Aortic branch vessel flow during resuscitative endovascular balloon occlusion of the aorta

The effect of an endovascular Heaney maneuver to achieve total hepatic isolation on survival, hemodynamic stability, retrohepatic bleeding, and collateral flow in a porcine model

PURPOSE

Combining resuscitative endovascular balloon occlusion of the aorta (REBOA) and the inferior vena cava (REBOVC) with open surgery is a new hybrid approach for treating retrohepatic vena caval injuries. We compared endovascular total hepatic isolation with supraceliac REBOA ± suprahepatic REBOVC and no occlusion in experimental retrohepatic vena cava bleeding regarding survival, bleeding volume, hemodynamic stability, and arterial collateral blood flow.

METHODS

Twenty-five anesthetized pigs (n = 6-7/group) were randomized to REBOA; REBOA + REBOVC; REBOA + infra and suprahepatic REBOVC + portal vein occlusion (endovascular Heaney maneuver, four-balloon-occlusion, 4BO) or no occlusion. After balloon inflation, free bleeding was initiated from an open sheath in the retrohepatic vena cava. Bleeding volume, right internal thoracic artery (RITA) blood flow, hemodynamics, and arterial blood variables were measured until death or up to 90 min.

RESULTS

The REBOA group had a longer median survival time (63 min) compared with the 4BO (24 min, P = 0.02) and no occlusion (30 min, P = 0.02) groups, not versus the REBOA + REBOVC group (49 min, P > 0.05). The first 15 min accumulated bleeding was comparable in all groups (P > 0.05); Thereafter, bleeding volume was higher in the REBOA group versus the 4BO group (P < 0.05), not versus the other groups. RITA blood flow and MAP were higher in the REBOA group versus the other groups after 10 min of bleeding (P < 0.05).

CONCLUSIONS

Endovascular Heaney maneuver was not beneficial for survival or hemodynamic stability in this porcine model, whereas supraceliac REBOA was. Anatomical differences in thoracoabdominal collaterals between pigs and humans must be considered when interpreting these results.

Impact of resuscitative endovascular balloon occlusion of the aorta on gastrointestinal function with a matched cohort study

Background

Resuscitative endovascular balloon occlusion of the aorta (REBOA) can temporarily control arterial hemorrhage in torso trauma; however, the abdominal visceral blood flow is also blocked by REBOA. The aim of this study was to evaluate the influence of REBOA on gastrointestinal function.

Methods

A retrospective review identified all trauma patients admitted to our trauma center between 2008 and 2019. We used propensity score matching analysis to compare the gastrointestinal function between subjects who underwent REBOA and those who did not. Data on demographics, feeding intolerance (FI), time to feeding goal achievement, and complications were retrieved.

Results

During the study period, 55 patients underwent REBOA. A total of 1694 patients met the inclusion criteria, 27 of whom were a subset of those who underwent REBOA. After 1:1 propensity score matching, the REBOA and no-REBOA groups were assigned 22 patients each. Patients in the REBOA group had a significantly higher incidence of FI (77% vs. 27%; OR, 9.1; 95% CI, 2.31 to 35.7; p=0.002) and longer time to feeding goal achievement (8 vs. 6 days, p=0.022) than patients in the no-REBOA group. Patients in the REBOA group also showed significantly prolonged durations of ventilator use (8 vs. 4 days, p=0.023). Furthermore, there was no difference in the mortality rate between the groups (9% vs. 9%, p=1.000).

Conclusions

REBOA was associated with gastrointestinal dysfunction. Our study findings can be useful in providing guidance on managing nutrition in trauma patients who undergo REBOA.

Level of evidence

Level IV.

Study type

Care management.

Efficacy of partial and complete resuscitative endovascular balloon occlusion of the aorta in the hemorrhagic shock model of liver injury

BACKGROUND

Resuscitative endovascular balloon occlusion of the aorta (REBOA) can temporarily control traumatic bleeding. However, its prolonged use potentially leads to ischemia-reperfusion injury (IRI). Partial REBOA (pREBOA) can alleviate ischemic burden; however, its security and effectiveness prior to operative hemorrhage control remains unknown. Hence, we aimed to estimate the efficacy of pREBOA in a swine model of liver injury using an experimental sliding-chamber ballistic gun.

METHODS

Twenty Landrace pigs were randomized into control (no aortic occlusion) (n=5), intervention with complete REBOA (cREBOA) (n=5), continuous pREBOA (C-pREBOA) (n=5), and sequential pREBOA (S-pREBOA) (n=5) groups. In the cREBOA and C-pREBOA groups, the balloon was inflated for 60 min. The hemodynamic and laboratory values were compared at various observation time points. Tissue samples immediately after animal euthanasia from the myocardium, liver, kidneys, and duodenum were collected for histological assessment using hematoxylin and eosin staining.

RESULTS

Compared with the control group, the survival rate of the REBOA groups was prominently improved (all P<0.05). The total volume of blood loss was markedly lower in the cREBOA group (493.14±127.31 mL) compared with other groups (P<0.01). The pH was significantly lower at 180 min in the cREBOA and S-pREBOA groups (P<0.05). At 120 min, the S-pREBOA group showed higher alanine aminotransferase (P<0.05) but lower blood urea nitrogen compared with the cREBOA group (P<0.05).

CONCLUSION

In this trauma model with liver injury, a 60-minute pREBOA resulted in improved survival rate and was effective in maintaining reliable aortic pressure, despite persistent hemorrhage. Extended tolerance time for aortic occlusion in Zone I for non-compressible torso hemorrhage was feasible with both continuous partial and sequential partial measures, and the significant improvement in the severity of acidosis and distal organ injury was observed in the sequential pREBOA.

MILD THERAPEUTIC HYPOTHERMIA REDUCES ISCHEMIA-REPERFUSION INJURY AFTER ZONE 1 REBOA IN A SWINE HEMORRHAGIC SHOCK MODEL

ABSTRACT

Background: Resuscitative balloon occlusion of the aorta (REBOA) is an endovascular hemostasis method used for the management of traumatic abdominal and pelvic hemorrhages. However, REBOA-associated ischemia-reperfusion injury complication limits its blocking time. We hypothesized that mild therapeutic hypothermia would relieve ischemia-reperfusion injury caused by prolonged zone 1 REBOA. Methods: Ten pigs were anesthetized, intubated, and subsequently struck with the experimental sliding-chamber ballistic gun to inflict liver damage. Animals were randomized to hypothermia (60 min of zone 1 REBOA with external cooling for 180 min, n = 5) or control (60 min of zone 1 REBOA with no external cooling, n = 5). Physiological and laboratory parameters were monitored and assessed. Distal organs were obtained for histologic analysis. Results: At 180 min, compared with the control, the hypothermia animals exhibited significantly increased pH and significantly reduced lactate, hemoglobin, and hematocrit (all P < 0.05). The change of lactate from 0 to 180 min in hypothermia animals was less than that in the control ( P = 0.02). The total bleeding in the control group was significantly less than the hypothermia ( P < 0.01). In the hypothermia group, prothrombin time at 120 and 180 min was significantly longer than that at baseline (all P < 0.05). Compared with the control, animals in the hypothermia group showed slighter pathological injury of the distal organs and significantly lower overall injury score (all P < 0.05). Conclusions: Mild therapeutic hypothermia during prolonged zone 1 REBOA offered extraordinary distal organ preservation and decreased metabolic acidosis.

REBOA for the Treatment of Blast Polytrauma: Zone 3 Provides Cerebral Perfusion, Attenuates Organ Dysfunction and Reperfusion Coagulopathy Compared to Zone 1 in a Swine Model

BACKGROUND

Resuscitative endovascular balloon occlusion of the aorta (REBOA) is a lifesaving therapy for hemorrhagic shock following pelvic/lower extremity injuries in military settings. However, Zone 1 aortic occlusion (AO; above the celiac artery), while providing brain/cardiac perfusion, may induce/worsen visceral ischemia and organ dysfunction. In contrast, AO Zone 3 (below the renal arteries) provides abdominal perfusion potentially minimizing ischemia/reperfusion injury. We hypothesized that, compared with AO Zone 1, AO Zone 3 provides neuro/cardioprotection while minimizing visceral ischemia and reperfusion coagulopathy after severe traumatic hemorrhage due to pelvic/lower extremity injuries.

METHODS

Fifty-kilogram male Yorkshire swine underwent a blast polytrauma injury followed by a resuscitation protocol with randomization to no AO (No AO, n = 6) or AO with REBOA at Zone 1 (AO Zone 1; n = 6) or Zone 3 (AO Zone 3; n = 4). Vital signs and intracranial pressure (ICP) were monitored for 240 minutes. Citrate native and tissue plasminogen activator challenge thrombelastography, prothrombin time, creatinine, lipase, total bilirubin, troponin, and enzyme-linked immunosorbent assays protein levels were measured at set intervals.

RESULTS

Both AO groups had significant increases in mean arterial pressure during aortic occlusion. All three groups had significant increases in ICP, but final ICP in the No AO group (26 ± 5.8 mm Hg) was significantly elevated compared with AO Zone 1 (17 ± 5.2 mm Hg) and AO Zone 3 (16 ± 4.2 mm Hg) ( p < 0.01). The final mean troponin in the No AO group (4.10 ± 5.67 ng/mL) was significantly higher than baseline (0.03 ± 0.02 ng/mL, p < 0.05), while the two AO groups had no significant changes ( p > 0.05). AO Zone 1 was the only group associated with hyperfibrinolysis ( p < 0.05) and significantly increased prothrombin time ( p < 0.05). Only AO Zone 1 group had significantly higher markers of organ damage.

CONCLUSION

Compared with AO Zone 1, AO Zone 3 provided similar neuro/cardioprotection but with less organ dysfunction and coagulopathy. This study suggests that Zone 3 REBOA may be preferable over Zone 1 for treating military relevant blast polytrauma with minimal intra-abdominal and chest trauma, but further clinical investigation is warranted.

A dumbbell rescue stent graft facilitates clamp-free repair of aortic injury in a porcine model

Objective

Noncompressible torso hemorrhage is a high-mortality injury. We previously reported improved outcomes with a retrievable rescue stent graft to temporize aortic hemorrhage in a porcine model while maintaining distal perfusion. A limitation was that the original cylindrical stent graft design prohibited simultaneous vascular repair, given the concern for suture ensnarement of the temporary stent. We hypothesized that a modified, dumbbell-shaped design would preserve distal perfusion and also offer a bloodless plane in the midsection, facilitating repair with the stent graft in place and improve the postrepair hemodynamics.

Methods

In an Institutional Animal Care and Use Committee-approved terminal porcine model, a custom retrievable dumbbell-shaped rescue stent graft (dRS) was fashioned from laser-cut nitinol and polytetrafluoroethylene covering and compared with aortic cross-clamping. Under anesthesia, the descending thoracic aorta was injured and then repaired with cross-clamping (n = 6) or dRS (n = 6). Angiography was performed in both groups. Operations were divided into phases: (1) baseline, (2) thoracic injury with either cross-clamp or dRS deployed, and (3) recovery, after which the clamp or dRS were removed. Target blood loss was 22% to simulate class II or III hemorrhagic shock. Shed blood was recovered with a Cell Saver and reinfused for resuscitation. Renal artery flow rates were recorded at baseline and during the repair phase and reported as a percentage of cardiac output. Phenylephrine pressor requirements were recorded.

Results

In contrast with cross-clamped animals, dRS animals demonstrated both operative hemostasis and preserved flow beyond the dRS angiographically. Recovery phase mean arterial pressure, cardiac output, and right ventricular end-diastolic volume were significantly higher in dRS animals (P = .033, P = .015, and P = .012, respectively). Whereas distal femoral blood pressures were absent during cross-clamping, among the dRS animals, the carotid and femoral MAPs were not significantly different during the injury phase (P = .504). Cross-clamped animals demonstrated nearly absent renal artery flow, in contrast with dRS animals, which exhibited preserved perfusion (P<.0001). Femoral oxygen levels (partial pressure of oxygen) among a subset of animals further confirmed greater distal oxygenation during dRS deployment compared with cross-clamping (P = .006). After aortic repair and clamp or stent removal, cross-clamped animals demonstrated more significant hypotension, as demonstrated by increased pressor requirements over stented animals (P = .035).

Conclusions

Compared with aortic cross-clamping, the dRS model demonstrated superior distal perfusion, while also facilitating simultaneous hemorrhage control and aortic repair. This study demonstrates a promising alternative to aortic cross-clamping to decrease distal ischemia and avoid the unfavorable hemodynamics that accompany clamp reperfusion. Future studies will assess differences in ischemic injury and physiological outcomes.

Clinical Relevance

Noncompressible aortic hemorrhage remains a high-mortality injury, and current damage control options are limited by ischemic complications. We have previously reported a retrievable stent graft to allow rapid hemorrhage control, preserved distal perfusion, and removal at the primary repair. The prior cylindrical stent graft was limited by the inability to suture the aorta over the stent graft owing to risk of ensnarement. This large animal study explored a dumbbell retrievable stent with a bloodless plane to allow suture placement with the stent in place. This approach improved distal perfusion and hemodynamics over clamp repair and heralds the potential for aortic repair while avoiding complications.

Intermittent thoracic resuscitative endovascular balloon occlusion of the aorta improves renal function compared to 60 min continuous application after porcine class III hemorrhage

Background

Resuscitative Endovascular Balloon Occlusion of the Aorta (REBOA) may be considered for stabilization of patients with hemorrhage from below the diaphragm. Occluding the aorta is a powerful means of hemorrhagic control but is also associated with acute kidney injury, which increases mortality in trauma patients. Allowing for intermittent distal blood flow during REBOA application (iREBOA) could decrease this risk, but circulatory consequences have not been sufficiently elucidated. Therefore, we investigated circulatory effects and the renal artery blood flow (RBF) in iREBOA versus continuous, complete aortic occlusion (cREBOA).

Methods

In a porcine model of uncontrolled class III hemorrhage (34% estimated total blood volume, mean 1360 mL), swine (n = 12, mean weight 60.3 kg) were randomly assigned to iREBOA: 3-min full deflation every 10 min (n = 6), or cREBOA (n = 6), for 60 min of thoracic (zone I) application. The animals then underwent 60 min of reperfusion (critical care phase).

Results

Survival was 100% in iREBOA and 83% in cREBOA. The intermittent balloon deflation protocol was hemodynamically tolerable in 63% of reperfusion intervals. Systolic blood pressure decreased during the reperfusion intervals in iREBOA animals (mean 108 mm Hg versus 169 mm Hg; p < 0.005). No differences were detected in heart rate, cardiac output or stroke volume between methods. Troponin I increased in cREBOA after 60 min (mean 666–187 ng/L, p < 0.05). The norepinephrine requirement increased in cREBOA during reperfusion (mean infusion time 12.5–5.5 min; p < 0.05). Total ischemic time decreased in iREBOA (60.0–48.6 min; p < 0.001). RBF increased in iREBOA during balloon deflations and after 60 min reperfusion (61%–39% of baseline RBF; p < 0.05). Urine output increased in iREBOA (mean 135–17 mL; p < 0.001). Nephronal osteopontin, a marker of ischemic injury, increased in cREBOA (p < 0.05).

Conclusion

iREBOA was survivable, did not cause rebleeding, decreased the total ischemic time and increased the renal blood flow, urine output and decreased renal ischemic injury compared to cREBOA. Intermittent reperfusions during REBOA may be preferred to be continuous, complete occlusion in prolonged application to improve renal function.

Zone 1 REBOA in a combat DCBI swine model does not worsen brain injury

BACKGROUND

Zone 1 resuscitative endovascular balloon occlusion of the aorta has been recommended for refractory shock after a dismounted complex blast injury for the austere combat scenario. While resuscitative endovascular balloon occlusion of the aorta should enhance coronary perfusion, there is a potential risk of secondary brain injury due to loss of cerebral autoregulation. We developed a combat casualty relevant dismounted complex blast injury swine model to evaluate the effects of resuscitative endovascular balloon occlusion of the aorta zone I on intracranial pressure and cerebral edema. We hypothesized that zone 1 aortic occlusion with resuscitative endovascular balloon occlusion of the aorta would increase mean arterial pressure transmitted in excessive intracranial pressure, thereby worsening brain injury.

METHODS

50 kg male Yorkshire swine were subjected to a combination dismounted complex blast injury model consisting of blast traumatic brain injury (50 psi, ARA Mobile Shock Laboratory), tissue injury (bilateral femur fractures), and hemorrhagic shock (controlled bleeding to a base deficit goal of 10 mEq/L). During the shock phase, pigs were randomized to no aortic occlusion (n = 8) or to 30 minutes of zone 1 resuscitative endovascular balloon occlusion of the aorta (zone 1 aortic occlusion group, n = 6). After shock, pigs in both groups received a modified Tactical Combat Casualty Care-based resuscitation and were monitored for an additional 240 minutes until euthanasia/death for a total of 6 hours. Intracranial pressure was monitored throughout, and brains were harvested for water content. Linear mixed models for repeated measures were used to compare mean arterial pressure and intracranial pressure between zone 1 aortic occlusion and no aortic occlusion groups.

RESULTS

After dismounted complex blast injury, the zone 1 group had a significantly higher mean arterial pressure during hemorrhagic shock compared to the control group (41.2 mm Hg vs 16.7 mm Hg, P = .002). During balloon occlusion, intracranial pressure was not significantly elevated in the zone 1 aortic occlusion group vs control, but intracranial pressure was significantly lower in the zone 1 group at the end of the observation period. In addition, the zone 1 aortic occlusion group did not have increased brain water content (zone 1 aortic occlusion: 3.95 ± 0.1g vs no aortic occlusion: 3.95 ± 0.3 g, P = .87). Troponin levels significantly increased in the no aortic occlusion group but did not in the zone 1 aortic occlusion group.

CONCLUSION

Zone 1 aortic occlusion using resuscitative endovascular balloon occlusion of the aorta in a large animal dismounted complex blast injury model improved proximal mean arterial pressure while not significantly increasing intracranial pressure during balloon inflation. Observation up to 240 minutes postresuscitation did not show clinical signs of worsening brain injury or cardiac injury. These data suggest that in a dismounted complex blast injury swine model, resuscitative endovascular balloon occlusion of the aorta in zone 1 may provide neuro- and cardioprotection in the setting of blast traumatic brain injury. However, longer monitoring periods may be needed to confirm that the neuroprotection is lasting.

The Underlying Cardiovascular Mechanisms of Resuscitation and Injury of REBOA and Partial REBOA

Introduction: Resuscitative Endovascular Balloon Occlusion of the Aorta (REBOA) is used for aortic control in hemorrhagic shock despite little quantification of its mechanism of resuscitation or cardiac injury. The goal of this study was to use pressure-volume (PV) loop analysis and direct coronary blood flow measurements to describe the physiologic changes associated with the clinical use of REBOA. Methods: Swine underwent surgical and vascular access to measure left ventricular PV loops and left coronary flow in hemorrhagic shock and subsequent placement of occlusive REBOA, partial REBOA, and no REBOA. PV loop characteristics and coronary flow are compared graphically with PV loops and coronary waveforms, and quantitatively with measures of the end systolic and end pressure volume relationship, and coronary flow parameters, with accounting for multiple comparisons. Results: Hemorrhagic shock was induced in five male swine (mean 53.6 ± 3.6 kg) as demonstrated by reduction of stroke work (baseline: 3.1 vs. shock: 1.2 L*mmHg, p < 0.01) and end systolic pressure (ESP; 109.8 vs. 59.6 mmHg, p < 0.01). ESP increased with full REBOA (178.4 mmHg; p < 0.01), but only moderately with partial REBOA (103.0 mmHg, p < 0.01 compared to shock). End systolic elastance was augmented from baseline to shock (1.01 vs. 0.39 ml/mmHg, p < 0.01) as well as shock compared to REBOA (4.50 ml/mmHg, p < 0.01) and partial REBOA (3.22 ml/mmHg, p = 0.01). Percent time in antegrade coronary flow decreased in shock (94%-71.8%, p < 0.01) but was rescued with REBOA. Peak flow increased with REBOA (271 vs. shock: 93 ml/min, p < 0.01) as did total flow (peak: 2136, baseline: 424 ml/min, p < 0.01). REBOA did not augment the end diastolic pressure volume relationship. Conclusion: REBOA increases afterload to facilitate resuscitation, but the penalty is supraphysiologic coronary flows and imposed increase in LV contractility to maintain cardiac output. Partial REBOA balances the increased afterload with improved aortic system compliance to prevent injury.

Resuscitative endovascular balloon occlusion of the aorta (REBOA) may be superior to resuscitative thoracotomy (RT) in patients with traumatic brain injury (TBI)

Background

The effects of aortic occlusion (AO) on brain injury are not well defined. We examined the impact of AO by resuscitative endovascular balloon occlusion of the aorta (REBOA) and resuscitative thoracotomy (RT) on outcomes in the setting of traumatic brain injury (TBI).

Methods

Patients sustaining TBI who underwent RT or REBOA in zone 1 (thoracic aorta) from September 2013 to December 2018 were identified. The indication for REBOA or RT was hemodynamic collapse due to hemorrhage below the diaphragm. Primary outcomes included mortality and systemic complications.

Results

282 patients underwent REBOA or RT. Of these, 76 had mild TBI (40 REBOA, 36 RT) and 206 sustained severe TBI (107 REBOA, 99 RT). Overall, the mean (±SD) age was 42±17 years, with an Injury Severity Score (ISS) of 40±17 and mean systolic blood pressure (SBP) at the time of REBOA or RT of 81±34 mm Hg. REBOA patients had a mean SBP at the time of AO of 78.39±29.45 mm Hg, whereas RT patients had a mean SBP of 83.18±37.87 mm Hg at the time of AO (p=0.24). 55% had ongoing cardiopulmonary resuscitation (CPR) at the time of AO, and the in-hospital mortality was 86%. Binomial logistic regression controlling for TBI severity, age, ISS, SBP at the time of AO, crystalloid infusion, and CPR during AO demonstrated that the odds of mortality are 3.1 times higher for RT compared with REBOA. No significant differences were found in systemic complications between RT and REBOA.

Discussion

Patients with TBI who receive REBOA may have improved survival, but no difference in systemic complications, compared with patients who receive RT for the same indication. Although some patients are receiving RT prior to arrest for extrathoracic hemorrhagic shock, these results suggest that REBOA should be considered as an alternative to RT when RT is chosen for the sole purpose of resuscitation in the setting of TBI.

Level of evidence

4.

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.

A randomized porcine study of the hemodynamic and metabolic effects of combined endovascular occlusion of the vena cava and the aorta in normovolemia and in hemorrhagic shock

BACKGROUND

Mortality from traumatic retrohepatic venous injuries is high and methods for temporary circulatory stabilization are needed. We investigated survival and hemodynamic and metabolic effects of resuscitative endovascular balloon occlusion of the aorta (REBOA) and vena cava inferior (REBOVC) in anesthetized pigs.

METHODS

Twenty-five anesthetized pigs in normovolemia or severe hemorrhagic shock (controlled arterial bleeding in blood bags targeting systolic arterial pressure of 50 mm Hg, corresponding to 40-50% of the blood volume) were randomized to REBOA zone 1 or REBOA+REBOVC zone 1 (n = 6-7/group) for 45 minutes occlusion, followed by 3-hour resuscitation and reperfusion. Hemodynamic and metabolic variables and markers of end-organ damage were measured regularly.

RESULTS

During occlusion, both the REBOA groups had higher systemic mean arterial pressure (MAP) and cardiac output (p < 0.05) compared with the two REBOA+REBOVC groups. After 60 minutes reperfusion, there were no statistically significant differences between the two REBOA groups and the two REBOA+REBOVC groups in MAP and cardiac output. The two REBOA+REBOVC groups had higher arterial lactate and potassium concentrations during reperfusion, compared with the two REBOA groups (p < 0.05). There was no major difference in end-organ damage markers between REBOA and REBOA+REBOVC. Survival after 1-hour reperfusion was 86% and 100%, respectively, in the normovolemic REBOA and REBOA+REBOVC groups, and 67% and 83%, respectively, in the corresponding hemorrhagic shock REBOA and REBOA+REBOVC groups.

CONCLUSION

Acceptable hemodynamic stability during occlusion and short-term survival can be achieved by REBOA+REBOVC with adequate resuscitation; however, the more severe hemodynamic and metabolic impacts of REBOA+REBOVC compared with REBOA must be considered.

LEVEL OF EVIDENCE

Prospective, randomized, experimental animal study. Basic science study, therapeutic.

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.

Distal organ inflammation and injury after resuscitative endovascular balloon occlusion of the aorta in a porcine model of severe hemorrhagic shock

BACKGROUND AND OBJECTIVE

Resuscitative Endovascular Balloon Occlusion of Aorta (REBOA) has emerged as a potential life-saving maneuver for the management of non-compressible torso hemorrhage in trauma patients. Complete REBOA (cREBOA) is inherently associated with the burden of ischemia reperfusion injury (IRI) and organ dysfunction. However, the distal organ inflammation and its association with organ injury have been little investigated. This study was conducted to assess these adverse effects of cREBOA following massive hemorrhage in swine.

METHODS

Spontaneously breathing and consciously sedated Sinclair pigs were subjected to exponential hemorrhage of 65% total blood volume over 60 minutes. Animals were randomized into 3 groups (n = 7): (1) Positive control (PC) received immediate transfusion of shed blood after hemorrhage, (2) 30min-cREBOA (A30) received Zone 1 cREBOA for 30 minutes, and (3) 60min-cREBOA (A60) given Zone 1 cREBOA for 60 minutes. The A30 and A60 groups were followed by resuscitation with shed blood post-cREBOA and observed for 4h. Metabolic and hemodynamic effects, coagulation parameters, inflammatory and end organ consequences were monitored and assessed.

RESULTS

Compared with 30min-cREBOA, 60min-cREBOA resulted in (1) increased IL-6, TNF-α, and IL-1β in distal organs (kidney, jejunum, and liver) (p < 0.05) and decreased reduced glutathione in kidney and liver (p < 0.05), (2) leukopenia, neutropenia, and coagulopathy (p < 0.05), (3) blood pressure decline (p < 0.05), (4) metabolic acidosis and hyperkalemia (p < 0.05), and (5) histological injury of kidney and jejunum (p < 0.05) as well as higher levels of creatinine, AST, and ALT (p < 0.05).

CONCLUSION

30min-cREBOA seems to be a feasible and effective adjunct in supporting central perfusion during severe hemorrhage. However, prolonged cREBOA (60min) adverse effects such as distal organ inflammation and injury must be taken into serious consideration.

Validation of a novel partial resuscitative endovascular balloon occlusion of the aorta device in a swine hemorrhagic shock model: Fine tuning flow to optimize bleeding control and reperfusion injury

OBJECTIVES

Partial restoration of aortic flow during resuscitative endovascular balloon occlusion of the aorta (REBOA) is advocated by some to mitigate distal ischemia. Our laboratory has validated the mechanics and optimal partial REBOA (pREBOA) flow rates using a prototype device. We hypothesize that pREBOA will increase survival when compared with full REBOA (fREBOA) in prolonged nonoperative management of hemorrhagic shock.

METHODS

Twenty swine underwent placement of aortic flow probes, zone 1 REBOA placement, and 20% blood volume hemorrhage. They were randomized to either solid organ or abdominal vascular injury. The pREBOA arm (10 swine) underwent full inflation for 10 minutes and then deflation to a flow rate of 0.5 L/min for 2 hours. The fREBOA arm (10 swine) underwent full inflation for 60 minutes, followed by deflation/resuscitation. The primary outcome is survival, and secondary outcomes are serologic/pathologic signs of ischemia-reperfusion injury and quantity of hemorrhage.

RESULTS

Two of 10 swine survived in the fREBOA group (2/5 solid organ injury; 0/5 abdominal vascular injury), whereas 7 of 10 swine survived in the pREBOA group (3/5 solid organ injury, 4/5 abdominal vascular injury). Survival was increased (p = 0.03) and hemorrhage was higher in the pREBOA group (solid organ injury, 1.36 ± 0.25 kg vs. 0.70 ± 0.33 kg, p = 0.007; 0.86 ± 0.22 kg vs. 0.71 ± 0.28 kg, not significant). Serum evidence of ischemia was greater with fREBOA, but this was not significant (e.g., lactate, 16.91 ± 3.87 mg/dL vs. 12.96 ± 2.48 mg/dL at 120 minutes, not significant). Swine treated with pREBOA that survived demonstrated trends toward lower alanine aminotransferase, lower potassium, and higher calcium. The potassium was significantly lower in survivors at 60 minutes and 90 minutes time points (5.97 ± 0.60 vs. 7.53 ± 0.90, p = 0.011; 6.67 ± 0.66 vs. 8.15 ± 0.78, p = 0.029). Calcium was significantly higher at 30 minutes, 60 minutes, and 90 minutes (8.56 ± 0.66 vs. 7.50 ± 0.40, p = 0.034; 8.63 ± 0.62 vs. 7.15 ± 0.49, p = 0.019; 8.96 ± 0.64 vs. 7.00, p = 0.028).

CONCLUSION

Prolonged pREBOA at a moderate distal flow rate provided adequate hemorrhage control, improved survival, and had evidence of decreased ischemic injury versus fREBOA. Prophylactic aggressive calcium supplementation may have utility before and during the reperfusion phase.

Indications and interventions of damage control orthopedic surgeries: an expert opinion survey

OBJECTIVES

The objectives of this study were to gather an expert opinion survey and to evaluate the suitability of summarized indications and interventions for DCO.

BACKGROUND

The indications to perform temporary surgery in musculoskeletal injuries may vary during the hospitalization and have not been defined. We performed a literature review and an expert opinion survey about the indications for damage control orthopaedics (DCO).

METHODS

Part I: A literature review was performed on the basis of the PubMed library search. Publications were screened for damage control interventions in the following anatomic regions: "Spine", "Pelvis", "Extremities" and "Soft Tissues". A standardized questionnaire was developed including a list of damage control interventions and associated indications. Part II: Development of the expert opinion survey: experienced trauma and orthopaedic surgeons participated in the consensus process.

RESULTS

Part I: A total of 646 references were obtained on the basis of the MeSH terms search. 74 manuscripts were included. Part II: Twelve experts in the field of polytrauma management met at three consensus meetings. We identified 12 interventions and 79 indications for DCO. In spinal trauma, percutaneous interventions were determined beneficial. Traction was considered harmful. For isolated injuries, a new terminology should be used: "MusculoSkeletal Temporary Surgery".

CONCLUSION

This review demonstrates a detailed description of the management consensus for abbreviated musculoskeletal surgeries. It was consented that early fixation is crucial for all major fractures, and certain indications for DCO were dropped. Authors propose a distinct terminology to separate local (MuST surgery) versus systemic (polytrauma: DCO) scenarios.

Titrate to equilibrate and not exsanguinate! Characterization and validation of a novel partial resuscitative endovascular balloon occlusion of the aorta catheter in normal and hemorrhagic shock conditions

BACKGROUND

Resuscitative endovascular balloon occlusion of the aorta (REBOA) is a significant advancement in the control of noncompressible truncal hemorrhage. However, its ischemic burden and reperfusion injury following balloon deflation limits its utilization. Partial restoration of aortic flow during REBOA has the potential to balance hemorrhage control and ischemia. This study validates the mechanics, physiology, and optimal partial flow rates using a prototype partial REBOA (pREBOA) device.

METHODS

Twenty-five swine underwent placement of aortic flow probes and zone 1 pREBOA. Experiment 1 (N = 5) animals were not injured and assessed the tested the catheters ability to titrate and control flow. Experiment 2 (N = 10) added 20% hemorrhage and either solid organ, or abdominal vascular injury to compare flow rate and rebleeding from injuries. Experiment 3 (N = 10) swine were similarly prepared, hemorrhaged, and underwent pREBOA at set partial flow rates for 2 hours followed by complete deflation for 30 minutes.

RESULTS

Balloon volume at minimum flow (mean, 0.09 L/min) was 3.5 mL to 6.0 mL. Half maximal flow was achieved with 56.5% of maximum balloon inflation. Partial REBOA allowed very fine titration of flow rates. Rebleeding occurred at 0.45 L/min to 0.83 L/min. Distal flow of 0.7 L/min had 50% survival, 0.5 had 100% survival, and 0.3 L had 50% survival with mean end lactates of 9.6, 12.6, and 13.3, respectively. There was a trend toward hyperkalemia and hypocalcemia in nonsurvivors.

CONCLUSION

The pREBOA device demonstrated a high level of titratability for restoration of aortic flow. An optimal partial flow of 0.5 L/min was effective at hemorrhage control while limiting the burden of ischemic injury, and extending the tolerable duration of zone 1 occlusion. Aggressive calcium supplementation prior to and during partial occlusion and reperfusion may be warranted to prevent hyperkalemic arrest.

Organ ischemia during partial resuscitative endovascular balloon occlusion of the aorta: Dynamic 4D Computed tomography in swine

Resuscitative endovascular balloon occlusion of the aorta (REBOA) increases proximal pressure, and simultaneously induces distal ischemia. We aimed to evaluate organ ischemia during partial REBOA (P-REBOA) with computed tomography (CT) perfusion in a swine model. The maximum balloon volume was recorded as total REBOA when the distal pulse pressure ceased. The animals (n = 4) were scanned at each 20% of the maximum balloon volume, and time-density curve (TDC) were analysed at the aorta, portal vein (PV), liver parenchyma, and superior mesenteric vein (SMV, indicating mesenteric perfusion). The area under the TDC (AUTDC), the time to peak (TTP), and four-dimensional volume-rendering images (4D-VR) were evaluated. The TDC of the both upper and lower aorta showed an increased peak and delayed TTP. The TDC of the PV, liver, and SMV showed a decreased peak and delayed TTP. The dynamic 4D-CT analysis suggested that organ perfusion changes according to balloon volume. The AUTDC at the PV, liver, and SMV decreased linearly with balloon inflation percentage to the maximum volume. 4D-VR demonstrated the delay of the washout in the aorta and retrograde flow at the inferior vena cava in the highly occluded status.

Blood flow of the venous system during resuscitative endovascular balloon occlusion of the aorta: Noninvasive evaluation using phase contrast magnetic resonance imaging

BACKGROUND

Resuscitative endovascular balloon occlusion of the aorta (REBOA) is a viable resuscitation approach for a subdiaphragmatic injury that can regulate arterial blood flow. On the other hand, the evaluation of venous or portal venous blood flow during REBOA remains insufficient because invasive cannulation or exposure of the vessel may affect the blood flow, and Doppler echography is highly operator-dependent. However, phase contrast magnetic resonance imaging has enabled accurate evaluation and noninvasive measurement. This study aimed to investigate the change of venous and portal venous blood flow during REBOA in a porcine model.

METHODS

Seven pigs were anesthetized, and a REBOA catheter was placed. The blood flows of the inferior vena cava (IVC), hepatic vein (HV), portal vein (PV), and superior vena cava (SVC) were measured using phase contrast magnetic resonance imaging, in both the balloon deflated (no-REBOA) and fully balloon inflated (REBOA) states. Mean arterial pressure (MAP), central venous pressure, cardiac index, and systemic vascular resistance index were measured.

RESULTS

The blood flows of the suprahepatic, infrahepatic, and distal IVC, HV, and PV in the no-REBOA state were 1.40 ± 0.36 L·min, 0.94 ± 0.16 L·min, 0.50 ± 0.19 L·min, 0.060 ± 0.018 L·min, and 0.32 ± 0.091 L·min, respectively. The blood flow of each section in the REBOA condition was significantly decreased at 0.41 ± 0.078 (33% of baseline), 0.15 ± 0.13 (15%), 0.043 ± 0.034 (9%), 0.029 ± 0.017 (37%), and 0.070 ± 0.034 L·min (21%), respectively. The blood flow of the SVC increased significantly in the REBOA condition (1.4 ± 0.63 L·min vs. 0.53 ± 0.14 L·min [257%]). Mean arterial pressure, central venous pressure, cardiac index, and systemic vascular resistance index were significantly increased after REBOA inflation.

CONCLUSION

Resuscitative endovascular balloon occlusion of the aorta decreased blood flows of the IVC, HV, and PV and increased blood flow of the SVC. This result could be explained by the collateral flow from the lower body to the SVC. A better understanding of the effect of REBOA on the venous and portal venous systems may help control liver injury.

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.