Addressing Limitations in Case-Control Study of Patients Undergoing Resuscitative Endovascular Balloon Occlusion of the Aorta

Increased mortality with resuscitative endovascular balloon occlusion of the aorta only mitigated by strong unmeasured confounding: An expanded analysis using the National Trauma Data Bank

BACKGROUND

Resuscitative endovascular balloon occlusion of the aorta (REBOA) is being increasingly adopted to manage noncompressible torso hemorrhage, but a recent analysis of the 2015 to 2016 Trauma Quality Improvement Project (TQIP) data set showed that placement of REBOA was associated with higher rates of death, lower extremity amputation, and acute kidney injury (AKI). We expand this analysis by including the 2017 data set, quantifying the potential role of residual confounding, and distinguishing between traumatic and ischemic lower extremity amputation.

METHODS

This retrospective study used the 2015 to 2017 TQIP database and included patients older than 18 years, with signs of life on arrival, who had no aortic injury and were not transferred. Resuscitative endovascular balloon occlusions of the aorta placed after 2 hours were excluded. We adjusted for baseline variables using propensity scores with inverse probability of treatment weighting. A sensitivity analysis was then conducted to determine the strength of an unmeasured confounder (e.g., unmeasured shock severity/response to resuscitation) that could explain the effect on mortality. Finally, lower extremity injury patterns of patients undergoing REBOA were inspected to distinguish amputation indicated for traumatic injury from complications of REBOA placement.

RESULTS

Of 1,392,482 patients meeting the inclusion criteria, 187 underwent REBOA. After inverse probability of treatment weighting, all covariates were balanced. The risk difference for mortality was 0.21 (0.14-0.29) and for AKI was 0.041 (-0.007 to 0.089). For the mortality effect to be explained by an unmeasured confounder, it would need to be stronger than any observed in terms of its relationship with mortality and with REBOA placement. Eleven REBOA patients underwent lower extremity amputation; however, they all suffered severe traumatic injury to the lower extremity.

CONCLUSION

There is no evidence in the TQIP data set to suggest that REBOA causes amputation, and the evidence for its effect on AKI is considerably weaker than previously reported. The increased mortality effect of REBOA is confirmed and could only be nullified by a potent confounder.

LEVEL OF EVIDENCE

Therapeutic/care management, level IV.

Validation of a Novel Clinical Criteria to Predict Candidacy for Aortic Occlusion: An Aortic Occlusion for Resuscitation in Trauma and Acute Care Surgery Study

For trauma patients with noncompressible truncal hemorrhage (NCTH), aortic occlusion (AO) is attempted with either resuscitative thoracotomy (RT) or the resuscitative endovascular balloon occlusion of the aorta (REBOA). However, it is often challenging to identify the group of patients who would benefit from AO procedures. We hypothesized that patients who met simple clinical criteria would have better outcomes following AO procedures. This is a retrospective cohort study using the Aortic Occlusion for Resuscitation in Trauma and Acute Care Surgery database (November 2013-August 2019) which included patients who arrived with signs of life and underwent AO procedures (RT or zone 1 REBOA). Outcomes were compared between patients who met the criteria (admission vital signs: Glasgow Coma Scale (GCS) ≥9 and systolic blood pressure <90 mm Hg) and those who did not. Subgroup analyses were then conducted on patients who had a REBOA placed and those who underwent RT. A total of 998 patients met our inclusion criteria. Of those, a REBOA was placed in 364 patients (37%), while 634 (64%) underwent RT. The overall mortality rate in the criteria (+) group was significantly lower than that in the criteria (-) group (62 vs. 79%, P < .001). In patients who survived beyond the emergency department following AO procedures, those who met the criteria underwent hemorrhage control procedures more frequently (83% vs. 57%, P < .001). Our data suggest that simple clinical criteria could guide the provider for proceeding with AO in patients with suspected NCTH.