[Diuresis as an index of the circulatory status during open-heart operations]

An intra-operative investigation of 24 patients showed glomerular filtration (GF) to be closely related to the state of systemic circulation. In cardiosurgical patients, GF is fairly accurate indicator of renal flow and microcirculation of the kidney. Without extracorporeal circulation (EC), decreased GF was associated with the presence of conditions resulting in reduced cardiac output, in spite of satisfactory arterial and central venous blood pressure values, and during EC, it was accompanied by hypotension even in the presence of high volumetric perfusion rate. An anesthesia retaining a fairly stable minute volume of heart does not result in any noticeable GF decrease. There is correlation between diuresis and CF at any stage of the operation, weak as it may be due to variations in water reabsorption. A sharp reduction in water reabsorption occurs during and after EC, with polyuria developing even in the presence of low CF and gross circulatory disorders. Therefore, in operations under EC, high rates of diuresis do not reflect the state of circulation. General assessment of the circulatory status and water reabsorption changes should be considered as well.