A 62 year old woman is in the ICU with septic shock and GI bleeding. She develops acute renal failure and is started on continous veno-venous hemodialysis (CVVHD) with regional citrate anticoagulation. Blood flow rate is 100 cc/min and dialysate flow rate is 2000 ml/hour. The bicarbonate rises to 36 mmol/L, forcing the respiratory therapist to hypoventilate the patient in order to normalize the serum pH.
How would you lower the serum HCO3 concentration? Why does this work?
(HINT: use the words “hemofiltration” and “convection” in your answer)