Thursday, May 17, 2018

Hemodialysis failure due to Hydroxocobalamin


Hydroxocobalamin is an antidote that was recently approved by the FDA in 2006 for the treatment of cyanide poisoning. For decades, cyanide poisoning has historically been treated using the cyanide antidote kit that contained a concoction of amyl nitrite, sodium nitrite and sodium thiosulfate. The problem with this antidote kit is that it can lead to hypotension and reduced oxygen-carrying capacity. In contrast, hydroxocobalamin does not cause these complications and therefore has become more widely used for suspected cyanide intoxication. 
We encountered a case of a young man who was found unresponsive and profoundly hypotensive. On arrival to the emergency room, he was in extremis with significant agonal breathing. His GCS was 3, he was hypothermic and hypotensive. He had AKI (creatinine 1.3mg/dl) and a severe anion gap metabolic acidosis (lactate >20). A bedside echocardiogram showed severely diminished cardiac function. Blood and urine toxicology screen were negative. Cyanide poisoning was suspected and as a result, he was given iv hydroxocobalamin.
Over the next few hours, he had an increasing pressor requirement and the decision was made to start dialysis to treat his acidosis and potentially remove any ingested toxins.
Hemodialysis was initiated emergently using a Fresenius 2008K machine, however this was confounded by a recurrent “blood leak alarm” that repeatedly shut down the machine despite there being no evidence of a leak occurring. After multiple trials to initiate hemodialysis with replacement of the dialyzer and the machine, this was aborted with plans to initiate CVVH.
Hydroxocobalamin causes an orange/red discoloration of bodily fluids and can permeate dialysate. This can lead to dialysis failure due to defraction of light from discolored dialysate, resulting in triggering of the blood leak sensor in certain hemodialysis machines. The case highlights the need for an awareness of hydroxocobalamin effects in hemodialysis and its potential to delay initiation of emergent dialysis in critically-ill patients.
More information on the case can be found here.
Posted by Kenneth Lim

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