Hydroxycobalamin-induced pigmented effluent during dialysis

A 51-year-old female patient with end-stage renal disease required continuous renal replacement therapy after successful treatment with hydroxycobalamin for vasoplegic syndrome after cardiac surgery. Multiple attempts at intermittent hemodialysis were technically problematic and unsafe because hydroxycobalamin triggered the blood leak detector on the 2008K Hemodialysis Machine (Fresenius Medical Care, Bad Homburg, Germany; Figure 1). Hemolysis blood tests were normal. Vasoplegic syndrome is a life-threatening complication of cardiac bypass surgery and can affect up to 30% of heart failure patients undergoing cardiovascular surgery. It is an off-label indication for hydroxycobalamin, which is a potent direct inhibitor of both nitric oxide and nitric oxide synthase. Hydroxycobalamin also inhibits soluble guanylate cyclase and increases elimination of innate hydrogen sulfide. Side effects include lymphocytopenia, nephrolithiasis with oxalate nephropathy, and chromaturia. There are no known contraindications. Consideration should be given to using a dialysis machine from a different manufacturer if available. For example, both Gambro Phoenix X36 (Baxter Healthcare Corporation, Deerfield, IL) and NxStage (Lawrence, MA) dialysis machines are unaffected by dialysate discoloration due to hydroxocobalamin. To ensure patient safety during continuous renal replacement therapy after hydroxycobalamin administration, cell counts from the effluent can be monitored regularly to assess for a true blood leak.