Systems and methods suitable for extracorporeal lung support are provided that expose blood, across a semipermeable membrane, to a dialysis liquid. The dialysis liquid features a buffering agent and has a high buffering capacity for H+ ions. Carbon dioxide, bicarbonate and hydrogen cations are transported across a semipermeable membrane into the dialysis liquid. The dialysis fluid may be recycled and repeatedly used, and its pH may be adjusted, and other fluids added to it. Certain substances may be removed from the blood, and the amount of these substances removed from the blood may be substantially automatically or substantially continuously monitored or quantified. The systems and methods are suitable for treating or preventing respiratory acidosis, metabolic acidosis, and diseases featuring lung malfunction, kidney malfunction, or liver malfunction.
