# Resuscitative Endovascular Balloon Occlusion of the Aorta (REBOA)
## Overview and Rationale
### Concept
REBOA is a technique for temporary endovascular aortic occlusion designed to control non-compressible torso hemorrhage. It functions as an internal aortic cross-clamp, augmenting proximal blood pressure while reducing distal blood loss, and serves as a bridge to definitive surgical repair. It can be used as an alternative or adjunct to resuscitative thoracotomy with aortic cross-clamping.
### Historical Context
The concept was first described during the Korean War in 1954 for hemorrhage control, but it experienced a resurgence of interest in the 2010s as smaller catheter technology (7 French sheaths) made the procedure more practical for emergency use. REBOA is now included in the 10th edition of ATLS as a consideration in hemorrhagic shock, and adoption is accelerating at trauma centers, though the evidence base remains observational.
## Aortic Zones
### Zone I (Descending Thoracic Aorta)
Zone I extends from the origin of the left subclavian artery to the celiac trunk. Balloon inflation here is indicated for abdominal and pelvic hemorrhage. It provides the most profound hemodynamic augmentation but carries the greatest ischemic risk to abdominal organs, including the gut, kidneys, and spinal cord.
### Zone II (Paravisceral Aorta)
Zone II spans from the celiac trunk to the lowest renal artery. This is a "no-go zone" — the balloon must never be inflated here because of the risk of occluding the mesenteric and renal arteries.
### Zone III (Infrarenal Aorta)
Zone III extends from the lowest renal artery to the aortic bifurcation. It is indicated for pelvic hemorrhage and junctional hemorrhage, particularly in the setting of unstable pelvic fractures. The ischemic burden is lower than with Zone I occlusion because only the lower extremities and pelvis are affected.
| Zone | Anatomic Boundaries | Indication | Balloon Volume | Ischemia Risk |
|---|---|---|---|---|
| I (Thoracic) | Left subclavian → celiac trunk | Abdominal/pelvic hemorrhage | 8–16 mL | High (gut, kidneys, spinal cord) |
| II (Paravisceral) | Celiac trunk → lowest renal artery | **NO INFLATION** | — | — |
| III (Infrarenal) | Lowest renal artery → aortic bifurcation | Pelvic/junctional hemorrhage | 4–8 mL | Lower (pelvis, lower extremities) |
## Indications
REBOA is indicated for non-compressible torso hemorrhage with hemorrhagic shock (systolic blood pressure below 90 mmHg) or loss of pulse. Specific scenarios include abdominal solid organ injury with hemodynamic instability, pelvic fracture hemorrhage unresponsive to binder placement and transfusion, junctional hemorrhage not amenable to tourniquet application, and cardiac arrest from a hemorrhagic etiology. The patient must have a potentially survivable injury for REBOA to be appropriate.
## Contraindications
REBOA is contraindicated in thoracic aortic injury such as dissection or transection, suspected injury proximal to the intended balloon zone, and known aortic aneurysm. Relative contraindications include the absence of surgical backup and non-hemorrhagic causes of shock. It is essential to understand that REBOA is not a definitive therapy — it requires rapid transition to the operating room.
## Procedure
### Access
The common femoral artery (CFA) is punctured, ideally under ultrasound guidance. Newer devices require only a 7 French sheath, which minimizes the arteriotomy. Either side can be used, though the left CFA may be preferable for anatomic reasons. A blind landmark technique using palpation at the mid-inguinal point is an alternative but is less reliable in hypotensive patients.
### Catheter Insertion and Positioning
The ER-REBOA catheter is a 7 French-compatible device designed for emergency use. Insertion depth is estimated by external measurement: for Zone I placement, the distance from the xiphoid process to the femoral access site is measured (approximately 45 to 50 centimeters), and for Zone III, the distance from the umbilicus to the access site (approximately 25 to 30 centimeters). Position should be confirmed with X-ray or fluoroscopy when possible.
### Balloon Inflation
The balloon is inflated with saline, never air, using the provided syringe. Zone I typically requires 8 to 16 milliliters depending on aortic diameter, while Zone III requires 4 to 8 milliliters. Proximal blood pressure augmentation confirms successful occlusion, and an arterial line placed proximal to the balloon is ideal for monitoring.
### Partial REBOA (pREBOA)
Partial inflation of the balloon allows some distal blood flow, theoretically reducing ischemia-reperfusion injury and potentially extending the safe occlusion time. While the concept is appealing, maintaining stable partial occlusion is technically challenging, and evidence remains limited.
## Complications
### Ischemic Injury
Zone I occlusion time should ideally be kept below 60 minutes. Zone III is better tolerated for longer periods. Organs at risk include the gut (mesenteric ischemia), kidneys (acute kidney injury), spinal cord (paraplegia), and lower extremities. Upon balloon deflation, ischemia-reperfusion injury can cause hyperkalemia, acidosis, and cardiovascular collapse.
### Access-Related
Femoral artery injury, dissection, or thrombosis can occur at the access site. Pseudoaneurysm formation, limb ischemia distal to the sheath, and retroperitoneal hemorrhage from the access are additional risks.
### Balloon-Related
Balloon migration, aortic injury (rare with compliant balloons), and balloon rupture are possible though uncommon complications.
## Deflation and Transition
Balloon deflation should be gradual, over 10 to 30 minutes, to prevent cardiovascular collapse from reperfusion. Blood products should be running during deflation. Clinicians must monitor for post-deflation hypotension, hyperkalemia, and acidosis. Deflation should be coordinated with the surgical team in the operating room. The sheath is removed by manual pressure, surgical closure, or a closure device.
## REBOA vs. Resuscitative Thoracotomy
### REBOA Advantages
REBOA is less invasive, faster to deploy in trained hands, and does not require a surgical sternotomy or thoracotomy skill set. It can be performed by non-surgeons with appropriate training and causes lower blood loss from the procedure itself.
### Resuscitative Thoracotomy Advantages
Resuscitative thoracotomy allows direct cardiac massage, addresses cardiac tamponade and cardiac injury directly, permits clamping of the pulmonary hilum for pulmonary hemorrhage, and has an established (if modest) evidence base.
### Current Controversy
No randomized controlled trials have compared REBOA to resuscitative thoracotomy. Observational data suggest similar or possibly better hemodynamic augmentation with REBOA, but selection bias limits conclusions. The AORTA registry and the UK-REBOA trial are the primary data sources. Notably, the UK-REBOA trial (2023) was stopped early and raised concerns — it did not demonstrate a survival benefit and showed potential harm, injecting significant uncertainty into the field.
## Implementation Considerations
### Training
Procedural training on simulation models and cadavers is essential. The BEST (Basic Endovascular Skills for Trauma) course provides structured instruction. Clinicians need familiarity with arterial access, catheter navigation, and balloon management. Low-volume centers may struggle to maintain competency, making regular simulation practice critical.
### Community vs. Academic Settings
Academic trauma centers offer higher case volume, surgical backup, and angiography suite access. Community emergency departments face challenges with limited surgical backup, longer transport times, and lower case volumes. Paradoxically, REBOA may be most useful in settings with prolonged transfer times where definitive surgery is unavailable — the very settings where maintaining competency is hardest. Equipment cost and shelf-life are additional practical considerations.
An anatomical illustration of the aorta showing the three REBOA zones in a coronal view of the torso. Zone I is shaded in red from the left subclavian artery to the celiac trunk, labeled "Zone I - Thoracic Aorta." Zone II is shaded in yellow from the celiac trunk to the lowest renal artery, labeled "Zone II - NO INFLATION (Paravisceral)." Zone III is shaded in green from the lowest renal artery to the aortic bifurcation, labeled "Zone III - Infrarenal Aorta." Key vascular landmarks (celiac trunk, SMA, renal arteries, aortic bifurcation) are labeled. A REBOA catheter is shown inserted via the right common femoral artery with the balloon inflated in Zone I.
A step-by-step procedural illustration of REBOA placement in four panels. Panel 1: Ultrasound-guided common femoral artery access with needle insertion using Seldinger technique. Panel 2: 7 Fr sheath insertion over guidewire. Panel 3: ER-REBOA catheter being advanced with external measurement from xiphoid to access site shown. Panel 4: Balloon inflated in Zone I with an arterial pressure tracing inset showing augmented proximal pressure post-inflation. Each panel is numbered and annotated with key technical points.
A comparison infographic showing REBOA versus resuscitative thoracotomy side by side. Left column shows REBOA with a diagram of endovascular balloon in the aorta, listing pros (less invasive, faster deployment, lower procedural blood loss) and cons (no cardiac access, ischemia time limits, limited evidence). Right column shows resuscitative thoracotomy with a diagram of open left chest with aortic cross-clamp, listing pros (direct cardiac access, addresses tamponade, established use) and cons (highly invasive, requires surgical skill, high procedural morbidity). A central question mark indicates the lack of RCT evidence comparing the two.
## Clinical Pearls
REBOA is a temporizing measure, not definitive treatment — it buys time to reach the operating room and nothing more. Zone II is a "no-go zone" where balloon inflation must never occur, as it would occlude the mesenteric and renal arteries. Zone I occlusion should be limited to less than 60 minutes to reduce the risk of devastating ischemia-reperfusion complications. Gradual balloon deflation with concurrent resuscitation prevents cardiovascular collapse during reperfusion. Ultrasound-guided CFA access is strongly preferred over the blind technique, particularly in hypotensive patients where landmarks are unreliable. The UK-REBOA trial raised serious concerns about potential harm, and the decision to deploy REBOA should involve discussion with the surgical team. External measurement from the xiphoid to the access site provides a reliable estimate of insertion depth for Zone I placement. Even at low-volume centers, REBOA training must be maintained through simulation if the device is stocked.
## References
- Morrison JJ, et al. Use of REBOA in combat casualty care and civilian trauma systems. *Shock*. 2014;41(Suppl 1):38-46.
- Brenner M, et al. AORTA Registry: REBOA in hemorrhagic shock. *J Trauma Acute Care Surg*. 2018;85:372-378.
- Jansen JO, et al. UK-REBOA Trial: Resuscitative endovascular balloon occlusion of the aorta for major trauma. *NEJM*. 2023;389:1493-1503.
- Bulger EM, et al. ACS TQIP Best Practices in the Management of Hemorrhagic Shock. 2022.
- Stannard A, et al. Resuscitative endovascular balloon occlusion of the aorta (REBOA) as an adjunct for hemorrhagic shock. *J Trauma*. 2011;71:1869-1872.