The collection of peripheral blood stem cells (PBSC) from two paediatric patients weighing under 10 kg on the Cobe Spectra v-6

Two children with Stage IV neuroblastoma received the Kushner protocol and Lenograstim 5 mcg/kg/day from Day 5 until completion of collections. Child 1, female, was collected after cycle 6, at 27 months old, weighing 9.2 kg and 80 cm in height. The second child, male, was collected after cycle 4, at 19 months old, 10 kg and 80 cm in height. All procedures were performed on the Cobe Spectra cell separator using ABO compatible packed red cells to prime the machine. Venous access was achieved via 11F Vascaths that were inserted under general anaesthetic. The first collection used the autoPBSC program but, due to an inability to satisfactorily correct a very low interface, all subsequent procedures were performed on the MNC program. We used 80 ml/kg to calculate their total blood volume (TBV) as the Cobe Spectra uses an adult algorthium that is less accurate for paediatric cases. We aimed to process 3–4 TBV, the inlet flow rate was 2 ml/kg, the collect rate 0.8 ml/min, with a total collect volume between 10% and 12% of TBV. Both children were supported during the procedure with calcium chloride infusions to prevent citrate toxicity. The Cobe Spectra requires an AC pump speed of greater than 1 ml/min for continuous adequate anti-coagulation. After programming the Cobe Spectra with the patient data and setting the AC:Inlet at 25:1, the AC flow rate was less than the required 1 ml/min. To overcome this problem, heparin was administered as a loading dose of 75 units/kg 30 min prior to procedure commencement and then followed by a low dose heparin infusion 10–15 units/kg/h (500 units/kg in 50 ml at 1 ml/h). Collections commenced when white cell count was greater than 4×109/l (Day post Chemotherapy Day 15 [Child 1], Day 17 [Child 2]). Sedation was not required and procedures were well tolerated. The median procedure time was 135 min (130–150) with a median TBVs processed of 3.3 (3–3.47). Target CD34 was 2–3×106/kg based on current weight. Collection results are shown in Table 1.