Self-expanding foam versus preperitoneal packing for exsanguinating pelvic hemorrhage

Abstract

Background: Mortality for pelvic fracture patients presenting with hemorrhagic shock ranges from 21% to 57%. The objective of this study was to develop a lethal and clinically relevant pelvic hemorrhage animal model with and without bony fracture for evaluating therapeutic interventions. ResQFoam is a self-expanding foam that has previously been described to significantly decrease mortality in large-animal models of abdominal exsanguination. We hypothesized that administration of ResQFoam into the preperitoneal space could decrease mortality in exsanguinating pelvic hemorrhage.

Methods: Two pelvic hemorrhage models were developed using noncoagulopathic swine. Pelvic hemorrhage model 1: bilateral, closed-cavity, major vascular retroperitoneal hemorrhage without bony pelvic fracture. After injury, animals received no treatment (control, n = 10), underwent preperitoneal packing using laparotomy pads (n = 11), or received ResQFoam (n = 10) injected into the preperitoneal space. Pelvic hemorrhage model 2: unilateral, closed-cavity, retroperitoneal hemorrhage injury (with intraperitoneal communication) combined with complex pelvic fracture. After injury, animals received resuscitation (control, n = 12), resuscitation with preperitoneal packing (n = 10) or with ResQFoam injection (n = 10) into the preperitoneal space.

Results: For model 1, only ResQFoam provided a significant survival benefit. The median survival times were 50 minutes and 67 minutes for preperitoneal packing and ResQFoam, compared with 6 minutes with controls ( p = 0.002 and 0.057, respectively). Foam treatment facilitated hemodynamic stabilization and resulted in significantly less hemorrhage (21.5 ± 5.3 g/kg) relative to controls (31.6 ± 5.0 g/kg, p < 0.001) and preperitoneal packing (32.7 ± 5.4 g/kg, p < 0.001). For model 2, both ResQFoam and preperitoneal packing resulted in significant survival benefit compared with controls. The median survival times were 119 minutes and 124 minutes for the preperitoneal packing and ResQFoam groups, compared with 4 minutes with controls ( p = 0.004 and 0.013, respectively).

Conclusion: Percutaneous injection of ResQFoam into the preperitoneal space improved survival relative to controls, and similar survival benefit was achieved compared with standard preperitoneal pelvic packing. The technology has potential to augment the armamentarium of tools to treat pelvic hemorrhage.

Figure 1.

(A) Representative image of Model #1 showing bilateral vascular injury sites with customized nozzle for foam delivery placed into the pre-peritoneal pelvic space via incisions adjacent to the inguinal incisions. (B) Computed tomography image of the pelvis showing bony fracture of the sacro-iliac joint and obturator ring (yellow arrows) for Model #2. (C) Representative image of Model #2 showing foam nozzle inserted into the pre-peritoneal pelvic space via incision adjacent to the inguinal incision (unilateral injury)

Figure 2.

Pelvic cavity pressure dynamics after injury for (A) Model #1 and (B) Model #2. In Model #1, individual curves are shown for the ResQFoam group since intervention time varied based on when mean arterial pressure reached < 30 mmHg. All other curves represent the mean.

Figure 3.

(A) Kaplan-Meier survival curve for Model #1 showing that ResQFoam intervention resulted in a significant survival benefit relative to the control group. (B) Kaplan-Meier survival curve for Model #2 showing that both ResQFoam and PPP intervention resulted in a significant survival benefit relative to the control group. Log-rank tests were used to compare the survival curves. Pair-wise comparisons between groups were made (with Tukey adjustment for multiple testing) when overall significance across the three groups were detected.

Figure 4.

Mean arterial pressure curves for Model #1 (A, B) and Model #2(C, D). A and C depict interval plots of the mean arterial pressure for each group within 5 minutes after injury. B and D depict mean values of mean arterial pressure from surviving animals throughout the study duration. In both models, mean arterial pressure rapidly decreases following injury, resulting in eventual exsanguination within the control group. ResQFoam and preperitoneal packing (PPP) interventions stabilize mean arterial pressure relative to controls.