Yorkshire/Landrace-cross swine (weight, 70-90 kg) were randomized to iliac artery repair either immediately or at 1, 3, or 6 hours after vessel loop occlusion and arteriotomy. A fifth group underwent excision of the arterial segment without repair to represent ligation. Class III shock was created by removing 35 % of total blood volume using a variable rate model. Animals were monitored for 14 days to serially collect markers of functional recovery.
Animals with ≤1 hour ischemia (control) had clinically normal limb function by the end of the 2-week observation period, with minimal muscle and nerve changes on histology. Separate analysis of contralateral, nonexperimental limbs revealed normal histology and function. After 3 hours of ischemia, functional recovery was impaired, with moderate-to-severe degeneration of nerve and muscle noted on histology. Animals undergoing 6 hours of ischemia or ligation had minimal electromyelography response and severe systemic inflammation, which correlated with severe muscle and nerve degeneration. Concurrent class III hemorrhagic shock was associated with a decrement in neuromuscular recovery across all groups but was greatest in groups undergoing ≥3 hours of extremity ischemia (P < .01).
This study demonstrates the feasibility of combined hemorrhagic shock and extremity ischemia-reperfusion in a large-animal survival model. The presence of hemorrhagic shock compounds the effect of extremity ischemia, reducing the ischemic threshold of the limb to <3 hours. Strategies to improve functional salvage after extremity vascular injury in the setting of shock should include attempts at restoration of flow ≤60 minutes.