For this reason, water used in hemodialysis is carefully purified before use. Initially, it is filtered and temperature-adjusted and its pH is corrected by adding an acid or base. Chemical buffers such as bicarbonate and lactate can alternatively be added to regulate the pH of the dialysate. Both buffers can stabilise the pH of the solution at a physiological level with no negative impacts on the patient. There is some evidence of a reduction in the incidence of heart and blood problems and high blood pressure events when using bicarbonate as the pH buffer compared to lactate. However, the mortality rates after using both buffers do not show a significative difference.