Early versus delayed restoration of flow with temporary vascular shunt reduces circulating markers of injury in a porcine model.
BACKGROUND
Temporary vascular shunting to restore flow after vascular injury has been advocated. The effectiveness of this adjunct in protecting against ischemic injury has not been established. This study will assess the temporal impact of shunts on ischemic injury and arterial flow.


METHODS
A porcine model of hind-limb ischemia via iliac artery occlusion was used (N = 36; weight [kg] +/- SD: 89 +/- 4.4). Animals were randomized into one control (Iscctrl) and four study groups (Isc0, Isc1, Isc3, and Isc6) according to ischemic time. Shunt placement followed ischemia, and flow and circulating injury markers were collected incrementally during 18 hours of reperfusion. Flow proportions and a calculated Ischemia Injury Index were used to characterize group differences.


RESULTS
There were no intergroup differences concerning initial weight, hemodynamic, or laboratory values. Shunt patency was 92% in the absence of anticoagulation. The proportion of common femoral arterial flow to baseline flow in the Isc6 group was lower than the Iscctrl group (p = 0.02). There was a similar trend with the Isc1 and Isc3 groups. The Ischemia Injury Index demonstrated that there was a difference in the Isc3 and Isc6 groups (late shunt placement) compared with the Iscctrl, Isc0, and Isc1 groups (early shunt placement) (p < 0.001).


CONCLUSIONS
This study provides physiologic insight into the benefit of shunts in a model of extremity ischemia. Early shunting protects the extremity from further ischemic insult and reduces circulating markers of tissue injury. Additionally, the presence of a shunt does not increase the Ischemic Injury Index and patency is maintained in the absence of heparinization.
Gifford
Shaun M
SM
Department of Vascular Surgery, Wilford Hall USAF Medical Center, Lackland AFB, Texas 78236, USA.
Eliason
Jonathan L
JL
Clouse
W Darrin
WD
Spencer
Jerry R
JR
Burkhardt
Gabe E
GE
Propper
Brandon W
BW
Dixon
Patricia S
PS
Zarzabal
Lee Ann
LA
Gelfond
Jonathan A
JA
Rasmussen
Todd E
TE
D000818:Animals; D001166:Arteriovenous Shunt, Surgical / Q000379:methods*; D007083:Iliac Artery / Q000293:injuries* / Q000601:surgery*; D007511:Ischemia / Q000097:blood / Q000517:prevention & control*; D035002:Lower Extremity / Q000098:blood supply / Q000293:injuries / Q000601:surgery; D008297:Male; D009132:Muscles / Q000293:injuries; D009211:Myoglobin / Q000097:blood; D011897:Random Allocation; D012720:Severity of Illness Index; D034421:Sus scrofa; D014857:Warfare
D009211:Myoglobin