LAUSR

A 7-month-old, 7 kg girl was admitted to the intensive care unit with kidney failure following a short illness. She was initially commenced on peritoneal dialysis (PD), with the addition of haemodialysis following a genetic diagnosis of primary hyperoxaluria. A Medcomp 8 Fr × 18 cm Hemo-Cath (REF SL 18P) was inserted into her right internal jugular vein (IJV) and was cut 1.5 cm from the tip to allow placement of the subcutaneous cuffs under the skin. The catheter tip position was confirmed on image intensifier to be at the cavoatrial junction, both lumens aspirated and flushed well, and each lumen was locked with heparin according to hospital guidelines [1]. The day following insertion, both lumens were difficult to aspirate and required high pressure on flushing, despite attempts at repositioning the patient and administration of tissue plasminogen activator (tPA). X-ray revealed the catheter tip projected over the mid superior vena cava, suggesting there had been retraction of the catheter (Fig. 1a). The catheter flows were unsuitable for haemodialysis and the patient returned to theatre the following day for revision of the line. After confirming a kink at the neck entry point, the catheter was repositioned. Both lumens were flushing and aspirating well intra-operatively, and this was also confirmed when the patient’s neck and body position were manoeuvred intra-operatively. The patient attended her first haemodialysis session immediately following the procedure and tolerated a successful 2 hr treatment. Of note, the arterial lumen was initially unable to be aspirated and required high pressure to flush; however, this improved with repositioning the patient with her right arm down. Issues with the arterial lumen of the permacath continued on subsequent haemodialysis sessions, with difficulty aspirating and poor blood flow rates due to elevated venous return pressure. The venous lumen continued to function well. Eleven days after insertion, x-ray showed inferior migration of the catheter tip within the right atrium (Fig. 1b). The next haemodialysis session was terminated early due to high venous return pressures (> 200 mmHg) and suboptimal maximal blood flow (30 mL/min). tPA was instilled according to hospital guidelines without satisfactory improvement. A maximal blood flow rate of 50 mL/min was able to be achieved; however, return pressures remained excessive (250 mmHg). The catheter was replaced with a Medcomp 10 Fr × 15 cm Split Cath (REF ASPC 15P-XL) inserted into the right IJV via a new incision slightly medial to the previous incision. A larger calibre, shorter catheter was chosen to allow higher flow rates and avoid migration of the catheter tip. The position was confirmed by image intensifier and both lumens were flushing and aspirating well in the operating theatre. Immediately after placement of the catheter, haemodialysis was attempted, but the arterial lumen was unable to be aspirated despite flushing well, and the child was in obvious pain. A contrast study demonstrated contrast appearing to escape the line from multiple sites into the surrounding tissue (Fig. 1c). The catheter was immediately The answers to these questions can be found at https://doi.org/10.1007/ s00467-020-04728-8.