Dialysate with High Partial Pressure of Oxygen Enhances Oxygenation in Blood during Simulated Circulation of Hemodialysis

摘要

Peripheral artery disease (PAD) is an important marker of systemic atherosclerosis, and often leads to significant morbidity and mortality, particularly in patients with end-stage renal disease. Hyperbaric oxygen therapy (HBOT) increases tissue oxygenation by administering 100% oxygen at greater than one atmosphere pressure, and has beneficial effects on hypoxic wound healing in patients with PAD. We hypothesized that increasing partial pressure of oxygen (PO_(2)) in the blood stream during hemodialysis (HD) improves the hypoxic tissue by a different mechanism from that of HBOT. We developed a device to enhance PO_(2) content in the dialysate. This study examined the effects of a commercially available dialysate and a high PO_(2) dialysate on PO_(2) in blood during simulated circulation in hemodialysis (HD). Batches of 1000 ml of bovine blood were prepared. We conducted HD for 120 min at a flow rate in blood pump of 200 ml/min and dialysate flow rate of 500 ml/min. KINDALY AF-2 containing bicarbonate was used as dialysate. All the experiments were performed at 310 K. Dialysate with high PO_(2) content was made using a gas compressor that increased PO_(2) in the dialysate up to 300 mmHg after deaeration. The gas compressor was installed between the reverse osmosis (RO) water line and the dialysis machine. We conducted HD by circulating bovine blood using either the conventional dialysate as control or the high PO_(2) dialysate. Blood samples were collected from both the inlet and outlet of the dialyzer during HD, and pH, PO_(2), PCO_(2), HCO_(3)~(-) and O_(2) saturation were determined. PO_(2) in blood and conventional dialysate were 42.0 mmHg and 145 mmHg, respectively, before circulation. PO_(2) was always higher at the outlet than at the inlet of the dialyzer after circulation started. With conventional dialysate, PO_(2) in blood sample increased gradually for the first 30 min after starting the experiment and then reached a plateau at 100 to 120 mmHg. With high PO_(2) dialysate, PO_(2) showed a plateau of 240 to 260 mmHg after increasing sharply for the first 30 min, and the values were higher compared to conventional dialysate. From these results, we speculate that conventional buffer dialysate transfers oxygen from the dialysate to the blood stream, and dialysate with high PO_(2) content enhances oxygenation of blood during HD. This system is a promising method to transport high PO_(2) to peripheral tissues leading to improvement of PAD.