Identification of serological markers for pre- and postoperative fasting periods

Summary Background & aims Prolonged preoperative fasting periods lead to catabolic states and decelerate recovery after surgery. Valid plasma markers reflecting the patients‘ metabolic state may improve tailored nutrition support before surgery. Within this study, we sought to advance the knowledge on fasting time-sensitive plasma markers that allow the metabolic characterisation of surgical patients for an optimised preoperative metabolic preparation. Methods Patients scheduled for elective surgery of the upper (n = 23) or lower (n = 27) gastrointestinal tract participated in a prospective observational study. Patients‘ charateristics and nutritional status were recorded and blood samples were drawn on the day of admission. Further blood samples were collected before skin incision of the surgical procedure, on postoperative day 3 and on the day of discharge. Values of clinical chemistry, electrolytes, hemograms and plasma amino acids were determined and correlated with fasting times. Results Preoperative fasting times were positively correlated with plasma levels of valine, leucine, serine, α-amino butyric acid, free fatty acids, 3-hydroxy butyric acid and significantly negative correlated with chloride and glutamic acid. Postoperative fasting times were correlated with erythrocytes, leukocytes and plasma levels of albumin, CRP, HDL, asparagine and 3-methylhistidine. The multivariate regression analysis revealed glutamic acid and valine as significant independent predictors of preoperative fasting periods. The regression model showed best performance (sensitivity of 90.91% and specificity of 92.31%) to detect patients fasted for ≥20 h. Conclusion Valine and glutamic acid appear as independent metabolic markers for accurate prediction of prolonged fasting periods, independent of the overall nutritional status, age or BMI of patients.