Development of circulatory and metabolic shock following transient portal triad occlusion

Liver ischemia is purposefully induced by portal triad occlusion (PTO) in several clinical situations including liver surgery for trauma, tumor, and transplantation. Despite significant morbidity from PTO, the hemodynamic and metabolic effects of PTO have not been evaluated relative to duration of ischemia. We investigated this using a total hepatic ischemia model. Rats received isoflurane anesthesia, carotid artery and jugular vein cannulation, and serial measurements of cardiac output (CO), mean arterial pressure (MAP), heart rate (HR), central venous pressure (CVP), stroke volume (SV), systemic vascular resistance (SVR), superior mesenteric artery blood flow (SMAF), intestinal vascular resistance (IVR), pH, pCO2, pO2, lactate, glucose, hematocrit (HCT), white blood cell count (WBC), and total neutrophils. Each group received 0, 15, 30, 45, or 60 min of PTO followed by 2 hr of reperfusion. All sham ischemia animals remained hemodynamically stable throughout the study. However, in the ischemic groups, there were significant time-dependent decreases in MAP, HR, CO, CVP, SV, SMAF, and pH, and increases in SVR, IVR, HCT, and lactate, while pCO2, pO2, glucose, and WBC remained stable. All of the ischemic animals survived except those that received 60 min of PTO. In this group, all of the animals survived the ischemic period; however, only one animal survived beyond 60 min of reperfusion. These data demonstrate a time-dependent circulatory and metabolic shock following PTO heralded by intestinal venous pooling and loss of intravascular fluid, and culminating in death. Careful hemodynamic monitoring and restoration of blood volume in the trauma patient may reduce morbidity and mortality.