Amino acid alterations and encephalopathy in the sepsis syndrome

Abstract

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.