Biological scoring system for early prediction of acute bowel ischemia after cardiac surgery: the PALM score.

Background: Bowel ischemia is a life-threatening emergency defined as an inadequate vascular perfusion leading to bowel inflammation resulting from impaired colonic/small bowel blood supply. Main issue for physicians regarding bowel ischemia diagnosis lies in the absence of informative and specific clinical or biological signs leading to delayed management, resulting in a poorer prognosis, especially after cardiac surgery. The aim of the present series was to propose a simple scoring system based on biological data for the diagnosis of bowel ischemia.
Methods: In a retrospective monocentric study, patients admitted in cardiac ICU, after cardiovascular surgery, were screened for inclusion. According to a 1:2 ratio (case-control), matching between two groups was based on sex, type of cardiovascular surgery, and the operative period (per month). Patients were divided into two groups: "ischemic group" which corresponds to patients with confirmed bowel ischemia and "non-ischemic group" which corresponds to patients without bowel ischemia. Primary objective was the conception of a scoring system for the diagnosis of bowel ischemia. Secondary objectives were to detail the postoperative morbidity and the diagnostic features for the distinction between acute mesenteric ischemia and ischemic colitis.
Results: Forty-eight patients (1.3%) had confirmed bowel ischemia ("ischemic group"). According to the 2:1 matching, 96 patients were included in the "non-ischemic group." Aspartate aminotransferase > 449 UI/L, lactate > 4 mmol/L, procalcitonin > 4.7 μg/L, and myoglobin > 1882 μg/L were found to be independently associated with bowel ischemia. Based on their respective odds ratios, points were assigned to each item ranging from 4 to 8. AUROCC [95% confidence interval] of the scoring system to diagnose bowel ischemia was 0.93 [0.91-0.95], p < 0.001. The optimal threshold after bootstrapping was ≥ 14 points; this yielded a sensitivity of 85.4%, a specificity of 94.8%, a positive likelihood ratio of 16.42, a negative likelihood ratio of 0.15, a Youden's index of 0.802, and a diagnostic odds ratio of 106.62.
Conclusions: A biological scoring system based on PCT, ASAT, lactate, and myoglobin measurement allows the diagnosis of bowel ischemia after cardiac surgery with high accuracy. This score could help clinician to propose an early diagnosis and an early treatment in this high mortality disease.