Objective: To compare biochemical changes in the blood and urine in the early phase of an experimental model of sepsis. Design: Experimental, prospective trial. Setting: ICU of the 1st Medical Department, Charles University, Medical School and Teaching Hospital Plzeň, Czech Republic. Department of Anaesthesia and Intensive Care, St. Anns University Hospital Brno, Czech Republic. Materials and methods: Twelve pigs weighing 24 kg (18; 30) were studied for 12 hrs after the induction of experimental G-negative volume-resuscitated sepsis. The sepsis was induced with a continuous live Pseudomonas aeruginosa i.v. infusion. Within the scope of the originál protocol aimed at researching the role of NO and oxidative stress on the splanchnic perfusion and metabolism, the haemodynamic parameters and diuresis were monitored in hourly intervals. At time points To, T2,T6 and T12 a biochemical analysis of the blood and urine was performed. The blood analysis comprised the acid-base status, blood gases, electrolytes, lactate and creatinine. The urine analysis included the pH, sodium, potassium, creatinine and osmolality measurements. Results: Development of metabolic acidosis (present at T2) lead to a significant drop in the urinary pH from 6.2 (5.0;8.0) to 5.5 (5.0;7.2). Sepsis caused sodium and potasssium retention, the sodium/potassium ratio changed randomly. Osmolality of the urine decreased significantly from 664 (489:811) mmol . kg-1 to 338 (167;625) mmol. kg1. Conclusion: Experimental G-negative sepsis lead to a decrease in the blood pH followed by a decrease in the urinary pH within a few hours. The clinical relevance of these early changes warrants further evaluation.

        Key words: sepsis - metabolic acidosis - urinary pH