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

Management of Combat Casualties during Aeromedical Evacuation from a Role 2 to a Role 3 Medical Facility

INTRODUCTION

Emergent clinical care and patient movements through the military evacuation system improves survival. Patient management differs when transporting from the point-of-injury (POI) to the first medical treatment facility (MTF) versus transporting from the Role 2 to the Role 3 MTF secondary to care rendered within the MTF, including surgery and advanced resuscitation. The objective of this study was to describe care provided to patients during theater inter-facility transports and compare with pre-hospital transports (POI to first MTF).

MATERIALS AND METHODS

We performed a retrospective chart review of patients with the Role 2 to the Role 3 transports in Afghanistan and Iraq from 2007 to 2016. Data collected included procedures and events at the MTF and during transport. We compared the intra-theater transport data (Role 2 to Role 3) to data from a previous study evaluating pre-hospiital transports (POI to first MTF).

RESULTS

We reviewed the records of 869 Role 2 to Role 3 transport patients. Role 2 to Role 3 transports were longer in duration compared to POI transports (39 minutes vs. 23 minutes) and were more likely to be staffed by advanced personnel (nurses, physician assistants, and physicians) (57% vs. 3%). The sample primarily consisted of military-aged males (mean age 27 years) who suffered from explosive or blunt force injuries. Procedures performed during each phase of care reflected the capabilities of the teams and locations. Pain and cardiac events were more common in POI evacuations compared to the Role 2 to Role 3 transports, but documentation of respiratory events, hemodynamic events, neurologic events, and equipment failure was more common during the Role 2 to Role 3 transports. Survival rates were slightly higher among the Role 2 to Role 3 cohort (98% vs. 95%, difference 3% [95% confidence interval of the difference 1-5%]).

CONCLUSIONS

Inter-facility transports (Role 2 to Role 3) are longer in duration, transport more complex patients, and are staffed by more advanced level provider types compared to transports from POI.

Emergency critical care: closing the gap between onset of critical illness and intensive care unit admission

Critical illness is an exquisitely time-sensitive condition and follows a disease continuum, which always starts before admission to the intensive care unit (ICU), in the majority of cases even before hospital admission. Reflecting the common practice in many healthcare systems that critical care is mainly provided in the confined areas of an ICU, any delay in ICU admission of critically ill patients is associated with increased morbidity and mortality. However, if appropriate critical care interventions are provided before ICU admission, this association is not observed. Emergency critical care refers to critical care provided outside of the ICU. It encompasses the delivery of critical care interventions to and monitoring of patients at the place and time closest to the onset of critical illness as well as during transfer to the ICU. Thus, emergency critical care covers the most time-sensitive phase of critical illness and constitutes one missing link in the chain of survival of the critically ill patient. Emergency critical care is delivered whenever and wherever critical illness occurs such as in the pre-hospital setting, before and during inter-hospital transfers of critically ill patients, in the emergency department, in the operating theatres, and on hospital wards. By closing the management gap between onset of critical illness and ICU admission, emergency critical care improves patient safety and can avoid early deaths, reverse mild-to-moderate critical illness, avoid ICU admission, attenuate the severity of organ dysfunction, shorten ICU length of stay, and reduce short- and long-term mortality of critically ill patients. Future research is needed to identify effective models to implement emergency critical care systems in different healthcare systems.

Reported adverse events during out-of-hospital mechanical ventilation and ventilatory support in emergency medical services and critical care transport crews: a systematic review

Background

Emergency medical services (EMS) and critical care transport crews constantly face critically-ill patients who need ventilatory support in scenarios where correct interventions can be the difference between life and death; furthermore, challenges like limited staff working on the patient and restricted spaces are often present. Due to these, mechanical ventilation (MV) can be a support by liberating staff from managing the airway and allowing them to focus on other areas; however, these patients face many complications that personnel must be aware of.

Aims

To establish the main complications related to out-of-hospital MV and ventilatory support through a systematic review.

Methodology

PubMed, BVS and Scopus were searched from inception to July 2021, following the PRISMA guidelines; search strategy and protocol were registered in PROSPERO. Two authors carried out an independent analysis of the articles; any disagreement was solved by mutual consensus, and data was extracted on a pre-determined spreadsheet. Only original articles were included, and risk of bias was assessed with quality assessment tools from the National Institutes of Health.

Results

The literature search yielded a total of 2,260 articles, of which 26 were included in the systematic review, with a total of 9,418 patients with out-of-hospital MV; 56.1% were male, and the age ranged from 18 to 82 years. In general terms of aetiology, 12.2% of ventilatory problems were traumatic in origin, and 64.8% were non-traumatic, with slight changes between out-of-hospital settings. Mechanical ventilation was performed 49.2% of the time in prehospital settings and 50.8% of the time in interfacility transport settings (IFTS). Invasive mechanical ventilation was used 98.8% of the time in IFTS while non-invasive ventilation was used 96.7% of the time in prehospital settings. Reporting of adverse events occurred in 9.1% of cases, of which 94.4% were critical events, mainly pneumothorax in 33.1% of cases and hypotension in 27.6% of cases, with important considerations between type of out-of-hospital setting and ventilatory mode; total mortality was 8.4%.

Conclusion

Reported adverse events of out-of-hospital mechanical ventilation vary between settings and ventilatory modes; this knowledge could aid EMS providers in promptly recognizing and resolving such clinical situations, depending on the type of scenario being faced.

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.

Interfacility Transport of Critically Ill Patients

OBJECTIVES

To assess recent advances in interfacility critical care transport.

DATA SOURCES

PubMed English language publications plus chapters and professional organization publications.

STUDY SELECTION

Manuscripts including practice manuals and standard (1990-2021) focused on interfacility transport of critically ill patients.

DATA EXTRACTION

Review of society guidelines, legislative requirements, objective measures of outcomes, and transport practice standards occurred in work groups assessing definitions and foundations of interfacility transport, transport team composition, and transport specific considerations. Qualitative analysis was performed to characterize current science regarding interfacility transport.

DATA SYNTHESIS

The Task Force conducted an integrative review of 496 manuscripts combined with 120 from the authors' collections including nonpeer reviewed publications. After title and abstract screening, 40 underwent full-text review, of which 21 remained for qualitative synthesis.

CONCLUSIONS

Since 2004, there have been numerous advances in critical care interfacility transport. Clinical deterioration may be mitigated by appropriate patient selection, pretransport optimization, and transport by a well-resourced team and vehicle. There remains a dearth of high-quality controlled studies, but notable advances in monitoring, en route management, transport modality (air vs ground), as well as team composition and training serve as foundations for future inquiry. Guidance from professional organizations remains uncoupled from enforceable regulations, impeding standardization of transport program quality assessment and verification.

Influence of Critical Care Transport Ventilator Management on Intensive Care Unit Care

OBJECTIVE

High tidal volume ventilation is associated with ventilator-induced lung injury. Early introduction of lung protective ventilation improves patient outcomes. This study describes ventilator management during critical care transport and the association between transport ventilator settings and ventilator settings in the intensive care unit (ICU).

METHODS

This was a retrospective review of mechanically ventilated adult patients transported to an academic medical center via a critical care transport program between January 2018 and April 2019. Ventilator settings during transport were compared with the initial and 6- and 12-hour postadmission ventilator settings.

RESULTS

Three hundred eighty patients were identified; 114 (30%) received tidal volumes > 8 mL/kg predicted body weight at the time of transfer. The transport handoff tidal volume strongly correlated with the ICU tidal volume (Pearson r = 0.7). Patients receiving high tidal volumes during transport were more likely to receive high tidal volumes initially upon transfer (relative risk [RR] = 4.6; 95% confidence interval [CI], 3.3-6.5) and at 6 and 12 hours after admission (RR = 2.6; 95% CI, 1.8-3.8 and RR = 2.7; 95% CI, 1.7-4.3, respectively).

CONCLUSION

Exposure to high tidal volumes during transport is associated with high tidal volume ventilation in the ICU, even up to 12 hours after admission. This study identifies opportunities for improving patient care through the application of lung protective ventilation strategies during transport.

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.

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.

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.

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.

Incidence of Hyperoxia in Combat Wounded in Iraq and Afghanistan: A Potential Opportunity for Oxygen Conservation

INTRODUCTION

Oxygen supplementation is frequently used in critically injured trauma casualties in the combat setting. Oxygen supplies in the deployed setting are limited so excessive use of oxygen may unnecessarily consume this limited resource. We describe the incidence of supraphysiologic oxygenation (hyperoxia) within casualties in the Department of Defense Trauma Registry (DoDTR).

METHODS

This is a subanalysis of previously published data from the DoDTR - we isolated casualties with a documented arterial blood gas (ABG) and categorized hyperoxia as an arterial oxygen >100 mmHg and extreme hyperoxia > 300 mmHg (a subset of hyperoxia). We defined serious injuries as those with an Abbreviated Injury Score (AIS) of 3 or greater. We defined a probable moderate traumatic brain injury of those with an AIS of 3 or greater for the head region and at least one Glasgow Coma Scale at 8 or less.

RESULTS

Our initial search yielded 28,222 casualties, of which 10,969 had at least one ABG available. Within the 10,969, the proportion of casualties experiencing hyperoxia in this population was 20.6% (2,269) with a subset of 4.1% (452) meeting criteria for extreme hyperoxia. Among those with hyperoxia, the median age was 25 years (IQR 21-30), most were male (96.8%), most frequently US forces (41.4%), injured in Afghanistan (68.3%), injured by explosive (61.1%), with moderate injury scores (median 17, IQR 10-26), and most (93.8%) survived to hospital discharge. A total of 17.8% (1,954) of the casualties underwent endotracheal intubation: 27.5% (538 of 1,954) prior to emergency department (ED) arrival and 72.5% (1,416 of 1,954) within the ED. Among those intubated in the prehospital setting, upon ED arrival 35.1% (189) were hyperoxic, and a subset of 5.6% (30) that were extremely hyperoxic. Among those intubated in the ED, 35.4% (502) were hyperoxic, 7.9% (112) were extremely hyperoxic. Within the 1,277 with a probable TBI, 44.2% (565) experienced hyperoxia and 9.5% (122) met criteria for extreme hyperoxia.

CONCLUSIONS

In our dataset, more than 1 in 5 casualties overall had documented hyperoxia on ABG measurement, 1 in 3 intubated casualties, and almost 1 in 2 TBI casualties. With limited oxygen supplies in theater and logistical challenges with oxygen resupply, efforts to avoid unnecessary oxygen supplementation may have material impact on preserving this scarce resource and avoid potential detrimental clinical effects from supraphysiologic oxygen concentrations.

Resuscitation and Evacuation from Low Earth Orbit: A Systematic Review

INTRODUCTION

Provision of critical care and resuscitation was not practical during early missions into space. Given likely advancements in commercial spaceflight and increased human presence in low Earth orbit (LEO) in the coming decades, development of these capabilities should be considered as the likelihood of emergent medical evacuation increases.

METHODS

PubMed, Web of Science, Google Scholar, National Aeronautics and Space Administration (NASA) Technical Server, and Defense Technical Information Center were searched from inception to December 2018. Articles specifically addressing critical care and resuscitation during emergency medical evacuation from LEO were selected. Evidence was graded using Oxford Centre for Evidence-Based Medicine guidelines.

RESULTS

The search resulted in 109 articles included in the review with a total of 2,177 subjects. There were two Level I systematic reviews, 33 Level II prospective studies with 647 subjects, seven Level III retrospective studies with 1,455 subjects, and two Level IV case series with four subjects. There were two Level V case reports and 63 pertinent review articles.

DISCUSSION

The development of a medical evacuation capability is an important consideration for future missions. This review revealed potential hurdles in the design of a dedicated LEO evacuation spacecraft. The ability to provide critical care and resuscitation during transport is likely to be limited by mass, volume, cost, and re-entry forces. Stabilization and treatment of the patient should be performed prior to departure, if possible, and emphasis should be on a rapid and safe return to Earth for definitive care.