The usefulness of plasma levels of mature and total adrenomedullin as biomarkers indicating the magnitude of surgical stress responses: A single-center, prospective, observational study

Background and aim: Adrenomedullin (AM), a vasodilatory peptide, is known for its pleiotropic actions. AM levels are increased under inflammatory conditions such as sepsis and can be useful as a prognostic biomarker. However, there are only a few reports on the physiological actions of AM in the perioperative period. The aim of this single-center, prospective, observational study was to investigate the changes in the plasma levels of mature AM (mAM) and total AM (tAM) observed during the perioperative period. Additionally, we aimed to determine the association between each AM level and immune-inflammatory parameters to explore the usefulness of AM as a biomarker of the magnitude of surgical stress responses. Methods: The levels of both mAM and tAM, in addition to the levels of presepsin, interleukin-6, procalcitonin, white blood cell, and C-reactive protein, were measured in blood samples obtained during the perioperative period. Other laboratory data, including sequential organ failure assessment (SOFA) and acute physiology and chronic health evaluation (APACHE) II scores, were obtained from individual clinical records. Correlations between each AM and clinical parameters were determined using Spearman's rank correlation. P-values < 0.05 were considered statistically significant. Results: One-hundred and twenty-three perioperative patients scheduled for three types of surgical procedures, including cardiopulmonary bypass surgery, abdominal surgery, and cervical laminoplasty, were included in this study. There was a moderate to strong correlation between each AM and immune-inflammatory parameters, SOFA score, and APACHE II score, as related to surgical trauma. Specifically, the strongest correlation was observed between each AM and SOFA score. Conclusions: These findings suggest that plasma AM levels may represent the most important inflammatory mediators that are evident in surgical stress responses. Relevance for patients: Since the levels of both tAM and mAM show the same trend, mAM and tAM may be equally used as biomarkers for the evaluation of the physiological status of surgical patients. Trial registration: This observational study was retrospectively registered with Japanese Clinical Trial Registry “UMIN-CTR” on March 19, 2018, and was given a trial ID number UMIN000031792.