Intraerythrocytic pH variations during hemodialysis: a 31P NMR study

Before hemodialysis, patients have an intraerythrocytic pH (pHi) and an extracellular pH, measured in whole blood (pHo), which are lower than those of healthy controls. During bicarbonate hemodialysis, pHi values continuously increase, approaching a normal value at the end of the session. Concomitantly, pHo values follow similar variations. During acetate hemodialysis, pHi values exhibit a steep initial decrease, reaching a minimum after about 15 minutes. Concurrently, however, pHo values decrease only slightly. This phenomenon seems to originate in the intraerythrocytic medium and might be due to a shift in intracellular CO2/bicarbonate equilibrium. This drop in pHi exhibits interpatient variability, suggesting that the magnitude of pH decrease would be correlated with the degree of the problems observed in some patients undergoing acetate hemodialysis.