Amino acid alterations and encephalopathy in the sepsis syndrome

Objective To evaluate the role of amino acid profiles in septic encephalopathy. Design Retrospective analysis. Setting Medical wards and medical ICU of a university hospital. Patients Patients with infections and normal mental status were compared with patients with septic shock and altered sensorium. Interventions Plasma amino acid levels and Acute Physiology and Chronic Health Evaluation (APACHE II) scores were determined. Measurements and main results Patients with septic shock and altered sensorium had higher circulating concentrations of ammonia (425 +/- 55 vs. 127 +/- 7 mmol/L) and the aromatic amino acids phenylalanine (122 +/- 19 vs. 74 +/- 3 mmol/L) and tryptophan (97 +/- 7 vs. 32 +/- 13 mmol/L), and lower levels of the branch-chain amino acid isoleucine (48 +/- 7 vs. 68 +/- 5 mmol/L) than patients with infections and normal sensorium (p less than .05). Aromatic amino acid levels correlated with APACHE II scores (R2 = .4, p less than .001) and mortality. APACHE II scores were higher in the septic shock patients (30 +/- 2 vs. 8 +/- 1, p less than .001), and these patients had a higher mortality rate (71% vs. 12%, p less than .01). Patients with septic shock who died had higher levels of ammonia (524 +/- 58 vs. 227 +/- 40 mmol/L, p less than .05) and sulfur-containing amino acids (172 +/- 31 vs. 61 +/- 7 mmol/L, p less than .05) than patients who survived. Conclusions Plasma amino acid profiles appear to be important in septic encephalopathy and the severity of septic disease.