Resuscitative endovascular balloon occlusion of the aorta for major abdominal venous injury in a porcine hemorrhagic shock model

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.

Validation of a miniaturized handheld arterial pressure monitor for guiding full and partial REBOA use during resuscitation

PURPOSE

Resuscitative endovascular balloon occlusion of the aorta (REBOA) is a well-validated method for the control of noncompressible truncal hemorrhage. In lower resource or battlefield settings, the need for arterial line setup and monitoring is problematic and potentially prohibitive. We sought to evaluate the accuracy and precision of a miniaturized portable device (Centurion COMPASS^®) versus standard arterial pressure monitoring using standard ER-REBOA and partial REBOA (pREBOA) as a high-fidelity and space-/time-conserving alternative.

METHODS

A total of 40 swine underwent a four-phase validation/precision study (each phase using five ER-REBOAs and five pREBOAs). Phases I/II evaluated accuracy with full and pREBOA in uninjured animals. Phases III/IV duplicated the previous phases but in a severe hemorrhagic shock model. Carotid and femoral pressures were monitored with both intra-arterial pressure systems and the COMPASS^® device. The vascular flow was measured by aortic flow probes. Correlation and Bland-Altman analysis were performed.

RESULTS

There was a strong correlation in accuracy testing of proximal and distal COMPASS^® devices compared to standard intra-arterial pressure monitoring (r = 0.94, 0.8; p < 0.005) as well as during precision testing (r = 0.98, 0.89 p < 0.005) in the uninjured phases. Similar accuracy and reliability were demonstrated in hemorrhagic shock, with a strong correlation for the proximal and distal COMPASS^® devices (r = 0.98, 0.97; p < 0.005), as well as during precision testing (r = 0.99, 0.95; p < 0.005) in both full and pREBOA scenarios. Bland-Altman analysis showed extremely low bias between the COMPASS^® and arterial line for both proximal (bias = 1.9) and distal (bias = 0.8) pressure measurements.

CONCLUSION

The COMPASS^® provides accurate and precise pressure measurements during standard and partial REBOA in both uninjured and shock conditions. This device may help extend and enhance capability in any low-resource/battlefield settings, or even eliminate the need for standard intra-arterial invasive pressure monitoring and external setup.

Effect of angioembolization for isolated complex pelvic injury: A post-hoc analysis of a nationwide multicenter trauma database in Japan

BACKGROUND AND IMPORTANCE

Complex pelvic injuries are among the types of trauma with the highest mortality. Treatment strategies should be based on the hemodynamic status, the anatomical type of fracture, and the associated injuries. Combination therapies, including preperitoneal pelvic packing, temporary mechanical stabilization, resuscitative endovascular balloon occlusion of the aorta, and angioembolization, are recommended for pelvic injuries.

OBJECTIVE

To investigate the effect of urgent angioembolization alone on severe pelvic injury-associated mortality.

DESIGN, SETTINGS, AND PARTICIPANTS

We used the Japan Trauma Data Bank database, a multicenter observational study, to retrospectively identify adult patients with isolated blunt pelvic injuries (Abbreviated Injury Scale [AIS] score: 3-5) from 2004 to 2018.

OUTCOME MEASURES AND ANALYSIS

The primary outcome measure was in-hospital mortality. We subdivided patients into two groups, those who underwent urgent angioembolization and non-urgent angioembolization, and compared their mortality rates. We performed multiple imputation and multivariable analyzes to compare the mortality rates between groups after adjusting for known potential confounding factors (age, sex, Glasgow Coma Scale score, systolic blood pressure on hospital arrival, Injury Severity Score, pelvic AIS score, laparotomy, resuscitative endovascular balloon occlusion of the aorta, and external fixation) and for within-hospital clustering using the generalized estimating equation.

MAIN RESULTS

We analyzed 4207 of 345,932 trauma patients, of whom 799 underwent urgent angioembolization. The in-hospital mortality rate was significantly higher in the urgent embolization group than in the non-urgent embolization group (7.4 vs. 4.0%; p < 0.01). However, logistic regression analysis revealed that the mortality rates of patients with urgent angioembolization significantly decreased after adjusting for factors independently associated with mortality (odds ratio: 0.60; 95% confidence interval: 0.37-0.96; p = 0.03).

CONCLUSION

Urgent angioembolization may be an effective treatment for severe pelvic injury regardless of the pelvic AIS score and the systolic blood pressure on hospital arrival.

Adenosine, lidocaine, and magnesium for attenuating ischemia reperfusion injury from resuscitative endovascular balloon occlusion of the aorta in a porcine model

BACKGROUND

Minimally invasive resuscitative endovascular balloon occlusion of the aorta (REBOA) following noncompressible hemorrhage results in significant ischemia reperfusion injury (IRI). Adverse outcomes from IRI include organ dysfunction and can result in profound hemodynamic and molecular compromise. We hypothesized that adenosine, lidocaine, and magnesium (ALM) attenuates organ injury and inflammation responses following REBOA IRI in a porcine model of hemorrhage.

METHODS

Animals underwent a 20% controlled hemorrhage followed by 45 minutes of supraceliac balloon occlusion. They were randomized into two groups: control (n = 9) and ALM intervention (n = 9) to include a posthemorrhage, pre-REBOA bolus (200 mL of 3% NaCl ALM) followed by a continuous drip (2 mL/kg per hour of 0.9% NaCl ALM) during the 4-hour resuscitative period. Primary outcomes included hemodynamic parameters, gene expression of inflammatory signaling molecules, and plasma concentrations of select cytokines and chemokines.

RESULTS

The ALM cohort demonstrated a significant reduction in cardiac output and cardiac index. Plasma concentrations of interleukin 2 and interleukin 10 were significantly lower 3 hours post-REBOA in animals treated with ALM versus vehicle. Interleukin 4 levels in plasma were also lower with ALM at 3 and 4 hours post-REBOA (p < 0.05). Liver expression of IL1RN, MTOR, and LAMP3 messenger RNA was significantly lower with ALM as compared with the vehicle. No significant difference in large bowel gene expression was observed between treatments.

CONCLUSION

In a porcine model of hemorrhage, ALM treatment mitigated inflammatory responses early during post-REBOA resuscitation. Our findings suggest that ALM use with trauma may reduce inflammatory injury and improve outcomes related to REBOA utilization.

Hemodynamic Effects of Cardiovascular Medications in a Normovolemic and Hemorrhaged Yorkshire-cross Swine Model

The Yorkshire-cross swine model is a valuable translational model commonly used to study cardiovascular physiologyand response to insult. Although the effects of vasoactive medications have been well described in healthy swine, the effects of these medications during hemorrhagic shock are less studied. In this study, we sought to expand the utility of the swine model by characterizing the hemodynamic changes that occurred after the administration of commonly available vasoactive medications during euvolemic and hypovolemic states. To this end, we anesthetized and established femoral arterial,central venous, and pulmonary arterial access in 15 juvenile Yorkshire-cross pigs. The pigs then received a series of rapidlymetabolized but highly vasoactive medications in a standard dosing sequence. After completion of this sequence, each pigunderwent a 30-mL/kg hemorrhage over 10 min, and the standard dosing sequence was repeated. We then used standard statisticaltechniques to compare the effects of these vasoactive medications on a variety of hemodynamic parameters betweenthe euvolemic and hemorrhagic states. All subjects completed the study protocol. The responses in the hemorrhagic state wereoften attenuated or even opposite of those in the euvolemic state. For example, phenylephrine decreased the mean arterialblood pressure during the euvolemic state but increased it in the hemorrhagic state. These results clarify previously poorlydefined responses to commonly used vasoactive agents during the hemorrhagic state in swine. Our findings also demonstratethe need to consider the complex and dynamic physiologic state of hemorrhage when anticipating the effects of vasoactivedrugs and planning study protocols.

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

ABSTRACT

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

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

BACKGROUND

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

METHODS

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

RESULTS

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

CONCLUSION

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

Computed tomography imaging of resuscitative endovascular balloon occlusion of the aorta (REBOA): pearls and pitfalls

Resuscitative endovascular balloon occlusion of the aorta (REBOA) is performed in patients with hemorrhagic shock who develop massive subdiaphragmatic bleeding. This procedure enables rapid and less invasive aortic blockade compared to resuscitative thoracotomy and aortic cross-clamp procedures. However, the REBOA procedure is often blindly performed in the emergency department without fluoroscopy, and the appropriateness of the procedure may be evaluated on computed tomography (CT) after REBOA. Therefore, radiologists should be familiar with the imaging features of REBOA. We present a pictorial review of the radiological findings of REBOA along with a description of the procedure, its complications, and pitfalls.

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

BACKGROUND

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

METHODS

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

RESULTS

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

CONCLUSION

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

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.

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

BACKGROUND

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

METHODS

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

RESULTS

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

CONCLUSION

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

Use of REBOA in the universe of magical realism: a real-world review

While reading the novella “Chronicle of a Death Foretold” by the Colombian Nobel Laureate Gabriel García-Marquez, we were surprised to realize that the injuries sustained by the main character could have been successfully treated had he received modern trauma care in which REBOA may have been considered. This is a discussion of Mr. Nasar's murder to explore whether he could have been saved by deploying REBOA as a surgical adjunct to bleeding control and resuscitation. In reading García-Marquez's novel we noted the events that unfolded at the time of Santiago Nasar's murder. To contextualize the claim that Mr. Nasar could have survived, had his injuries been treated with REBOA, we explored and illustrated what could have done differently and why. On the day of his death, Mr. Nasar sustained multiple penetrating stab wounds. Although he received multiple stab wounds to his torso, the book describes seven potentially fatal injuries, resulting in hollow viscus, solid viscus, and major vascular injuries. We provided a practical description of the clinical and surgical management algorithm we would have followed in Mr. Nasar's case. This algorithm included the REBOA deployment for hemorrhage control and resuscitation. The use of REBOA as part of the surgical procedures performed could have saved Mr. Nasar's life. Based on our current knowledge about REBOA in trauma surgery, we claim that its use, coupled with appropriate surgical care for hemorrhage control, could have saved Santiago Nasar's life, and thus prevent a death foretold.

Use of bilobed partial resuscitative endovascular balloon occlusion of the aorta is logistically superior in prolonged management of a highly lethal aortic injury

BACKGROUND

Resuscitative endovascular balloon occlusion of the aorta (REBOA) is a viable technique for management of noncompressible torso hemorrhage. The major limitation of the current unilobed fully occlusive REBOA catheters is below-the-balloon ischemia-reperfusion complications. We hypothesized that partial aortic occlusion with a novel bilobed partial (p)REBOA-PRO would result in the need for less intraaortic balloon adjustments to maintain a distal goal perfusion pressure as compared with currently available unilobed ER-REBOA.

METHODS

Anesthetized (40-50 kg) swine randomized to control (no intervention), ER-REBOA, or pREBOA-PRO underwent supraceliac aortic injury. The REBOA groups underwent catheter placement into zone 1 with initial balloon inflation to full occlusion for 10 minutes followed by gradual deflation to achieve and subsequently maintain half of the baseline below-the-balloon mean arterial pressure (MAP). Physiologic data and blood samples were collected at baseline and then hourly. At 4 hours, the animals were euthanized, total blood loss and urine output were recorded, and tissue samples were collected.

RESULTS

Baseline physiologic data and basic laboratories were similar between groups. Compared with control, interventions similarly prolonged survival from a median of 18 minutes to over 240 minutes with comparable mortality trends. Blood loss was similar between partial ER-REBOA (41%) and pREBOA-PRO (51%). Partial pREBOA-PRO required a significantly lower number of intraaortic balloon adjustments (10 ER-REBOA vs. 3 pREBOA-PRO, p < 0.05) to maintain the target below-the-balloon MAP. The partial ER-REBOA group developed significantly increased hypercapnia, fibrin clot formation on TEG, liver inflammation, and IL-10 expression compared with pREBOA-PRO.

CONCLUSION

In this highly lethal aortic injury model, use of bilobed pREBOA-PRO for a 4-hour partial aortic occlusion was logistically superior to unilobed ER-REBOA. It required less intraaortic balloon adjustments to maintain target MAP and resulted in less inflammation.

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.

Resuscitative endovascular balloon occlusion of the inferior vena cava is made hemodynamically possible by concomitant endovascular balloon occlusion of the aorta-A porcine study

BACKGROUND

Resuscitative endovascular balloon occlusion of the vena cava inferior (REBOVC) may provide a minimal invasive alternative for hepatic vascular and inferior vena cava isolation in severe retrohepatic bleeding. However, circulatory stability may be compromised by the obstruction of venous return. The aim was to explore which combinations of arterial and venous endovascular balloon occlusions, and the Pringle maneuver, are hemodynamically possible in a normovolemic pig model. The hypothesis was that lower-body venous blood pooling from REBOVC can be avoided by prior resuscitative endovascular aortic balloon occlusion (REBOA).

METHODS

Nine anesthetized, ventilated, instrumented, and normovolemic pigs were used to explore the hemodynamic effects of 11 combinations of REBOA and REBOVC, with or without the Pringle maneuver, in randomized order. The occlusions were performed for 5 minutes but interrupted if systolic blood pressure dropped below 40 mm Hg. Hemodynamic variables were measured.

RESULTS

Proximal REBOVC, isolated or in combination with other methods of occlusion, caused severely decreased systemic blood pressure and cardiac output, and had to be terminated before 5 minutes. The decreases in systemic blood pressure and cardiac output were avoided by REBOA at the same or a more proximal level. The Pringle maneuver had similar hemodynamic effects to proximal REBOVC.

CONCLUSION

A combination of REBOA and REBOVC provides hemodynamic stability, in contrast to REBOVC alone or with the Pringle maneuver, and may be a possible adjunct in severe retrohepatic venous bleedings.

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.

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

BACKGROUND

Resuscitative endovascular balloon occlusion of the aorta (REBOA) is accepted as a resuscitation adjunct and bridge to definitive hemostasis. The ischemic burden of REBOA may be mitigated by a partial REBOA (P-REBOA) strategy permitting longer occlusion times and military use for combat trauma. We evaluated REBOA and P-REBOA in a swine multiple trauma model with uncontrolled solid organ hemorrhage and delayed resuscitation and surgical hemostasis.

METHODS

Anesthetized swine (51.9 ± 2.2 kg) had 20 mL/kg hemorrhage and closed femur fracture. Splenic transection was performed and free bleeding permitted for 10 minutes. Controls (n = 5) were hemorrhaged but had no REBOA, REBOA (n = 8) had 60 minutes complete zone 1 occlusion, P-REBOA (n = 8) had 15 minutes complete occlusion and 45 minutes 50% occlusion. Splenectomy was performed and plasma (15 mL/kg) resuscitation initiated 5 minutes prior to deflation. Resuscitation goal was 80 mm Hg systolic with epinephrine as needed. Animals were monitored for 6 hours.

RESULTS

An initial study with 120-minute occlusion had universal fatality in three REBOA (upon deflation) and three P-REBOA animals (after 60 minutes inflation). With 60-minute occlusion, mortality was 100%, 62.5%, and 12.5% in the control, REBOA, and P-REBOA groups, respectively (p < 0.05). Survival time was shorter in controls (120 ± 89 minutes) than REBOA and P-REBOA groups (241 ± 139, 336 ± 69 minutes). Complete REBOA hemorrhaged less during inflation (1.1 ± 0.5 mL/kg) than Control (5.6 ± 1.5) and P-REBOA (4.3 ± 1.4), which were similar. Lactate was higher in the REBOA group compared with the P-REBOA group after balloon deflation, remaining elevated. Potassium increased in REBOA after deflation but returned to similar levels as P-REBOA by 120 minutes.

CONCLUSION

In a military relevant model of severe uncontrolled solid organ hemorrhage 1-hour P-REBOA improved survival and mitigated hemodynamic and metabolic shock. Two hours of partial aortic occlusion was not survivable using this protocol due to ongoing hemorrhage during inflation. There is potential role for P-REBOA as part of an integrated minimally invasive field-expedient hemorrhage control and resuscitation strategy.

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

BACKGROUND

Resuscitative endovascular balloon occlusion of the aorta (REBOA) is a torso hemorrhage control adjunct. Aortic branch vessel flow (BVF) during REBOA is poorly characterized and has implications for ischemia-reperfusion injury. The aim of this study is to quantify BVF in hypovolemic shock with and without REBOA.

METHODS

Female swine (79-90 kg) underwent anesthesia, 40% controlled hemorrhage and sonographic flow monitoring of the carotid, hepatic, superior mesenteric, renal, and femoral arteries. Animals were randomized to REBOA (n = 5) or no-REBOA (n = 5) for 4 hours, followed by full resuscitation and balloon deflation for 1 hour.

RESULTS

All animals were successfully induced into hemorrhagic shock with a mean decrease of flow in all vessels of 50% from baseline (p < 0.001). Deployment of REBOA resulted in a 200% to 400% increase in carotid flow, but near complete abolition of BVF distal to the balloon. The no-REBOA group saw recovery of BVF to 100% of baseline in all measured vessels, except the hepatic at 50% to 75%. two-way analysis of variance confirmed a significant difference between the groups throughout the protocol (p < 0.001). During resuscitation, the REBOA group saw BVF restore to between 25% and 50%, but never achieving baseline values. The lactate at 4 hours was significantly higher in the REBOA versus no-REBOA group (17.2 ± 0.1 vs. 4.9 ± 1.4; p < 0.001).

CONCLUSION

REBOA not only abolishing BVF during occlusion, but appears to have a post-REBOA effect, reducing visceral perfusion. This may be a source of REBOA associated ischemia-reperfusion injury and warrants further investigation in order to mitigate this effect.

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.

Preperitoneal balloon tamponade and resuscitative endovascular balloon occlusion of the aorta: Alternatives to open packing for pelvic fracture-associated hemorrhage

BACKGROUND

The objective of this study was to compare the efficacy of preperitoneal balloon tamponade (PPB), resuscitative endovascular balloon occlusion of the orta (REBOA), and open preperitoneal packing (OP) in a realistic animal model of pelvic fracture-associated hemorrhage.

METHODS

Thirty-nine swine underwent creation of open-book pelvic fracture and iliac vascular injury. Animals were randomized to no intervention (n = 7), OP (n = 10), PPB (n = 9), zone 1 REBOA (n = 7), and zone 3 REBOA (n = 6) at a mean arterial pressure less than 40 mm Hg from uncontrolled hemorrhage. Primary outcome was survival at 1 hour. Secondary outcomes included survival in the immediate 10 m following intervention reversal, peak preperitoneal pressure (PP), blood loss, bleed rate, and peak lactate.

RESULTS

Prior to injury, no difference was measured between groups for weight, hemodynamics, lactate, and hematocrit (all p = NS). The injury was uniformly lethal without intervention, with survival time (mean) of 5 m, peak PP of 14 mm Hg, blood loss of 960 g, bleed rate of 450 g/m, and peak lactate of 2.6 mmol/L. Survival time (m) was extended to 44 with OP, 60 with PPB, and 60 with REBOA (p < 0.01). Peak PP (mm Hg) was 19 with OP, 23 with PPB, 10 with zone 1 REBOA, and 6 with zone 3 REBOA (p < 0.05). Blood loss (g) was 850 with OP, 930 with PPB, 610 with zone 1 REBOA, and 370 with zone 3 REBOA (p < 0.01). Peak lactate (mmol/L) was 3.3 with OP, 4.3 with PPB, 13.4 with zone 1 REBOA, and 5.3 with zone 3 REBOA (p < 0.01). Only 33% of zone 1 REBOA animals survived the initial 10 m after balloon deflation, compared to 60% for OP, 67% for PPB, and 100% for zone 3 REBOA (p < 0.01).

CONCLUSION

Preperitoneal balloon tamponade and zone 3 REBOA are effective alternatives to OP in this animal model of lethal pelvic fracture-associated hemorrhage. Zone 1 REBOA extends survival time but with high mortality upon reversal.

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.

Outcomes and complications for portal vein or superior mesenteric vein injury: No improvement in the era of damage control resuscitation

INTRODUCTION

Portal vein (PV) and superior mesenteric vein (SMV) injuries are lethal. We hypothesised outcomes have improved with modern trauma care.

METHODS

We reviewed patients presenting to our Level 1 trauma centre over ten-years with PV/SMV injuries, analysing physiology, operative management, associated injuries, and outcomes.

RESULTS

Twenty-four patients had 7 PV and 15 SMV injuries, 2 had both; all had operative exploration. Sixty-seven percent had penetrating trauma. While many had normal vitals, profound acidosis was common. All patients had ≥2 additional abdominal injuries, liver most common (50%). Additional abdominal vascular injuries were more common in non-survivors than survivors: IVC 46% vs 22%, common hepatic artery 20% vs 0%, SMA 26% vs 11%. The mean injury severity score (ISS) was 32.4, and the mean new injury severity score (NISS) was 44.5. Mortality was 63%. Eleven patients died from exsanguination, two from SMV thrombosis, and two from sequelae of other injuries. All survivors had venorrhaphy, as did 8 non-survivors. Non-survivors were also shunted; had ligation; or bypass, shunting, and ligation. Three exsanguinated prior to repair. Two survivors had SMV related complications. One with proximal SMV injury developed severe venous congestion and multiple enterocutaneous fistulae. Another developed an arterioportal fistula, managed with embolisation and percutaneous portal vein stenting.

CONCLUSION

Despite advances (REBOA, damage control surgery and resuscitation, liberal use of ED thoracotomy), PV and SMV injuries remain lethal. Injuries to other structures are ubiquitous. Early exsanguination is the major cause of death. All survivors had successful venorrhaphy; those who required more complex repairs died. Compromised mesenteric venous flow causes morbidity and mortality.

Examination of hemodynamics in patients in hemorrhagic shock undergoing Resuscitative Endovascular Balloon Occlusion of the Aorta (REBOA)

BACKGROUND

The objective of this study was to investigate the hemodynamic effects of aortic occlusion (AO) during Resuscitative Endovascular Balloon Occlusion of the Aorta (REBOA) using a sophisticated continuous vital sign (CVS) monitoring tool.

METHODS

Patients admitted between February 2013 and May 2017 at a tertiary center that received REBOA were included. Patients in cardiac arrest before or at the time of REBOA were excluded. Time of AO was documented by time-stamped videography and correlated with CVS data.

RESULTS

28 patients were included, mean (standard deviation) ISS was 38 (11). 18 received Zone 1 (distal thoracic aorta) and 10 received Zone 3 (distal abdominal aorta) AO. Among Zone 1 patients the pre-AO systolic blood pressure (SBP) nadir was 64 (19) mmHg, which increased to a mean of 124 (29) mmHg within 5 min after AO (p < 0.01). Among Zone 3 patients the pre-AO SBP nadir was 75 (19) mmHg, which increased to a mean of 98 (14) mmHg within 5 min after AO (p < 0.01). 72% of Zone 1 patients had episodes during AO where SBP was less than 90 mmHg as compared to 80% of Zone 3 patients (p = 0.51). 100% of Zone 1 patients had periods during AO where SBP was greater than 140 mmHg as compared to 70% Zone 3 patients (p = 0.04). The overall mean decrease in SBP after balloon deflation was 13 (20) mmHg (p < 0.01), with similar decreases among groups (14 (21) mmHg vs 12 (18) mmHg for Zone 1 and 3 patients, respectively (p = 0.85)). Patients undergoing Zone 1 AO were more likely to have an acute change (increase or decrease) in their heart rate immediately after AO as compared to Zone 3 AO (p = 0.048).

CONCLUSIONS

Significant hemodynamic alterations occur before, during, and after AO. The effects of Zone 1 AO on blood pressure and heart rate appear different than Zone 3 AO. This may have important implications for cardiac or cerebral function and perfusion goals, particularly with concomitant injuries such as cardiac contusion or traumatic brain injury.

Extending the golden hour for Zone 1 resuscitative endovascular balloon occlusion of the aorta: Improved survival and reperfusion injury with intermittent versus continuous resuscitative endovascular balloon occlusion of the aorta of the aorta in a porcine severe truncal hemorrhage model

BACKGROUND

Noncompressible hemorrhage can be controlled using resuscitative endovascular balloon occlusion of the aorta (REBOA). Prolonged ischemia limits REBOA application during Zone 1 deployment. Intermittent inflation/deflation may effectively mitigate this problem.

METHODS

A lethal abdominal vascular injury was created in 28 swines. Animals were randomized to controls (n = 7), 60 minutes full REBOA (FR, n = 5), time-based intermittent REBOA (iRT, n = 7), and pressure-based REBOA (iRP, n = 9). Intermittent groups had an initial inflation for 15 minutes, followed by 10-minute inflation: 3-minute deflation cycles (iRT), or an inflate/deflate schedule based on mean arterial pressure (MAP) less than 40 mm Hg (iRP). Experiments were concluded after 120 minutes or death (MAP < 20 mm Hg).

RESULTS

Intermittent REBOA animals all survived to 120 minutes versus 15 minutes for controls and 63 minutes for FR (p < 0.001). After 60 minutes, FR animals were more hypotensive (MAP 20 mm Hg vs. 80 mm Hg [iRP] and 100 mm Hg [iRT]; p < 0.001), had lower cardiac output (1.06 mL/min vs. 5.1 L/min [iRP] and 8.2 L/min [iRT]; p < 0.001), higher lactate (12.5 mg/dL vs. 8.5 mg/dL [iRP], p = 0.02), and decreased clot firmness on rotational thromboelastometry than iRP/T (64 mm vs. 69 mm [iRP] and 69 mm [iRT], p = 0.04). Acidosis was worse in iRT versus iRP at 120 minutes (pH 7.28 vs. pH 7.12; p = 0.02), improved lactate (11.9 mg/dL vs. 16.3 mg/dL; p = 0.04), and decreased whole blood resuscitation (452 mL vs. 646 mL, p = 0.05). Blood loss (clot weight) was higher in controls (2.0 kg) versus iRT and iRP (1.16 kg and 1.23 kg; p < 0.01) and not different from FR (0.87 kg; p = 0.10).

CONCLUSION

Intermittent REBOA can maintain supraceliac hemorrhage control while decreasing distal ischemia in a swine model. Prolonged survival times, decreased acidosis, and lower resuscitation requirements indicate that this technique could potentially extend Zone 1 REBOA deployment times. Schedules based on MAP may be superior to time-based regimens.

Large Animal Models of Proximal Aortic Balloon Occlusion in Traumatic Hemorrhage: Review and Identification of Knowledge Gaps Relevant to Expanded Use

BACKGROUND

The aim of this study was to review and summarize the large animal data on resuscitative endovascular balloon occlusion of the aorta (REBOA) for traumatic hemorrhage and identify knowledge gaps pertinent to the proposed broader use of the technique in prehospital situations.

METHODS

A review of published large animal models of traumatic hemorrhage incorporating REBOA with a primary outcome of the effect of aortic occlusion was performed. Data were collected on experimental protocols, hemodynamic effects, resuscitation requirements, mortality, metabolic and tissue consequences of induced ischemia-reperfusion, and effects on hemorrhage volume and other injuries.

RESULTS

A limited number of REBOA studies exist, and there is variability in the species and size of animals used. Various controlled and uncontrolled hemorrhage protocols have been studied, and a number of balloon devices used. Hemodynamic effects of occlusion were consistent as were basic systemic physiological effects. Minimal study of the effects of partial aortic occlusion and hemodynamic and metabolic physiology distal to the balloon has been performed, and partial or complete occlusion times >90 min have not been studied.

CONCLUSIONS

Significant knowledge gaps exist, which are potentially relevant to the expanded use of REBOA. Investigation into the physiology of partial occlusion and the metabolic effects and potential mitigation strategies for large-scale ischemia and reperfusion are particularly needed.

Three cases of resuscitative endovascular balloon occlusion of the aorta (REBOA) in austere pre-hospital environment-technical and methodological aspects

Background

The present paper describes three cases where ER-REBOA® was used with partial aorta occlusion (AO), by performing a partial resuscitative endovascular balloon occlusion of the aorta or pREBOA, in an austere pre-hospital military environment.

In addition, because no specific REBOA algorithm for pre-hospital environment exists yet, this paper seeks to fill this gap, proposing a new pragmatic REBOA algorithm.

Methods

Belgian Special Operations Surgical Team applied REBOA in three patients according to a decisional algorithm, based on the MIST acronym used for trauma patients. Only 3 ml, in the first instance, was inflated in the balloon to get AO. The balloon was then progressively deflated, and reperfusion was tracked through changes of end-tidal carbon dioxide (EtCO₂).

Results

Systolic blood pressure (SBP) before ER-REBOA® placement was not higher than 60 mmHg. However, within the first 5 min after AO, SBP improved in all three cases. Due to the aortic compliance, a self-made pREBOA was progressively achieved while proximal SBP was raising with intravenous fluid infusion. Afterwards, during deflation, a steep inflection point was observed in SBP and EtCO₂.

Conclusions

ER-REBOA® is suitable for use in an austere pre-hospital environment. The MIST acronym can be helpful to select the patients for which it could be beneficial. REBOA can also be performed with pREBOA in a dynamic approach, inflating only 3 mL in the balloon and using the aortic compliance. Furthermore, while proximal SBP can be convenient to follow the occlusion, EtCO₂ can be seen as an easy and interesting marker to follow the reperfusion.

Mechanisms of electrical vasoconstriction

BACKGROUND

Electrical vasoconstriction is a promising approach to control blood pressure or restrict bleeding in non-compressible wounds. We explore the neural and non-neural pathways of electrical vasoconstriction in-vivo.

METHODS

Charge-balanced, asymmetric pulses were delivered through a pair of metal disc electrodes. Vasoconstriction was assessed by measuring the diameter of rat saphenous vessels stimulated with low-voltage (20 V, 1 ms) and high-voltage (150 V, 10 μs) stimuli at 10 Hz for 5 min. Activation pathways were explored by topical application of a specific neural agonist (phenylephrine, alpha-1 receptor), a non-specific agonist (KCl) and neural inhibitors (phenoxybenzamine, 25 mg/ml; guanethidine, 1 mg/ml). Acute tissue damage was assessed with a membrane permeability (live-dead) fluorescent assay. The Joule heating in tissue was estimated using COMSOL Multiphysics modeling.

RESULTS

During stimulation, arteries constricted to 41 ± 8% and 37 ± 6% of their pre-stimulus diameter with low- and high-voltage stimuli, while veins constricted to 80 ± 18% and 40 ± 11%, respectively. In arteries, despite similar extent of constriction, the recovery time was very different: about 30 s for low-voltage and 10 min for high-voltage stimuli. Neural inhibitors significantly reduced low-voltage arterial constriction, but did not affect high-voltage arterial or venous constriction, indicating that high-voltage stimuli activate non-neural vasoconstriction pathways. Adrenergic pathways predominantly controlled low-voltage arterial but not venous constriction, which may involve a purinergic pathway. Viability staining confirmed that stimuli were below the electroporation threshold. Modeling indicates that heating of the blood vessels during stimulation (< 0.2 °C) is too low to cause vasoconstriction.

CONCLUSIONS

We demonstrate that low-voltage stimuli induce reversible vasoconstriction through neural pathways, while high-voltage stimuli activate non-neural pathways, likely in addition to neural stimulation. Different stimuli providing precise control over the extent of arterial and venous constriction as well as relaxation rate could be used to control bleeding, perfusion or blood pressure.

Could resuscitative endovascular balloon occlusion of the aorta improve survival among severely injured patients with post-intubation hypotension?

Current literature shows the association of post-intubation hypotension and increased odds of mortality in critically ill non-trauma and trauma populations. However, there is a lack of research on potential interventions that can prevent or ameliorate the consequences of endotracheal intubation and thus improve the prognosis of trauma patients with post-intubation hypotension. This review paper hypothesizes that the deployment of REBOA among trauma patients with PIH, by its physiologic effects, will reduce the odds of mortality in this population. The objective of this paper is to review the current literature on REBOA and post-intubation hypotension, and, furthermore, to provide a rational hypothesis on the potential role of REBOA in severely injured patients with post-intubation hypotension.