Resuscitative endovascular balloon occlusion of the aorta in combat and austere environments

Abstract

BACKGROUND

Non-compressible torso hemorrhage (NCTH) is a leading cause of preventable death in austere environments. Extended evacuation times prioritize far-forward hemorrhage control. Resuscitative endovascular balloon occlusion of the aorta (REBOA) preserves proximal perfusion, shifting from specialized centers to prehospital combat settings.

AIM

To investigate the feasibility, safety, and clinical outcomes of REBOA for NCTH in combat and austere environments.

METHODS

A PRISMA-ScR-guided scoping review searched five databases, with reference-list screening of included studies and key reviews, of humans receiving REBOA for NCTH in combat, prehospital, or austere environments. Two independent reviewers extracted patient characteristics, procedural parameters, and clinical outcomes. Quality was assessed via Joanna Briggs Institute tools and the Newcastle-Ottawa Scale.

RESULTS

From 1138 records, 8 studies, met criteria: 35 individually reported cases and 15 eligible cases from one registry cohort, of 50. Because the registry reported aggregate data only, all denominators below refer to the 35 individually reported cases. Casualties were predominantly young men in severe hemorrhagic shock after penetrating or blast injury. Access was via the common femoral artery, percutaneous in 23 of 35 (65.7%), with the balloon in zone 1 in 31 of 35 (88.6%). Survival to transfer or discharge was 91.4% (32 of 35); crude mortality was 8.6% (3 of 35). Complications were access-site thrombosis or limb ischemia in 4 of 35 (11.4%), one balloon rupture, and one reperfusion-related acute kidney injury.

CONCLUSION

REBOA has been utilized in select combat and austere casualties, demonstrating hemodynamic improvement. However, this uncontrolled evidence precludes conclusions regarding efficacy or superiority, thereby not supporting its routine clinical deployment.

Key Words: Resuscitative endovascular balloon occlusion of the aorta; Combat trauma; Austere environment; Non-compressible torso hemorrhage; Prehospital hemorrhage control; Hemorrhagic shock

Core Tip: In austere and combat environments, non-compressible torso hemorrhage presents a critical challenge due to prolonged evacuation times and limited resources. Resuscitative endovascular balloon occlusion of the aorta has been increasingly described in these settings as an adjunctive intervention. This scoping review maps the current evidence on its use across diverse operational contexts, including prehospital and military care. However, available data are limited, heterogeneous, uncontrolled, and predominantly observational, highlighting variability in practice and important knowledge gaps that warrant further structured investigation.

INTRODUCTION

Non-compressible torso hemorrhage (NCTH) remains a leading cause of potentially preventable death in both civilian and military austere environments[1,2]. In modern combat scenarios and disaster settings, the traditional concept of the “golden hour” for delivering casualties to definitive damage control surgery is often unfeasible due to extended evacuation times, geographical barriers, and logistical constraints[3,4]. Consequently, the need for effective, far-forward hemorrhage control interventions has become a critical priority for military medicine[5].

To address this challenge, resuscitative endovascular balloon occlusion of the aorta (REBOA) has emerged as a minimally invasive, life-saving adjunct[6]. First introduced during the Korean War[7] and further investigated in early animal models[8], REBOA involves the percutaneous insertion of a balloon catheter into the aorta to temporarily occlude blood flow distal to the balloon[7,8]. This technique effectively mitigates distal exsanguination and preserves proximal perfusion to the heart and brain until definitive surgical hemostasis can be achieved[9,10].

Recent technological advancements, such as the development of lower-profile, fluoroscopy-free catheters, have facilitated the introduction of this technology from specialized civilian trauma centers to pre-hospital and combat casualty care/military settings[11,12].

Case series from recent conflicts, including operations by Special Operations Surgical Teams and applications in rotary-wing platforms, have demonstrated that REBOA can be successfully deployed in austere environments to stabilize patients with severe NCTH[13-15]. Furthermore, to reduce the risks of ischemia-reperfusion injury associated with the complete aortic occlusion, more recent strategies such as partial REBOA (pREBOA) and intermittent occlusion are currently being explored to avoid those complications, extending the safe window of occlusion during prolonged field care[3,16].

In spite of emergent clinical reports, the implementation of prehospital REBOA in military settings and austere environments still faces difficulties, including the need for specialized training, challenging arterial access in shocked patients and a lack of standardized international guidelines[5,17]. Therefore, understanding the feasibility, safety and operational outcomes of REBOA across those domains remains a pivotal area of ongoing research and clinical development[2,18].

Existing systematic reviews have attempted to evaluate the effectiveness of prehospital REBOA; however, the available evidence is limited to small, heterogeneous, and predominantly descriptive studies, precluding meaningful comparative or causal inference. Therefore, a scoping review is more appropriate to comprehensively map the current evidence base, characterize operational practices, and identify key knowledge gaps across diverse austere and combat settings[17].

The primary goal of this scoping review is to systematically identify, map, and synthesize existing literature regarding the use of REBOA in combat, military, disaster, and austere environments. This includes settings such as forward-deployed surgical facilities (role 1, role 2, or equivalent), humanitarian missions, and isolated or resource-constrained regions. Specifically, the reviewers seek to answer: “What is known about the use of REBOA for the management of hemorrhage in combat, disaster, and austere environments?”.

MATERIALS AND METHODS

Study design and methodological framework

This study was conducted as a scoping review following the methodological guidance of the Joanna Briggs Institute (JBI) for scoping reviews[19]. Reporting followed the Preferred Reporting Items for Systematic Reviews and Meta-Analyses Extension for Scoping Reviews (PRISMA-ScR)[20]. A scoping review design was selected to map the extent, nature, and characteristics of the available evidence on the use of REBOA in combat and austere environments, and to identify existing knowledge gaps.

Protocol and registration

The review protocol was prospectively registered in the Open Science Framework[21]. Any deviations from the protocol were minor and related to refinement of database-specific search strategies, without changes to the review objectives or eligibility criteria.

Review question and population-concept-context framework

In accordance with the JBI recommendations for scoping reviews, the review question was structured using the population-concept-context framework[19]. The population of interest included military personnel and civilians presenting with NCTH or hemorrhagic shock. The concept focused on the use of REBOA, including both partial and complete aortic occlusion across any anatomical zone. The context encompassed combat, prehospital, disaster, and other austere environments, including forward-deployed care settings such as role 1 and role 2 facilities, aeromedical evacuation platforms, and resource-constrained regions.

Eligibility criteria

All original studies reporting the use of REBOA in human patients within combat, austere, prehospital, or disaster environments were eligible for inclusion, including forward-deployed settings such as role 1 and role 2 facilities. Eligible study designs comprised randomized controlled trials, prospective and retrospective observational studies, case series, and case reports reporting clinical data. For the purposes of this scoping review, REBOA was considered eligible when applied in out-of-hospital or resource-constrained environments prior to arrival at definitive surgical care, regardless of occlusion strategy (partial or complete) or anatomical zone. Studies conducted exclusively in in-hospital settings (role 3 or higher), animal or cadaveric models, and simulation-based studies without clinical data were excluded. Eligibility was determined by the setting in which REBOA was deployed, not by the setting of subsequent definitive care. Systematic, scoping, and narrative reviews were screened for mapping purposes and reference tracking but were not used as sources of primary clinical data. Editorials, commentaries, and conference abstracts without full-text data were also excluded. Studies focusing on non-traumatic or non-hemorrhagic indications were not considered. No restrictions were applied regarding publication year, language, or patient age; when necessary, translation was supported by bilingual reviewers or artificial intelligence-assisted tools with human verification.

Operational definitions

The following definitions were adopted for the methodological development of the article (Supplementary Table 1).

Information sources and search strategy

A comprehensive literature search was performed in PubMed/MEDLINE, EMBASE, Web of Science, Scopus and the Cochrane Library. Searches were conducted using a combination of controlled vocabulary (e.g., Medical Subject Heading and Emtree) and free-text terms appropriate to each database, and database-specific search strategies were developed to account for differences in indexing systems and search interfaces according to the PRISMA-ScR[20]. In line with JBI guidance for scoping reviews, the search process was iterative, with refinement of search terms and strategies occurring as familiarity with the literature increased[19]. The complete electronic search strategies for all databases are provided in the Supplementary material. The last search was conducted in March of 2026. In addition, reference lists of included studies and key reviews were manually screened to identify additional relevant publications.

Selection of sources of evidence

All retrieved records were imported into reference management software for deduplication using Zotero. Prior to formal screening, the reviewers conducted an initial calibration exercise to ensure consistent application of the eligibility criteria. Records were then uploaded to the Rayyan platform to facilitate study screening. Titles and abstracts were independently screened by two reviewers. When abstracts were unavailable, full-text articles were screened to determine eligibility. Full texts of potentially eligible studies were subsequently assessed for inclusion. Disagreements at any stage were resolved by discussion between the two reviewers, with adjudication by a third reviewer when consensus could not be reached, in accordance with JBI guidance[19]. The study selection process is summarized in a PRISMA-ScR flow diagram. Where more than one report described the same patient cohort, the most comprehensive report was retained as the index source and the overlapping reports were not counted separately, to avoid double-counting of patients. Potential overlap was assessed by comparing authorship, operational program, deployment period, and reported case details.

Data charting process and data items

Data charting was performed using a standardized and pilot-tested form, consistent with JBI scoping review methodology, and conducted in an iterative manner, allowing refinement of data items as familiarity with the evidence increased. Data were charted independently by two reviewers and cross-checked for accuracy. Charted variables included study design, patient characteristics (including age and mechanism of injury), clinical setting and level of care, indication for REBOA, procedural details (including vascular access, occlusion zone, and duration of occlusion), operator background, and transport characteristics. Outcomes were charted at the last time point reported by each source. Where a source reported survival only to transfer, no later outcome was assumed and none was imputed. No case was excluded for missing outcome data.

Critical appraisal of individual sources of evidence

Although critical appraisal is not mandatory in scoping reviews, an assessment of methodological quality was conducted to contextualize the available evidence. Methodological quality was evaluated independently by two reviewers, with disagreements resolved by consensus and adjudication by a third reviewer when necessary. Observational studies were assessed using the Newcastle-Ottawa Scale (NOS), while case series and case reports were evaluated using JBI critical appraisal tools[19,22]. Reports describing one or two individually presented patients were appraised with the JBI checklist for case reports, and reports presenting a series of three or more patients with the JBI checklist for case series. The registry-based cohort was appraised with the NOS; because this cohort was single-arm and had no comparison group, the item on selection of the non-exposed cohort and the two comparability stars could not be awarded. Item-level ratings for every included study are presented in Supplementary Table 2. The results of the quality assessment were not used to determine study eligibility or to weight findings, but rather to provide descriptive context regarding methodological characteristics and potential limitations of the included studies. The inherent limitations of these tools, including constraints related to applicability across heterogeneous study designs and the use of summary scoring systems, were acknowledged.

Synthesis of results

Results were synthesized descriptively. No quantitative synthesis or meta-analysis was performed, as the aim of this scoping review was to map the breadth and characteristics of the available evidence rather than to generate pooled effect estimates, and due to substantial heterogeneity in study designs, populations, settings, and reported outcomes. Data were grouped according to environment type, level of care, and reported outcomes. Findings are presented narratively and in tabular form to describe the existing evidence and identify knowledge gaps across diverse austere and combat settings.

RESULTS

From all the 1138 studies that appeared in the databases, after deduplication, a total of 878 were screened by title and abstract. Seven articles were excluded due to insufficient data, ineligible study design, or settings outside the scope of this review[23]. Only 17 studies were selected for full-text review and 8[4,10,13-15,18,24,25] met the inclusion criteria, as demonstrated in the PRISMA-ScR diagram (Figure 1). Two further reports were excluded from separate counting because they described patients already captured by a larger included series, as detailed below. All articles selected for this review are published and complete. Regarding risk of bias assessment, no study was excluded on quality grounds. Case reports scored 7 to 8 of 8 points and case series 7 to 8 of 10 points on the relevant JBI checklists. The registry-based cohort scored 6 of 9 stars on the NOS; the three unawarded stars correspond to the selection item on the non-exposed cohort and the two comparability stars, none of which can be applied to a single-arm design. Item-level ratings for each study, including the individual criteria met, are presented in Supplementary Table 2. The baseline characteristics of the included studies are displayed in Supplementary Table 3.

Figure 1 Flowchart of study selection. The flowchart illustrates the process of selecting studies for the scoping review.

A total of 50 cases were included in this scoping review: 35 individually reported cases across seven studies and 15 eligible cases from the registry-based cohort. Patients were predominantly young men in severe hemorrhagic shock following penetrating or blast injuries, aged 18 years to 54 years in the individually reported cases[4,10,13-15,24,25]; the registry cohort reported 88% male sex (15 of 17) and a median age of 21 years (interquartile range: 21-31) in the totality of the cohort, no specifying for the 15 included patients[18]. The main outcomes are displayed in Supplementary Table 4. For case series comprising up to three patients, individual case data were detailed within a single cell. For studies including more than three cases, the reported vital signs and continuous variables were presented as ranges. The majority of the literature consists of case reports[4,14,25] and limited case series[10,15,24]. Additionally, the data includes one retrospective registry-based study[18] and one larger retrospective case series[13].

Because the registry-based cohort[18] reports only aggregate data, all procedural, complication and outcome denominators below refer to the 35 individually reported cases from the seven non-registry studies unless otherwise stated. Two reports by Manley et al[12] and Manley et al[26] described casualties treated by the same United States Air Force Special Operations Surgical Team, whose complete twenty-patient experience was subsequently reported by Northern et al[13]. The four cases reported by Manley et al[12] and the two cases in the later report by the same group[26] share authorship, operational program, and overlapping deployment periods with that series, and the later report explicitly refers to a cumulative team total of twenty REBOA cases. Because these six cases are very likely already represented within the series of Northern et al[13], counting them separately would double-count the same patients. We therefore retained Northern et al[13] as the index source for this cohort and did not include the two reports by Manley et al[12] and Manley et al[26] in the study count, patient tally, baseline and outcome tables, or critical appraisal. This yielded a final total of 8 studies and 50 reported cases.

The registry-based cohort reported by Taheri et al[18] was assessed separately. Its 17 cases were the only REBOA placements identified in a query of the Department of Defense Trauma Registry covering 2007 to 2023, and all occurred from 2017 to 2019; this total is smaller than the single series of Northern et al[13] alone. Twelve of the 17 registry patients (70%) were local civilians, whereas the included case series describe combatant casualties. Patient-level overlap could not be formally excluded, as registry records are de-identified and the registry authors acknowledge this possibility themselves; any such overlap is nevertheless bounded by the five non-civilian cases (two United States military and three partner-force casualties), and the cohort was therefore retained. Of the 17 cases, 15 (88%) had REBOA placed at a role 2 facility and 2 (12%) at a role 3 facility, so only the 15 role 2 cases met the setting criterion of this review.

Sample sizes varied substantially across the included literature based on the study design. Individual case reports and smaller case series described the use of REBOA in cohorts ranging from 1 patient to 5 patients[4,10,14,15,24,25]. The largest retrospective case series reported 20 patients[13], and the registry-based cohort reported 17 cases, of which 15 were eligible[18].

The studied populations predominantly consisted of military personnel, partner forces, and combatants injured in austere, out-of-hospital, or deployed combat environments[4,10,13-15,18,24,25]. A smaller proportion of the literature reported on local civilians treated at military facilities[18].

Facility type

REBOA interventions were performed across the full gradient of forward care, as defined in Supplementary Table 1 and assigned study-by-study in Supplementary Table 2. In settings without surgical capability, the balloon was deployed at a forward military stabilization point[4], at a tactical casualty collection point[10], and during en route rotary-wing aeromedical evacuation[14]. At the first echelons of care, occlusion was performed by surgeons working in role 1 stabilization centers and forward surgical teams[24], by a Special Operations Surgical Team functioning as a mobile forward surgical unit that received casualties directly from the battlefield[13], and at role 2 military treatment facilities[15,18,25]. In every included study, REBOA was deployed at or before the first echelon with surgical capability, and no included case involved aortic occlusion performed at role 3 or higher. Definitive damage control and vascular repair were subsequently performed at role 2 or role 3 facilities following evacuation[13,15,18,24,25]. A subset of the literature reported on local civilian trauma populations treated at military facilities[18].

Mechanism and severity

The predominant mechanisms of injury were penetrating trauma and blast injuries sustained in combat, including gunshot wounds, artillery splinters, and improvised explosive devices[4,10,13-15,18,24,25]. Severe blunt trauma, primarily from motor vehicle collisions, was exceedingly rare and only observed in a small percentage of cases within a registry cohort[18]. The patient populations represented critically wounded individuals. In one case series, it was reported that the Injury Severity Score ranged from 20 points to 66 points[10]. In the Taheri et al’s cohort[18], it was reported an Injury Severity Score of 24-41 (interquartile range), for all the 17 patients, not being able to identify this value for the 15 patients considered for this study.

Obvious and assumed injuries

Casualties primarily presented with NCTH originating from the abdomen and pelvis, which was assumed due to mechanism and shock state[4,10,13,15,18,24,25]. External examinations routinely revealed obvious injuries such as traumatic extremity amputations, mangled limbs, and open fractures[4,10,13,15,25]. Significant associated injuries frequently included traumatic brain injuries[14], significant pelvic ring disruptions[10,15,24], and massive multisystem trauma involving solid organs and major vascular structures[4,13,15,18,24,25].

Pre-hospital status

Patients consistently presented in hemorrhagic shock. Pre-insertion systolic blood pressures were routinely recorded as unmeasurable or critically depressed, ranging widely from 45 mmHg to 90 mmHg prior to aortic occlusion[4,10,13-15,24,25]. Traumatic cardiac arrest either immediately before or during the REBOA insertion was reported in the most critically exsanguinating cohorts, necessitating aggressive resuscitative measures or external cardiac massage prior to successful balloon inflation[14,15,24].

Meaningful pre-hospital interventions

Besides endovascular occlusion, a variety of mechanical and physiological interventions was employed to mitigate bleeding and stabilize the airway. The application of combat tourniquets was predominant for managing compressible junctional and extremity hemorrhage[4,25]. Definitive airway management via endotracheal intubation or surgical cricothyroidotomy was frequently performed[10,14,24]. Other documented meaningful interventions included single or bilateral chest drains[15] and the early administration of tranexamic acid[4,10,24].

Prehospital volume resuscitation and use of blood

Hemostatic resuscitation protocols heavily emphasized blood products over crystalloids. While low-volume crystalloid administration (50-500 mL) occurred in some isolated instances[4,10,24], massive transfusion protocols were standard. The transfusion of fresh or cold-stored whole blood was prioritized, especially within military settings[10,13-14,18,24]. Blood component therapy was also utilized, with packed red blood cells and liquid/fresh frozen plasma[4,10,13,15,24,25].

Technical analysis

REBOA was most commonly deployed via the common femoral artery with balloon placement in aortic zone 1 in approximately 88.6% (31 of 35) of the specifically detailed cases[4,10,13-15,24,25]. Initial vascular access was established using percutaneous techniques in 23 of 35 cases, approximately 65.7% of cases, primarily via portable ultrasound guidance with micro-introducer needles, or via open surgical cutdowns in 12 of 35 cases, approximately 34.3% of cases when percutaneous attempts failed or were bypassed, relying on external anatomical landmarks and ultrasound[4,10,13-15,24,25].

Catheter and sheath sizes varied, with the 7-Fr ER-REBOA™^® (Prytime) being the most widely utilized device across case series[10,13-14,25]. Other modern devices included the 4-Fr COBRA-OS^® and the 7-Fr pREBOA-PRO™^® for partial occlusion[4,24]. Other deployed cohorts described using 7-Fr Rescue Balloons or 10-Fr MIT devices[15]. The balloon was most frequently deployed initially in aortic zone 1 (31 cases) to control abdominal exsanguination. Zone 3 was used, either as the initial position (4 cases) or by repositioning from zone 1, for isolated severe pelvic and lower-extremity trauma[13,15,24,25].

To reduce ischemic burden during extended evacuations, practitioners successfully utilized advanced balloon management techniques, including partial and intermittent occlusion[4,10,13,14]. Individual occlusion episodes ranged from 7 minutes to 55 minutes[4,13]. The longest single episode comprised 5 minutes of complete followed by 50 minutes of partial zone 1 occlusion during transport[4]. In one casualty, a 40-minute zone 1 occlusion was followed, after a period of reperfusion, by a further 25-minute zone 3 occlusion, giving 65 minutes of aortic occlusion in total[15]. Subsequently, they were removed at more complex facilities, most commonly via open arteriotomy repair, manual compression, or the fascia suture technique[10,13,15,24,25].

Major outcome, survival rate and mortality

Survival was reported using two different endpoints across the included studies, and we therefore report them separately rather than as a single pooled figure. Two studies followed casualties only until handover to the next echelon of care and reported survival to transfer: The 20 patients of Northern et al[13] and the 3 of de Schoutheete et al[10], all of whom were evacuated alive (23 of 23). The remaining five studies reported survival to discharge or at 30 days, covering 12 patients[4,14,15,24,25]; 9 of these 12 survived (75.0%). Three deaths occurred, all in this group: One patient in Reva et al[15] delivered in clinical death, one in Gumeniuk et al[24] following delayed evacuation and massive hemorrhage, and one in Brown et al[14] who deteriorated from a primary gunshot wound to the head.

Combining both endpoints as a composite of survival to transfer or discharge, 32 of the 35 individually reported cases survived (91.4%), and crude mortality was 8.6% (3 of 35). Study-level mortality was 0% in Akrish et al[4], de Schoutheete et al[10], Northern et al[13] and Knipp et al[25]; 20% (1 of 5) in Gumeniuk et al[24]; 33.3% (1 of 3) in Reva et al[15]; and 100% (1 of 1) in the single case reported by Brown et al[14]. Because survival to transfer and survival to discharge are not equivalent endpoints, the composite figure should be read as the proportion of cases surviving to the last time point reported by each source, not as a discharge survival rate. No case had a missing or unclear outcome at the endpoint reported by its source, and where a source reported only survival to transfer, no later outcome was imputed.

In the registry-based study by Taheri et al[18], survival to hospital discharge was reported in 14 of the 17 registry cases (82.4%), corresponding to 3 deaths (17.6%). Outcomes were not reported by role of care, so the corresponding figure for the 15 eligible role 2 cases cannot be isolated. Mortality across the scoping review was most frequently attributed to massive exsanguination, delayed evacuation, severe traumatic brain injuries, and secondary asystole[14,15,24].

Transport time

Evacuation times from the initial balloon inflation to the next definitive tier of surgical care were inconsistent due to the battlefield environment, while the time from injury to first evaluation also varied widely across settings. Rapid aeromedical or ground transfers enabled some casualties to be evaluated within 15 minutes to 27 minutes of injury, whereas delayed evacuations before or during resuscitation extended to two hours or more, and up to 4.5 hours in the most prolonged cases[4,10,13-15,24,25].

Individual outcome and complications

Individuals that survived transportation subsequently underwent surgical approaches, including exploratory laparotomies, pelvic packing, decompressive craniectomies, right groin explorations, and definitive vascular repairs[4,13-15,24]. Femoral artery thrombosis and acute limb ischemia were the most common complications, documented in 4 of 35 clinical patients (11.4%)[10,24,25]. An another and further case of femoral artery thrombosis was reported by Reva et al[15], but occurred in the common femoral artery contralateral to the access site, being injury-related and not related to the vascular access. These access-site events occurred in two patients in de Schoutheete et al[10] (one intraoperatively and one secondary to post-evacuation suture error), one in Gumeniuk et al[24] managed via surgical thrombectomy, and one in Knipp et al[25] where popliteal artery embolism in a casualty receiving 183 blood products necessitated a below-knee amputation. Device-related failure was limited to a single suspected balloon rupture from over-inflation in zone 3[13]. Systemically, one patient in Reva et al[15] developed severe ischaemia-reperfusion syndrome and acute kidney injury requiring 30 days of haemodialysis, secondary to the contralateral arterial injury rather than aortic occlusion. No REBOA-associated infectious, local access-site infection, or distal venous embolic complications were documented. These outcomes and REBOA deployment associated complications are also reported in Supplementary Table 4.

DISCUSSION

The findings of this review indicate that REBOA has been used, with encouraging short-term results, in selected casualties with life-threatening NCTH in austere and combat environments. The evidence consists of case reports, case series, and a single registry-based cohort with no comparison between REBOA and an alternative resuscitative strategy. These reports establish that REBOA can be performed far forward and that hemodynamic improvement was commonly observed after balloon inflation, without conclusions about efficacy, or about superiority over other methods of hemorrhage control. Casualties were selected individually by the treating teams, and favorable outcomes tend to reach publication more readily than unfavorable ones, so the reported results are best read as descriptive. Despite the important hemorrhagic shock in those patients and prolonged transport time, the deployment of REBOA was consistently reported alongside immediate hemodynamic improvement. This can be observed by marked improvements in systolic blood pressure across multiple cohorts[4,13,14]. This rapid restoration of central perfusion has been described in individual reports as an important factor in bridging critically injured combatants and local civilian casualties until definitive hemorrhage control surgery[10].

The evolution of endovascular technology has been substantial in using REBOA, from well-resourced civilian trauma centers to far-forward austere settings. The predominant use of low-profile, fluoroscopy-free catheters, such as the 7-Fr ER-REBOA^®, combined with the utilization of portable ultrasound for percutaneous arterial access, has enabled non-vascular specialists in resource-constrained environments to perform the procedure[25]. Furthermore, the literature highlights an increasing use of dynamic balloon management, including partial and intermittent occlusion strategies. These techniques have been employed to mitigate ischemia-reperfusion injuries associated with prolonged complete aortic occlusion, effectively extending the safe window for patient evacuation[4,10,13,14]. According to our results, the reported complications of femoral artery thrombosis and acute limb ischemia are consistent with recent literature; however, with only 35 individually reported cases and no denominators for unreported events, no reliable estimate of their incidence in austere settings can be derived.

Furthermore, REBOA has been described as not replacing the need for hemostatic resuscitation, functioning instead as a mechanical bridge to definitive hemostasis. The literature consistently demonstrates that the success of aortic occlusion in combat casualties is heavily reliant on concurrent massive transfusion protocols, particularly those prioritizing whole blood over crystalloids or standard component therapy[13,18]. Austere surgical teams frequently utilized whole blood transfusions from walking blood banks alongside REBOA to combat trauma-induced coagulopathy and replace massive blood loss, highlighting that endovascular hemorrhage control must be inextricably linked to robust logistical support and damage control resuscitation pathways[13,25].

Despite its potential, the utilization of REBOA in critically injured patients remains associated with substantial risks and notable mortality in specific severely injured cohorts, reflecting the extreme underlying injury severity[14,15,24]. In one report, the postoperative course was complicated by severe access-site and systemic morbidities[25]. These findings show that REBOA has been used for the prevention of immediate exsanguination, with reported temporary physiological stabilization, resulting in an overall survival influenced by the subsequent management of metabolic and ischemic complications. Future efforts must focus on standardized training for austere providers, improvement of partial occlusion protocols, and optimization of patient selection to mitigate end-organ damage[4,18,25].

Access-site arterial thrombosis or acute limb ischemia was observed in 4 of the 35 individually reported cases (11.4%). Civilian syntheses report access-site and limb ischemic events across a wide range[27,28], but the two figures are not comparable: The cases assembled here were not followed under a common protocol, survival was reported only to transfer for 23 of the 35 cases, and complication ascertainment after handover was inconsistent and undocumented across sources. The observed proportion should therefore be read as a lower bound on what occurred, not as an incidence estimate. Comprehensive reviews of REBOA complications have shown that distal embolization and lower limb ischemia remain the most prevalent procedure-related events, with reported incidence between 4% and 52.6%, followed by vascular and access-site complications (1.2%-11.1%), bleeding-related events (1.4%-28.6%), and pseudoaneurysms (2%-14%)[28].

The one case of acute kidney injury requiring temporary renal replacement therapy occurred in a patient who developed reperfusion syndrome following restoration of flow to a limb rendered ischaemic by a traumatic contralateral common femoral artery injury, rather than by aortic occlusion itself[15]. No case of acute kidney injury attributable to aortic occlusion itself was reported, whereas civilian series describe acute kidney injury after zone 1 occlusion at rates between 5.6% and 46%[28]. Given that most included casualties were not followed beyond transfer, this difference cannot be interpreted as a lower risk in austere settings.

Reported occlusion times were generally short but cannot be pooled. Individual durations were published for only 10 of the 35 cases; the two largest sources reported a study-level mean of 21 minutes[13] and a range of 15 minutes to 50 minutes[24] respectively, without case-level data. Among the cases with individual durations, single occlusion episodes ranged from 11 minutes to 55 minutes[4,14], the longest comprising 5 minutes of complete followed by 50 minutes of partial zone 1 occlusion during transport[4]. Reva et al[15] reported a mean zone 1 occlusion of 27 minutes across three cases, and in one casualty a 40-minute zone 1 occlusion was followed, after reperfusion, by a further 25-minute zone 3 occlusion. No overall mean is presented, as combining a study-level mean, a range, and individual case durations would not yield an interpretable figure. Furthermore, no REBOA-associated infectious or distal venous thromboembolic events were reported in any included study. This absence is uninformative rather than reassuring: 23 of the 35 individually reported cases were followed only to transfer, and complications with a delayed presentation would not have been captured by the reporting sources[27,28]. Mitigation strategies established in civilian practice - including ultrasound-guided percutaneous arterial access, smaller-profile sheaths (4-7 Fr), partial or titratable aortic occlusion (pREBOA-PRO and emerging variable aortic control devices), strict adherence to recommended occlusion time limits (≤ 30 minutes in zone 1 and ≤ 60 minutes in zone 3), and rigorous surveillance of access-site perfusion before and after sheath removal - may therefore warrant consideration if REBOA is adapted for combat casualty care and prehospital deployment, although none of these strategies has been evaluated comparatively in an austere setting[27,28].

This scoping review has limitations that must be acknowledged. First, regarding the review process, although a comprehensive search strategy encompassing multiple electronic databases and grey literature was conducted, relevant unpublished data or classified military casualty reports may have been inadvertently excluded. Second, the available evidence base consists predominantly of retrospective case reports and small-to-moderate case series, with a small overall sample size of patients, which carry inherent selection, survival and publication biases. In addition, because several reports arose from the same operational teams, two overlapping reports were not counted separately, and the aggregate figure is presented as cases reported across studies rather than as confirmed unique individuals. Because registry records are de-identified, we could not confirm at patient level that no case in the registry-based cohort corresponds to a patient described in an included case report or series, although several lines of evidence indicate that any such overlap would be limited. Outcomes in the registry-based cohort are reported for all 17 cases because they are not disaggregated by role of care; the 15 eligible role 2 cases could therefore not be analysed separately. Third, there was substantial clinical and methodological heterogeneity across the included studies regarding patient demographics, mechanisms of injury, specific austere settings and the types of REBOA devices utilized. This significant heterogeneity, combined with the general lack of standardized non-REBOA control groups in the primary literature, precluded any meaningful quantitative synthesis or meta-analysis. Finally, medical documentation in combat and disaster environments is notoriously challenging; consequently, there were inconsistencies and missing data regarding precise prehospital physiological parameters, exact occlusion durations, and specific evacuation timelines in several of the included reports.

CONCLUSION

REBOA has been used in selected casualties with life-threatening NCTH in austere and combat environments, and the included reports describe restoration of central perfusion and use of the balloon as a bridge to definitive surgical care. The introduction of low-profile, fluoroscopy-free devices coincides with deployment closer to the point of injury. In every included report REBOA was used alongside hemostatic resuscitation, particularly whole blood transfusion, rather than in place of it. Access-site thrombosis and acute limb ischemia were the complications most often reported, in a small number of cases and without denominators for unreported events. The evidence assembled here is uncontrolled, drawn from case reports, case series and a single registry cohort with no comparator, and therefore describes what has been attempted rather than what works: It does not establish efficacy or superiority over other hemorrhage-control strategies, and does not support routine deployment. Comparative studies, prospective registries with standardized reporting, and agreed indications for far-forward use are needed before the role of REBOA in these settings can be defined.