Establishment of an Acute Superior Mesenteric Artery Injury Model for Damage Control Surgery

Background

Managements of superior mesenteric artery (SMA) injuries are difficult and often result in a disappointing outcome. Damage control surgery (DCS) has been approved to be an effective and reliable strategy for severe trauma victims. We aimed to build up a severe trauma-shock-hypothermia model of SMA injuries for DCS study and determine the optimal time to institute DCS.

Methods

Pigs were anesthetized and instrumented with arterial and a thermodilution cardiac output catheter. SMA flow was interrupted while animals were hemorrhaged to 45% estimated blood volume. Pigs were maintained shock and intestine ischemia for three durations: intestine ischemia for 30 min (I-30; n = 6), 60 min (I-60; n = 6), and 90 min (I-90; n = 6). Cold lactated Ringer's (10 mL/kg) was infused to induce hypothermia. SMA was then declamped and kept in reperfusion for 6 h. Hemodynamic data and serum samples were collected during shock and resuscitation. Distal ileum was collected at the end of ischemia and reperfusion.

Results

All animals presented with disastrous conditions at the end of ischemia: low temperature, severe acidosis, decreased blood pressure, depressed cardiac output, and oxygen delivery. I-90 animals suffered the lowest temperature, the most severe acidosis, lowest blood pressure, and depressed cardiac output and oxygen delivery. Coagulopathy developed in I-90, whereas normal prothrombin time and thrombin time were detected in I-30 and I-60. Aspartate aminotransferase, lactate dehydrogenase, creatine kinase, and alkaline phosphatase were equally within groups (P > 0.05). All (6/6) of I-30, 83.3% (5/6) of I-60, and 16.7% (1/6) of I-90 pigs survived (P < 0.01). Base excess in I-90 was much lower than that in I-30 and I-60 animals.

Conclusions

We first built up an acute SMA injury animal model for DCS investigations and determined that the optimal institution time of DCS was before 60 min after SMA injury in the trauma-shock-hypothermia swine model.

Key Words: superior mesenteric artery, SMA injury model, damage control surgery, ischemia