Large volume leukapheresis for peripheral blood stem cell collection in children under 10thinspkg in weight
Large volume leukapheresis for peripheral blood stem cell collection in children under 10 kg in weight
I Martin1, A Albert2, I Alcorta1, J Estella1, S Rives1, T Toll1 and E Tuset1
1Services of Hematology Hospital Sant Joan de D Passeig Sant Joan de D 08950 Espluges, Spain2Services of Surgery, Hospital Sant Joan de D Passeig Sant Joan de D 08950 Esplugues, SpainReceived 22 July 2002; Accepted 22 August 2002.
Peripheral blood stem cell (PBSC) collection in children under 10 kg in weight is certainly a technical challenge. The main concerns for apheresis in these patients are citrate toxicity, high extracorporeal volume, vascular access and patient’s tolerance. This highlights the importance of a recent paper,1 which provides an alternative to apheresis, although it appears limited to very good mobilizers.
The main problem in our opinion is vascular access. At our institution, we insert a central line under general anesthesia in the operating room. We use a 10 F double lumen catheter (PermCath, Palex SA) which is placed at the right atrium entrance through a cutdown in the internal jugular vein. The jugular vein is preserved and hemorrhage around the catheter is prevented by a vascular purse string suture closing the vein opening around the catheter. The apheresis catheter is brought out through a separate skin incision leaving a subcutaneous tunnel. Fixation in place is accomplished by a subcutaneous foam cuff built in the catheter and a skin stitch holding the exterior end to the head skin in a comfortable position. A soft elastic head band holds the double line end from pulling during sudden head movements. This catheter is maintained after apheresis, throughout the transplantation procedure.
To avoid citrate toxicity we maintain an ACD infusion rate of 0.9 ml/min/l of blood volume (BV). Using a standard 12:1 ACD ratio the access flow would be 10.8 ml/min/l of BV. For a patient with a blood volume of 500 ml, as reported by Koristek,1 the access flow would be 5.4 ml/min. To move this flow in the range of 10 ml/min recommended by the manufacturer we reduce the ACD ratio to 24:1. After processing 3 BVs we reduce the ACD ratio to 30:1. To avoid coagulation of the circuit we add heparin (3000 IU/500 ml ACD A) to the anticoagulant bag resulting in a heparin infusion rate of 5.4 IU/min/l of BV (2.7 IU/min in a patient with 500 ml blood volume). Also, we add 5 ml ACD A aseptically to the collection bag to prevent aggregation or coagulation of the product.
The extracorporeal volume of the circuit is approximately 165 ml. To avoid hypovolemia and anemia, at the beginning of the procedure we prime the circuit with reconstituted irradiated and leukodepleted whole blood. The reconstituted blood is prepared at a hematocrit equal to that of the patient and after initial saline priming the procedure is begun by aspiratin christian louboutin outlet g the blood from the blood unit, which is allowed to reach the return line. The procedure is then paused, access and return lines are connected to the patient and the apheresis is then continued aspirating blood from the patient.
Tolerance of children to the tedious and prolonged procedure is good if a comfortable atmosphere is created: in our apheresis unit they are accompanied by their parents, watching TV or a video christian louboutin outlet film, playing with their toys or just sleeping.
Using this approach we have recently performed large volume leukapheresis in three patients under 10 kg. Age, weight, diagnoses, preapheresis WBC and CD34 values and CD34 cells collected are shown in Table 1. The procedures were well tolerated wi christian louboutin outlet th no adverse effects.
In summary, large volume leukapheresis in patients under 10 kg can be safely a christian louboutin outlet nd effectively performed with the COBE Spectra AutoPBSC with minimal technical difficulties.