An overview of therapeutic apheresis in pediatrics

Therapeutic apheresis in pediatrics requires selected modifications due to the child's smaller size, blood volume, and developmental age. Red blood cell priming is used to prevent dilution of the child's hematocrit from the normal saline prime. Continuous flow cell separators maintain isovolemia. Discontinuous flow machines cause alterations in the blood volume which may be poorly tolerated by small and critically ill children. Whole blood volumes are calculated on 100 cc/kg for newborns and 70 cc/kg for toddlers and children. Although peripheral access may be used in older children, the majority of pediatric patients require central venous lines preferably the stiffer apheresis or dialysis double lumen catheters. Anticoagulants include heparin, anticoagulant citrate dextrose (ACD), or a combination of both. The heparin dose is titrated to achieve activated clotting times of 180-220 seconds. Children are more sensitive to the hypocalcaemic effects of ACD especially if citrated replacement products such as fresh frozen plasma are used. Prevention or treatment of low ionized calcium levels may include decreased citrate rates, calcium addition to 5% albumin replacement, calcium gluconate infusions, intravenous boluses of calcium chloride, or a change in anticoagulant. Apheresis risks can be reduced through adequate monitoring and preventive measures. The most commonly performed treatments are plasma exchanges and peripheral blood stem cell collections. Diversional activities appropriate for the child's developmental age are provided to allay anxiety, to divert attention, and to elicit cooperation. In conclusion, size and clinical condition are not exclusionary criteria for apheresis.