Continuous urine oxygen tension monitoring in patients undergoing cardiac surgery

To evaluate the effect of cardiopulmonary bypass (CPB) on urine oxygen tension (PuO2) and to determine whether perioperative PuO2 can predict postoperative renal dysfunction in patients undergoing cardiac surgery.Prospective clinical study.A university research laboratory, a university-affiliated hospital.Ninety-eight consecutive adult patients undergoing coronary artery bypass surgery or valvular surgery.PuO2 was continuously measured by inserting a polarographic electrode into the urinary tube connected to a Foley catheter.PuO2 was constant before CPB and then progressively decreased after the start of CPB. It partially recovered at weaning from CPB but did not completely return to its original level until the end of surgery. Postoperative serum creatinine concentrations were significantly higher in patients whose PuO2 decreased after CPB, as compared with those whose PuO2 was constant or increased. The amplitude and the rate of recovery in PuO2 after CPB were significantly associated with peak values of postoperative serum creatinine concentrations.These results suggest the possibility of PuO2 detecting an early stage of renal dysfunction in cardiac surgery, although further studies will be required to substantiate it.