Longitudinal analysis of serum intestinal fatty acid-binding protein in a patient with non-occlusive mesenteric ischemia following brachial plexus block-induced hypotension: a case study

Intestinal fatty acid-binding protein (I-FABP) is a promising biomarker for small-bowel ischemia including non-occlusive mesenteric ischemia (NOMI). A 75-year-old woman with diabetic nephropathy sustained a distal radius fracture. Two days later, she underwent a brachial plexus block to facilitate orthopedic surgery, which resulted in hypotension. Despite prompt fluid resuscitation and ephedrine administration, the patient developed abdominal pain. Contrast-enhanced computed tomography revealed hepatic portal venous gas, but no direct evidence of small-bowel ischemia. The gastrointestinal surgery team opted for cautious in-hospital observation overnight. Unfortunately, the patient's condition significantly worsened the following day, prompting an urgent laparotomy. Surgery confirmed ileal segment necrosis, macroscopically characterized by a distinctive geographic pattern. Retrospective analysis of stored serum samples using a human enzyme-linked immunosorbent assay demonstrated that I-FABP levels were moderately elevated (7.2 ng/mL) at the initial outpatient visit for the fracture, peaked (17.9 ng/mL) at the clinical onset of NOMI, and returned to normal (0.7 ng/mL) by postoperative day 2. Serum I-FABP levels correlated with the progression of NOMI, showing potential as an early detection marker. However, the longitudinal analysis of serum I-FABP also highlighted significant challenges of this biomarker, including the influence of renal function and the importance of sampling timing.