Background: Plasma markers for intestinal ischemia have not proven to be accurate. The value of L-lactate is unclear. Experimental models based on open surgery confound the effects of surgical trauma with that of ischemia. The aim was to create an endovascular model for acute superior mesenteric artery thromboembolism, and then to study L-lactate and lactate dehydrogenase (LD) activity in plasma and peritoneal fluid in pigs with extensive, high-grade intestinal ischemia.
Materials and methods: Nine pigs underwent full superior mesenteric artery embolization with 4 h of intended intestinal ischemia, whereas six were control animals. Sampling of central venous and arterial blood was performed throughout the experiment, ending with laparotomy to collect peritoneal fluid and segmental intestinal biopsies. A pathologist, blinded to the performed interventions, graded the ischemic lesions.
Results: There were no differences in plasma L-lactate (P = 0.61) or LD activity levels (P = 0.69), measured at different time points from baseline to end of study, between animals with extensive, high-grade intestinal ischemia and sham. Intraperitoneal L-Lactate (P = 0.005) and LD activity (P = 0.018) levels were elevated compared with sham. There were differences in grades of ischemia in the duodenum (P = 0.003), small intestine (P < 0.001), proximal (P < 0.001), and sigmoid (P = 0.032) colon between experimental animals and sham. The grade of small bowel ischemia (n = 15) correlated to intraperitoneal fluid L-lactate (r = 0.80; P < 0.001) and LD activity levels (r = 0.72; P = 0.003).
Conclusions: This endovascular study in a porcine model showed that L-lactate and LD activity levels in peritoneal fluid, not in plasma, reflect intestinal ischemia. The study suggests that plasma L-lactate not is a useful early marker in patients with suspicion of intestinal ischemia.