Procedure-related complications

The most common overall procedure-related complication is related to distal embolization and lower limb ischemia, with a frequency of 16% (range: 4–52.6%). Vascular and access site complications are also highly reported, with studies reporting a range of 1.2–11.1%. Conversely, bleeding-related complications are less commonly documented, with incidence rates ranging from 1.4% to 28.6%. Pseudoaneurysms are less likely with rates ranging from 2% to 14%. There is a high incidence of complications from lower limb compartment syndrome and lower limb amputation associated with the procedure.8 9

Access-related vascular injuries and mitigations

Vascular complications related to catheter insertion are commonly reported in REBOA literature. These can occur during different steps of the REBOA technique including during initial access of the femoral artery, insertion of the sheath or balloon catheter or balloon inflation, resulting in various serious vascular injuries with an incidence between 1.2% and 11.1%.8 9

Ordoñez et al10 demonstrated that 16% of patients experienced vascular-related complications associated with groin access during REBOA, including femoral artery dissection (8%), thrombosis (4%), pseudoaneurysm (2%), and local infection (2%). Notably, none of the 14 patients who underwent REBOA with the 7-French (Fr) sheath encountered access complications.10

Furthermore, other reported complications encompass arterial pseudoaneurysm at the access site and distal embolic events, with incidence rates of 2.2% and 4.3%, respectively, alongside two instances of balloon migration after deployment.11

Among various studies, access-related limb ischemic complications were noted in 8.6% of REBOA survivors. Extremity ischemia occurred in 5.2% of cases, distal embolism in 6.0%, and a combination of both in 2.6%.10 12–19 Laverty et al19 conducted a recent study investigating the prevalence of access-related limb ischemia issues in REBOA survivors, along with associated clinical, technical, and device risk factors.

Additional studies reported the following complication rates: arterial dissection (2.4%), pseudoaneurysm (0.4%), embolization (2%), clinically significant bleeding (0.6%), limb ischemia (3.9%), compartment syndrome (0.7%), and limb loss (0.7%).10 12 13 15 17 20 21

Balloon placement complications and mitigations

After REBOA insertion guided by external landmarks for the desired occlusion zone, confirmation of balloon placement before inflation is crucial and typically recommended through X-ray (XR) imaging.22 However, time-sensitive emergencies and resource limitations may pose challenges for obtaining XR. Balloon morphology is assessed for overinflation or underinflation before securing the catheter. Various methods, including fluoroscopy, haptic feedback, loss of contralateral pulse, or monitoring arterial wave form on the contralateral side, are employed to measure balloon volume after inflation and evaluate the degree of occlusion.22

In situations where XR is impractical, physiological responses and anatomic landmarks can be used for confirming balloon position. Non-radiographic techniques, such as US-guided viewing via subxiphoid, transperitoneal, or transesophageal approaches, present alternative options to overcome the limitations of standard fluoroscopic imaging. However, these techniques may pose challenges in emergency situations.32 Overinflation of the balloon can lead to substantial morbidity and mortality, causing damage to the vessel wall.33 First-generation devices typically feature compliant balloons, contrasting with semicompliant or non-compliant balloons. The risk of aortic rupture and severe hypotension is heightened by balloon distortion, especially when proximal and distal occlusion confirmation techniques are unreliable, making accurate measurement of overinflation challenging.31

Balloon occlusion complications and mitigations

Automated variable aortic control

Endovascular variable aortic control (EVAC) emerges as a strategy to address challenges associated with traditional devices, aiming to titrate down to partial occlusion manually, manage hemodynamic shifts, and balance priorities of hemostasis, blood pressure (BP) augmentation, and distal organ perfusion.37 40 EVAC employs an algorithm-driven automated flow-regulating syringe device controller connected to existing REBOA catheters. This set-up enables precise regulation of aortic flow by making small adjustments in balloon filling volume based on real-time diastolic BP measurements above the balloon.37 In preclinical models, this approach has demonstrated effective mitigation of the ischemic burden associated with sustained aortic occlusion while minimizing hemorrhage.41–43

Partial REBOA

Partial REBOA (pREBOA) represents a strategy for controlled slow aortic flow past a titratable balloon, mitigating ischemic insult below the balloon and maintaining physiological central aortic and cerebral pressures.44 Preclinical models indicate that even minimal blood flow to distal limbs with pREBOA leads to fewer adverse hemodynamic changes, reduced ischemia/reperfusion injury, and decreased inflammatory factors, while effectively controlling hemorrhage.36 45 46 Additionally, preclinical data support pREBOA’s capability to safely extend occlusion time to over 60 minutes in zone 1.47

Despite limited clinical evidence for pREBOA,34 35 48 studies by Matsumura et al48 and others show promising outcomes. Matsumura et al demonstrated that patients undergoing pREBOA had better hemodynamic responses and longer occlusion time compared with conventional REBOA (median 58 minutes vs. 33 minutes), with comparable mortality.48 Another retrospective study revealed reduced end-organ dysfunction, fewer ventilator and intensive care unit days, and decreased vasopressor requirement in patients undergoing pREBOA compared with conventional REBOA.35

However, achieving effective partial occlusion manually poses challenges. Manual manipulation using low-fidelity methods results in highly variable and imprecise distal aortic flow rates, making it difficult to titrate distal flow precisely, especially during ongoing hemorrhage.49 The compliance of first-generation catheter balloons, like the Eliason-Rasmussen REBOA (ER-REBOA), limits control during deflation, leading to an all-or-nothing approach.16 35 Challenges also arise from difficulty in predicting optimal balloon volume for transition from complete to partial occlusion and the unpredictable interaction of fully compliant balloons with the aortic wall.48 50 51

To address these challenges, purpose-built devices like the pREBOA-PRO (Prytime Medical Inc., Boerne, TX) offer titratable partial aortic occlusion with a semicompliant balloon. Preclinical studies demonstrate its feasibility, providing responsive management of deflation and gradual distal aortic flow, potentially limiting distal ischemia and reperfusion injury compared with complete aortic occlusion.38 52–55 The pREBOA-PRO device enables longer zone 1 deployment without frequent adjustments, improving outcomes.34 38 Its dual arterial line capability allows real-time monitoring of central aortic and distal femoral artery pressures, providing evidence of ongoing perfusion and guiding resuscitation.34 In a clinical setting, the use of pREBOA-PRO devices allowed longer zone 1 total occlusion times without worsening distal ischemic injury compared with complete occlusion devices.34 Improved feasibility and controlled partial occlusion make pREBOA-PRO a promising advancement for trauma patients, providing improved outcomes while avoiding hemodynamic collapse.

Sheath removal complications and mitigations

In the final step of the procedure, sheath removal can result in complications. Distal thrombus around the sheath and arterial dissection during cannulation and/or insertion can be worsened by prolonged occlusion and in-dwelling sheath times. Furthermore, documented cases of lower limb ischemia leading to amputation were attributed to sheath removal, which resulted from ongoing systemic ischemia.10 12–19 24 Assessment of perfusion prior to and after removal of the sheath should be performed routinely and surveilled by those with endovascular experience.

Systemic-related complications

Systemic complications associated with aortic occlusion procedures like REBOA pose inherent risks despite their benefits. While REBOA aims to restore central BP and control NCTH below the balloon, prolonged occlusion carries the risk of ischemia-reperfusion injuries to distal organs, including spinal cord ischemia and acute kidney injury (AKI).13 15 16 21 24 25 56 57 Acute kidney failure is a consistently documented systemic complication, with incidence rates ranging from 5.6% to 46%, making it one of the most frequently reported complications. Infection and sepsis rates range from 2% to 36%, while pulmonary-related complications, such as acute respiratory distress syndrome (ARDS) and multisystem organ failure, occur at rates ranging from 7.1% to 17.5%.12 13 24 56 Gastrointestinal complications show relative consistency, with variability observed in other complications. Additionally, prolonged hypoperfusion can lead to hyperkalemia, acidosis, and coagulopathy.5 12 58

Aortic rupture

While uncommon, aortic rupture which presents as hemorrhagic shock or limb ischemia has been reported in an animal study as a complication of overinflation.33 Although this is a very rare complication, one study reported ipsilateral common iliac artery rupture after inadvertent inflation in the incorrect location, and another demonstrated that iatrogenic left common iliac artery damage is a risk.18 23

Amputations

In a 2023 study, 3.8% of patients with ER-REBOA and 6.7% of patients with pREBOA required amputations.27 57

Lower extremity complications

The overall incidence of lower extremity complications was low. A review of lower extremity complications in patients who underwent REBOA placement did not show any difference in rates of lower extremity amputation (5.3%), exploration (14%), fasciotomy (7%), or thrombectomy (3.5%) when compared with no-REBOA patients.59

Compartment syndrome

Extremity compartment syndrome, a complication on the rise, has been reported in two separate studies, with incidence rates ranging from 6% to 15%.13 21 These findings are supported by Chien et al60 which found their lower limb compartment syndrome incidence rate at 4.3%.

Acute kidney injury

Another noteworthy systemic complication due to ischemia-reperfusion-related complications included AKI.5 13 15 16 21 24 25 56 AKI has been a prevalent complication documented in many REBOA studies, with incidence rates varying from higher to no significance compared with no-REBOA use.13 15 16 21 24 25 56 61 AKI is caused by REBOA due to a multitude of factors. Studies that report higher rates of AKI have the majority of the REBOA performed in zone 1 and for longer occlusion times.13 16 21 25 56 In contrast, studies with lower or no significant difference in AKI rates compared with no-REBOA groups performed REBOA mainly in zone 3 with or without shorter occlusion times.15 60 62 63 In addition, Brenner et al24 reported that as the use of REBOA becomes more widespread, higher rates of AKI are being reported, potentially related to various factors, including ischemia of distal muscle beds, systemic inflammatory response activation, and additional insults such as contrast-enhanced CT scans and angiography procedures. Remarkably, patients treated with pREBOA had a significantly lower AKI incidence at 6.7% compared with those treated with ER-REBOA at 40%.57

Pulmonary

In an extensive examination of REBOA complications, studies revealed a diverse spectrum of adverse events, including pulmonary complications.12 13 24 56 A comparative study involving REBOA with angioembolization or preperitoneal pelvic packing reported a 12.1% incidence of ARDS and acute lung injury (ALI).24 Additionally, DuBose et al11 documented ARDS or ALI at 2.6%, pneumonia at 6.1%, and multiorgan dysfunction at 6.1%.11 Chien et al60 reported 2.2% ARDS and 4.3% pulmonary embolism among REBOA patients.60 The occurrence of ARDS and ALI in REBOA patients may be linked to factors such as thromboxane release, leukocyte priming, complement activation, tumor necrosis factor synthesis, and complications related to mechanical ventilation, abdominal surgery, atelectasis, fluid shifts, and crystalloid resuscitation.6

Sepsis

Among the common complications reported were sepsis and infections.10 13 24 25 Bacteremia affected 2.7% of patients, and the incidence of pneumonia reached 8.4% in a related study.27

Similarly, DuBose et al11 reported sepsis or septic shock in 6.1% of patients and an additional study found surgical site infection rates at 3.3%, severe sepsis at 3.2%, and cases of enteric fistulas.60

Other

Paraplegia occurred in a small percentage, 1.5% of patients, while the rate of myocardial infarction was 0.8%.11

Coagulopathies

Thrombotic complications are a significant concern associated with REBOA, as its deployment causes non-specific coagulation disturbances due to flow obstruction and stasis of deoxygenated blood below the balloon. This results in persistent inflammatory pathways, systemic platelet activation, and platelet–leukocyte interactions, while suppressing anti-inflammatory and thrombolytic compounds.5 6 10 12 13 15 16 20 21 24 60 The imbalance between prothrombotic effects and insufficient fibrinolytic activity increases the incidence of venous thromboembolism (VTE) and deep vein thrombosis (DVT). In a study, the REBOA group showed significantly higher rates of VTE (14% vs. 6.5%) and DVT (11.8% vs. 5.4%) compared with the no-REBOA group (p=0.023 and p=0.035, respectively).60

Understanding the effects of aortic occlusion on systemic coagulation and inflammation is challenging due to co-occurring trauma and hemorrhage. Patients may present with various alterations influenced by trauma-related physiological derangements. The potential contribution of REBOA to complications is related to ischemia, where restricted oxygen and nutrient supply can lead to cellular and subcellular damages, endothelial breakdown, platelet activation, fibrin cross-linking, microthrombi formation, and persistent inflammatory pathways. This cascade may cause significant cellular damage, intravascular thrombi formation, secondary ischemia, and organ failure.64

Multiorgan dysfunction

Multiorgan dysfunction syndrome was correlated with REBOA deployment and ranged from 3.4% to 47.6%.11 13 24 25 Organ dysfunction and failure result from ischemia brought on by the prolonged occlusion of the aorta.65 66 Another potential pathway implicated in REBOA organ dysfunction is related to the damage to the endothelial glycocalyx, which can lead to inflammation, vascular permeability, and end-organ dysfunction. Shedding of glycocalyx components into the patients’ blood may thus serve as a biomarker of impending disruption.6 These comprehensive studies underscore the need for careful consideration of potential complications when employing REBOA in trauma patients, calling for an informed and cautious approach in its utilization.11 27

On the other hand, it is important to note that multiorgan dysfunction may in turn be associated with other factors present in this group of patients, such as hemorrhagic shock and hypotension, so this complication cannot be attributed exclusively to the use of the balloon.59

Moreover, other studies have reported cases of myocardial dysfunction during full REBOA, indicating potential complications affecting the heart.5 12 58 This can be explained by the severe acidosis (pH <7.2) that leads to transmembrane electrolyte shifts and malfunction of intracellular proteins, significantly impacting the myocardium. Consequently, this can lead to decreased cardiac output and refractory hypotension.58 High potassium levels on balloon deflation and late increases can also cause cardiac instability.58 The ‘trauma lethal diamond of death’, where lactic acidosis hampers cardiac performance, leading to hypothermia, disrupts the coagulation cascade and is aggravated by hypocalcemia. This impaired coagulopathy, in turn, may cause ongoing hemorrhage, worsening hemorrhagic shock, and exacerbates acidosis.58 Further studies analyzing human data are needed to assess the impact of both local and systemic hypothermias during REBOA on ischemia-reperfusion injury and coagulation specifically. These will possibly rely on development of deployable regional cooling and distal perfusion solutions.64

Metabolic and electrolyte derangements

Metabolic and electrolyte derangements represent another complication of REBOA.5 12 58 In swine models of aortic occlusion, metabolic derangements including hypocalcemia and hyperkalemia, resulting from REBOA use, are common and may worsen long after reperfusion despite resuscitation. It was observed that lactic acidosis, hyperkalemia, hypoglycemia, and hypocalcemia are complications after REBOA and are severe enough to necessitate intervention regardless of the occlusion’s level, degree, or duration.5 12 58 Notably, it was shown that lactic acid, a by-product of anaerobic metabolism causing acidosis, reaches its peak approximately an hour after reperfusion and normalizes with adequate resuscitation. Hyperkalemia is a common finding in trauma patients, where the condition can become more severe due to ischemic cellular lysis, acidosis-driven electrolyte shifts between intracellular and extracellular spaces, and reduced potassium clearance from subsequent ischemic renal dysfunction. The specific cause of hypoglycemia is not completely understood, but it could relate to a combination of factors, such as REBOA-induced adrenal ischemia, liver dysfunction, and potential pancreatic responses to hyperkalemia or transient ischemia. Also, hypocalcemia was observed in connection with lactic acidosis, potentially resulting from augmented calcium binding to free lactate ions, modified responsiveness of parathyroid hormone, intracellular calcium shifts, and phosphate chelation of calcium. These conditions, largely resulting from increased ischemia, may require aggressive pharmacological countermeasures.58

Mortality

REBOA holds promise in improving outcomes for patients with NCTH compared with RT. However, the impact on mortality remains inconsistent, with rates ranging from 29% to 88%.10 12–21 25 56 This represents an improvement from the previously reported mortality rates of 91.5% and 92.6% from older studies.5 11 26 In multivariable analysis, prehospital cardiac arrest, penetrating trauma, decreased total Glasgow Coma Scale score, older age, and increased total Injury Severity Score were associated with higher mortality.26 67 Survival after REBOA has also been shown to be dependent on hemodynamic status at the time of aortic occlusion.6 Recently, a study published by Jansen et al68 evaluated the role of REBOA compared with standard treatment versus standard treatment alone in patients with exsanguinating hemorrhages.68 Two groups were randomized, one with 46 REBOA and standard care (SC) patients and the other with 44 SC patients. The authors showed that the use of REBOA associated with treatment did not reduce and may have increased patient mortality. However, these results should be analyzed cautiously since due to the limited sample size.68 The REBOA group had, in general, lower systolic BP than the SC group, making it questionable whether these patients may have survived, regardless of advanced resuscitation. The Abbreviated Injury Scales in the groups were similar, except for head injury, where the REBOA group scored higher. Traumatic brain injury itself is associated with mortality. Another relevant fact to be considered concerns the time the REBOA was applied.68 The presented data show that the IQR in the REBOA group was from 56 to a concerning 156 minutes, causing patients to bleed for hours until bleeding control was achieved. Another important finding was the time taken to insert the balloon, which averaged 32 minutes, a significantly high figure, making it clear that team training plays a vital role in the outcome to be expected.68 We must emphasize that the time between trauma, effective control of bleeding, and adequate team training plays a decisive role in the results and in reducing complications related to the method.

Data surrounding REBOA’s success in improving mortality outcomes remain inconsistent. An analysis of the AORTA (Aortic Occlusion in Resuscitation for Trauma and Acute Care Surgery) registry during a 5-year period (2014–2018) showed a 22%/year decrease in REBOA mortality over the study’s time frame. The authors attribute some of this improvement to a 10 mm Hg increase in the systolic BP threshold used to dictate proceeding with REBOA and shifting to earlier deployment of REBOA (ie, patients had less severe physiological derangement at time of REBOA placement) as well as shift from zone 1 placement to zone 3.27 The most recent data out of the Japan Trauma Data Bank showed a reduced mortality rate in severely injured trauma patients and significantly lower OR for in‐hospital mortality rate in patients treated with REBOA compared with open aortic cross-clamping.69

On the other hand, another study published by Harfouche et al59 reinforced the positive role of REBOA when used in high-volume trauma centers.59 This retrospective evaluation compared pre-REBOA and REBOA (deployed in zone 3) periods based on data from the R. Adams Cowley Shock Trauma Center, a quaternary center with 6000–7000 admissions per year where 102 481 patients were included in the study. The results showed that in-hospital mortality was significantly lower in the group receiving REBOA (19.3%) versus 44.7% (p=0.001) in the historical control group, and the 30-day survival rate was significantly higher when comparing the groups (p=0.035).59 There is no doubt that the use of endovascular occlusion of the aorta has an essential role in the management of unstable trauma patients. The best way to decrease the risk of the previously mentioned complications is proper patient selection and refined technique using US-guided arterial accesses and small-diameter devices as much as possible.