Investigation of Fluid- and Electrolyte Balance in Post Cardiac-surgery Patients

Critically ill patients need intravenous fluid therapy in order to correct or prevent problems with their fluid and/or electrolyte status and for renal protection. The decision for the optimal composition and amount of IV-fluids can be difficult and complex. It is well known that errors in fluid- and electrolyte management contribute to overall morbidity and mortality. For decades, urinary sodium was used to diagnose renal disease. Nevertheless, renal excretion of sodium is largely impaired in critically ill patients, particularly in patients with acute kidney injury. Due to the high frequent measurement of renal output, it would be possible to measure the urinary electrolytes and its relative changes. Urinary electrolyte measurement may alert for the presence of the development of an akute kidney injury before occurring increases in creatinine or oliguria. The rationale of this investigation is therefore to collect data related to fluid- and electrolyte management from critically ill patients in order to find patterns of fluid- and electrolyte imbalances which may lead to disturbances and further, may allow an early detection of acute kidney injury.