Arterio-venous differences in glutamate concentration predict clinical outcomes in acute respiratory distress syndrome

Abstract Background We aimed to explore whether the arterio-venous (A-V) differences in amino acids are useful for diagnosing and predicting acute respiratory distress syndrome (ARDS) outcomes, thereby guiding clinical therapy. The enrolled subjects included 36 adult patients with ARDS admitted in the intensive care unit (ICU) and 38 age- and sex-matched controls. Patients with ARDS were further divided into mild, moderate, and severe categories, and into survivor and non-survivor subgroups. Serum samples from the radial artery and jugular vein were collected on the first day following ICU admission, and the serum concentrations of 15 amino acids from the arterial and venous blood were measured by high performance liquid chromatography (HPLC) on the LC-10DVP system. Results We found that the arteriovenous (A-V) differences in glutamate (Glu) concentration in patients with ARDS were significantly greater than those in controls. Although no significant A-V differences were found in other amino acids between controls and patients with ARDS, surprisingly, survivors showed greater A-V differences in Glu concentration than non-survivors. Particularly, non-survivors who died within 2 weeks following ICU admission showed significantly less A-V differences in Glu concentration compared to those of survivors. Conclusions A-V differences in Glu concentration may be a biological marker for ARDS, with a significant association with mortality.