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 < .05). Aromatic amino acid levels correlated with APACHE II scores (r² = .4, p < .001) and mortality. APACHE II scores were higher in the septic shock patients (30 ± 2 vs. 8 ± 1, p < .001), and these patients had a higher mortality rate (71% vs. 12%, p < .01). Patients with septic shock who died had higher levels of ammonia (524 ± 58 vs. 227 ± 40 mmol/L, p < .05) and sulfur-containing amino acids (172 ± 31 vs. 61 ± 7 mmol/L, p < .05) than patients who survived. Conclusions: Plasma amino acid profiles appear to be important in septic encephalopathy and the severity of septic disease.