Vladimir Premru

The kinetics of myoglobin in severe rhabdomyolysis and dialysis-dependent myoglobinuric acute kidney injury (Mb-AKI) is still not well elucidated, and more detailed knowledge could improve the now empiric use of rapid extracorporeal myoglobin removal by high cut-off (HCO) hemodialysis treatments. Eighteen adult patients with severe dialysis-dependent Mb-AKI (median serum concentration of myoglobin 57.4 mg/L) participated in the prospective clinical study, assessing myoglobin kinetics during HCO hemodiafiltration (HCO HDF). High initial serum concentrations of myoglobin (median 57.4 mg/L), together with protracted myoglobin appearance in the blood, indicated a large accumulation of myoglobin in body fluids. Extra-renal endogenous metabolic myoglobin clearance was delayed, with a slow exponential fall in serum myoglobin (t½ 35 h). A mean myoglobin clearance of 90-94 mL/min, a reduction ratio of 80%, and a rapid exponential fall (t½ 1 h) in serum and dialysate myoglobin were achieved by HCO HDF. Half of the cumulative myoglobin removal was accomplished in 3-5 h, with an additional removal of 7% each hour thereafter. A 2.4-fold rebound in serum myoglobin followed the HCO procedures. Large amounts of myoglobin are released into the circulation, and its endogenous metabolic clearance in dialysis-dependent Mb-AKI is slow. Owing to its rapid and highly efficient myoglobin elimination, HCO HDF may represent a valuable tool in the initial management of severe Mb-AKI, with a potential for earlier application in the future.

Serum creatine kinase (CK) is routinely used as a marker in the assessment of rhabdomyolysis and acute myoglobinuric kidney injury (Mb‐AKI), while the use of myoglobin is much less explored in this respect. We retrospectively analyzed the incidence of Mb‐AKI (creatinine [Cr] > 200 μmol/L) and the need for hemodialysis (HD) in 484 patients (70.5% males) with suspected rhabdomyolysis, grouped according to peak serum myoglobin (A: 1–5 mg/L, B: 5–15 mg/L, C: >15 mg/L). The median peak myoglobin was 7163 μg/L. Both peak Cr and peak CK were significantly higher in group C. The incidence of Mb‐AKI was 24.6% in group A, 38.6% in group B (P < 0.01 vs. group A), and significantly higher (64.9%) in group C (P < 0.001 vs. groups A and B). Fifty‐one patients (10.5%) needed HD, the proportion increasing from 6.7% in group A, and 12.3% in group B (NS), to 28.1% in group C (P < 0.001 vs. group A, P 0.01 vs. group B), and reaching 36.8% with myoglobin >20 mg/L. Creatine kinase correlated with the severity of rhabdomyolysis, but less so with Mb‐AKI. The peak Cr levels were not significantly different between patients divided by CK 60 μkat/L, or grouped into CK tertiles or quartiles. A significant proportion of patients with rhabdomyolysis experienced Mb‐AKI, whose frequency increased in parallel with myoglobin levels. Myoglobin levels above 15 mg/L were most significantly related to the development of AKI and the need for HD. Blood myoglobin could serve as a valuable early predictor and marker of rhabdomyolysis and Mb‐AKI.

Two single-lumen, noncuffed catheters in the same jugular vein have been used as preferred vascular access in our hemodialysis (HD) and apheresis patients in past years. The aim of this retrospective study was to analyze the clinical outcome of such a vascular access and the reasons for catheter removal. In 129 adult patients, aged 69 ± 13 years, 56% males, treated by HD (121 patients) or apheresis (8 patients), two single lumen, pre-curved 8 Fr catheters (Medcomp, Harleysville, PA, USA) inserted into the same jugular vein were used as vascular access between January 2009 and April 2010. The catheters were inserted into the left jugular vein in 21 patients, and into the right jugular vein in 108 patients. A 30% solution of trisodium-citrate was used as a locking solution, and 2% mupirocin ointment was routinely applied to the exit site. The catheters were removed in 86 patients after 1-288 days, median 17.5 days. In 74 patients, there was either no need for further dialysis or an arteriovenous fistula was constructed (17 patients). In 10 patients, wire exchange was performed for correction of a displaced functional catheter (after 6-201 days), and in only two patients the catheters were removed due to infection on days 10 and 184. The longest period of a catheter functioning without intervention was 387 days. Fifteen patients died with functional catheters left in place (duration 1-387 days). In four patients, the catheters were still functional at the time of analysis (duration 198-268 days). Another nine patients were transferred to other dialysis centers (after they had been followed up at our center lasting for 1-63 days), with no data on their outcome after transfer. Fifteen patients were lost to follow up after insertion. Two single-lumen, noncuffed catheters in the same jugular vein, locked with 30% citrate, seem to be a safe and long lasting method of vascular access for hemodialysis and apheresis in some patients, but further prospective studies are needed to evaluate the clinical outcome of this type of vascular access.

The aim of our retrospective study was to present the success of surgical thrombectomy in acutely thrombosed, arteriovenous (AV), expanded polytetrafluoroethylene (ePTFE) grafts. Patients from hemodialysis centers in Slovenia were admitted to our dialysis center after acute thrombosis of their AV graft to undergo surgical thrombectomy under local anesthesia as an outpatient procedure. In 55 chronic hemodialysis patients, of whom 26 were men (47.3%), with a mean age of 63 ± 13 years (range 35-84 years), and diabetes mellitus in 11 patients (20%), 59 ePTFE AV grafts thrombosed. A total of 129 thrombectomies were performed, on average 2.2 ± 2.1 per graft (range 1-13). Primary patency (defined as the time from AV graft creation to first thrombosis) was 638 ± 633 days (range 10-2586, median 418 days), secondary patency (defined as the time from first thrombectomy to abandonment) was 451 ± 472 days (range 0-1994, median 305 days), and cumulative patency (defined as the time from creation to abandonment) was 1089 ± 685 days (range 25-3020, median 1031 days). In 46 (78%) of the AV grafts, the first thrombectomy was successful. The secondary patency rates after 1, 2, 3, 4, and 5 years were 76%, 66%, 54%, 14%, and 14%, respectively (13/59 unsuccessfully thrombectomized grafts were excluded). Cumulative patency after 1, 2, 3, 4, and 5 years was 88.1%, 67.8%, 44.7%, 27.1%, and 16.9%, respectively. In conclusion, surgical thrombectomy after thrombosis of an AV graft in the arm or thigh, performed by interventional nephrologists and followed, if required, by angioplasty, significantly prolonged the patency of the majority of thrombosed AV grafts.

Acute renal failure is a major complication of rhabdomyolysis. New membranes for hemodialysis have been developed with a high cut‐off pore size allowing efficient removal of myoglobin. We report on six patients treated by hemodiafiltration with a high cut‐off membrane (HCO‐HDF) for myoglobinuric acute renal failure. Rhabdomyolysis was caused by infection in two patients, by a statin in one patient and a non‐traumatic crush in another, and followed cardiovascular surgery in two others. Ten HCO‐HDF procedures were performed. A high cut‐off hemofilter was used, with citrate anticoagulation and postdilutional fluid substitution of 2–3 L/h, dialysate flow 500 mL/min, and blood flow within 250–300 mL/min. Albumin losses were replaced by infusion of human albumin solution, and the mean myoglobin reduction ratio was 77% (range, 62–89%). An excellent clearance of 81 mL/min (range 42–131 mL/min) was achieved. Nearly 5 g of myoglobin was removed into the dialysate collected in one of the procedures. A high rebound in serum myoglobin, on average to 244% of the post‐procedure myoglobin level, was observed. The four patients alive at the time remained anuric for a week. Slow myoglobin elimination with a mean half‐time of 39 h (range 19–59 h) was observed in that period. Highly efficient myoglobin removal by high cut‐off membrane hemodiafiltration was demonstrated in our patients. Rapid redistribution from the extracellular fluid and sustained myoglobin release were suggested by the high rebound observed. Elimination of myoglobin within the body was shown in our study to occur slowly during the period of anuria.