The Effect of Short Term Dialysis Catheter Position on Dialyser Lifespan. Unblinded, randomised, controlled trial to assess the effect of placing the proximal tip placement of a short term dialysis catheters on continuous renal replacement (CRRT) circuit lifespan in intensive care unit (ICU) patients with severe acute kidney injury (AKI).

All patients will receive an Edwards Lifesciences silicone double lumen 13.5F short-term dialysis catheter (STDC) (manufactured by Medical Components, Harleysville, PA, USA). The Edwards Lifesciences STDC is designed with a proximal return lumen and three return side ports lying within 3 cm of the proximal tip. There are four arterial side ports that lie within 3.5cm and 6 cm distal of the proximal end. In this study, patients will be randomized to receive either a shorter length STDC [15 cm if placed through the right great thoracic vein(GTV) and 20cm if placed through the left GTV] aiming at placing the tip of the STDC in the SVC or a longer length STDC [20 cm if placed in the right GTV and 24cm if placed in the left GTV] aiming at placing the tip of the STDC in the proximal right atrium (RA). The full length of the STDC will be placed inside the GTV by securing the hub of the STDC against the skin at the insertion site. Because the STDCs are labelled clearly with its length at the distal hub of the catheters it was impossible to blind treating clinicians in this study. Other than the length and depth of the STDC placement, the treating physicians were responsible for all other aspects of the continuos renal replacement therapy [CRRT] and clinical care, including when to initiate and cease CRRT, escalation of anticoagulation during CRRT including the use of systemic anticoagulation or citrate dialysis if dialyzer lifespan was judged to be unacceptably short, and whether a change in STDC was necessary due to vascular access problem or catheter-related infection. Dialysis data will be collected from the bedside nursing chart for the duration of the CRRT (if less than 10 days) or until a maximum of 10 days after the initiation of CRRT. Dialysis data was no longer collected if the patient meet one of the exclusion criteria. Exclusion criteria include the use of systematic anticoagulation or citrate dialysis, the placement of the STDC in the femoral vein or requirement of a tunnelled long-term dialysis catheter. Patients requiring a change in STDC due to suspected catheter-related infection or vascular access problem would receive a STDC with its proximal tip targeted at the same position according to their initial randomization status and remain in the study until they reach an above endpoint. Therefore some patients will require more than one intervention. Data about complications from placing the STDC will be collected for the duration that the STDC remains insitu regardless of whether the patient is receiving CRRT, intermittent haemodialysis or no renal replacement therapy. All patients receive a portable CXR following the insertion of a STDC. Two thoracic radiologists, who are blinded to the randomization status of the patients, will reported the position of the proximal tip of each patient and this report was not available to the treating physicians.