Effect of partial and complete aortic balloon occlusion on survival and shock in a swine model of uncontrolled splenic hemorrhage with delayed resuscitation

Hydrogen gas inhalation therapy may not work sufficiently to mitigate oxidative stress induced with REBOA

Hemorrhagic shock is a significant cause of trauma-related mortality. Resuscitative endovascular balloon occlusion of the aorta (REBOA) is a less-invasive aortic occlusion maneuver for severe hemorrhagic shock but potentially inducing oxidative stress injuries. In an animal model, this study investigated hydrogen gas inhalation therapy's potential to mitigate post-REBOA ischemia-reperfusion injuries (IRIs). Ten healthy female swine underwent REBOA placement after induced 40% hemorrhagic shock. They were observed during the IRI phase after a 60-minute Zone 1 occlusion for 180 minutes until euthanasia. 2% hydrogen gas inhalation was started simultaneously with REBOA inflation in the hydrogen group. We evaluated survival time, lactate, and 8-hydroxy-2'-deoxyguanosine (8-OHdG) biomarkers, gross findings, and pathological grades. One swine in the control group died at 90 min, and the remaining animals survived throughout the experiment. Survival analysis showed no significant differences between the two groups (control vs. hydrogen, 4/5 vs. 5/5; Log-rank, P = 0.317). Lactate levels during and after REBOA suggested a tendency towards lower levels in the hydrogen group (10.5 ± 4.2 vs. 7.6 ± 2.3 mmol/L, peak, T = 90). Serum 8-OHdG concentrations showed a lower trend in the hydrogen group (Range: 0.12-0.32 vs. 0.11-0.19 ng/mL). The villi of the ileum were destroyed during REBOA inflation and after reperfusion. Changes in the pathological grade of the ileum demonstrated no significant differences in both groups (2.8 ± 1.0 vs. 2.0 ± 1.0, proximal ileum, T = 240). Hydrogen gas inhalation therapy exhibited no significant difference compared to the control group in survival, lactate level, 8-OHdG, and intestinal mucosal injury following REBOA in a hemorrhagic shock model. Although it may slightly reduce mortality, biomarkers, and intestinal pathology, hydrogen gas inhalation therapy was not shown to have sufficient evidence to mitigate REBOA-IRI.

Transcatheter Arterial Embolization for Blunt Splenic Injury With Resuscitative Endovascular Balloon Occlusion of the Aorta: The Significance of Early Involvement of Radiologists

Splenectomy is a common procedure for managing splenic injury in patients with unstable vital signs. Transcatheter arterial embolization (TAE) has emerged as a limited alternative to splenectomy, although the role of TAE can be expanded upon the stabilization of vital signs. The current case report discusses a man in his 50s, in shock after a motor vehicle accident, who was successfully stabilized using resuscitative endovascular balloon occlusion of the aorta (REBOA), followed by splenic artery embolization (SAE) instead of splenectomy, with early involvement of diagnostic and interventional radiologists from the initial stage of care. We also discuss the difficulties of SAE under REBOA and the significance of the early involvement of radiologists in trauma care.

AI algorithm for personalized resource allocation and treatment of hemorrhage casualties

A deep neural network-based artificial intelligence (AI) model was assessed for its utility in predicting vital signs of hemorrhage patients and optimizing the management of fluid resuscitation in mass casualties. With the use of a cardio-respiratory computational model to generate synthetic data of hemorrhage casualties, an application was created where a limited data stream (the initial 10 min of vital-sign monitoring) could be used to predict the outcomes of different fluid resuscitation allocations 60 min into the future. The predicted outcomes were then used to select the optimal resuscitation allocation for various simulated mass-casualty scenarios. This allowed the assessment of the potential benefits of using an allocation method based on personalized predictions of future vital signs versus a static population-based method that only uses currently available vital-sign information. The theoretical benefits of this approach included up to 46% additional casualties restored to healthy vital signs and a 119% increase in fluid-utilization efficiency. Although the study is not immune from limitations associated with synthetic data under specific assumptions, the work demonstrated the potential for incorporating neural network-based AI technologies in hemorrhage detection and treatment. The simulated injury and treatment scenarios used delineated possible benefits and opportunities available for using AI in pre-hospital trauma care. The greatest benefit of this technology lies in its ability to provide personalized interventions that optimize clinical outcomes under resource-limited conditions, such as in civilian or military mass-casualty events, involving moderate and severe hemorrhage.

A randomized porcine study of hemorrhagic shock comparing end-tidal carbon dioxide targeted and proximal systolic blood pressure targeted partial resuscitative endovascular balloon occlusion of the aorta in the mitigation of metabolic injury

BACKGROUND

The definition of partial resuscitative endovascular balloon occlusion of the aorta (pREBOA) is not yet determined and clinical markers of the degree of occlusion, metabolic effects and end-organ injury that are clinically monitored in real time are lacking. The aim of the study was to test the hypothesis that end-tidal carbon dioxide (ETCO₂) targeted pREBOA causes less metabolic disturbance compared to proximal systolic blood pressure (SBP) targeted pREBOA in a porcine model of hemorrhagic shock.

MATERIALS AND METHODS

Twenty anesthetized pigs (26-35 kg) were randomized to 45 min of either ETCO₂ targeted pREBOA (pREBOA_ETCO2, ETCO₂ 90-110% of values before start of occlusion, n = 10) or proximal SBP targeted pREBOA (pREBOA_SBP, SBP 80-100 mmHg, n = 10), during controlled grade IV hemorrhagic shock. Autotransfusion and reperfusion over 3 h followed. Hemodynamic and respiratory parameters, blood samples and jejunal specimens were analyzed.

RESULTS

ETCO₂ was significantly higher in the pREBOA_ETCO2 group during the occlusion compared to the pREBOA_SBP group, whereas SBP, femoral arterial mean pressure and abdominal aortic blood flow were similar. During reperfusion, arterial and mesenteric lactate, plasma creatinine and plasma troponin concentrations were higher in the pREBOA_SBP group.

CONCLUSIONS

In a porcine model of hemorrhagic shock, ETCO₂ targeted pREBOA caused less metabolic disturbance and end-organ damage compared to proximal SBP targeted pREBOA, with no disadvantageous hemodynamic impact. End-tidal CO₂ should be investigated in clinical studies as a complementary clinical tool for mitigating ischemic-reperfusion injury when using pREBOA.

Resuscitative Endovascular Balloon Occlusion of the Aorta is Associated with Increased Risk of Extremity Compartment Syndrome

BACKGROUND

Resuscitative endovascular balloon occlusion of the aorta (REBOA) has been used as a temporizing procedure to control intra-abdominal or pelvic bleeding. Theoretically, occlusion of the aorta and the resulting ischemia-reperfusion of the lower extremities may increase the risk of extremity compartment syndrome (CS). To date, no study has addressed systematically the incidence and risk factors of CS following REBOA intervention. The purpose of this study was to address this knowledge gap.

METHODS

Adult trauma patients from the American College of Surgeons Trauma Quality Improvement Program (ACS-TQIP) database (2016-2019) were included. Patients who received REBOA within 4 h of admission were compared to patients without REBOA after propensity score matching for demographics, vital signs on admission, comorbidities, injury severity of different body regions, pelvic and lower extremity fractures, vascular trauma to the lower extremities, fixation for fractures, angioembolization (AE) for pelvis, preperitoneal pelvic packing (PPP), laparotomy, and venous thromboembolism (VTE) prophylaxis. The primary outcomes were rates of lower extremity CS and fasciotomy and acute kidney injury (AKI). Secondary outcomes included mortality.

RESULTS

There were 534 patients who received REBOA matched with 1043 patients without REBOA. Overall, patients in the REBOA group had significantly higher rates of CS than no REBOA patients [5.4% vs 1.1%, p < 0.001, OR: 5.39]. The risk of CS remained significantly higher in the subgroups of patients with or without pelvic or lower extremity fractures, as well as in the subgroup of patients with associated extremity vascular injury [11.2% vs 1.5%, p < 0.001, OR: 8.12].The fasciotomy and AKI rates were significantly higher in the REBOA group (5.8% vs 1.2%, p < 0.001 and 12.9% vs 7.4%, p< 0.001 respectively).

CONCLUSION

REBOA use is associated with a higher risk of lower extremity CS, fasciotomy and AKI, especially in patients with associated lower extremity vascular injuries. These complications should be taken into account when considering REBOA use, and close observation for this complication should always be part of the routine monitoring.

Acute Kidney Injury in Hypotensive Trauma Patients Following Resuscitative Endovascular Balloon Occlusion of the Aorta Placement

BACKGROUND

ER-Resuscitative Endovascular Balloon Occlusion of the Aorta (ER-REBOA) is an adjunct tool to achieve hemostasis in trauma patients with non-compressible torso hemorrhage. The development of the partial REBOA (pREBOA) allows for distal perfusion of organs while maintaining occlusion of the aorta. The primary aim of this study was to compare rates of acute kidney injury (AKI) in trauma patients who had placement of either a pREBOA or ER-REBOA.

METHODS

A retrospective chart review of adult trauma patients who underwent REBOA placement between September 2017 and February 2022 was performed. Baseline demographics, information on REBOA placement, and post-procedure complications including AKI, amputations, and mortality were recorded. Chi-squared and T-test analyses were performed with P < .05 considered to be significant.

RESULTS

A total of 68 patients met study inclusion criteria with 53 patients (77.9%) having an ER-REBOA. 6.7% of patients treated with pREBOA had a resulting AKI, while 40% of patients treated with ER-REBOA had a resulting AKI, and this difference was significant (P < .05). The rates of rhabdomyolysis, amputations, and mortality were not significantly different between the two groups.

CONCLUSION

The results from this case series suggest that patients treated with pREBOA have a significantly lower incidence of developing an AKI compared to ER-REBOA. There were no significant differences in rates of mortality, and amputations. Future prospective studies are needed to further characterize the indications and optimal use for pREBOA.

Next-Generation REBOA (Resuscitative Endovascular Balloon Occlusion of the Aorta) Device Precisely Achieves Targeted Regional Optimization in a Porcine Model of Hemorrhagic Shock

INTRODUCTION

Limitations such as time-dependent distal ischemia have slowed the adoption of resuscitative endovascular balloon occlusion of the aorta (REBOA) for noncompressible hemorrhage. Next-generation REBOA technologies may allow for controlled partial flow, known as targeted regional optimization, to reduce distal ischemia. We aimed to characterize the efficacy of one such catheter in a porcine model of lethal hemorrhagic shock.

METHODS

Noncompressible hemorrhage from an iliac injury was induced in anesthetized swine (Sus scrofa) (70-90 kg), targeting 30% total blood volume. Animals were then randomized to partial aortic occlusion (PO) with targeted distal mean arterial pressure (MAP) of 35-40 mm of mercury (mm Hg) and complete aortic occlusion (CO) (n = 8 per group) for 90 min. All groups were then resuscitated during a two-h critical care (CC) phase, with flow rate and MAP recorded continuously at the distal infrarenal aorta and proximal carotid artery, and analyzed with two-way repeated measures analysis of variance with S-N-K post-hoc test.

RESULTS

During aortic occlusion, MAP distal to the balloon was consistently maintained at 35.8 ± 0.3 mm Hg in the PO group compared to 27.1 ± 0.3 mm Hg in the CO group (P < 0.05), which also corresponded to higher flow rates (202.9 ± 4.8 mL/min PO versus 25.9 ± 0.8 mL/min CO; P < 0.05). MAP proximal to the balloon was significantly higher with CO versus PO (109.2 ± 2.3 mm Hg versus 85.2 ± 2.3 mm Hg; P < 0.05). During the CC phase, distal aortic flow and MAP were not significantly different between groups. However, creatinine returned to baseline levels by the end of the study in the PO group, but not the CO group. One animal died in the CO group, whereas none died in the PO group.

CONCLUSIONS

This is the first examination of the next-generation pREBOA-PRO in a porcine model of lethal hemorrhagic shock. We show technical feasibility of this technique to precisely achieve targeted regional optimization without device failure or complication. The ability to titrate balloon inflation and thus distal flow/pressure may extend the therapeutic window of REBOA by mitigating distal ischemia.

Advanced partial occlusion controller allows for increased precision during targeted regional optimization in a porcine model of hemorrhagic shock

BACKGROUND

Targeted regional optimization (TRO), a partial resuscitative endovascular balloon occlusion of the aorta strategy, may mitigate distal ischemia and extend the window of effectiveness for this adjunct. An automated device may allow greater control and precise regulation of flow past the balloon, while being less resource-intensive. The objective of this study was to assess the technical feasibility of the novel advanced partial occlusion controller (APOC) in achieving TRO at multiple distal pressures.

METHODS

Female swine (n = 48, 68.1 ± 0.7 kg) were randomized to a target distal mean arterial pressure (MAP) of 25 mm Hg, 35 mm Hg, or 45 mm Hg by either manual (MAN) or APOC regulation (n = 8 per group). Uncontrolled hemorrhage was generated by liver laceration. Targeted regional optimization was performed for 85 minutes, followed by surgical control and a 6-hour critical care phase. Proximal and distal MAP and flow rates were measured continuously.

RESULTS

At a target distal MAP of 25 mm Hg, there was no difference in the MAP attained (APOC: 26.2 ± 1.05 vs. MAN: 26.1 ± 1.78 mm Hg) but the APOC had significantly less deviance (10.9%) than manual titration (14.9%, p < 0.0001). Similarly, at a target distal MAP of 45 mm Hg, there was no difference in mean pressure (44.0 ± 0.900 mm Hg vs. 45.2 ± 1.31 mm Hg) but APOC had less deviance (9.34% vs. 11.9%, p < 0.0001). There was no difference between APOC and MAN in mean (34.6 mm Hg vs. 33.7 mm Hg) or deviance (9.95% vs. 10.4%) at a target distal MAP of 35 mm Hg, respectively. The APOC made on average 77 balloon volume adjustments per experiment compared with 29 by manual titrations.

CONCLUSION

The novel APOC consistently achieved and sustained precisely regulated TRO across all groups and demonstrated reduced deviance at the 25 mm Hg and 45 mm Hg groups compared with manual titration.

Targeted Regional Optimization in Action: Dose-Dependent end Organ Ischemic Injury with Partial Aortic Occlusion in The Setting of Ongoing Liver Hemorrhage

INTRODUCTION

Targeted regional optimization (TRO) describes partial resuscitative endovascular balloon occlusion of the aorta (REBOA) strategy that allows for controlled distal perfusion to balance hemostasis and tissue perfusion. This study characterized hemodynamics at specific targeted distal flow rates in a swine model of uncontrolled hemorrhage to determine if precise TRO by volume was possible.

METHODS

Anesthetized swine were subjected to liver laceration and randomized into TRO at distal flows of 300 (n = 8), 500 (n = 8) or 700 ml/min (n = 8). After 90 minutes, the animals received damage control packing and were monitored for 6 hours. Hemodynamic parameters were measured continuously, and hematology and serologic labs obtained at predetermined intervals.

RESULTS

During TRO, the average percent deviation from the targeted flow was lower than 15.9% for all cohorts. Average renal flow rates were significantly different across all cohorts during TRO phase (p<0.0001; TRO300 = 63.1 ± 1.2; TRO500=133.70 ± 1.93; TRO700=109.3 ± 2.0), with the TRO700 cohort having less renal flow than TRO500. The TRO500 and TRO700 average renal flow rates inverted during the ICU phase (p < 0.0001; TRO300=86.20 ± 0.40; TRO500=148.50 ± 1.45; TRO700= 181.1 ± 0.70). There was higher BUN, creatinine, and potassium in the TRO300 cohort at the end of the experiment, but no difference in lactate or pH between cohorts.

CONCLUSION

This study demonstrated technical feasibility of TRO as a strategy to improve outcomes after prolonged periods of aortic occlusion and resuscitation in the setting of ongoing solid organ hemorrhage. A dose-dependent ischemic end-organ injury occurs beginning with partial aortic occlusion that progresses through the critical care phase, with exaggerated effect on renal function.

Challenges and Opportunities for Endovascular Treatment of Hemorrhage in Combat Casualty Care

ABSTRACT

The care of the hemorrhaging patient continues to evolve. The use of endovascular techniques to treat hemorrhage has increased significantly in civilian trauma care over the past 15 years and is identified as a major national trauma care research priority. Endovascular techniques are being increasingly employed to treat major thoracoabdominal arterial injuries and resuscitative endovascular balloon occlusion of the aorta is being adopted at trauma centers as a supportive adjunct to resuscitation in the exsanguinating patient. Emerging endovascular technology offers the opportunity to provide temporary or permanent control of non-compressible torso hemorrhage, which remains a vexing problem in combat casualty care. Endovascular advances have not been translated to the care of combat casualties to any significant degree, however. This review provides a summary and analysis of the gap between civilian endovascular hemorrhage control and combat casualty care practice to better align future research and development efforts.

Targeted Regional Optimization: Increasing the Therapeutic Window for Endovascular Aortic Occlusion In Traumatic Hemorrhage

ABSTRACT

Resuscitative endovascular balloon occlusion of the aorta (REBOA) allows for effective temporization of exsanguination from non-compressible hemorrhage (NCTH) below the diaphragm. However, the therapeutic window for aortic occlusion is time-limited given the ischemia-reperfusion injury generated. Significant effort has been put into translational research to develop new strategies to alleviate the ischemia-reperfusion injury and extend the application of endoaortic occlusion. Targeted regional optimization (TRO) is a partial REBOA strategy to augment proximal aortic and cerebral blood flow while targeting minimal threshold of distal perfusion beyond the zone of partial aortic occlusion. The objective of TRO is to reduce the degree of ischemia caused by complete aortic occlusion while providing control of distal hemorrhage. This review provides a synopsis of the concept of TRO, pre-clinical, translational experiences with TRO and early clinical outcomes. Early results from TRO strategies are promising; however, further studies are needed prior to large-scale implementation into clinical practice.

End-tidal Carbon Dioxide as an Indicator of Partial REBOA and Distal Organ Metabolism in Normovolemia and Hemorrhagic Shock in Anesthetized Pigs

INTRODUCTION

It is difficult to estimate the ischemic consequences when using partial resuscitative endovascular balloon occlusion of the aorta (REBOA). The aim was to investigate if end-tidal carbon dioxide (ETCO2) is correlated to degree of aortic occlusion, measured as distal aortic blood flow, and distal organ metabolism, estimated as systemic oxygen consumption (VO2), in a porcine model of normovolemia and hemorrhagic shock.

MATERIALS AND METHODS

Nine anesthetized pigs (25-32 kg) were subjected to incremental steps of zone 1 aortic occlusion (reducing distal aortic blood flow by 33%, 66%, and 100%) during normovolemia and hemorrhagic grade IV shock. Hemodynamic and respiratory variables, and blood samples, were measured. Systemic VO2 was correlated to ETCO2 and measures of partial occlusion previously described.

RESULTS

Aortic occlusion gradually lowered distal blood flow and pressure, whereas ETCO2, VO2 and carbon dioxide production decreased at 66% and 100% aortic occlusion. Aortic blood flow correlated significantly to ETCO2 during both normovolemia and hemorrhage (R = 0.84 and 0.83, respectively) and to femoral mean pressure (R = 0.92 and 0.83, respectively). Systemic VO2 correlated strongly to ETCO2 during both normovolemia and hemorrhage (R = 0.91 and 0.79, respectively), blood flow of the superior mesenteric artery (R = 0.77 and 0.85, respectively) and abdominal aorta (R = 0.78 and 0.78, respectively), but less to femoral blood pressure (R = 0.71 and 0.54, respectively).

CONCLUSION

ETCO2 was correlated to distal aortic blood flow and VO2 during incremental degrees of aortic occlusion thereby potentially reflecting the degree of aortic occlusion and the ischemic consequences of partial REBOA. Further studies of ETCO2, and potential confounders, in partial REBOA are needed before clinical use.

Efficacy of past, present, and future fluid strategies in an improved large animal model of non-compressible intra-abdominal hemorrhage

BACKGROUND

Noncompressible hemorrhage is a leading cause of potentially survivable combat death, with the vast majority of such deaths occurring in the out-of-hospital environment. While large animal models of this process are important for device and therapeutic development, clinical practice has changed over time and past models must follow suit. Developed in conjunction with regulatory feedback, this study presents a modernized, out-of-hospital, noncompressible hemorrhage model, in conjunction with a randomized study of past, present, and future fluid options following a hypotensive resuscitation protocol consistent with current clinical practice.

METHODS

We performed a randomized controlled experiment comparing three fluid resuscitation options in Yorkshire swine. Baseline data from animals of same size from previous experiments were analyzed (n = 70), and mean systolic blood pressure was determined, with a permissive hypotension resuscitation target defined as a 25% decrease from normal (67 mm Hg). After animal preparation, a grade IV to V liver laceration was induced. Animals bled freely for a 10-minute "time-to-responder" period, after which resuscitation occurred with randomized fluid in boluses to the goal target: 6% hetastarch in lactated electrolyte injection (HEX), normal saline (NS), or fresh whole blood (FWB). Animals were monitored for a total simulated "delay to definitive care" period of 2 hours postinjury.

RESULTS

At the end of the 2-hour study period, 8.3% (1 of 12 swine) of the HEX group, 50% (6 of 12 swine) of the NS group, and 75% (9 of 12 swine) of the FWB had survived (p = 0.006), with Holm-Sidak pairwise comparisons showing a significant difference between HEX and FWB and (p = 0.005). Fresh whole blood had significantly higher systemic vascular resistance and hemoglobin levels compared with other groups (p = 0.003 and p = 0.001, respectively).

CONCLUSION

Survival data support the movement away from HEX toward NS and, preferably, FWB in clinical practice and translational animal modeling. The presented model allows for future research including basic science, as well as translational studies of novel diagnostics, therapeutics, and devices.

Resuscitative Endovascular Balloon Occlusion of the Aorta (REBOA) Use in Animal Trauma Models

BACKGROUND

Resuscitative Endovascular Balloon Occlusion of the Aorta (REBOA) was developed to prevent traumatic exsanguination. We aim to identify the outcomes in animal models with 1) partial versus complete REBOA occlusion and 2) zone 1 versus 2 placements.

METHODS

The PRISMA guidelines were followed. We conducted a search of PubMed, EMBASE and Google Scholar for REBOA studies in animal trauma models using the following search terms: "REBOA trauma", "REBOA outcomes" "REBOA complications". SYRCLE's RoB Tool was utilized for the risk of bias and study quality assessment.

RESULTS

Our search yielded 14 RCTs for inclusion. Eleven studies directly investigated partial REBOA versus total aortic occlusion. Overall, partial REBOA techniques were associated with similar attainment of proximal MAP but with significantly less ischemic burden. Significant mortality benefit with partial occlusion was observed in three studies. Survival time post-occlusion also was improved with zone 3 placement versus zone 1 (100% versus 33%; P < 0.01).

CONCLUSIONS

There appears to be a fine balance between desired proximal arterial pressure and time of occlusion for overall survival and subsequent risk of distal ischemia. Many "partial occlusion" techniques may be superior in attaining such balance over prolonged REBOA inflation where no distal flow is allowed. Tailored zone 3 placement may offer significant mortality and morbidity advantages compared to sustained total occlusion and indiscriminate zone 1 placement strategies. As clear conclusions regarding REBOA are unlikely to be established in animal models, larger randomized investigations utilizing human subjects are needed to describe optimal REBOA technique and applicability in greater detail.

Is cerebral perfusion maintained during full and partial resuscitative endovascular balloon occlusion of the aorta in hemorrhagic shock conditions?

BACKGROUND

Partial resuscitative endovascular balloon occlusion of the aorta (pREBOA) is a technology that occludes aortic flow and allows for controlled deflation and restoration of varying distal perfusion. Carotid flow rates (CFRs) during partial deflation are unknown. Our aim was to measure CFR with the different pREBOA balloon volumes and correlate those to the proximal mean arterial pressure (PMAP) and a handheld pressure monitoring device (COMPASS; Mirador Biomedical, Seattle, WA).

METHODS

Ten swine underwent a hemorrhagic injury model with carotid and iliac arterial pressures monitored via arterial lines. Carotid and aortic flow rates were monitored with Doppler flow probes. A COMPASS was placed to monitor proximal pressure. The pREBOA was inflated for 15 minutes then partially deflated for an aortic flow rate of 0.7 L/min for 45 minutes. It was then completely deflated. Proximal mean arterial pressures and CFR were measured, and correlation was evaluated. Correlation between CRF and COMPASS measurements was evaluated.

RESULTS

Carotid flow rate increased 240% with full inflation. Carotid flow rate was maintained at 100% to 150% of baseline across a wide range of partial deflation. After full deflation, CFR transiently decreased to 45% to 95% of baseline. There was strong positive correlation (r > 0.85) between CFR and PMAP after full inflation, and positive correlation with partial inflation (r > 0.7). Carotid flow rate had strong correlation with the COMPASS with full REBOA (r > 0.85) and positive correlation with pREBOA (r > 0.65).

CONCLUSION

Carotid flow rate is increased in a hemorrhagic model during full and partial inflation of the pREBOA and correlates well with PMAP. Carotid perfusion appears maintained across a wide range of pREBOA deflation and could be readily monitored with a handheld portable COMPASS device instead of a standard arterial line setup.

Real-time bedside management and titration of partial resuscitative endovascular balloon occlusion of the aorta without an arterial line: Good for pressure, not for flow!

BACKGROUND

Partial resuscitative endovascular balloon occlusion of the aorta (pREBOA) attempts to minimize ischemia/reperfusion injury while controlling hemorrhage. There are little data on optimal methods to evaluate and titrate partial flow, which typically requires invasive arterial line monitoring. We sought to examine the use of a miniaturized handheld digital pressure device (COMPASS; Mirador Biomedical, Seattle, WA) for pREBOA placement and titration of flow.

METHODS

Ten swine underwent standardized hemorrhagic shock. Carotid and iliac pressures were monitored with both arterial line and COMPASS devices, and flow was monitored by aortic and superior mesenteric artery flow probes. Partial resuscitative endovascular balloon occlusion of the aorta was inflated to control hemorrhage for 15 minutes before being deflated to try targeting aortic flow of 0.7 L/min (using only the COMPASS device) by an operator blinded to the arterial line pressures and aortic flow. Correlations between COMPASS and proximal/distal arterial line were evaluated, as well as actual aortic flow.

RESULTS

There was strong correlation between the distal mean arterial pressure (MAP) and the distal COMPASS MAP (r = 0.979, p < 0.01), as well as between the proximal arterial line and the proximal COMPASS on the pREBOA (r = 0.989, p < 0.01). There was a significant but weaker correlation between the distal compass MAP reading and aortic flow (r = 0.47, p < 0.0001), although it was not clinically significant and predicted flow was not achieved in a majority of the procedures. Of 10 pigs, survival times ranged from 10 to 120 minutes, with a mean survival of 50 minutes, and 1 pig surviving to 120 minutes.

CONCLUSION

Highly reliable pressure monitoring is achieved proximally and distally without arterial lines using the COMPASS device on the pREBOA. Despite accurate readings, distal MAPs were a poor indicator of aortic flow, and titration based upon distal MAPs did not provide reliable results. Further investigation will be required to find a suitable proxy for targeting specific aortic flow levels using pREBOA.

Partial Resuscitative Endovascular Balloon Occlusion of the Aorta: A Systematic Review of the Preclinical and Clinical Literature

BACKGROUND

Resuscitative endovascular balloon occlusion of the aorta (REBOA) has become a standard adjunct for the management of life-threatening truncal hemorrhage, but the technique is limited by the sequalae of ischemia distal to occlusion. Partial REBOA addresses this limitation, and the recent Food and Drug Administration approval of a device designed to enable partial REBOA will broaden its application. We conducted a systematic review of the available animal and clinical literature on the methods, impacts, and outcomes associated with partial REBOA as a technique to enable targeted proximal perfusion and limit distal ischemic injury. We hypothesize that a systematic review of the published animal and human literature on partial REBOA will provide actionable insight for the use of partial REBOA in the context of future wider clinical implementation of this technique.

METHODS

Using the Preferred Reporting Items for Systematic Reviews and Meta-Analyses for Protocols guidelines, we conducted a search of the available literature which used partial inflation of a REBOA balloon catheter. Findings from 22 large animal studies and 14 clinical studies met inclusion criteria.

RESULTS

Animal and clinical results support the benefits of partial REBOA including extending the resuscitative window extended safe occlusion time, improved survival, reduced proximal hypertension, and reduced resuscitation requirements. Clinical studies provide practical physiologic targets for partial REBOA including a period of total occlusion followed by gradual balloon deflation to achieve a target proximal pressure and/or target distal pressure.

CONCLUSIONS

Partial REBOA has several benefits which have been observed in animal and clinical studies, most notably reduced ischemic insult to tissues distal to occlusion and improved outcomes compared with total occlusion. Practical clinical protocols are available for the implementation of partial REBOA in cases of life-threatening torso hemorrhage.

Therapeutic cardiac arrest as an adjunct to resuscitative endovascular balloon occlusion of the aorta: Bridging the gap from fatal hemorrhage to definitive surgical control in swine

BACKGROUND

Uncontrolled hemorrhage is the leading cause of potentially survivable combat casualty mortality, with 86.5% of cases resulting from noncompressible torso hemorrhage. Resuscitative endovascular balloon occlusion of the aorta (REBOA) is a minimally invasive technique used to stabilize patients with noncompressible torso hemorrhage; however, its application can take an average of 8 minutes to place. One therapeutic capable of bridging this gap is adenosine-lidocaine-magnesium (ALM), which at high doses induces a reversible cardioplegia. We hypothesize by using ALM as an adjunct to REBOA, the ALM-induced cardiac arrest will temporarily halt exsanguination and reduce blood loss, allowing for REBOA placement and control of bleeding.

METHODS

Male Yorkshire swine (60-80 kg) were randomly assigned to REBOA only or ALM-REBOA (n = 8/group). At baseline, uncontrolled hemorrhage was induced via a 1.5-cm right femoral arteriotomy, and hemorrhaged blood was quantified. One minute after injury (S1), ALM was administered, and 7 minutes later (T0), zone 1 REBOA inflation occurred. If cardiac arrest ensued, cardiac function either recovered spontaneously or advanced life support was initiated. At T30, surgical hemostasis was obtained, and REBOA was deflated. Animals were resuscitated until they were humanely euthanized at T90.

RESULTS

During field care phase, heart rate and end-tidal CO2 of the ALM-REBOA group were significantly lower than the REBOA only group. While mean arterial pressure significantly decreased from baseline, no significant differences between groups were observed throughout the field care phase. There was no significant difference in survival between the two groups (ALM-REBOA = 89% vs. REBOA only = 100%). Total blood loss was significantly decreased in the ALM-REBOA group (REBOA only = 24.32 ± 1.89 mL/kg vs. ALM-REBOA = 17.75 ± 2.04 mL/kg, p = 0.0499).

CONCLUSION

Adenosine-lidocaine-magnesium is a novel therapeutic, which, when used with REBOA, can significantly decrease the amount of blood loss at initial presentation, without compromising survival. This study provides proof of concept for ALM and its ability to bridge the gap between patient presentation and REBOA placement.

Zone-dependent acute circulatory changes in abdominal organs and extremities after resuscitative balloon occlusion of the aorta (REBOA): an experimental model

INTRODUCTION

Resuscitative endovascular balloon occlusion of the aorta (REBOA) may be used in severely injured patients with uncontrollable bleeding. However, zone-dependent effects of REBOA are rarely described. We compared the short-term zone- and organ-specific microcirculatory changes in abdominal organs and the extremity during occlusion of the aorta in a standardized porcine model.

METHODS

Male pigs were placed under general anesthesia, for median laparotomy to expose intra-abdominal organs. REBOA placement occurred in Zone 1 (from origin left subclavian artery to celiac trunk), Zone 2 (between the coeliac trunk and most caudal renal artery) and Zone 3 (distal most caudal renal artery to aortic bifurcation). Local microcirculation of the intra-abdominal organs were measured at the stomach, colon, small intestine, liver, and kidneys. Furthermore, the right medial vastus muscle was included for assessment. Microcirculation was measured using oxygen-to-see device (arbitrary units, A.U). Invasive blood pressure measurements were recorded in the carotid and femoral artery (ipsilateral). Ischemia/Reperfusion (I/R)-time was 10 min with complete occlusion.

RESULTS

At baseline, microcirculation of intra-abdominal organs differed significantly (p < 0.001), the highest flow was in the kidneys (208.3 ± 32.9 A.U), followed by the colon (205.7 ± 36.2 A.U.). At occlusion in Zone 1, all truncal organs showed significant decreases (p < 0.001) in microcirculation, by 75% at the colon, and 44% at the stomach. Flow-rate changes at the extremities were non-significant (n.s). During occlusion in Zone 2, a significant decrease (p < 0.001) in microcirculation was observed at the colon (- 78%), small intestine (- 53%) and kidney (- 65%). The microcirculatory changes at the extremity were n.s. During occlusion in Zone 3, truncal and extremity microcirculatory changes were n.s.

CONCLUSION

All abdominal organs showed significant changes in microcirculation during REBOA. The intra-abdominal organs react differently to the same occlusion, whereas local microcirculation in extremities appeared to be unaffected by short-time REBOA, regardless of the zone of occlusion.

Resuscitative Endovascular Balloon Occlusion of the Aorta (REBOA): update and insights into current practices and future directions for research and implementation

Background

In this review, we assess the state of Resuscitative Endovascular Occlusion of the Aorta (REBOA) today with respect to out-of-hospital (OOH) vs. inhospital (H) use in blunt and penetrating trauma, as well as discuss areas of promising research that may be key in further advancement of REBOA applications.

Methods

To analyze the trends in REBOA use, we conducted a review of the literature and identified articles with human or animal data that fit the respective inclusion and exclusion criteria. In separate tables, we compiled data extracted from selected articles in categories including injury type, zone and duration of REBOA, setting in which REBOA was performed, sample size, age, sex and outcome. Based on these tables as well as more detailed review of some key cases of REBOA usage, we assessed the current state of REBOA as well as coagulation and histological disturbances associated with its usage. All statistical tests were 2-sided using an alpha=0.05 for significance. Analysis was done using SAS 9.5 (Cary, NC). Tests for significance was done with a t-test for continuous data and a Chi Square Test for categorical data.

Results

In a total of 44 cases performed outside of a hospital in both military and civilian settings, the overall survival was found to be 88.6%, significantly higher than the 50.4% survival calculated from 1,807 cases of REBOA performed within a hospital (p<.0001). We observe from human data a propensity to use Zone I in penetrating trauma and Zone III in blunt injuries. We observe lower final metabolic markers in animal studies with shorter REBOA time and longer follow-up times.

Conclusions

Further research related to human use of REBOA must be focused on earlier initiation of REBOA after injury which may depend on development of rapid vascular access devices and techniques more so than on any new improvements in REBOA. Future animal studies should provide detailed multisystem organ assessment to accurately define organ injury and metabolic burden associated with REBOA application. Overall, animal studies must involve realistic models of injury with severe clinical scenarios approximating human trauma and exsanguination, especially with long-term follow-up after injury.

Automated Partial Versus Complete Resuscitative Endovascular Balloon Occlusion of the Aorta for the Management of Hemorrhagic Shock in a Pig Model of Polytrauma: a Randomized Controlled Pilot Study

INTRODUCTION

Endovascular variable aortic control (EVAC) is an automated partial resuscitative endovascular balloon occlusion of the aorta (REBOA) platform designed to mitigate the deleterious effects of complete REBOA. Long-term experiments are needed to assess potential benefits. The feasibility of a 24-hour experiment in a complex large animal trauma model remains unknown.

MATERIALS AND METHODS

Anesthetized swine were subjected to controlled hemorrhage, blunt thoracic trauma, and tibial fractures. Animals were then randomized (N = 3/group) to control (No balloon support), 90 minutes of complete supraceliac REBOA, or 10 minutes of supraceliac REBOA followed by 80 minutes of EVAC. One hundred ten minutes after injury, animals were resuscitated with shed blood, the REBOA catheter was removed. Automated critical care under general anesthesia was maintained for 24 hours.

RESULTS

Animals in the control and EVAC groups survived to the end of the experiment. Animals in the REBOA group survived for 120, 130, and 660 minutes, respectively. Animals in the EVAC group displayed similar mean arterial pressure and plasma lactate concentration as the control group by the end of the experiment. Histologic analysis suggested myocardial injury in the REBOA group when compared with controls.

CONCLUSIONS

This study demonstrates the feasibility of intermediate-term experiments in a complex swine model of polytrauma with 90 minutes of REBOA. EVAC may be associated with improved survival at 24 hours when compared with complete REBOA. EVAC resulted in normalized physiology after 24 hours, suggesting that prolonged partial occlusion is possible. Longer studies evaluating partial REBOA strategies are needed.

Mitigating Ischemia-Reperfusion Injury Using a Bilobed Partial REBOA Catheter: Controlled Lower-Body Hypotension

BACKGROUND

Non-compressible torso hemorrhage (NCTH) is the leading cause of potentially preventable death on the battlefield. Resuscitative endovascular balloon occlusion of the aorta (REBOA) aims to restore central blood pressure and control NCTH below the balloon, but risks ischemia-reperfusion injury to distal organs when prolonged. We tested a bilobed partial REBOA catheter (pREBOA), which permits some of the blood to flow past the balloon.

METHODS

Female swine (n = 37, 6 groups, n = 5-8/group), anesthetized and instrumented, were exponentially hemorrhaged 50% of estimated blood volume (all except time controls [TC]). Negative controls (NC) did not receive REBOA or resuscitation. Positive controls (PC) received retransfusion after 120 min. REBOA groups received REBOA for 120 min, then retransfusion. Balloon was fully inflated in the full REBOA group (FR), and was partially inflated in partial REBOA groups (P45 and P60) to achieve a distal systolic blood pressure of 45 mm Hg or 60 mm Hg.

RESULTS

Aortic occlusion restored baseline values of proximal mean arterial pressure, cardiac output, and carotid flow in pREBOA groups. Lactate reached high values during occlusion in all REBOA groups (9.9 ± 4.2, 8.0 ± 4.1, and 10.7 ± 2.9 for P45, P60, and FR), but normalized by 6 to 12 h post-deflation in the partial groups. All TC and P60 animals survived 24 h. The NC, PC, and P45 groups survived 18.2 ± 9.5, 19.3 ± 10.6, and 21.0 ± 8.4 h. For FR animals mean survival was 6.2 ± 5.8 h, significantly worse than all other animals (P < 0.01, logrank test).

CONCLUSIONS

In this porcine model of hemorrhagic shock, animals undergoing partial REBOA for 120 min survived longer than those undergoing full occlusion.

A New Pressure-Regulated, Partial Resuscitative Endovascular Balloon Occlusion of the Aorta Device Achieves Targeted Distal Perfusion

BACKGROUND

Resuscitative endovascular balloon occlusion of the aorta (REBOA) reduces blood loss and improves hemodynamics. Complete occlusion results in distal ischemia, limiting its use for prolonged care. This study evaluated two next-generation partial REBOA (pREBOA) catheters and their ability to achieve targeted distal aortic flow.

MATERIALS AND METHODS

Swine underwent hemorrhagic shock, complete aortic occlusion, controlled continuous balloon deflation, and targeted distal perfusion (TDP; 300-mL/min) phases. They were randomized into three groups (n = 6/group), one managed with the current ER-REBOA (ER), and two with the new pREBOA technologies: a bilobed (BL) device and a semicompliant pREBOA-PRO (PRP). Hemodynamics including flow rates and mean arterial pressures at the carotid artery and infrarenal aorta were recorded.

RESULTS

Hemodynamics were comparable between groups during hemorrhage and complete occlusion phases. During the controlled continuous balloon deflation phase, the distal aortic flow rate strongly correlated with percent balloon volume in BL and PRP groups, suggesting a precise control of distal perfusion. The slope of flow-balloon-volume curves was greater in the ER group than BL and PRP groups, indicating the change in distal aortic flow rate was more sensitive to the balloon volume (less titratable) when using ER. During the TDP phase, variation in distal aortic flow and mean arterial pressure with respect to the target flow was lower in ER and PRP groups, than the BL group.

CONCLUSIONS

Pressure-regulated occlusion using the next-generation pREBOA catheters is more controlled than the first-generation ER-REBOA catheter and allow for targeted and precise distal perfusion.

Partial Versus Complete Resuscitative Endovascular Balloon Occlusion of the Aorta in Exsanguinating Trauma Patients With Non-Compressible Torso Hemorrhage

Hemorrhage is a major cause of death globally, yet our options to control the condition have remained limited. The standard intervention for patients suffering from a non-compressible torso hemorrhage (NCTH) typically involves resuscitative thoracotomy (RT) with aortic cross-clamping. Apart from being extraordinarily invasive, the survival rates for this procedure remain low. Over the years, research has surfaced that offers much promise regarding the use of resuscitative endovascular balloon occlusion of the aorta (REBOA) in exsanguinating patients. Although this type of procedure is not yet universally recognized as a gold standard, it holds some hope for the development of additional research regarding how we can make use of this advancement to improve survival in trauma patients. Complete REBOA (c-REBOA) has not gained wide acceptance due to the undeniable effects it has on normal physiology, metabolic effects, long-term complications, and mortality. Partial REBOA (p-REBOA) is not yet fully validated by research but could potentially be the answer to our problem. The critical question that we should address at this juncture is as follows: how can we improve the survival of patients with an NCTH in the least invasive way possible, while also reducing the feared complications associated with c-REBOA?

Can Resuscitative Endovascular Balloon Occlusion of the Aorta Fly? Assessing Aortic Balloon Performance for Aeromedical Evacuation

BACKGROUND

Noncompressible torso hemorrhage remains a leading cause of death. Resuscitative Endovascular Balloon Occlusion of the Aorta (REBOA) placement may occur before transport; however, its efficacy has not been demonstrated at altitude. We hypothesized that changes in altitude would not result in blood pressure changes proximal to a deployed REBOA.

METHODS

A simulation model for 7Fr guidewireless REBOA was used at altitudes up to 22,000 feet. Female pigs then underwent hemorrhagic shock to a mean arterial pressure (MAP) of 40 mm Hg. After hemorrhage, a REBOA catheter was deployed in the REBOA group and positioned but not inflated in the no-REBOA group. Animals underwent simulated aeromedical evacuation at 8000 ft or were left at ground level. After altitude exposure, the balloon was deflated, and the animals were observed.

RESULTS

Taking the REBOA catheter to 22,000 ft in the simulation model resulted in a lower systolic blood pressure but a preserved MAP. In the porcine model, REBOA increased both systolic blood pressure and MAP compared with no-REBOA (P < 0.05) and was unaffected by altitude. No differences in postflight blood pressure, acidosis, or systemic inflammatory response were observed between ground and altitude REBOA groups.

CONCLUSIONS

REBOA maintained MAP up to 22,000 feet in an inanimate model. In the porcine model, REBOA deployment improved MAP, and the balloon remained effective at altitude.

Total resuscitative endovascular balloon occlusion of the aorta causes inflammatory activation and organ damage within 30 minutes of occlusion in normovolemic pigs

Background

Resuscitative endovascular balloon occlusion of the aorta (REBOA) causes physiological, metabolic, end-organ and inflammatory changes that need to be addressed for better management of severely injured patients. The aim of this study was to investigate occlusion time-dependent metabolic, end-organ and inflammatory effects of total REBOA in Zone I in a normovolemic animal model.

Methods

Twenty-four pigs (25-35 kg) were randomized to total occlusion REBOA in Zone I for either 15, 30, 60 min (REBOA15, REBOA30, and REBOA60, respectively) or to a control group, followed by 3-h reperfusion. Hemodynamic variables, metabolic and inflammatory response, intraperitoneal and intrahepatic microdialysis, and plasma markers of end-organ injuries were measured during intervention and reperfusion. Intestinal histopathology was performed.

Results

Mean arterial pressure and cardiac output increased significantly in all REBOA groups during occlusion and blood flow in the superior mesenteric artery and urinary production subsided during intervention. Metabolic acidosis with increased intraperitoneal and intrahepatic concentrations of lactate and glycerol was most pronounced in REBOA30 and REBOA60 during reperfusion and did not normalize at the end of reperfusion in REBOA60. Inflammatory response showed a significant and persistent increase of pro- and anti-inflammatory cytokines during reperfusion in REBOA30 and was most pronounced in REBOA60. Plasma concentrations of liver, kidney, pancreatic and skeletal muscle enzymes were significantly increased at the end of reperfusion in REBOA30 and REBOA60. Significant intestinal mucosal damage was present in REBOA30 and REBOA60.

Conclusion

Total REBOA caused severe systemic and intra-abdominal metabolic disturbances, organ damage and inflammatory activation already at 30 min of occlusion.