Acid-base homeostasis during hemodialysis: New insights into the mystery of bicarbonate disappearance during treatment.

Acid-base homeostasis during hemodialysis: New insights into the mystery of bicarbonate disappearance during treatment. Semin Dial. 2018 May 29;: Authors: Sargent JA, Marano M, Marano S, Gennari FJ Abstract In patients receiving hemodialysis, it has long been recognized that much more bicarbonate is delivered during treatment than ultimately appears in the blood. To gain insight into this mystery, we developed a model that allows a quantitative analysis of the patient's response to rapid alkalinization during hemodialysis. Our model is unique in that it is based on the distribution of bicarbonate in the extracellular fluid and assesses its removal from this compartment by mobilization of protons (H+ ) from buffers and other sources. The model was used to analyze the pattern of rise in blood bicarbonate concentration ([HCO3- ]), calculated from measurements of pH and PCO2 , in patients receiving standard bicarbonate hemodialysis. Model analysis demonstrated two striking findings: (1) 35% of the bicarbonate added during hemodialysis was due to influx and metabolism of acetate, despite its low concentration in the bath solution, because of the rapidly collapsing gradient for bicarbonate influx. (2) Almost 90% of the bicarbonate delivered to the patients was neutralized by H+ generation. Virtually all the new H+ came from intracellular sources and included both buffering and organic acid production. The small amount of added bicarbonate ...
Source: Seminars in Dialysis - Category: Urology & Nephrology Authors: Tags: Semin Dial Source Type: research