Bicarbonate and Lipocalin in Systemic Inflammatory Response Syndrome (SIRS) Study

Inclusion Criteria: * Consent obtained * Diagnosis of SIRS. Requires any TWO of: temperature \> 38°C or \< 36°C OR heart rate \> 90 beats/min OR respiratory rate \> 20 breaths/min. PaCO2 \< 32 mm Hg OR alteration of white blood cell count \> 12,000 cells/mm3, \< 4,000 cells/mm3, or the presence of \> 10% immature neutrophils * elevated lipocalin level * Arterial line already in place * Central venous catheter already in place * Age ≥ 18 years * Within 24 hours of admission to the ICU Exclusion Criteria: * Unlikely to remain in ICU for \>72 hours * Moribund patient * Pre-existing CKD, transplant or ESRD * Receiving (or about to receive) continuous renal replacement therapy for acute renal failure at time of enrolment * Diagnosis of acute GN, AIN, vasculitis or post-renal aetiology * Known/suspected study allergy to sodium bicarbonate * Enrolling physician concern about patient enrolment