Eliminating Cross Contamination from Intravenous Cyclosporine and Tacrolimus and Accurate Blood Sampling

Cyclosporine and tacrolimus given intravenously bind to the venous access device (VAD) used for infusion, and if sampled from the same site result in false high levels. Central VAD lumen contamination in a patient with sub-therapeutic levels of tacrolimus prompted the nursing staff to investigate infusion and blood sampling practices.  Details on both the infusion and blood sampling for all inpatients receiving intravenous (IV) cyclosporine and tacrolimus on the adult transplant unit were documented in the electronic medical record. The names of both nurses confirming at the bedside correct connection of the labeled IV tubing to the dedicated, labeled lumen were recorded.  For both infusions and blood sampling for trough levels the VAD and lumen color were documented. 

 Accidental contamination was defined as a drug infusing incorrectly through a lumen that was not dedicated and labeled on the VAD.  Over a period of five months, eleven patients received intravenous infusions of cyclosporine and nine patients received intravenous tacrolimus.  There were no accidental contaminations during this period. Despite no accidental contaminations, blood sampling results from non-dedicated lumens of central VADs for patients receiving tacrolimus were elevated when compared to results obtained peripherally. These patients had blood trough levels obtained through central and peripheral routes for comparison weekly.  All patients had elevated levels of tacrolimus from the non-infusion lumen(s) of the central VAD despite documentation confirming that the drug had been infused through the dedicated lumen and levels were obtained correctly.  This was not the case for any of the 11 patients receiving cyclosporine. 

 A review of the literature reveals similar results, based on studies of cyclosporine and tacrolimus levels obtained from both central and peripheral sources, showing cross contamination of lumens within the same VAD for patients receiving tacrolimus but none for cyclosporine. Possible reasons for cross contamination are reported as being due to the properties of tacrolimus or cross contamination of the drug at the exit site of the distal end of individual lumens.

 Nursing practice has not changed with regards to patients receiving intravenous cyclosporine.  A change in practice for patients receiving tacrolimus infusions was made standardizing the use of the distal lumen of a staggered VAD as dedicated for infusion.  Evidence suggests that incompatible drugs do not precipitate if infused through staggered lumens as the drugs do not have time to mix at the exit site. Since this change in practice, no cross contamination with tacrolimus has occurred.  This option allows patients to avoid peripheral venipuncture.  Other centers may consider this for their patients if they also find that use of staggered lines yield consistently reliable levels.