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Performance of a Novel Temporary Arterial Shunt in a Military-Relevant Controlled Hemorrhage Swine Model.

BACKGROUND
In military trauma, temporary vascular shunts (TVSs) restore arterial continuity until delayed vascular reconstruction, often for a period of hours. A novel US Air Force-developed trauma specific vascular injury shunt (TS-VIS) incorporates an accessible sideport for intervention or monitoring which may improve patency under adverse hemodynamic conditions. Our objective was to evaluate TS-VIS patency in the setting of volume-limited resuscitation from hemorrhagic shock.


METHODS
Female swine (70-90kg) underwent 30% hemorrhage and occlusion of the left external iliac artery (LEIA) for 30min. Animals were allocated to one of three groups (n=5/group) by LEIA treatment: Sundt shunt (SUNDT), TS-VIS with arterial pressure monitoring (TS-VIS), or TS-VIS with heparin infusion (10u/kg/h, TS-VISHep). Animals were resuscitated with up to 3 units whole blood to maintain a MAP >60mmHg and were monitored for 6 hours. Bilateral femoral arterial flow was continuously monitored with transonic flow probes, and shunt thrombosis was defined as the absence of flow for greater than 5 minutes.


RESULTS
No intergroup differences in MAP or flow were observed at baseline or following hemorrhage. Animals were hypotensive at shunt placement (MAP 35.5±7.3 mmHg); resuscitation raised MAP to >60 mmHg by 26.5±15.5 min. Shunt placement required 4.5 ± 1.8 minutes with no difference between groups. Four SUNDT thrombosed (3 before 60 min). One SUNDT thrombosed at 240min, two TS-VIS and one TS-VISHep thrombosed between 230 and 282 min. Median patency was 21 min for SUNDT and 360 min for both TS-VIS groups (P=0.04). While patent, all shunts maintained flow between 60 and 90% of contralateral.


CONCLUSIONS
The TS-VIS demonstrated sustained patency superior to the Sundt under adverse hemodynamic conditions. No benefit was observed by the addition of localized heparin therapy over arterial pressure monitoring by the TS-VIS sideport.


LEVEL OF EVIDENCE
Level II, preclinical (translational) randomized trial.