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Date: May 23rd, 2019

Reference: Joseph et al. Nationwide Analysis of Resuscitative Endovascular Balloon Occlusion of the Aorta in Civilian Trauma. JAMA Surgery March 2019.

Guest Skeptic: Dr. Robert Edmonds is an emergency physician in the US Air Force in Virginia. This is Bob’s tenth visit to the SGEM.

DISCLAIMER: THE VIEWS AND OPINIONS OF THIS PODCAST DO NOT REPRESENT THE UNITED STATES GOVERNMENT OR THE US AIR FORCE.

Case: You are working at a Level 1 Trauma Center and are alerted to an incoming Type A trauma. After donning your PPE (personal protective equipment) and greeting the trauma surgeon in your resuscitation bay, nursing delivers report that you are about to receive a 24-year-old male that was involved in an explosion that knocked the patient from their vehicle. They have an unstable pelvis and were intubated in the field for airway protection due to a low Glasgow Coma Scale (GCS) score.  Vitals are heart rate 112 bpm, blood pressure 110/60 mmHg, respiratory rate 16 bpm (intubated), oxygen saturation 94%, afebrile and the patient is four minutes from arrival.  You have a brief conversation with your trauma surgeon regarding these findings, and upon arrival of the patient, you note an intubated airway, equal bilateral breath sounds, and a rapid regular heart rate.  The patient’s eyes are closed and makes minimal movements with his extremities. Your surgeon rapidly asks for the REBOA kit and begins catheterization of the femoral artery while you have a professional yet rapid debate about the need to complete the primary survey and roll the patient to examine their back.

Background: Resuscitative endovascular balloon occlusion of the aorta (REBOA) was first used 50 years ago in the Korean War but was not mentioned in emergency medicine literature until 1986.  Its use declined in the 1990s and early 2000s, but during the past decade, it has gained the attention of trauma surgeons in military and civilian settings, potentially due to advances in the technology and smaller catheter sizes.

The evidence for REBOA is conflicting.  Animal studies have shown REBOA to temporize exsanguinating hemorrhage and to restore perfusion.  Some human studies [1,2] have shown benefit but a recent registry study from Japan [3] showed the use of REBOA associated with higher mortality.  The authors noted a lack of multi-institutional data at a national level regarding efficacy and safety of REBOA in the United States, which prompted their study.

The American College of Emergency Physicians (ACEP) and American College of Surgeons Committee on Trauma (ACS COT) in 2018 put out a joint statement for the use of REBOA [4]. They discuss some general observations, indication for REBOA, and guidelines for REBOA use and implementation.

ACEP and ACS COT also discuss the transfer, management, special circumstances (deployed military settings), training, credentialing and quality assurance of REBOA.

Clinical Question: What are the outcomes of trauma patients after REBOA placement?

Reference: Joseph et al. Nationwide Analysis of Resuscitative Endovascular Balloon Occlusion of the Aorta in Civilian Trauma. JAMA Surgery March 2019.

  • Population: All adult (over 18 years of age) patients in the ACS-TQIP database from 2015-2016.
    • Exclusions: Patients who were dead on arrival, were transferred from other facilities, had missing physiological parameters, or who underwent resuscitative thoracotomy were excluded.
  • Intervention: Patients who received REBOA within one hour of presentation to the emergency department
  • Comparison: Patients who did not receive REBOA (matched in a 1:2 intervention to comparison group)
  • Outcome:
    • Primary Outcomes: Emergency department mortality, 24-hour mortality, and mortality after 24 hours
    • Secondary Outcomes: Transfusion requirements at four hours and 24 hours after injury, in hospital complications (DVT, PE, CVA, MI, extremity compartment syndrome, unplanned return to the operating room, lower limb amputation), hospital length of stay and intensive care length of stay

Authors’ Conclusions: “Placement of REBOA in severely injured trauma patients was associated with a higher mortality rate compared with a similar cohort of patients with no placement of REBOA.  Patients in the REOBA group also had higher rates of acute kidney injury and lower leg amputations.  There is a need for a concerted effort to clearly define when and in which patient population REBOA has benefit.”

Quality Checklist for Observational Study:

  1. Did the study address a clearly focused issue? Yes
  2. Did the authors use an appropriate method to answer their question? Yes
  3. Was the cohort recruited in an acceptable way? Yes
  4. Was the exposure accurately measured to minimize bias? Yes
  5. Was the outcome accurately measured to minimize bias? Yes
  6. Have the authors identified all-important confounding factors? Yes
  7. Was the follow up of subjects complete enough? Yes
  8. How precise are the results/is the estimate of risk? Reasonably precise
  9. Do you believe the results? Yes
  10. Can the results be applied to the local population? Yes
  11. Do the results of this study fit with other available evidence? Yes

Key Results: There was 593,818 adult trauma patients identified in the retrospective analysis. They matched the 140 patients who received REBOA to 280 patients who did not receive REBOA. The mean age of patients was around 43 years, ¾ being male and a median Injury Severity Score (ISS) of 28.

Overall mortality rate was higher in the REBOA group compared to the no-REBOA group.

  • Primary Outcomes:
    • Overall mortality was worse (35.7% vs. 18.9%, p=0.01)
    • Mortality in the emergency department was not different
    • 24-hour mortality was worse (26.4% vs. 11.8%, p =0.01)
    • In hospital mortality after 24 hours was not different
  • Secondary Outcomes:
    • Transfusion requirements, hospital LOS and ICU LOS were not different
    • Most of the in-hospital complications were not different (DVT, PE, CVA, MI, extremity compartment syndrome, unplanned return to the operating room)
    • Acute kidney injury was worse in the REBOA group (10.7% vs. 3.2% p=0.02)
    • Amputation of lower limbs was greater in the REBOA group (3.6% vs. 0.7% p=0.04)

  1. Confounders: The authors mention in their conclusion that a limitation of this study is the retrospective nature of the database.Specifically, they couldn’t account for some important confounders, such as the type and size of the catheter used, the zone of placement (zone 1, 2, or 3), the duration of aortic occlusion, or the responsiveness of the patient to the initial resuscitation beforeREBOA placement. Each of these factors may have impacted the findings, most significantly the responsiveness to the initial resuscitation may have significantly impacted the selection of patients for REBOA placement.
  2. Propensity Score and Matching: The propensity score was described by Rosenbaum and Rubin in 1983 to be the probability of treatment assignment conditional on observed baseline covariates. Propensity score matching takes treated and untreated subjects with a similar propensity score and matches them. These authors did propensity score matching for a variety of things (demographics, vital signs, mechanism of injury, injury severity score, head abbreviated injury scale score, each body region abbreviated injury scale score, pelvic fractures, lower extremity vascular injuries and fractures, and number and grades of intra-abdominal solid organ injuries). While this can help improve the accuracy of observational studies, this statistical technique cannot achieve the same rigor of a randomized trial design.
  3. 1:2 matching: The authors used 1:2 matching of REBOA to control. This likely was done in an attempt to increase statistical power of a fairly rare event. Only 140 of the 593,818 patients underwent REBOA (0.02% of the study population). It bears mentioning that this underpins their allegation that despite 50 deaths in intervention and 53 deaths in the control, the denominators were different, so the overall mortality in the intervention (35.7%) was nearly double the control (18.9%).
  4. Multiple Primary Outcomes: How many times will I have to say…there can only be one primary outcome (Highlander)? Another way of saying this would be…I do not think “primary” means what they think it means (Princess Bride).
  5. Additional Secondary Outcomes: The authors’ methods outline several primary and secondary outcomes. Acute kidney injury is not listed in their methods or abstracted data but makes a surprise appearance in their results section as a statistically significant finding without mention of their definition of acute kidney injury.

Comment on Authors’ Conclusion Compared to SGEM Conclusion: We agree with the authors’ conclusion

SGEM Bottom Line: REBOA is currently an intervention of uncertain benefit. Although it has shown promise in some studies, this investigation leaves its therapeutic potential in question, and arguably demonstrates harm. There may be substantial benefit in select groups of trauma patients, but these groups are not yet known.

Case Resolution: After several frustrated unsuccessful attempts by the trauma surgeon to place the femoral artery line to later upsize to a REBOA catheter, the patient is finally rolled, and two large wounds are noted on the patient’s back.  These are explored briefly and dressed with combat gauze just prior to transporting the patient to the operating room.

Clinical Application: In civilian settings, the use of REBOA appears to have substantial risks of harm without clear evidence of benefit. Outside of a trial setting to find select groups that could benefit, it is doubtful that this is safe or effective for patient care.

Dr. Robert Edmonds

What Do I Tell My Patient? If my patient is injured enough to be a possible candidate for REBOA, I’m probably not able to have much of a conversation with them.  I can tell their family afterwards that REBOA is a therapy that still has an evolving body of evidence, and as there are very real threats of harm, it is not always an intervention our hospital elects to perform.

Keener Kontest: Last weeks’ winner was Dr. David McAdams a PGY-3 in Emergency Medicine from Oklahoma. He knew the largest civil monetary penalty settlement related to an EMTALA violation for non-psychiatric case was $170,000.

Listen to the podcast to hear this weeks’ trivia question. If you know the answer, send an email to TheSGEM@gmail.com with “keener” in the subject line. The first correct answer will receive a cool skeptical prize.

Other FOAMed:

 

Remember to be skeptical of anything you learn, even if you heard it on the Skeptics’ Guide to Emergency Medicine.

  1. DuBose JJ, Scalea TM, Brenner M, et al; AAST AORTA Study Group. The AAST prospective Aortic Occlusion for Resuscitation in Trauma and Acute Care Surgery (AORTA) registry: data on contemporary utilization and outcomes of aortic occlusion and resuscitative balloon occlusion of the aorta (REBOA).J Trauma Acute Care Surg. 2016;81 (3):409-419. doi:10.1097/TA.0000000000001079
  2. Brenner M, Inaba K, Aiolfi A, et al; AAST AORTA Study Group. Resuscitative endovascular balloon occlusion of the aorta and resuscitative thoracotomy in select patients with hemorrhagic shock: early results from the American Association for the Surgery of Trauma’s Aortic Occlusion in Resuscitation for Trauma and Acute Care Surgery Registry.J Am Coll Surg. 2018;226(5):730-740. doi:10.1016/j.jamcollsurg.2018.01.044
  3. Norii T, Crandall C, Terasaka Y. Survival of severe blunt trauma patients treated with resuscitative endovascular balloon occlusion of the aorta compared with propensity score–adjusted untreated patients.J Trauma Acute Care Surg. 2015; 78(4):721-728. doi:10.1097/TA. 0000000000000578
  4. Brenner et al. Joint statement from the American College of Surgeons Committee on Trauma (ACS COT) and the American College of Emergency Physicians (ACEP) regarding the clinical use of Resuscitative Endovascular Balloon Occlusion of the Aorta (REBOA). BMJ 2018