Study procedures
Subjects were connected to basic vital signs monitoring (Philips IntelliVue MP70; Philips, Eindhoven, The Netherlands), i.e. pulse-oximetry, ECG, and oscillometric blood pressure. Vital signs were continuously recorded in the electronic patient record (Epic; Epic System Corporation, USA). A 20G arterial catheter was placed in the radial artery of the non-dominant hand under local anaesthesia. An interventional radiologist placed a venous access sheath in the femoral vein (with the tip of the catheter located in the distal iliac vein) under local anaesthesia. Another catheter was inserted via the sheath with the tip in the renal vein, and the position was verified with contrast medium and fluoroscopy. O3