, little difference was found between those patients not enterally fed preflight and those enterally fed across collected demographic, mission, and clinical parameters. Likewise, no difference was found between those enterally fed during AE and those withheld. Yet, 83% of the study's patients were not fed, and 18% of those that were fed had feeding withheld for AE.

CONCLUSIONS

It appeared that the Clinical Practice Guidelines (CPGs) reinforced the value of feeding, but may well have sensitized to the threat of aspiration. It also appeared that early enteral feeding was underprescribed and AE feeding withholds were overprescribed. Consequently, an algorithm was devised for the Theater Validating Flight Surgeon, bearing in mind relevant preflight/inflight/clinical issues, with prescriptions designed to boost feeding, diminish AE withholding, and minimize complications.

Descriptive Analysis of Intratheater Critical Care Air Transport Team Patient Movements During Troop Drawdown: Afghanistan (2017-2019)

BACKGROUND

The majority of critical care air transport (CCAT) flights are regulated, meaning that a theater-validating flight surgeon has confirmed that the patient is medically cleared for flight and that evacuation is appropriate. If the conditions on the ground do not allow for this process, the flight is unregulated. Published data are limited regarding CCAT unregulated missions to include the period of troop drawdown at the end of the Afghanistan conflict. The objective of our study was to characterize the unregulated missions within Afghanistan during troop drawdown and compare them to regulated missions during the same timeframe.

STUDY DESIGN

We performed a retrospective review of all CCAT medical records of patients transported via CCAT within Afghanistan between January 2017 and December 2019. We abstracted data from the records, including mission characteristics, patient demographics, injury descriptors, preflight military treatment facility procedures, CCAT procedures, in-flight CCAT treatments, in-flight events, and equipment issues. Following descriptive and comparative analysis, a Cochran-Armitage test was performed to evaluate the statistical significance of the trend in categorical data over time. Multivariable regression was used to assess the association between vasopressors and preflight massive transfusions, preflight surgical procedures, injury patterns, and age.

RESULTS

We reviewed 147 records of patients transported via CCAT: 68 patients were transported in a regulated fashion and 79 on an unregulated flight. The number of patients evacuated increased year-over-year (n = 22 in 2017, n = 57 in 2018, and n = 68 in 2019, P < .001), and the percentage of missions that were unregulated grew geometrically (14%, n = 3 in 2017; 37%, n = 21 in 2018; and 81%, n = 55 in 2019, P < .001). During the time studied, CCAT teams were being used more to decompress forward surgical teams (FST) and, therefore, they were transporting patients just hours following initial damage control surgery in an unregulated fashion. In 2 instances, CCAT decompressed an FST following a mass casualty, during which aeromedical evacuation (AE) crews assisted with patient care. For the regulated missions, the treatments that were statistically more common were intravenous fluids, propofol, norepinephrine, any vasopressors, and bicarbonate. During unregulated missions, the statistically more common treatments were ketamine, fentanyl, and 3% saline. Additional analysis of the mechanically ventilated patient subgroup revealed that vasopressors were used twice as often on regulated (38%) vs. unregulated (13%) flights. Multivariable regression analysis demonstrated that traumatic brain injury (TBI) was the only significant predictor of in-flight vasopressor use (odds ratio = 3.53, confidence interval [1.22, 10.22], P = .02).

CONCLUSION

During the troop drawdown in Afghanistan, the number of unregulated missions increased geometrically because the medical footprint was decreasing. During unregulated missions, CCAT providers used ketamine more frequently, consistent with Tactical Combat Casualty Care guidelines. In addition, TBI was the only predictor of vasopressor use and may reflect an attempt to adhere to unmonitored TBI clinical guidelines. Interoperability between CCAT and AE teams is critical to meet mass casualty needs in unregulated mission environments and highlights a need for joint training. It remains imperative to evaluate changes in mission requirements to inform en route combat casualty care training.

Team Coordination Style Is an Adaptive, Emergent Property of Interactions Between Critical Care Air Transport Team Personnel

OBJECTIVE

Critical Care Air Transport (CCAT) teams care for critically ill or injured patients during long-duration flights. Despite the differences between the CCAT domain and a more traditional clinical setting, CCAT clinicians are not explicitly trained how to coordinate care in the aircraft environment. We characterized the team coordination patterns adopted by CCAT teams and explored any links between team coordination style and performance.

METHODS

This retrospective study used transcripts from 91 CCAT teams as they completed simulated patient care scenarios during an advanced training course. Qualitative and quantitative measures were used to characterize team behavior.

RESULTS

Vocalized content varied by team role, with physicians acting as leaders. The type of content verbalized by each team role depended on the team coordination style. The team coordination style and the content of vocalized messages were not affected by prior team member deployment or the characteristics of particular scenarios, and the team coordination style did not predict measures related to patient status.

CONCLUSION

Individual team member coordination behaviors vary depending on the coordination style used by the team as a whole. Coordination style appears to arise from the interactions among individual team members rather than in response to situational factors external to the team.

Improved Adherence to Best Practice Ventilation Management After Implementation of Clinical Practice Guideline (CPG) for United States Military Critical Care Air Transport Teams (CCATTs)

BACKGROUND

Critical Care Air Transport Teams (CCATTs) play a vital role in the transport and care of critically ill and injured patients in the combat theater to include mechanically ventilated patients. Previous research has demonstrated improved morbidity and mortality when lung protective ventilation strategies are used. Our previous study of CCATT trauma patients demonstrated frequent non-adherence to the Acute Respiratory Distress Syndrome Network (ARDSNet) protocol and a corresponding association with increased mortality. The goals of our study were to examine CCATT adherence with ARDSNet guidelines in non-trauma patients, compare the findings to our previous publication of CCATT trauma patients, and evaluate adherence before and after the publication of the CCATT Ventilator Management Clinical Practice Guideline (CPG).

METHODS

We performed a retrospective chart review of ventilated non-trauma patients who were evacuated out of theater by Critical Care Air Transport Teams (CCATT) between January 2007 and April 2015. Data abstractors collected flight information, oxygenation status, ventilator settings, procedures, and in-flight assessments. We calculated descriptive statistics to determine the frequency of compliance with the ARDSNet protocol before and after the CCATT Ventilator CPG publication and the association between ARDSNet protocol adherence and in-flight events.

RESULTS

We reviewed the charts of 124 mechanically ventilated patients transported out of theater via CCATT on volume control settings. Seventy percent (n = 87/124) of records were determined to be Non-Adherent to ARDSNet recommendations predominately due to excessive tidal volume settings and/or high FiO2 settings relative to the patient's positive end-expiratory pressure setting. The Non-Adherent group had a higher proportion of in-flight respiratory events. Compared to our previous study of ventilation guideline adherence in the trauma population, the Non-Trauma population had a higher rate of non-adherence to tidal volume and ARDSNet table recommendations (75.6% vs. 61.5%). After the CPG was rolled out, adherence improved from 24% to 41% (P = 0.0496).

CONCLUSIONS

CCATTs had low adherence with the ARDSNet guidelines in non-trauma patients transported out of the combat theater, but implementation of a Ventilator Management CPG was associated with improved adherence.

Relevance of Deployment Experience and Clinical Practice Characteristics on Military Critical Care Air Transport Team Readiness: A Study of Simulation Construct Validity

INTRODUCTION

The Critical Care Air Transport Team (CCATT) Advanced course utilizes fully immersive high-fidelity simulations to train CCATT personnel and assess their readiness for deployment. This study aims to (1) determine whether these simulations correctly discriminate between students with previous deployment experience ("experienced") and no deployment experience ("novices") and (2) examine the effects of students' clinical practice environment on their performance during training simulations.

MATERIALS AND METHODS

Critical Care Air Transport Team Advanced student survey data and course status (pass/no pass) between March 2006 and April 2020 were analyzed. The data included students' specialty, previous exposure to the CCATT Advanced course, previous CCATT deployment experience, years in clinical practice (<5, 5-15, and >15 years), and daily practice of critical care (yes/no), as well as a description of the students' hospital to include the total number of hospital (<100, 100-200, 201-400, and >400) and intensive care unit (0, 1-10, 11-20, and >20) beds. Following descriptive analysis and comparative tests, multivariable regression was used to identify the predictors of passing the CCATT Advanced course.

RESULTS

A total of 2,723 surveys were analyzed: 841 (31%) were physicians (MDs), 1,035 (38%) were registered nurses, and 847 (31%) were respiratory therapists (RTs); 641 (24%) of the students were repeating the course for sustainment training and 664 (24%) had previous deployment experience. Grouped by student specialty, the MDs', registered nurses', and RTs' pass rates were 92.7%, 90.6%, and 85.6%, respectively. Multivariable regression results demonstrated that deployment experience was a robust predictor of passing. In addition, the >15 years in practice group had a 47% decrease in the odds of passing as compared to the 5 to 15 years in practice group. Finally, using MDs as the reference, the RTs had a 61% decrease in their odds of passing. The daily practice of critical care provided a borderline but nonsignificant passing advantage, whereas previous CCATT course exposure had no effect.

CONCLUSION

Our primary result was that the CCATT Advanced simulations that are used to evaluate whether the students are mission ready successfully differentiated "novice" from "experienced" students; this is consistent with valid simulation constructs. Finally, novice CCATT students do not sustain their readiness skills during the period between mandated refresher training.

Evacuation Strategies for U.S. Casualties with Traumatic Brain Injury (TBI) with and without Polytrauma

INTRODUCTION

According to the Military Health System Traumatic Brain Injury (TBI) Center of Excellence, 51,261 service members suffered moderate to severe TBI in the last 21 years. Moderate to severe TBI in service members is usually related to blast injury in combat operations, which necessitates medical evacuation to higher levels of care. Prevention of secondary insult, and mitigation of the unique challenges associated with the transport of TBI patients in a combat setting are important in reducing the morbidity and mortality associated with this injury. The primary goal of this study was a secondary analysis comparing the impact of time to transport on clinical outcomes for TBI patients without polytrauma versus TBI patients with polytrauma transported out of the combat theater via Critical Care Air Transport Teams (CCATT). Our secondary objective was to describe the occurrence of in-flight events and interventions for TBI patients without polytrauma versus TBI with polytrauma to assist with mission planning for future transports.

MATERIALS AND METHODS

We performed a secondary analysis of a retrospective cohort of 438 patients with TBI who were evacuated out of theater by CCATT from January 2007 to May 2014. Polytrauma was defined as abbreviated injury scale (AIS) of at least three to another region in addition to head/neck. Time to transport was defined as the time (in days) from injury to CCATT evacuation out of combat theater. We calculated descriptive statistics and examined the associations between time to transport and preflight characteristics, in-flight interventions and events, and clinical outcomes for TBI patients with and without polytrauma.

RESULTS

We categorized patients into two groups, those who had a TBI without polytrauma (n = 179) and those with polytrauma (n = 259). Within each group, we further divided those that were transported within 1 day of injury, in 2 days, and 3 or more days. Patients with TBI without polytrauma transported in 1 or 2 days were more likely to have a penetrating injury, an open head injury, a preflight Glascow Coma Score (GCS) of 8 or lower, and be mechanically ventilated compared to those transported later. Patients without polytrauma who were evacuated in 1 or 2 days required more in-flight interventions compared to patients without polytrauma evacuated later. Patients with polytrauma who were transported in 2 days were more likely to receive blood products, and patients with polytrauma who were evacuated within 1 day were more likely to have had at least one episode of hypotension en route. Polytrauma patients who were evacuated in 2-3 days had higher hospital days compared to polytrauma with earlier evacuations. There was no significant difference in mortality between any of the groups.

CONCLUSIONS

In patients with moderate to severe TBI transported via CCATT, early evacuation was associated with a higher rate of in-flight hypotension in polytrauma patients. Furthermore, those who had TBI without polytrauma that were evacuated in 1-2 days received more in-flight supplementary oxygen, blood products, sedatives, and paralytics. Given the importance of minimizing secondary insults in patients with TBI, recognizing this in this subset of the population may help systematize ways to minimize such events. Traumatic Brain Injury patients with polytrauma may benefit from further treatment and stabilization in theater prior to CCATT evacuation.

Strategic air medical evacuation of critically ill patients involving an intensive care physician: A retrospective analysis of 16 years of mission data

BACKGROUND

Strategic medical evacuation (MEDEVAC) allows airborne repatriation of soldiers injured or sick on missions to their national territory. The aim of this study was to describe the epidemiology of strategic MEDEVAC performed by intensive care physicians (ICP) and to analyze the role of the ICP in the management of critical care situations in flight.

METHODS

All soldiers who had high or medium dependency conditions and who benefited from a strategic MEDEVAC with an ICP on board between 1 January 2001 and 30 November 2017 were included in this epidemiological retrospective study.

RESULTS

A total of 452 soldiers were repatriated; the causes of repatriation were either trauma (n = 245; 54%) or medical pathologies (n = 207; 46%). Two hundred and seventy-six (61%) evacuations were performed within 48 h. The median annual number of strategic MEDEVAC with an ICP was 26 [20-32]. One hundred and fifty-five (34%) patients were mechanically ventilated and 103 (23%) received catecholamines. The median SAPS II score was 13 [8-24]. One hundred and seventy-eight adverse events were identified, of which 123 (69%) related to a worsening of the patient's clinical condition and 30 (20%) related to a technical problem. Forty-seven (20%) patients who initially appeared stable worsened during the flight. No deaths occurred on board, however, and no flights had to be diverted due to an uncontrolled care situation.

CONCLUSION

The results suggested that the presence of an ICP ensured a continued high-level care for patients with serious trauma and medical injuries, due to the medical and aeronautical expertise that resulted from the theoretical and practical training of the personnel on board. Based on these results, lessons regarding future MEDEVAC flights could be learned in order to continue to improve patient outcome.

Influence of Time to Transport to a Higher Level Facility on the Clinical Outcomes of US Combat Casualties with TBI: A Multicenter 7-Year Study

INTRODUCTION

Traumatic brain injury (TBI) is a leading cause of death and disability worldwide and is associated with mortality rates as high as 30%. Patients with TBI are at high risk for secondary injury and need to be transported to definitive care expeditiously. However, the physiologic effects of aeromedical evacuation are not well understood and may compound these risks. Combat TBI patients may benefit from delayed aeromedical evacuation. The goal of this study was to evaluate the impact of transport timing out of theater via Critical Care Air Transport Teams (CCATT) to a higher level facility on the clinical outcomes of combat casualties with TBI.

MATERIALS AND METHODS

We performed a retrospective review of patients with TBI who were evacuated out of theater by CCATT from January 2007 to May 2014. Data abstractors collected flight information, vital signs, procedures, in-flight assessments, and outcomes. Time to transport was defined as the time from injury to CCATT evacuation out of combat theater. We calculated descriptive statistics and constructed regression models to determine the association between time to transport and clinical outcomes. This study was approved by the U.S. Air Force 59th Medical Wing Institutional Review Board.

RESULTS

We analyzed the records of 438 patients evacuated out of theater via CCATT and categorized them into three groups: patients who were transported in one day or less (n = 165), two days (n = 163), and three or more days (n = 110). We used logistic regression models to compare outcomes among patients who were evacuated in two days or three or more days to those who were transported within one day while adjusting for demographics, injury severity, and injury type. Patients who were evacuated in two days or three or more days had 50% lower odds of being discharged on a ventilator and were twice as likely to return to duty or be discharged home than those who were evacuated within one day. Additionally, patients transported in three or more days were 70% less likely to be ventilated at discharge with a GCS of 8 or lower and had 30% lower odds of mortality than those transported within one day.

CONCLUSIONS

In patients with moderate to severe TBI, a delay in aeromedical evacuation out of the combat theater was associated with improved mortality rates and a higher likelihood of discharge to home and return to duty dispositions. This study is correlational in nature and focused on CCATT transports from Role III to Role IV facilities; as such, care must be taken in interpreting our findings and future studies are needed to establish a causal link between delayed evacuation and improved discharge disposition. Our study suggests that delaying aeromedical evacuation of TBI patients when feasible may confer benefit.

Patients With Traumatic Brain Injury Transported by Critical Care Air Transport Teams: The Influence of Altitude and Oxygenation during Transport

INTRODUCTION

Traumatic brain injuries (TBIs) are life-threatening, and air transport of patients with TBI requires additional considerations. To mitigate the risks of complications associated with altitude, some patients fly with a cabin altitude restriction (CAR) to limit the altitude at which an aircraft's cabin is maintained. The goal of this study was to examine the effects of CARs on patients with TBI transported out of theater via Critical Care Air Transport Teams.

MATERIALS AND METHODS

We conducted a retrospective chart review of patients with moderate-to-severe TBI evacuated out of combat theater to Landstuhl Regional Medical Center via Critical Care Air Transport Teams. We collected demographics, flight and injury information, procedures, oxygenation, and outcomes (discharge disposition and hospital/ICU/ventilator days). We categorized patients as having a CAR if they had a documented CAR or maximum cabin altitude of 5,000 feet or lower in their Critical Care Air Transport Teams record. We calculated descriptive statistics and constructed regression models to evaluate the association between CAR and clinical outcomes.

RESULTS

We reviewed the charts of 435 patients, 31% of which had a documented CAR. Nineteen percent of the sample had a PaO2 lower than 80 mm Hg, and 3% of patients experienced a SpO2 lower than 93% while in flight. When comparing preflight and in-flight events, we found that the percentage of patients who had a SpO2 of 93% or lower increased for the No CAR group, whereas the CAR group did not experience a significant change. However, flying without a CAR was not associated with discharge disposition, mortality, or hospital/ICU/ventilator days. Further, having a CAR was not associated with these outcomes after adjusting for additional flights, injury severity, injury type, or preflight head surgery.

CONCLUSIONS

Patients with TBI who flew with a CAR did not differ in clinical outcomes from those without a CAR.

Characterization of Long-range Aeromedical Transport and Its Relationship to the Development of Traumatic Extremity Compartment Syndrome: A 7-year, Retrospective Study

BACKGROUND

Military aeromedical transport evacuates critically injured patients are for definitive care, including patients with or at risk for developing traumatic compartment syndrome of the extremities (tCSoE). Compartment pressure changes of the extremities have not been determined to be associated with factors inherent to aeromedical transport in animal models, but the influence of aeromedical evacuation (AE) transport on the timing of tCSoE development has not been studied in humans. Using a registry-based methodology, this study sought to characterize the temporal features of lower extremity compartment syndrome relative to the timing of transcontinental AE. With this approach, this study aims to inform practice in guidelines relating to the timing and possible effects of long-distance AE and the development of lower extremity compartment syndrome. Using patient care records, we sought to characterize the temporal features of tCSoE diagnosis relative to long-range aeromedical transport. In doing so, we aim to inform practice in guidelines relating to the timing and risks of long-range AE and postulate whether there is an ideal time to transport patients who are at risk for or with tCSoE.

METHODS

We performed a retrospective record review of patients with a diagnosis of tCSoE who were evacuated out of theater from January 2007 to May 2014 via aeromedical transport. Data abstractors collected flight information, laboratory values, vital signs, procedures, in-flight assessments, and outcomes. We used the duration of time from injury to arrival at Landstuhl Regional Medical Center (LRMC) to represent time to transport. We compared groups based on time of tCSoE (inclusive of upper and lower extremity) diagnosis relative to injury day and time of transport (preflight versus postflight). We used descriptive statistics and multivariable regression models to determine the associations between time to transport, time to tCSoE diagnosis, and outcomes.

RESULTS

Within our study window, 238 patients had documentation of tCSoE. We found that 47% of patients with tCSoE were diagnosed preflight and 53% were diagnosed postflight. Over 90% in both groups developed tCSoE within 48 hours of injury; the time to diagnosis was similar for casualties diagnosed pre- and postflight (P = .65). There was no association between time to arrival at LRMC and day of tCSoE diagnosis (risk ratio, 1.06; 95% CI, 0.96-1.16).

CONCLUSION

The timing of tCSoE diagnosis is not associated with the timing of transport; therefore, AE likely does not influence the development of tCSoE.

Descriptive Analysis of Cardiac Patients Transported by Critical Care Air Transport Teams

INTRODUCTION

Critical Care Air Transport Teams (CCATTs) transport critically ill patients within and out of theaters of combat operations. Studies of the CCATT population reveal as many as 35% of patients have a non-trauma diagnosis, of which more than half are cardiac.The purpose of this retrospective study was to describe the epidemiology of critically ill patients with cardiac diagnoses evacuated from theater via CCATT.

MATERIALS AND METHODS

We conducted a retrospective review of 290 medical patients with a primary cardiac diagnosis transported from any theater of operation to Landstuhl Regional Medical Center, Germany from January 2007 to April 2015.

RESULTS

The majority of patients were male with an average age of 46 ± 11 years, US contractors (47%, n = 137), followed by US Active Duty (32%, n = 93). Patients had an average BMI of 29 ± 5; 62% of cardiac patients were either overweight or obese. The most common cardiac diagnoses were ST elevation myocardial infarction, Non-ST elevation myocardial infarction, and angina. Pre-flight vital signs indicate overall patients were stable prior to evacuation, with the majority receiving supplemental oxygen and only 5% requiring mechanical ventilation. Eighty-one percent of patients experienced at least one cardiac event during flight, however less than 5% required adjustment to oxygen or ventilator settings.

CONCLUSIONS

Critically ill cardiac patients make up a significant portion of patients transported out of the combat theater. These patients are older, overweight and have identified risk factors for cardiac morbidity. More strenuous pre-deployment screening for risk factors and prevention strategies could minimize the use of military resources to evacuate these patients from the combat theater.

En Route Resuscitation - Utilization of CCATT to Transport and Stabilize Critically Injured and Unstable Casualties

INTRODUCTION

The U.S. Air Force utilizes specialized Critical Care Air Transport Teams (CCATT) for transporting "stabilized" patients. Given the drawdown of military forces from various areas of operation, recent CCATT operations have increasingly involved the evacuation of unstable and incompletely resuscitated patients from far forward, austere locations. This brief report describes unique cases representative of the evolving CCATT mission and provides future direction for changes in doctrine and educational requirements in preparation for en route combat casualty care.

METHODS AND MATERIALS

This case series describes three patients who required significant resuscitation during CCATT transport from austere locations between April and November 2017. Approval for this project was received from the US Air Force 59th Medical Wing Institutional Review Board as non-research.

RESULTS

Case 1: CCATT was dispatched to transport patient 1 who was reported to have a head injury after a fall. Upon evaluation of the patient onboard the aircraft, it was discovered that the patient was in cardiac arrest. Cardiopulmonary resuscitation was performed during tactical takeoff with frequent combat maneuvers. The patient developed a palpable pulse after three rounds of CPR, three doses of epinephrine, and one unit of packed red blood cells. Point of care laboratory analysis demonstrated a profoundly elevated lactate level. Cyanide poisoning was a concern but there was no antidote available in the available equipment set. After delivery to a medical facility, blood samples were positive for cyanide. Over the next 2 weeks, the patient improved and was discharged home, neurologically intact. Case 2: Patient 2 sustained complex blast injuries and bilateral lower extremity amputations. He required early transport for continuous renal replacement therapy (CRRT). The patient received 200 units of blood products in the 24 hours prior to transport and developed renal failure, pulmonary edema, and elevated ICP. During the 7 hour flight, Patient 2 received frequent adjustments of vasopressor medications, multiple Dakins solution soaks and flushes, and 1 unit of fresh frozen plasma. He remained alive 2 months later. Case 3: The team was notified to collect an urgent patient with a blast lung injury and bilateral lower extremity amputations. The ground team encountered difficulty ventilating the patient. Patient 3 arrived in the back of a pickup truck accompanied by medics and being bag valve mask ventilated with a pulse oximetry reading of 65%. He was secured to the floor of the aircraft which departed within 5 minutes of arrival. An ultrasound of the lungs showed no pneumothorax. By the end of the flight, the patient's oxygen saturation had risen to 95% and he was delivered to the emergency department in stable condition. He later passed away in the operating room due to severe blast lung and cardiac contusion.

CONCLUSION

This brief report demonstrates the need of CCATT in the transport of unstable patients from forward deployed locations. The Air Force has adapted and is continuing to adapt CCATT training, equipment, onboard diagnostics and therapies, and team members' clinical skills to meet en route care combat casualty needs.

Resuscitative Endovascular Balloon Occlusion of the Aorta: A Bridge to Flight Survival

Trauma endures as the leading cause of death worldwide, and most deaths occur in the first 24 hours after initial injury as a result of hemorrhage. Historically, about 90% of battlefield deaths occur before the injured person arrives at a theater hospital, and most are due to noncompressible hemorrhage of the torso. Resuscitative endovascular balloon occlusion of the aorta is an evolving technique to quickly place a balloon into the thoracic or abdominal aorta to efficiently block blood flow to distal circulation. Maneuvers, such as resuscitative endovascular balloon occlusion of the aorta, to control endovascular hemorrhage offer a potential intervention to control noncompressible hemorrhage. This technique can be performed percutaneously or open in prehospital environments to restore hemodynamic functions and serve as a survival bridge until the patient is delivered to a treatment facility for definitive surgical hemostasis. This article describes the indications, complications, and application of resuscitative endovascular balloon occlusion of the aorta to military and civilian aeromedical transport.

En Route Critical Care Transfer From a Role 2 to a Role 3 Medical Treatment Facility in Afghanistan

BACKGROUND

En route care is the transfer of patients requiring combat casualty care within the US military evacuation system. No reports have been published about en route care of patients during transfer from a forward surgical facility (role 2) to a combat support hospital (role 3) for comprehensive care.

OBJECTIVE

To describe patients transferred from a role 2 to a role 3 US military treatment facility in Afghanistan.

METHODS

A retrospective review of data from the Joint Trauma System Role 2 Database was conducted. Patient characteristics were described by en route care medical attendants.

RESULTS

More than one-fourth of patients were intubated at transfer (26.9%), although at transfer fewer than 10% of patients had a base deficit of more than 5 (3.5%), a pH of less than 7.3 (5.2%), an international normalized ratio of more than 2 (0.8%), or temporary abdominal or chest closure (7.4%). The en route care medical attendant was most often a nurse (35.5%), followed by technicians (14.1%) and physicians (10.0%). Most patients (75.3%) were transported by medical evacuation (on rotary-wing aircraft).

CONCLUSION

This is the first comprehensive review of patients transported from a forward surgical facility to a more robust combat support hospital in Afghanistan. Understanding the epidemiology of these patients will inform provider training and the appropriate skill mix for the transfer of postsurgical patients within a combat setting.

Emergency Physicians at War

Operation Enduring Freedom (OEF-A) in Afghanistan and Operation Iraqi Freedom (OIF) represent the first major, sustained wars in which emergency physicians (EPs) fully participated as an integrated part of the military’s health system. EPs proved invaluable in the deployments, and they frequently used the full spectrum of trauma and medical care skills. The roles EPs served expanded over the years of the conflicts and demonstrated the unique skill set of emergency medicine (EM) training. EPs supported elite special operations units, served in medical command positions, and developed and staffed flying intensive care units. EPs have brought their combat experience home to civilian practice. This narrative review summarizes the history, contributions, and lessons learned by EPs during OEF-A/OIF and describes changes to daily clinical practice of EM derived from the combat environment.

Impact of Critical Care Air Transport Team (CCATT) ventilator management on combat mortality

BACKGROUND

Aeromedical evacuation platforms such as Critical Care Air Transport Teams (CCATTs) play a vital role in the transport and care of critically injured and ill patients in the combat theater. Mechanical ventilation is used to support patients with failing respiratory function and patients requiring high levels of sedation. Mechanical ventilation, if not managed appropriately, can worsen or cause lung injury and contribute to increased morbidity. The purpose of this study was to evaluate the impact of ARDSNet protocol compliance during aeromedical evacuation of ventilated combat injured patients.

METHODS

We performed a retrospective chart review of combat injured patients transported by CCATTs from Afghanistan to Landstuhl Regional Medical Center (LRMC) in Germany between January 2007 and January 2012. After univariate analyses, we performed regression analyses to assess compliance and post-flight outcomes. Cox proportional hazard models were used to evaluate associations between the risk factor of non-compliance with increased number of ventilator, ICU, or hospital days. Nominal logistic regression models were performed to evaluate the association between non-compliance and mortality.

RESULTS

Sixty-two percent (n = 669) of 1,086 patients required mechanical ventilation during transport. A total of 650 patients required volume-controlled mechanical ventilation and were included in the analysis. Of the 650 subjects, 62% (n = 400) were non-compliant per tidal volume and ARDSNet table recommendations. The groups were similar in all demographic variables, except the Non-compliant group had a higher Injury Severity Score compared to the Compliant group. Subjects in the Compliant group were less likely to have an incidence of acute respiratory distress, acute respiratory failure, and ventilator-associated pneumonia when combing the variables (2% vs. 7%, p < 0.0069). The Non-compliant group had an increased incidence of in-flight respiratory events, required more days on the ventilator and in the ICU, and had a higher mortality rate.

CONCLUSIONS

Compliance with the ARDSNet guidelines was associated with a decrease in ventilator days, ICU days, and 30-day mortality.

LEVEL OF EVIDENCE

Therapeutic/care management, level IV.

Incidence, risk factors, and mortality associated with acute respiratory distress syndrome in combat casualty care

BACKGROUND

The overall incidence and mortality of acute respiratory distress syndrome (ARDS) in civilian trauma settings have decreased over the past four decades; however, the epidemiology and impact of ARDS on modern combat casualty care are unknown. We sought to determine the incidence, risk factors, resource utilization, and mortality associated with ARDS in current combat casualty care.

METHODS

This was a retrospective review of mechanically ventilated US combat casualties within the Department of Defense Trauma Registry (formerly the Joint Theater Trauma Registry) during Operation Iraqi Freedom/Enduring Freedom (October 2001 to August 2008) for ARDS development, resource utilization, and mortality.

RESULTS

Of 18,329 US Department of Defense Trauma Registry encounters, 4,679 (25.5%) required mechanical ventilation; ARDS was identified in 156 encounters (3.3%). On multivariate logistic regression, ARDS was independently associated with female sex (odds ratio [OR], 2.62; 95% confidence interval [CI], 1.21-5.71; p = 0.02), higher military-specific Injury Severity Score (Mil ISS) (OR, 4.18; 95% CI, 2.61-6.71; p < 0.001 for Mil ISS ≥25 vs. <15), hypotension (admission systolic blood pressure <90 vs. ≥90 mm Hg; OR, 1.76; 95% CI, 1.07-2.88; p = 0.03), and tachycardia (admission heart rate ≥90 vs. <90 beats per minute; OR, 1.53; 95% CI, 1.06-2.22; p = 0.02). Explosion injury was not associated with increased risk of ARDS. Critical care resource utilization was significantly higher in ARDS patients as was all-cause hospital mortality (ARDS vs. no ARDS, 12.8% vs. 5.9%; p = 0.002). After adjustment for age, sex, injury severity, injury mechanism, Mil ISS, hypotension, tachycardia, and admission Glasgow Coma Scale score, ARDS remained an independent risk factor for death (OR, 1.99; 95% CI, 1.12-3.52; p = 0.02).

CONCLUSIONS

In this large cohort of modern combat casualties, ARDS risk factors included female sex, higher injury severity, hypotension, and tachycardia, but not explosion injury. Patients with ARDS also required more medical resources and were at greater risk of death compared with patients without ARDS. Thus, ARDS remains a significant complication in current combat casualty care.

LEVEL OF EVIDENCE

Prognostic/epidemiologic study, level III.

Impact of Anemia in Critically Ill Burned Casualties Evacuated From Combat Theater via US Military Critical Care Air Transport Teams

BACKGROUND

US military Critical Care Air Transport Teams (CCATT) transport critically ill burn patients out of theater. Blood transfusion may incur adverse effects, and studies report lower hemoglobin (Hgb) value may be safe for critically ill patients. There are no studies evaluating the optimal Hgb value for critically ill burn patients prior to CCATT evacuation.

OBJECTIVE

The aim of the study was to determine if critically ill burn casualties with an Hgb of 10 g/dL or less, transported via CCATT, have similar clinical outcomes at 30 days as compared with patients with an Hgb of greater than 10 g/dL.

METHODS

We conducted an institutional review board-approved retrospective cohort study involving patients transported via CCATT. We separated our study population into two cohorts based on Hgb levels at the time of theater evacuation: Hgb ≤10 g/dL or Hgb ≥10 g/dL. We compared demographics, injury description, physiologic parameters, and clinical outcomes.

RESULTS

Of the 140 subjects enrolled, 29 were Hgb ≤10, and 111 were Hgb ≥10. Both groups were similar in age and percent total body surface area burned. Those Hgb ≤10 had a higher injury severity score (34 ± 19.8 vs. 25 ± 16.9, P = 0.02) and were more likely to have additional trauma (50% vs. 25%, P = 0.04). Modeling revealed no persistent differences in mortality, and other clinical outcomes measured.

CONCLUSIONS

Critical Care Air Transport Teams transport of critically ill burn patients with an Hgb of 10 g/dL or less had no significant differences in complications or mortality as compared with patients with an Hgb of greater than 10 g/dL. In this study, lower hemoglobin levels did not confer greater risk for worse outcomes.

Provision of nutrition support therapies in the recent Iraq and Afghanistan conflicts

This article describes the experience of nutrition support practitioners, specifically dietitians, providing care to combat casualties. It provides a brief overview of dietitians' induction into armed service but focuses primarily on their role in providing nutrition support during the most recent conflicts in Iraq and Afghanistan. The current system of combat casualty care is discussed with specific emphasis on providing early and adequate nutrition support to U.S. combat casualties from injury, care in theater combat support hospitals (CSHs)/expeditionary medical support (EMEDs), and en route care during critical care air transport (CCAT) up to arrival at treatment facilities in the United States. The article also examines practices and challenges faced in the CSHs/EMEDs providing nutrition support to non-U.S. or coalition patients. Over the past decade in armed conflicts, dietitians, physicians, nurses, and other medical professionals have risen to challenges, have implemented systems, and continue working to optimize treatment across the spectrum of combat casualty care.

Aeromedical evacuation of combat patients by military critical care air transport teams with a lower hemoglobin threshold approach is safe

BACKGROUND

Military critical care air transport teams (CCATT) evacuate critically ill and injured patients out of theater for tertiary treatment. Teams are led by a physician, nurse, and respiratory technician. Current aeromedical guidelines require a hemoglobin (Hgb) of 9 g/dL or greater to evacuate; however, civilians report that an Hgb of 8 g/dL or less is safe in critically ill patients. This study aimed to compare postflight short-term and 30-day patient outcomes for CCATT patients evacuated out of theater with an Hgb of 8 g/dL or less with those with an Hgb of greater than 8 g/dL.

METHODS

We conducted a retrospective record review of all traumatically injured patients evacuated from theater by CCATT between March 2007 and December 2011. We recorded demographics, injury descriptions, vital signs, laboratory values, adverse events, and disposition at 30 days. Patients were separated into those with a preflight Hgb of 8 g/dL or less versus those with greater than 8 g/dL. Continuous data were analyzed using Student's t tests or Wilcoxon tests and reported as mean ± SD. χ or Fisher's exact tests were performed. Stepwise, multifactorial logistic regression models were used. Statistical significance was considered with p < 0.05.

RESULTS

Of 1,252 patients, 1,033 had a preflight Hgb of greater than 8 and 219 had an Hgb of 8 or less. Age, sex proportions, vitals, laboratory values, and Injury Severity Score (ISS; 24±13) were similar. The group with 8 or less had more blast injuries (68% vs. 76%, p = 0.01). No associations were identified between preflight Hgb levels and adverse outcomes. Disposition at 30 days was similar. We also compared preflight Hgb greater than 7 versus 7 or less (n = 1,212 vs. 45). Those with an Hgb greater than 7 had a greater incidence of hospitalization at 30 days (77% vs. 67%, p = 0.04). The group with an Hgb of 7 or less had more subjects discharged home or returning to duty (10% vs. 21%, p = 0.04).

CONCLUSION

Evacuating CCATT patients with an Hgb of 8 or less had similar adverse outcomes and mortality at 30 days compared with those with an Hgb greater than 8. Patients with an Hgb of 7 or less had higher rates of hospital discharge and decreased incidence of hospitalization at 30 days.

LEVEL OF EVIDENCE

Prognostic/epidemiologic study, level III.