Endovascular variable aortic control (EVAC) versus resuscitative endovascular balloon occlusion of the aorta (REBOA) in a swine model of hemorrhage and ischemia reperfusion injury

Prehospital Partial Resuscitative Endovascular Balloon Occlusion of the Aorta for Exsanguinating Subdiaphragmatic Hemorrhage

Importance

Hemorrhage is the most common cause of preventable death after injury. Most deaths occur early, in the prehospital phase of care.

Objective

To establish whether prehospital zone 1 (supraceliac) partial resuscitative endovascular balloon occlusion of the aorta (Z1 P-REBOA) can be achieved in the resuscitation of adult trauma patients at risk of cardiac arrest and death due to exsanguination.

Design, Setting, and Participants

This was a prospective observational cohort study (Idea, Development, Exploration, Assessment and Long-term follow-up [IDEAL] 2A design) with recruitment from June 2020 to March 2022 and follow-up until discharge from hospital, death, or 90 days evaluating a physician-led and physician-delivered, urban prehospital trauma service in the Greater London area. Trauma patients aged 16 years and older with suspected exsanguinating subdiaphragmatic hemorrhage, recent or imminent hypovolemic traumatic cardiac arrest (TCA) were included. Those with unsurvivable injuries or who were pregnant were excluded. Of 2960 individuals attended by the service during the study period, 16 were included in the study.

Exposures

ZI REBOA or P-REBOA.

Main Outcomes and Measures

The main outcome was the proportion of patients in whom Z1 REBOA and Z1 P-REBOA were achieved. Clinical end points included systolic blood pressure (SBP) response to Z1 REBOA, mortality rate (1 hour, 3 hours, 24 hours, or 30 days postinjury), and survival to hospital discharge.

Results

Femoral arterial access for Z1 REBOA was attempted in 16 patients (median [range] age, 30 [17-76] years; 14 [81%] male; median [IQR] Injury Severity Score, 50 [39-57]). In 2 patients with successful arterial access, REBOA was not attempted due to improvement in clinical condition. In the other 14 patients (8 [57%] of whom were in traumatic cardiac arrest [TCA]), 11 successfully underwent cannulation and had aortic balloons inflated in Z1. The 3 individuals in whom cannulation was unsuccessful were in TCA (failure rate = 3/14 [21%]). Median (IQR) pre-REBOA SBP in the 11 individuals for whom cannulation was successful (5 [46%] in TCA) was 47 (33-52) mm Hg. Z1 REBOA plus P-REBOA was associated with a significant improvement in BP (median [IQR] SBP at emergency department arrival, 101 [77-107] mm Hg; 0 of 10 patients were in TCA at arrival). The median group-level improvement in SBP from the pre-REBOA value was 52 (95% CI, 42-77) mm Hg (P < .004). P-REBOA was feasible in 8 individuals (8/11 [73%]) and occurred spontaneously in 4 of these. The 1- and 3-hour postinjury mortality rate was 9% (1/11), 24-hour mortality was 27% (3/11), and 30-day mortality was 82% (9/11). Survival to hospital discharge was 18% (2/11). Both survivors underwent early Z1 P-REBOA.

Conclusions and Relevance

In this study, prehospital Z1 P-REBOA is feasible and may enable early survival, but with a significant incidence of late death.

Trial Registration

ClinicalTrials.gov Identifier: NCT04145271.

INVESTIGATING THE RELATIONSHIP BETWEEN BLEEDING, CLOTTING, AND COAGULOPATHY DURING AUTOMATED PARTIAL REBOA STRATEGIES IN A HIGHLY LETHAL PORCINE HEMORRHAGE MODEL

ABSTRACT

Background: Death due to hemorrhagic shock, particularly, noncompressible truncal hemorrhage, remains one of the leading causes of potentially preventable deaths. Automated partial and intermittent resuscitative endovascular balloon occlusion of the aorta (i.e., pREBOA and iREBOA, respectively) are lifesaving endovascular strategies aimed to achieve quick hemostatic control while mitigating distal ischemia. In iREBOA, the balloon is titrated from full occlusion to no occlusion intermittently, whereas in pREBOA, a partial occlusion is maintained. Therefore, these two interventions impose different hemodynamic conditions, which may impact coagulation and the endothelial glycocalyx layer. In this study, we aimed to characterize the clotting kinetics and coagulopathy associated with iREBOA and pREBOA, using thromboelastography (TEG). We hypothesized that iREBOA would be associated with a more hypercoagulopathic response compared with pREBOA due to more oscillatory flow. Methods: Yorkshire swine (n = 8/group) were subjected to an uncontrolled hemorrhage by liver transection, followed by 90 min of automated pREBOA, iREBOA, or no balloon support (control). Hemodynamic parameters were continuously recorded, and blood samples were serially collected during the experiment (i.e., eight key time points: baseline (BL), T0, T10, T30, T60, T90, T120, T210 min). Citrated kaolin heparinase assays were run on a TEG 5000 (Haemonetics, Niles, IL). General linear mixed models were employed to compare differences in TEG parameters between groups and over time using STATA (v17; College Station, TX), while adjusting for sex and weight. Results: As expected, iREBOA was associated with more oscillations in proximal pressure (and greater magnitudes of peak pressure) because of the intermittent periods of full aortic occlusion and complete balloon deflation, compared to pREBOA. Despite these differences in acute hemodynamics, there were no significant differences in any of the TEG parameters between the iREBOA and pREBOA groups. However, animals in both groups experienced a significant reduction in clotting times (R time: P < 0.001; K time: P < 0.001) and clot strength (MA: P = 0.01; G: P = 0.02) over the duration of the experiment. Conclusions: Despite observing acute differences in peak proximal pressures between the iREBOA and pREBOA groups, we did not observe any significant differences in TEG parameters between iREBOA and pREBOA. The changes in TEG profiles were significant over time, indicating that a severe hemorrhage followed by both pREBOA and iREBOA can result in faster clotting reaction times (i.e., R times). Nevertheless, when considering the significant reduction in transfusion requirements and more stable hemodynamic response in the pREBOA group, there may be some evidence favoring pREBOA usage over iREBOA.

The employment of resuscitative endovascular balloon occlusion of the aorta in deployed settings

BACKGROUND

Resuscitative endovascular balloon occlusion of the aorta (REBOA) has been often used in place of open aortic occlusion for management of hemorrhagic shock in trauma. There is a paucity of data evaluating REBOA usage in military settings.

STUDY DESIGN AND METHODS

We queried the Department of Defense Trauma Registry (DODTR) for all cases with at least one intervention or assessment available within the first 72 h after injury between 2007 and 2023. We used relevant procedural codes to identify the use of REBOA within the DODTR, and we used descriptive statistics to characterize its use.

RESULTS

We identified 17 cases of REBOA placed in combat settings from 2017 to 2019. The majority of these were placed in the operating room (76%) and in civilian patients (70%). A penetrating mechanism caused the injury in 94% of cases with predominantly the abdomen and extremities having serious injuries. All patients subsequently underwent an exploratory laparotomy after REBOA placement, with moderate numbers of patients having spleen, liver, and small bowel injuries. The majority (82%) of included patients survived to hospital discharge.

DISCUSSION

We describe 17 cases of REBOA within the DODTR from 2007 to 2023, adding to the limited documentation of patients undergoing REBOA in military settings. We identified patterns of injury in line with previous studies of patients undergoing REBOA in military settings. In this small sample of military casualties, we observed a high survival rate.

Complications associated with the use of resuscitative endovascular balloon occlusion of the aorta (REBOA): an updated review

Resuscitative endovascular balloon occlusion of the aorta (REBOA) has become part of the arsenal to temporize patients in shock from severe hemorrhage. REBOA is used in trauma to prevent cardiovascular collapse by preserving heart and brain perfusion and minimizing distal hemorrhage until definitive hemorrhage control can be achieved. Significant side effects, including death, ischemia and reperfusion injuries, severe renal and lung damage, limb ischemia and amputations have all been reported. The aim of this article is to provide an update on complications related to REBOA. REBOA has emerged as a critical intervention for managing severe hemorrhagic shock, aiming to temporize patients and prevent cardiovascular collapse until definitive hemorrhage control can be achieved. However, this life-saving procedure is not without its challenges, with significant reported side effects. This review provides an updated overview of complications associated with REBOA. The most prevalent procedure-related complication is distal embolization and lower limb ischemia, with an incidence of 16% (range: 4-52.6%). Vascular and access site complications are also noteworthy, documented in studies with incidence rates varying from 1.2% to 11.1%. Conversely, bleeding-related complications exhibit lower documentation, with incidence rates ranging from 1.4% to 28.6%. Pseudoaneurysms are less likely, with rates ranging from 2% to 14%. A notable incidence of complications arises from lower limb compartment syndrome and lower limb amputation associated with the REBOA procedure. Systemic complications include acute kidney failure, consistently reported across various studies, with incidence rates ranging from 5.6% to 46%, representing one of the most frequently documented systemic complications. Infection and sepsis are also described, with rates ranging from 2% to 36%. Pulmonary-related complications, including acute respiratory distress syndrome and multisystem organ failure, occur in this population at rates ranging from 7.1% to 17.5%. This comprehensive overview underscores the diverse spectrum of complications associated with REBOA.

Near-infrared spectroscopy for kidney oxygen monitoring in a porcine model of hemorrhagic shock, hemodilution, and REBOA

Acute kidney injury is a common complication of trauma and hemorrhagic shock. In a porcine model of hemorrhagic shock, resuscitative endovascular balloon aortic occlusion (REBOA) and hemodilution, we hypothesized that invasive kidney oxygen concentration measurements would correlate more strongly with noninvasive near infra-red spectroscopy (NIRS) oxygen saturation measurements when cutaneous sensors were placed over the kidney under ultrasound guidance compared to placement over the thigh muscle and subcutaneous tissue. Eight anesthetized swine underwent hemorrhagic shock 4 of which were resuscitated with intravenous fluids prior to the return of shed blood (Hemodilution protocol) and 4 of which underwent REBOA prior to resuscitation and return of shed blood (REBOA protocol). There was a moderate correlation between the NIRS and kidney tissue oxygen measurements (r = 0.61 p < 0.001; r = 0.67 p < 0.001; r = 0.66 p < 0.001for left kidney, right kidney, and thigh NIRS respectively). When the animals were separated by protocol, the Hemodilution group showed a weak or nonsignificant correlation between NIRS and kidney tissue oxygen measurements (r = 0.10 p < 0.001; r = 0.01 p = 0.1007; r = 0.28 p < 0.001 for left kidney, right kidney, and thigh NIRS respectively). This contrasts with the REBOA group, where left and right kidney as well as thigh NIRS were moderately correlated with kidney tissue oxygen (r = 0.71 p < 0.001; r = 0.74 p < 0.001; r = 0.70 p < 0.001; for left kidney, right kidney, and thigh NIRS respectively). There was a strong correlation between both kidney NIRS signals and thigh NIRS measurements (r = 0.85 p < 0.001; r = 0.88 p < 0.001;for left kidney vs thigh and right kidney vs thigh respectively). There was also a strong correlation between left and right kidney NIRS (r = 0.90 p < 0.001). These relationships were maintained regardless of the resuscitation protocol. These results suggest that kidney NIRS measurements were more closely related to thigh NIRS measurements than invasive kidney tissue oxygen concentration.

Improving the precision of shock resuscitation by predicting fluid responsiveness with machine learning and arterial blood pressure waveform data

Fluid bolus therapy (FBT) is fundamental to the management of circulatory shock in critical care but balancing the benefits and toxicities of FBT has proven challenging in individual patients. Improved predictors of the hemodynamic response to a fluid bolus, commonly referred to as a fluid challenge, are needed to limit non-beneficial fluid administration and to enable automated clinical decision support and patient-specific precision critical care management. In this study we retrospectively analyzed data from 394 fluid boluses from 58 pigs subjected to either hemorrhagic or distributive shock. All animals had continuous blood pressure and cardiac output monitored throughout the study. Using this data, we developed a machine learning (ML) model to predict the hemodynamic response to a fluid challenge using only arterial blood pressure waveform data as the input. A Random Forest binary classifier referred to as the ML fluid responsiveness algorithm (MLFRA) was trained to detect fluid responsiveness (FR), defined as a ≥ 15% change in cardiac stroke volume after a fluid challenge. We then compared its performance to pulse pressure variation, a commonly used metric of FR. Model performance was assessed using the area under the receiver operating characteristic curve (AUROC), confusion matrix metrics, and calibration curves plotting predicted probabilities against observed outcomes. Across multiple train/test splits and feature selection methods designed to assess performance in the setting of small sample size conditions typical of large animal experiments, the MLFRA achieved an average AUROC, recall (sensitivity), specificity, and precision of 0.82, 0.86, 0.62. and 0.76, respectively. In the same datasets, pulse pressure variation had an AUROC, recall, specificity, and precision of 0.73, 0.91, 0.49, and 0.71, respectively. The MLFRA was generally well-calibrated across its range of predicted probabilities and appeared to perform equally well across physiologic conditions. These results suggest that ML, using only inputs from arterial blood pressure monitoring, may substantially improve the accuracy of predicting FR compared to the use of pulse pressure variation. If generalizable, these methods may enable more effective, automated precision management of critically ill patients with circulatory shock.

Revisiting the promise, practice and progress of resuscitative endovascular balloon occlusion of the aorta

PURPOSE OF REVIEW

The use of Resuscitative Endovascular Balloon Occlusion of the Aorta (REBOA) to temporarily control bleeding and improve central perfusion in critically injured trauma patients remains a controversial topic. In the last decade, select trauma services around the world have gained experience with REBOA. We discuss the recent observational data together with the initial results of the first randomized control trial and provide a view on the next steps for REBOA in trauma resuscitation.

RECENT FINDINGS

While the observational data continue to be conflicting, the first randomized control trial signals that in the UK, in-hospital REBOA is associated with harm. Likely a result of delays to haemorrhage control, views are again split on whether to abandon complex interventions in bleeding trauma patients and to only prioritize transfer to the operating room or to push REBOA earlier into the post injury phase, recognizing that some patients will not survive without intervention.

SUMMARY

Better understanding of cardiac shock physiology provides a new lens in which to evaluate REBOA through. Patient selection remains a huge challenge. Invasive blood pressure monitoring, combined with machine learning aided decision support may assist clinicians and their patients in the future. The use of REBOA should not delay definitive haemorrhage control in those patients without impending cardiac arrest.

Automated partial resuscitative endovascular balloon occlusion of the aorta reduces blood loss and hypotension in a highly lethal porcine liver injury model

BACKGROUND

Partial and intermittent resuscitative endovascular balloon occlusion of the aorta (pREBOA and iREBOA, respectively) are lifesaving techniques designed to extend therapeutic duration, mitigate ischemia, and bridge patients to definitive hemorrhage control. We hypothesized that automated pREBOA balloon titration compared with automated iREBOA would reduce blood loss and hypotensive episodes over a 90-minute intervention phase compared with iREBOA in an uncontrolled liver hemorrhage swine model.

METHODS

Twenty-four pigs underwent an uncontrolled hemorrhage by liver transection and were randomized to automated pREBOA (n = 8), iREBOA (n = 8), or control (n = 8). Once hemorrhagic shock criteria were met, controls had the REBOA catheter removed and received transfusions only for hypotension. The REBOA groups received 90 minutes of either iREBOA or pREBOA therapy. Surgical hemostasis was obtained, hemorrhage volume was quantified, and animals were transfused to euvolemia and then underwent 1.5 hours of automated critical care.

RESULTS

The control group had significantly higher mortality rate (5 of 8) compared with no deaths in both REBOA groups, demonstrating that the liver injury is highly lethal ( p = 0.03). During the intervention phase, animals in the iREBOA group spent a greater proportion of time in hypotension than the pREBOA group (20.7% [16.2-24.8%] vs. 0.76% [0.43-1.14%]; p < 0.001). The iREBOA group required significantly more transfusions than pREBOA (21.0 [20.0-24.9] mL/kg vs. 12.1 [9.5-13.9] mL/kg; p = 0.01). At surgical hemostasis, iREBOA had significantly higher hemorrhage volumes compared with pREBOA (39.2 [29.7-44.95] mL/kg vs. 24.7 [21.6-30.8] mL/kg; p = 0.04).

CONCLUSION

Partial REBOA animals spent significantly less time at hypotension and had decreased transfusions and blood loss. Both pREBOA and iREBOA prevented immediate death compared with controls. Further refinement of automated pREBOA is necessary, and controller algorithms may serve as vital control inputs for automated transfusion.

LEVEL OF EVIDENCE

Therapeutic/Care Management; Level III.

Partial Resuscitative Endovascular Balloon Occlusion of the Aorta Limits Ischemia-Reperfusion Injury After Simulated Aeromedical Evacuation

INTRODUCTION

One of the advantages of partial Resuscitative Endovascular Balloon Occlusion of the Aorta (pREBOA) compared to the original model is the mitigation of reperfusion injury. The safety and efficacy of pREBOA have not been demonstrated in the setting of aeromedical evacuation. We hypothesized that the pREBOA would result in less ischemia-reperfusion injury after altitude exposure.

METHODS

Twenty-four swine underwent femur fracture with hemorrhage for 20 min, followed by resuscitative endovascular balloon occlusion of the aorta (REBOA) deployment to Zone 1 and were randomized to pREBOA-PRO (Prytime Medical Devices Inc) full inflation, partial inflation, or sham inflation and then an altitude exposure of ground level or 8000 ft for 15 min. The primary endpoint was to examine if the balloon functioned at altitude. Our secondary endpoint was investigating evidence of ischemia-reperfusion by hemodynamic instability, electrolyte derangements, and acidosis. Comparisons were made by ANOVA.

RESULTS

After deflation, the partially inflated group maintained a higher mean arterial pressure (MAP) compared to fully inflated group (P = 0.026). Full REBOA pigs were more tachycardic compared to sham pREBOA at ground (P < 0.001) and this was exacerbated at altitude (P < 0.001). Full REBOA pigs were more acidotic than sham and pREBOA at ground pigs (P = 0.0006 and P = 0.0002, respectively). Altitude increased the acidosis in full REBOA pigs, resulting in a greater base deficit (P < 0.0001), lactate (P < 0.0001), and IL-6 (P = 0.006).

CONCLUSIONS

PREBOA resulted in less severe ischemia-reperfusion injury at both altitude and ground, while full balloon inflation at altitude exacerbated acidosis and ischemia-reperfusion injury. Efforts should therefore be made to utilize partial balloon occlusion when employing the REBOA catheter.

Partial vs Full Resuscitative Endovascular Balloon Occlusion of the Aorta (REBOA) in a Swine Model of Raised Intracranial Pressure and Hemorrhagic Shock

BACKGROUND

Partial resuscitative endovascular balloon occlusion of the aorta (pREBOA) is a potential method to mitigate the ischemia observed in full REBOA (fREBOA). However, the effect of pREBOA on cerebral perfusion in the setting of raised intracranial pressure (rICP) is unknown. The aim was to evaluate the effects of no REBOA (nREBOA) vs pREBOA vs fREBOA on cerebral perfusion in a swine model of rICP and hemorrhagic shock.

STUDY DESIGN

Anesthetized swine (n = 18) underwent instrumentation. Controlled hemorrhage was performed over 30 minutes. rICP was achieved using an intracranial Fogarty catheter inflated to achieve an ICP of 20 mmHg. Animals underwent intervention for 30 minutes, followed by resuscitation. The primary outcome was cerebral perfusion measured by ICP (millimeters of mercury), cerebral perfusion pressure (CPP; millimeters of mercury), and cerebral blood flow (CBF; milliliters per minute per 100 g) derived from CT perfusion. The secondary outcomes included hemodynamics and lactate (millimoles per liter).

RESULTS

The peak ICP of pREBOA animals (22.7 ± 2.5) was significantly lower than nREBOA and fREBOA. pREBOA CPP was significantly higher compared with nREBOA and fREBOA during resuscitation. The pREBOA CBF was greater during intervention and resuscitation compared with nREBOA (p < 0.001). Systolic blood pressure was similar between pREBOA and fREBOA, and coronary perfusion was significantly greater in pREBOA. fREBOA had significantly higher lactate during the intervention (9.3 ± 1.3) and resuscitation (8.9 ± 3.5) compared with nREBOA and pREBOA.

CONCLUSION

pREBOA produced greater cerebral perfusion, as demonstrated by more favorable CPP, CBF, and ICP values. fREBOA was associated with metabolic derangement and diminished pressure during resuscitation. pREBOA is superior to fREBOA in a swine model and should be considered over fREBOA for aortic occlusion.

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.

Development of a computational fluid dynamic model to investigate the hemodynamic impact of REBOA

Background: Resuscitative endovascular balloon occlusion of the aorta (REBOA) is a lifesaving intervention for major truncal hemorrhage. Balloon-tipped arterial catheters are inserted via the femoral artery to create a temporary occlusion of the aorta, which minimizes the rate of internal bleeding until definitive surgery can be conducted. There is growing concern over the resultant hypoperfusion and potential damage to tissues and organs downstream of REBOA. To better understand the acute hemodynamic changes imposed by REBOA, we developed a three-dimensional computational fluid dynamic (CFD) model under normal, hemorrhage, and aortic occlusion conditions. The goal was to characterize the acute hemodynamic changes and identify regions within the aortic vascular tree susceptible to abnormal flow and shear stress. Methods: Hemodynamic data from established porcine hemorrhage models were used to build a CFD model. Swine underwent 20% controlled hemorrhage and were randomized to receive a full or partial aortic occlusion. Using CT scans, we generated a pig-specific aortic geometry and imposed physiologically relevant inlet flow and outlet pressure boundary conditions to match in vivo data. By assuming non-Newtonian fluid properties, pressure, velocity, and shear stresses were quantified over a cardiac cycle. Results: We observed a significant rise in blood pressure (∼147 mmHg) proximal to REBOA, which resulted in increased flow and shear stress within the ascending aorta. Specifically, we observed high levels of shear stress within the subclavian arteries (22.75 Pa). Alternatively, at the site of full REBOA, wall shear stress was low (0.04 ± 9.07E-4 Pa), but flow oscillations were high (oscillatory shear index of 0.31). Comparatively, partial REBOA elevated shear levels to 84.14 ± 19.50 Pa and reduced flow oscillations. Our numerical simulations were congruent within 5% of averaged porcine experimental data over a cardiac cycle. Conclusion: This CFD model is the first to our knowledge to quantify the acute hemodynamic changes imposed by REBOA. We identified areas of low shear stress near the site of occlusion and high shear stress in the subclavian arteries. Future studies are needed to determine the optimal design parameters of endovascular hemorrhage control devices that can minimize flow perturbations and areas of high shear.

Automated aortic endovascular balloon volume titration prevents re-arrest immediately after return of spontaneous circulation in a swine model of nontraumatic cardiac arrest

Objectives

Endovascular aortic occlusion as an adjunct to cardiopulmonary resuscitation (CPR) for non-traumatic cardiac arrest is gaining interest. In a recent clinical trial, return of spontaneous circulation (ROSC) was achieved despite prolonged no-flow times. However, 66% of patients re-arrested upon balloon deflation. We aimed to determine if automated titration of endovascular balloon volume following ROSC can augment diastolic blood pressure (DBP) to prevent re-arrest.

Methods

Twenty swine were anesthetized and placed into ventricular fibrillation (VF). Following 7 minutes of no-flow VF and 5 minutes of mechanical CPR, animals were subjected to complete aortic occlusion to adjunct CPR. Upon ROSC, the balloon was either deflated steadily over 5 minutes (control) or underwent automated, dynamic adjustments to maintain a DBP of 60 mmHg (Endovascular Variable Aortic Control, EVAC).

Results

ROSC was obtained in ten animals (5 EVAC, 5 REBOA). Sixty percent (3/5) of control animals rearrested while none of the EVAC animals rearrested (p = 0.038). Animals in the EVAC group spent a significantly higher proportion of the post-ROSC period with a DBP > 60 mmHg [median (IQR)] [control 79.7 (72.5–86.0)%; EVAC 97.7 (90.8–99.7)%, p = 0.047]. The EVAC group had a statistically significant reduction in arterial lactate concentration [7.98 (7.4–8.16) mmol/L] compared to control [9.93 (8.86–10.45) mmol/L, p = 0.047]. There were no statistical differences between the two groups in the amount of adrenaline (epinephrine) required.

Conclusion

In our swine model of cardiac arrest, automated aortic endovascular balloon titration improved DBP and prevented re-arrest in the first 20 minutes after ROSC.

Maintaining Zone 1 Occlusion is a Dynamic Process: The Effects of Proximal Pressure and Blood Transfusion During REBOA

BACKGROUND

Resuscitative endovascular balloon occlusion of the aorta (REBOA) provides hemodynamic support to patients with non-compressible truncal hemorrhage. As cardiac output increases due to aortic occlusion (AO), aortic diameter will increase as a function of compliance, potentially causing unintended flow around the balloon.

MATERIALS AND METHODS

Swine (N = 10) were instrumented to collect proximal mean arterial blood pressure (pMAP), distal MAP (dMAP), balloon pressure (bP), balloon volume (bV), and distal aortic flow (Qaorta). A 7-Fr automated REBOA catheter was positioned in Zone 1. At T0, animals underwent 30% total blood volume hemorrhage over 30 min followed by balloon inflation to complete AO. Automated balloon inflation occurred from T30-T60 when Qaorta was detected. Period of interest was T55-T60, while the balloon actively worked to maintain AO during transfusion of shed blood.

RESULTS

Median weight of the cohort was 73.75 [IQR:71.58-74.45] kg. During T40-T55 and T55-T60, median pMAP was 88.95 [IQR:76.80-109.92] and 108.13 [IQR:99.13-119.51] mmHg, P = 0.07. Median Qaorta during T40-T55, and T55-T60 was 0.81 [IQR:0.41-0.96], and 1.53 [IQR:1.07-1.96] mL/kg/min, P = 0.06. Median number of balloon inflations during T40-T55 was 0.00 [IQR:0.00-0.75] and increased during active transfusion to 10.00 [IQR:5.25-14.00], P = 0.001.

DISCUSSION

In clinical practice, following initial establishment of AO, progressive balloon inflations are required to maintain AO in response to intrinsic and transfusion-mediated increases in cardiac output, blood pressure, and aortic diameter.

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.

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.

Resuscitative endovascular balloon occlusion of the aorta in combat casualties: The past, present, and future

BACKGROUND

Noncompressible torso hemorrhage is a leading cause of preventable death on the battlefield. Intra-aortic balloon occlusion was first used in combat in the 1950s, but military use was rare before Operation Iraqi Freedom and Operation Enduring Freedom. During these wars, the combination of an increasing number of deployed vascular surgeons and a significant rise in deaths from hemorrhage resulted in novel adaptations of resuscitative endovascular balloon occlusion of the aorta (REBOA) technology, increasing its potential application in combat. We describe the background of REBOA development in response to a need for minimally invasive intervention for hemorrhage control and provide a detailed review of all published cases (n = 47) of REBOA use for combat casualties. The current limitations of REBOA are described, including distal ischemia and reperfusion injury, as well as ongoing research efforts to adapt REBOA for prolonged use in the austere setting.

LEVEL OF EVIDENCE

Level V.

Focal intra-colon cooling reduces organ injury and systemic inflammation after REBOA management of lethal hemorrhage in rats

Resuscitative endovascular balloon occlusion of the aorta (REBOA) is a lifesaving maneuver for the management of lethal torso hemorrhage. However, its prolonged use leads to distal organ ischemia-reperfusion injury (IRI) and systemic inflammatory response syndrome (SIRS). The objective of this study is to investigate the blood-based biomarkers of IRI and SIRS and the efficacy of direct intestinal cooling in the prevention of IRI and SIRS. A rat lethal hemorrhage model was produced by bleeding 50% of the total blood volume. A balloon catheter was inserted into the aorta for the implementation of REBOA. A novel TransRectal Intra-Colon (TRIC) device was placed in the descending colon and activated from 10 min after the bleeding to maintain the intra-colon temperature at 37 °C (TRIC37°C group) or 12 °C (TRIC12°C group) for 270 min. The upper body temperature was maintained at as close to 37 °C as possible in both groups. Blood samples were collected before hemorrhage and after REBOA. The organ injury biomarkers and inflammatory cytokines were evaluated by ELISA method. Blood based organ injury biomarkers (endotoxin, creatinine, AST, FABP1/L-FABP, cardiac troponin I, and FABP2/I-FABP) were all drastically increased in TRIC37°C group after REBOA. TRIC12°C significantly downregulated these increased organ injury biomarkers. Plasma levels of pro-inflammatory cytokines TNF-α, IL-1b, and IL-17F were also drastically increased in TRIC37°C group after REBOA. TRIC12°C significantly downregulated the pro-inflammatory cytokines. In contrast, TRIC12°C significantly upregulated the levels of anti-inflammatory cytokines IL-4 and IL-10 after REBOA. Amazingly, the mortality rate was 100% in TRIC37°C group whereas 0% in TRIC12°C group after REBOA. Directly cooling the intestine offered exceptional protection of the abdominal organs from IRI and SIRS, switched from a harmful pro-inflammatory to a reparative anti-inflammatory response, and mitigated mortality in the rat model of REBOA management of lethal hemorrhage.

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.

Reperfusion repercussions: A review of the metabolic derangements following resuscitative endovascular balloon occlusion of the aorta

BACKGROUND

Current resuscitative endovascular balloon occlusion of the aorta (REBOA) literature focuses on improving outcomes through careful patient selection, diligent catheter placement, and expeditious definitive hemorrhage control. However, the detection and treatment of post-REBOA ischemia-reperfusion injury (IRI) remains an area for potential improvement. Herein, we provide a review of the metabolic derangements that we have encountered while managing post-REBOA IRI in past swine experiments. We also provide data-driven clinical recommendations to facilitate resuscitation post-REBOA deflation that may be translatable to humans.

METHODS

We retrospectively reviewed the laboratory data from 25 swine across three varying hemorrhagic shock models that were subjected to complete REBOA of either 45 minutes, 60 minutes, or 90 minutes. In each model the balloon was deflated gradually following definitive hemorrhage control. Animals were then subjected to whole blood transfusion and critical care with frequent electrolyte monitoring and treatment of derangements as necessary.

RESULTS

Plasma lactate peaked and pH nadired long after balloon deflation in all swine in the 45-minute, 60-minute, and 90-minute occlusion models (onset of peak lactate, 32.9 ± 6.35 minutes, 38.8 ± 10.55 minutes, and 49.5 ± 6.5 minutes; pH nadir, 4.3 ± 0.72 minutes, 26.9 ± 12.32 minutes, and 42 ± 7.45 minutes after balloon deflation in the 45-, 60-, and 90-minute occlusion models, respectively). All models displayed persistent hypoglycemia for more than an hour following reperfusion (92.1 ± 105.5 minutes, 125 ± 114.9 minutes, and 96 ± 97.8 minutes after balloon deflation in the 45-, 60-, and 90-minute occlusion groups, respectively). Hypocalcemia and hyperkalemia occurred in all three groups, with some animals requiring treatment more than an hour after reperfusion.

CONCLUSION

Metabolic derangements resulting from REBOA use are common and may worsen long after reperfusion despite resuscitation. Vigilance is required to detect and proactively manage REBOA-associated IRI. Maintaining a readily available "deflation kit" of pharmacological agents needed to treat common post-REBOA electrolyte abnormalities may facilitate management.

LEVEL OF EVIDENCE

Level V.

Resuscitative endovascular balloon occlusion of the aorta in a pediatric swine model: Is 60 minutes too long?

BACKGROUND

Resuscitative endovascular balloon occlusion of the aorta (REBOA) is recommended in adults with a noncompressible torso hemorrhage with occlusion times of less than 60 minutes. The tolerable duration in children is unknown. We used a pediatric swine controlled hemorrhage model to evaluate the physiologic effects of 30 minutes and 60 minutes of REBOA.

METHODS

Pediatric swine weighing 20 kg to 30 kg underwent a splenectomy and a controlled 60% total blood volume hemorrhage over 30 minutes, followed by either zone 1 REBOA for 30 minutes (30R) or 60 minutes (60R). Swine were then resuscitated with shed blood and received critical care for 240 minutes.

RESULTS

During critical care, the 30R group's (n = 3) pH, bicarbonate, base excess, and lactate were no different than baseline, while at the end of critical care, these variables continued to differ from baseline in the 60R group (n = 5) and were worsening (7.4 vs. 7.2, p < 0.001, 30.4 mmol/L vs. 18.4 mmol/L, p < 0.0001, 5.6 mmol/L vs. -8.5 mmol/L, p < 0.0001, 2.4 mmol/L vs. 5.7 mmol/L, p < 0.001, respectively). Compared with baseline, end creatinine and creatinine kinase were elevated in 60R swine (1.0 mg/dL vs. 1.7 mg/dL, p < 0.01 and 335.4 U/L vs. 961.0 U/L, p < 0.001, respectively), but not 30R swine (0.9 mg/dL vs. 1.2 mg/dL, p = 0.06 and 423.7 U/L vs. 769.5 U/L, p = 0.15, respectively). There was no difference in survival time between the 30R and 60R pediatric swine, p = 0.99.

CONCLUSION

The physiologic effects of 30 minutes of zone 1 REBOA in pediatric swine mostly resolved during the subsequent 4 hours of critical care, whereas the effects of 60 minutes of REBOA persisted and worsened after 4 hours of critical care. Sixty minutes of zone 1 REBOA may create an irreversible physiologic insult in a pediatric population.

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.

Resuscitative endovascular balloon occlusion of the aorta (REBOA) in a swine model of hemorrhagic shock and blunt thoracic injury

PURPOSE

While resuscitative endovascular balloon occlusion of the aorta (REBOA) is contraindicated in patients with aortic injuries, this technique may benefit poly-trauma patients with less extreme thoracic injuries. The purpose of this study was to characterize the effects of thoracic injury on hemodynamics during REBOA and the changes in pulmonary contusion over time in a swine model.

METHODS

Twelve swine were anesthetized, instrumented, and randomized to receive either a thoracic injury with 5 impacts to the chest or no injury. All animals underwent controlled hemorrhage of 25% blood volume followed by 45 min of Zone 1 REBOA. Animals were then resuscitated with shed blood, observed during a critical care period, and euthanized after 6 h of total experimental time.

RESULTS

There were no differences between the groups at baseline. The only difference after 6 h was a lower hemoglobin in the thoracic trauma group (8.4 ± 0.8 versus 9.4 ± 0.6 g/dL, P = 0.04). The average proximal mean arterial pressures were significantly lower in the thoracic trauma group during aortic occlusion [103 (98-108) versus 117 (115-124) mmHg, P = 0.04]. There were no differences between the pulmonary contusion before REBOA and at the end of the experiment in size (402 ± 263 versus 356 ± 291 mL, P = 0.782) or density (- 406 ± 127 versus - 299 ± 175 HFU, P = 0.256).

CONCLUSIONS

Thoracic trauma blunted the proximal arterial pressure augmentation during REBOA but had minimal impacts on resuscitative outcomes. This initial study indicates that REBOA does not seem to exacerbate pulmonary contusion in swine, but blunt thoracic injuries may attenuate the expected rises in proximal blood pressure during REBOA.

A three-tier Rescue stent improves outcomes over balloon occlusion in a porcine model of noncompressible hemorrhage

BACKGROUND

Noncompressible hemorrhage remains a high-mortality injury, and aortic balloon occlusion poses limitations in terms of distal ischemic injury. Our hypothesis was that a retrievable Rescue stent would confer improved outcome over aortic balloon occlusion.

METHODS

A three-tier, retrievable stent graft was laser welded from nitinol and polytetrafluoroethylene to provide rapid thoracic and abdominal coverage with an interval bare metal segment to preserve visceral flow. Anesthetized swine had injury of the thoracic or abdominal aorta followed by balloon occlusion or a Rescue stent. A 1-hour long damage-control phase with blood repletion was used to simulate the prolonged interval between injury and repair, especially in the battlefield setting. Following the damage-control phase, the balloon or stent were retrieved followed by vascular repair and recovery to 48 hours. Animals were compared in terms of hemodynamics, blood loss, neurophysiologic spinal cord ischemia, ischemic organ injury, and survival.

RESULTS

Despite antegrade hemorrhage control, balloon occlusion averaged 3.5 L of retrograde hemorrhage, loss of visceral perfusion, and permanent spinal cord ischemia by neurophysiology in six of seven animals. After permanent repair, all balloon occlusion animals died with only a single short term (5 hours) survivor. Conversely, Rescue stent animals revealed rapid hemorrhage control (in under 2 minutes) whether the injury was thoracic or abdominal with improved hemodynamics, preserved visceral flow, reduced spinal cord ischemia, negligible histologic organ injury and survival to end of study in all abdominal injured animals (n = 6) and four of six thoracic injured animals, with two deaths related to arrhythmia.

CONCLUSION

Compared with aortic balloon occlusion, a Rescue stent offers superior hemorrhage control and survival by virtue of reduced ischemic injury and direct control of the hemorrhagic injury. The Rescue stent may become a useful tool for damage control, especially on the battlefield where definitive repair presents logistical challenges.

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.

Accumulative occlusion time correlates with postoperative pulmonary complications in patients undergoing pelvic and sacrum tumor resection assisted by abdominal aortic balloon occlusion: a retrospective cohort study

Background

Postoperative pulmonary complications (PPCs) seems to be high in patients undergoing pelvic and sacrum tumor resection assisted by abdominal aortic balloon occlusion. We hypothesized that the accumulative occlusion time (AOT) of the abdominal aortic balloon may be predictive of PPCs. The objective of the study was to identify the influence of AOT on PPCs.

Methods

Retrospectively analyzed perioperative factors of 584 patients who underwent pelvic and sacrum tumor resection assisted by abdominal aortic balloon occlusion in our hospital from January 1, 2016 to December 31, 2018. PPCs including suspected pulmonary infection, atelectasis, pulmonary edema, pleural effusion, respiratory failure were clinically diagnosed. Perioperative parameters among patients with and without PPCs were compared. A receiver operating characteristic (ROC) analysis was conducted to evaluate the discriminative power of AOT with regard to PPCs. A multivariate logistic-regression model was finally established to identify independent risk factors for PPCs.

Results

The incidence of PPCs was 15.6% (91 patients). The median AOT in PPCs group was significantly higher than that in non-PPCs group (P <  0.001). The hospital stay was significantly prolonged in PPCs group (P <  0.001). The ROC analysis showed an AOT of 119 min as the threshold value at which the joint sensitivity (88.60%) and specificity (31.87%) was maximal. Finally, AOT ≥ 119 min (P = 0.046; odds ratio (OR) = 2.074), age (P < 0.001; OR = 1.032), ASA grade III (P = 0.015; OR = 3.264), and estimated blood loss (P = 0.022; OR = 1.235) were independent risk factors of PPCs by multivariate logistic regression analysis.

Conclusion

The incidence of PPCs in patients undergoing the pelvic and sacrum tumor surgery assisted by abdominal aortic balloon occlusion was 15.6%. AOT ≥ 119 min was an independent predictor for PPCs. Surgeons should strive to minimize the AOT within 2 h.

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.

Not ready for prime time: Intermittent versus partial resuscitative endovascular balloon occlusion of the aorta for prolonged hemorrhage control in a highly lethal porcine injury model

BACKGROUND

Partial resuscitative endovascular balloon occlusion of the aorta (pREBOA) and intermittent REBOA (iREBOA) are techniques to extend the therapeutic duration of REBOA by balloon titration for distal flow or cyclical balloon inflation/deflation to allow transient distal flow, respectively. We hypothesized that manually titrated pREBOA would reduce blood losses and ischemic burden when compared with iREBOA.

METHODS

Following 20% blood volume controlled hemorrhage, 10 anesthetized pigs underwent uncontrolled hemorrhage from the right iliac artery and vein. Once in hemorrhagic shock, animals underwent 15 minutes of complete zone 1 REBOA followed by 75 minutes of either pREBOA or iREBOA (n = 5/group). After 90 minutes, definitive hemorrhage control was obtained, animals were resuscitated with the remaining collected blood, and then received 2 hours of critical care.

RESULTS

There were no differences in mortality. Animals randomized to iREBOA spent a larger portion of the time at full occlusion when compared with pREBOA (median, 70 minutes; interquartile range [IQR], 70-80 vs. median, 20 minutes; IQR, 20-40, respectively; p = 0.008). While the average blood pressure during the intervention period was equivalent between groups, this was offset by large fluctuations in blood pressure and significantly more rescue occlusions for hypotension with iREBOA. Despite lower maximum aortic flow rates, the pREBOA group tolerated a greater total amount of distal aortic flow during the intervention period (median, 20.9 L; IQR, 20.1-23.0 vs. median, 9.8 L; IQR, 6.8-10.3; p = 0.03) with equivalent abdominal blood losses. Final plasma lactate and creatinine concentrations were equivalent, although iREBOA animals had increased duodenal edema on histology.

CONCLUSION

Compared with iREBOA, pREBOA reduced the time spent at full occlusion and the number of precipitous drops in proximal mean arterial pressure while delivering more distal aortic flow but not increasing total blood loss in this highly lethal injury model. Neither technique demonstrated a survival benefit. Further refinement of these techniques is necessary before clinical guidelines are issued.

Resuscitative endovascular balloon occlusion of the aorta induced myocardial injury is mitigated by endovascular variable aortic control

BACKGROUND

The cardiac effects of resuscitative endovascular balloon occlusion of the aorta (REBOA) are largely unknown. We hypothesized that increased afterload from REBOA would lead to cardiac injury, and that partial flow using endovascular variable aortic control (EVAC) would mitigate this injury.

METHODS

Eighteen anesthetized swine underwent controlled 25% blood volume hemorrhage. Animals were randomized to either Zone 1 REBOA, Zone 1 EVAC, or no intervention (control) for 45 minutes. Animals were then resuscitated with shed blood, observed during critical care, and euthanized after a 6-hour total experimental time. Left ventricular function was measured with a pressure-volume catheter, and blood samples were drawn at routine intervals.

RESULTS

The average cardiac output during the intervention period was higher in the REBOA group (9.3 [8.6-15.4] L/min) compared with the EVAC group (7.2 [5.8-8.0] L/min, p = 0.01) and the control group (6.8 [5.8-7.7] L/min, p < 0.01). At the end of the intervention, the preload recruitable stroke work was significantly higher in both the REBOA and EVAC groups compared with the control group (111.2 [102.5-148.6] and 116.7 [116.6-141.4] vs. 67.1 [62.7-87.9], p = 0.02 and p < 0.01, respectively). The higher preload recruitable stroke work was maintained throughout the experiment in the EVAC group, but not in the REBOA group. Serum troponin concentrations after 6 hours were higher in the REBOA group compared with both the EVAC and control groups (6.26 ± 5.35 ng/mL vs 0.92 ± 0.61 ng/mL and 0.65 ± 0.38 ng/mL, p = 0.05 and p = 0.03, respectively). Cardiac intramural hemorrhage was higher in the REBOA group compared with the control group (1.67 ± 0.46 vs. 0.17 ± 0.18, p = 0.03), but not between the EVAC and control groups.

CONCLUSION

In a swine model of hemorrhagic shock, complete aortic occlusion resulted in cardiac injury, although there was no direct decrease in cardiac function. EVAC mitigated the cardiac injury and improved cardiac performance during resuscitation and critical care.

Efficacy of intermittent versus standard resuscitative endovascular balloon occlusion of the aorta in a lethal solid organ injury model

BACKGROUND

High-grade solid organ injury is a major cause of mortality in trauma. Use of resuscitative endovascular balloon occlusion of the aorta (REBOA) can be effective but is limited by ischemia-reperfusion injury. Intermittent balloon inflation/deflation has been proposed as an alternative, but the safety and efficacy prior to operative hemorrhage control is unknown.

METHODS

Twenty male swine underwent standardized high-grade liver injury, then randomization to controls (N = 5), 60-min continuous REBOA (cR, n = 5), and either a time-based (10-minute inflation/3-minute deflation, iRT = 5) or pressure-based (mean arterial pressure<40 during deflation, iRP = 5) intermittent schedule. Experiments were concluded after 120 minutes or death.

RESULTS

Improved overall survival was seen in the iRT group when compared to cR (p < 0.01). Bleeding rate in iRT (5.9 mL/min) was significantly lower versus cR and iRP (p = 0.02). Both iR groups had higher final hematocrit (26% vs. 21%) compared to cR (p = 0.03). Although overall survival was lower in the iRP group, animals surviving to 120 minutes with iRP had decreased end organ injury (Alanine aminotransferase [ALT] 33 vs. 40 in the iRT group, p = 0.03) and lower lactate levels (13 vs. 17) compared with the iRT group (p = 0.03). No differences were seen between groups in terms of coagulopathy based on rotational thromboelastometry.

CONCLUSION

Intermittent REBOA is a potential viable adjunct to improve survival in lethal solid organ injury while minimizing the ischemia-reperfusion seen with full REBOA. The time-based intermittent schedule had the best survival and prolonged duration of tolerable zone 1 placement. Although the pressure-based schedule was less reliable in terms of survival, when effective, it was associated with decreased acidosis and end-organ injury.

Renal effects of three endoaortic occlusion strategies in a swine model of hemorrhagic shock

INTRODUCTION

Trauma patients are predisposed to kidney injury. We hypothesized that in shock, zone 3 REBOA would increase renal blood flow (RBF) compared to control and that a period of zone 3 occlusion following zone 1 occlusion would improve renal function compared to zone 1 occlusion alone.

MATERIALS AND METHODS

Twenty-four anesthetized swine underwent hemorrhagic shock, 45 min of zone 1 REBOA (Z1, supraceliac), zone 3 REBOA (Z3, infrarenal), or no intervention (control) followed by resuscitation with shed blood and 5 h of critical care. In a fourth group (Z1Z3), animals underwent 55 min of zone 3 REBOA following zone 1 occlusion. Physiologic parameters were recorded, blood and urine were collected at specified intervals.

RESULTS

During critical care, there were no differences in RBF between the Z1 and Z3 groups. The average RBF during critical care in Z1Z3 was significantly lower than in Z3 alone (98.2 ± 23.9 and 191.9 ± 23.7 mL/min; p = 0.046) and not different than Z1. There was no difference in urinary neutrophil gelatinase-associated lipocalin-to-urinary creatinine ratio between Z1 and Z1Z3. Animals in the Z1Z3 group had a significant increase in the ratio at the end of the experiment compared to baseline [median (IQR)] [9.2 (8.2-13.2) versus 264.5 (73.6-1174.6)]. Following Z1 balloon deflation, RBF required 45 min to return to baseline.

CONCLUSION

Neither zone 3 REBOA alone nor zone 3 REBOA following zone 1 REBOA improved renal blood flow or function. Following zone 1 occlusion, RBF is restored to baseline levels after approximately 45 min.

Resuscitative Endovascular Balloon Occlusion of the Aorta: Review of the Literature and Applications to Veterinary Emergency and Critical Care

While hemorrhagic shock might be the result of various conditions, hemorrhage control and resuscitation are the corner stone of patient management. Hemorrhage control can prove challenging in both the acute care and surgical settings, especially in the abdomen, where no direct pressure can be applied onto the source of bleeding. Resuscitative endovascular balloon occlusion of the aorta (REBOA) has emerged as a promising replacement to resuscitative thoracotomy (RT) for the management of non-compressible torso hemorrhage in human trauma patients. By inflating a balloon at specific levels (or zones) of the aorta to interrupt blood flow, hemorrhage below the level of the balloon can be controlled. While REBOA allows for hemorrhage control and augmentation of blood pressure cranial to the balloon, it also exposes caudal tissue beds to ischemia and the whole body to reperfusion injury. We aim to introduce the advantages of REBOA while reviewing known limitations. This review outlines a step-by-step approach to REBOA implementation, and discusses common challenges observed both in human patients and during translational large animal studies. Currently accepted and debated indications for REBOA in humans are discussed. Finally, we review possible applications for veterinary patients and how REBOA has the potential to be translated into clinical veterinary practice.

Zones matter: Hemodynamic effects of zone 1 vs zone 3 resuscitative endovascular balloon occlusion of the aorta placement in trauma patients

INTRODUCTION

Resuscitative endovascular balloon occlusion of the aorta (REBOA) has emerged as a therapy for hemorrhagic shock to limit ongoing bleeding and support proximal arterial pressures. Current REBOA algorithms recommend zone selection based on suspected anatomic location of injury rather than severity of shock. We examined the effects of Zone 1 versus Zone 3 REBOA in patients enrolled in the American Association for the Surgery of Trauma Aortic Occlusion for Resuscitation in Trauma and Acute Care Surgery (AORTA) Registry.

PATIENTS AND METHODS

The prospective observational AORTA Registry was queried from November 2013 to November 2017. Patients who received REBOA were included if their initial systolic blood pressure (SBP) was less than 90 mmHg upon arrival and they were not receiving cardiopulmonary resuscitation.

RESULTS

There were 762 patients recorded in the AORTA database during the study period. Of these, 245 underwent REBOA and 99 patients met inclusion criteria. The initial balloon position was Zone 1 in 55 patients, Zone 3 in 36 patients, and unknown or Zone 2 in 8 patients. The change in proximal SBP was greater after REBOA in the Zone 1 group compared to the Zone 3 group (58 ± 4 mmHg vs 41 ± 4 mmHg, P = 0.008). The zone of occlusion was significantly associated with the change in proximal SBP in a linear regression analysis which included initial SBP, Glasgow Coma Scale score, and Injury Severity Score (Coefficient 26.82, 95% Confidence Interval 8.11-45.54, P = 0.006).

CONCLUSIONS

In the hypotensive trauma patient, initial Zone 1 REBOA provides maximal hemodynamic support. Algorithms recommending initial Zone 3 placement for hypotensive trauma patients should be reconsidered.