Indications for the use of REBOA are summarized below. These indications mirror the indications for resuscitative thoracotomy with the exception that shock or arrest secondary to penetrating chest trauma is a contraindication to REBOA (See the JTS Emergency Resuscitative Thoracotomy, 18 Jul 2018 CPG).¹⁴

Indications

Due to the mixed literature supporting the use of REBOA, it is imperative that REBOA only be considered in the appropriate patients with access to rapid definitive hemorrhage control, placed by trained providers, and with medical/surgical support personnel facile not only in setting up and managing REBOA and its required equipment, but also the care of the patient (both while the REBOA is in place and after removal of the balloon and its arterial sheath). REBOA is only a bridge to definitive hemorrhage control; therefore, all these variables necessitate consideration.

It is also important to be mindful that REBOA is a temporizing measure, and once the balloon for aortic occlusion is inflated, surgical capabilities must be available with definitive hemorrhagic control achieved within a maximum of 60 minutes since inflation (Partial: Zone 1 –2 hours, Zone 3 – 4 hours).

Patients where REBOA can be considered:

1. Traumatic arrest without evidence of thoracic, neck, or upper extremity hemorrhage (closed cardiac compressions must concomitantly be performed).
2. Severe hemorrhagic shock or suspected impending traumatic arrest with non-compressible truncal hemorrhage below the diaphragm.
3. Complex lower extremity amputations (high thigh injuries) where tourniquets and junctional tourniquets have been ineffective at hemorrhage control.

Initial Management

Initial management priorities for patients with traumatic arrest or impending arrest include early control of hemorrhage and hemostatic resuscitation as described in the JTS Damage Control Resuscitation CPG.^18,80 The initial focus in patients presenting in profound hemorrhagic shock, to include loss of pulses, is to determine the best resuscitative strategy, and whether resuscitation is appropriate or futile in a moribund patient. The following must be rapidly determined:

• Mechanism and pattern of injury
• Presence of a pulse
• Duration of cardiac arrest
• Presence or absence of an organized, narrow complex cardiac rhythm and/or organized cardiac activity by ultrasound
• Resources available
• Availability of surgical capability for definitive hemorrhage control
• Number of concurrent casualties

Patients exsanguinating from abdominal, pelvic, or junctional lower extremity bleeding may be candidates for REBOA. Such patients are identified by penetrating mechanism of injury to abdomen or pelvis, blast or blunt mechanism with positive FAST or suspected pelvic fracture, or massive proximal lower extremity trauma with signs of impending cardiovascular collapse.

Exsanguinating hemorrhage in the chest must be ruled out prior to placing REBOA—this can be done with bilateral chest tube placement, x-ray, or thoracic ultrasound. In cases of major chest hemorrhage, occlusion of the aorta may increase thoracic bleeding and is thus best addressed via thoracotomy or sternotomy.

A decision algorithm for (RAO) is found in Appendix A. If RAO is performed, concurrent hemostatic resuscitation and closed chest cardiac massage must continue while the procedure is performed.⁵⁰ If RAO is not performed, resuscitative efforts should cease unless there is a compelling reason to consider a non-traumatic arrest.

Resuscitative  Thoracotomy

The gold standard for aortic occlusion in traumatic arrest remains a left anterolateral thoracotomy (See JTS Emergent Resuscitative Thoracotomy CPG).

Trans-abdominal  Aortic  Occlusion

The aorta can also be occluded trans-abdominally at any point along its length. It can be occluded with either application of a clamp, or compression with a retractor or the surgeon’s hand. Alternatively, if there is limited surgical assistance or a need to reduce the number of instruments in the upper abdomen, a balloon aortic occlusion at Zone 1 or Zone 3 can be considered, depending on where the focus of bleeding is located.

As with all other forms of RAO, restoration of aortic perfusion should be carefully coordinated with the rest of the team to minimize the effects of reperfusion and blood volume shifts.

It should be noted that reperfusion after partial balloon occlusion can occur with gradual titration of volume while monitoring the response of above and below balloon pressures over 10 - 30 minutes to minimize negative hemodynamic consequences during reperfusion. With complete occlusion REBOA catheters, it is not possible to gradually titrate stable reperfusion as the balloon configuration essentially provides “all or none” occlusion.

REBOA  Steps

REBOA can be considered in 6 sequential steps:

1. Arterial access and positioning of sheath
2. Positioning of the balloon
3. Inflation of the balloon
4. Establish degree of aortic occlusion (partial vs complete)
5. Operative/procedural control of bleeding
6. Deflation of the balloon
7. Sheath removal

REBOA can be performed preemptively in patients with high-risk injury patterns and unstable physiologic parameters as described above. In this way, REBOA can be proactive rather than reactive in appropriate patients. The indications for REBOA are summarized in Appendix A for traumatic arrest and Appendix B in cases of profound shock. If proximal aortic occlusion is required, this is termed Zone 1, whereas distal aortic occlusion is termed Zone 3. Zone 1 REBOA deployment will be used in most patients presenting with hemorrhagic shock, and may be used in all patients with traumatic arrest, regardless of injury pattern, due to the benefits on a patient’s MAP.^51,81

Arterial access:

In clinical situations where REBOA is being considered, early placement of an arterial line in the common femoral artery (CFA) is recommended. CFA access has consistently been identified as the rate limiting step to REBOA deployment.³² Obtaining early CFA access in the form of an arterial line can greatly decrease REBOA placement time: an existing common femoral arterial line can quickly be re-wired and upsized to a 4 - 7 Fr sheath (depending on what system is used) for REBOA in the event of patient deterioration. It can also be used to transduce the distal SBP with the pREBOA-PRO™ partially inflated.

Goal proximal SBP in REBOA is between 90 - 110 mmHg. If there is concern for traumatic brain injury a SBP > 110 mmHg has been advocated (See the JTS CPG Traumatic Brain Injury and Neurosurgery in the Deployed Environment CPG).⁵³ If utilizing (MAP goals instead of SBP, it is recommended to maintain MAP of 55 - 65 mmHg proximal to the balloon. Only after that range is achieved does the user consider if the patient's physiology requires partial or complete occlusion.

Positioning and Inflation of Balloon:

Aortic Zones:

Zone 1: ~46cm

Zone 3: ~28 cm

•  Zone 1: Placement of aortic balloon in the descending thoracic aorta (insert catheter to Zone 1 markers (45 - 49 cm at the level of the sheath) or measure the balloon with P tip from sternal notch to arterial sheath).
• Consider using for suspected infradiaphragmatic hemorrhage with high suspicion for intra-abdominal hemorrhage (positive FAST, significant mechanism of injury that involves the abdomen).
• Zone 2: DO NOT PLACE REBOA IN THIS ZONE—placement here risks injuring or thrombosing mesenteric vessels supplying abdominal visceral organs.
• Zone 3: Placement of aortic balloon directly above the aortic bifurcation (insert catheter to Zone 3 markers [26 - 29 cm] or measure P-tip from the xyphoid process to arterial sheath). Only use when intra-abdominal hemorrhage has been ruled out (negative FAST or mechanism/injury pattern that is not consistent with a concomitant abdominal injury). Consider use for: pelvic hemorrhage, junctional hemorrhage, profuse hemorrhage from high traumatic lower extremity amputations not controlled by tourniquets.

Complete Aortic Occlusion:

Zone 1 REBOA – 60 minutes maximum, optimally < 30 minutes.

Zone 3 REBOA – 60 minutes.

Preclinical research has shown a Zone 1 complete aortic occlusion time of 60 minutes or more results in significant metabolic derangement and organ damage that may negate any benefits obtained by its assistance with hemorrhage control.^54,74 In comparison, complete occlusion time of 30 minutes or less significantly improved outcomes without evidence of severe physiologic costs.

Zone 3 REBOA historically has been considered acceptable for up to 4 - 6 hours;^52-55 however, recent analysis in preclinical models have led to the revised recommendation to target Zone 3 balloon occlusion times of no greater than 60 minutes.^55-57,58

Partial Aortic Occlusion:

Zone 1 – 2 hours; Zone 3 – 4 hours

Distal SBP => 20mmHg (20 - 50 mmHg) or MAP ~20 mmHg

Partial aortic occlusion is defined as having partial blood flow past the balloon to minimize the risk of ischemia with longer occlusion times. In the absence of measuring flow, the best clinical surrogate is blood pressure. To accurately control inflation, the user will need to monitor the pressures proximal and distal to the inflated balloon. Two arterial line transducers and set ups are required to accomplish this. Similarly, during prolonged aortic occlusion, monitoring blood the proximal and distal pressures is necessary to determine the extent of partial occlusion. The distal mean arterial pressure is more accurately correlated with flow below the balloon than the above the balloon pressure.⁵⁹ The minimum recommended distal SBP considered to be a successful partial occlusion is 20 mmHg,³⁹ with a desirable target systolic blood pressure range of 20 - 50 mmHg.⁴⁹ If utilizing MAP instead of SBP it is recommended to maintain a MAP of 20 mmHg (below the balloon) since MAP and SBP are very close in this low-pressure range. This increases the occlusion time in Zone 1 to at least 2 hours and Zone 3 to at least 4 hours in both preclinical and clinical data.^38-39 Due to the semi compliant design of the pREBOA-PRO™ catheter, several investigators have documented that inflation of the balloon does not need to be adjusted after initial setting of below MAP.³⁹

The provider, or assistant, should promptly document placement time, pre-/post-placement blood pressure and MAP, and REBOA insertion distance. Use the Aortic Occlusion (AO) procedure note that is found in Appendix F for specific REBOA documentation. Whether using a complete or partial occlusion catheter, balloon volume and inflation time should be noted at the insertion site for reference by all providers caring for the patient. The provider is responsible for prevention of catheter migration, particularly during patient transport. A provider who is knowledgeable about the management of REBOA should attend to the patient while awaiting definitive surgical repair, to include transport. The trained provider is responsible for ensuring a safe and competent hand off.

Securing the REBOA

Due to its placement in a pulsatile vessel, the REBOA will migrate without properly securing it. In addition to suturing the femoral arterial sheath to the skin, the REBOA catheter must be secured at the appropriate distance marker either by hand or with a suture to the skin tied directly to the catheter to keep the catheter in place at the appropriate distance marker, especially during transport.

Maintaining the REBOA

The arterial line for the REBOA is narrow and can thrombose easily. Frequent flushing of the arterial line by medical personnel is often necessary every 15 minutes if remaining in place. Careful and diligent monitoring of the arterial waveform is necessary: if it appears the arterial waveform has dampened, flushing of the arterial line may be necessary. Often, it may be helpful once the patient is better resuscitated to place a radial arterial line to continue to monitor proximal blood pressure in the event that the REBOA arterial line thromboses, malfunctions, and/or can no longer transduce (as this may occur in a low flow state).

Balloon Deflation

The balloon should be deflated once definitive hemorrhage control has been obtained. Communication with the assistant holding the apparatus securing the catheter and the anesthesia team is critical before consideration of deflating the balloon. When deflating the balloon, turn the three-way stopcock and withdraw saline slowly and deflate the balloon slowly. A good rule of thumb is to deflate the balloon 1 ml every minute. During and after balloon deflation, the team should be prepared for hemodynamic changes related to reperfusion, washout of metabolic byproducts, and acidosis. Ensure adequate blood product resuscitation prior to balloon deflation.

Complete Occlusion:

If using complete occlusion catheters (ER-REBOA-PLUS™, COBRA-OS®, etc.) this step can be anticipated to result in a significant decrease in afterload and hypotension and may result in cardiac collapse. Additional resuscitation may be needed even with slow balloon deflation. The user can anticipate approximately a 10% change in flow past the balloon during deflation with as little as 0.2 ml of fluid removal. Intermittent balloon inflation and deflation may be necessary during ongoing resuscitation until hemodynamic stability is restored.

Partial Occlusion:

If using pREBOA-PRO™ the user is advised to gradually remove fluid from the balloon every 10 minutes to increase the distal SBP by 20 mmHg. These small adjustments in flow over time should mitigate the ischemic reperfusion changes often encountered with removing an aortic clamp or deflating a complete occlusion aortic balloon. This slow deliberate deflation method will minimize the need for reinflation unless further hemorrhage is encountered.

Catheter Removal

During catheter removal, ensure that the balloon is fully deflated. If significant resistance is felt as the catheter is being removed, it is likely that the balloon cannot pass through the sheath. In this case, the balloon and the arterial sheath must be removed together. See below on sheath management and removal.

Sheath Management and Removal:

After placing a REBOA, careful management of the femoral sheath is imperative. The majority of complications associated with REBOA use are related to the sheath and access site complications. Reported femoral access complications include arterial disruption, dissection, pseudoaneurysms, hematoma, thromboembolic phenomenon, and extremity ischemia. These complications have resulted in limb loss.^29,30

Due to the risk of sheath dislodgement or vessel wall damage, excessive patient movement should be avoided. Patients with indwelling sheaths should be positioned supine or reverse Trendelenburg only. If the patient must be moved or turned, they should be kept in a flat position and log rolled. Avoid flexing the hip.

This may be performed either at the Role 3 facility or as soon as possible after arrival at a Role 4 facility, depending on resources available to perform and interpret the ultrasound. When CT scanning is available or already obtained, access site can also be evaluated on this study and replace need for ultrasound.

Once definitive hemorrhage control has been obtained, the REBOA sheath should be removed

If arterial pressure monitoring is still required, perform at an alternate arterial line site. Prior to removal, an angiogram through the sheath to document distal limb perfusion is best practice, though not always available. If a large sheath size is used, a patient is coagulopathic, or there is technical difficulty in sheath removal, a cut down and arterial repair, patch or graft may be required. This may be best accomplished in the Role 3 environment with access to specialists and/or surgical backup.²⁶ It is also helpful to leave the sheath in place when performing a surgical repair as this will help guide to the location of the access during the exposure of the femoral artery.

When there is concern for re-bleeding, the sheath may be left in place without aortic occlusion. By leaving the sheath in place, the REBOA can easily be reinserted, and aortic occlusion can quickly be obtained if rebleeding occurs or hemorrhage continues.^60,76 In general, and situation/resource dependent, the sheath should be left in place during any active or ongoing resuscitation. The sheath should not be removed immediately prior to transport and is best removed where vascular complications can be treated and managed. See section on indwelling sheath management.

Indwelling Arterial Sheath Management:

See Appendix G.

Indwelling femoral arterial sheaths are associated with a significant risk of thrombosis, embolization, and limb ischemia, and require careful management, particularly in austere and transport environments. The sheath should be flushed immediately after placement to clear blood from the sheath and prevent early thrombosis. In general, the sheath should be left in place during ongoing resuscitation or prior to transport, as premature removal may result in loss of vascular access, hemorrhage, or inability to rapidly re-establish aortic occlusion. All arterial sheaths must be maintained with continuous flow, maintained on pressure or frequently flushed (at least every hour) to prevent thrombosis. In a combat or austere environment, often this is best achieved with a pressure bag and arterial line transduction or, alternatively, continuous infusion of saline or heparinized saline when not contraindicated at a fixed low rate. Sheaths with stagnant blood will thrombose rapidly, particularly in deployed environments. If not on continuous flow, the sheath should be flushed at least hourly. A sheath that does not aspirate blood easily should be considered thrombosed until proven otherwise; in this circumstance, the sheath should not be flushed, as this may result in distal embolization of clotted blood, and management should proceed according to thrombosed sheath protocols (Appendix H). While the sheath remains in place, hourly neurovascular checks of the affected extremity are essential to identify complications in a timely manner. Prior to sheath removal, evaluation of sheath position and the access site is recommended, particularly when placement occurred under emergent conditions; this may be performed using physical examination, plain radiography, CT imaging with or without contrast, or angiography when available. The sheath should not be removed immediately prior to transport and is best removed in an environment capable of recognizing and managing vascular complications. 

Even in an austere environment, protocols for use and follow-on care should be planned and discussed prior to implementation. Team training and awareness of pitfalls are critical to ensure the best possible outcomes.

Following sheath removal, consideration for more frequent monitoring during the first six hours when feasible should be considered. Most access-related complications occur within the first 1–6 hours after sheath removal, with the highest rate in the first 2 hours.

Surgical Management of Femoral Arterial Sheath Complications (Surgical Repair Tips):

When surgical management of a femoral arterial sheath is required, a cutdown directly over the sheath is recommended to allow controlled removal and minimize hematoma formation. The sheath should be left in place during exposure, as it provides tamponade and serves as a guide to the artery. Bleeding is to be expected when cutting down over a sheath and proximal control should be thought through, whether this is under the inguinal ligament or by gaining control in the retroperitoneum, especially when a hematoma already is present (See Appendix I).

Proximal control may be obtained using endovascular or open techniques. Open technique consists of control of the iliac artery in the abdomen or retroperitoneum. Endovascular methods consist of a REBOA positioned in Zone 3 or Fogarty balloon catheter to provide temporary proximal control. Balloon occlusion at the femoral access site can also be achieved by inserting and inflating a balloon through the existing access prior to cutdown; however, this is an advanced endovascular technique and may not be feasible in austere environments. “Up-and-over” balloon control from the contralateral femoral artery is another option but is often not readily available in deployed settings.

The most reliable proximal control in the setting of a large or expanding hematoma, or when the sheath has already been removed, is open retroperitoneal exposure of the external iliac artery. Surgeons should have a low threshold to proceed directly to retroperitoneal exposure in these scenarios, as proximal control may not be achievable safely from a standard groin approach.

During repair of the access site, arterial dissection and thrombosis are common and should be actively assessed. The arteriotomy should be repaired with attention to full-thickness closure and restoration of luminal integrity. Intraoperative ultrasound is highly useful and may allow assessment of vessel patency, detection of thrombus, and confirmation of distal flow without the need to extend the arteriotomy.

Even in an austere environment, protocols for use and follow on care should be planned and discussed prior to implementation. Team training and awareness of pitfalls are critical to ensure the best possible outcomes.