Standard apheresis techniques require modification of use in children. particularly those with serious concurrent medical problems, as they are prone to apheresis-induced disturbances of volume. metabolism. and coagulation. We report I12 plasma exchanges (TPE) on 11 children. 9 of whom weighcd less than 20 kg and 7 of whom were critically ill. All were treated o n continuous flow apparatus; sevcn on centrifugal systems (CS). two o n a meinbrane filtration system (MFS). and two o n both. Perturbations of blood and red blood cell (RBC) volume were prevented by priming the extracorporeal circuits with a red cell saline mixture having an hematocrit equal to or greater than the patient's hematocrit. Priming volume and minimal flow rates were 170 ml and 40 cc/min (MFS) and 350 ml and 10 cc/min (CS). TPE dose varied from 1.3 to 3 plasma volumes. Iinmunoglobulins fell by the following ainounts: IpG 43.7%,. IgA 36.7%. and IgM 4 1 8 per plasma voluiiie. Platelets fell by 20-90% (CS) and 5-7% (MFS). Vascular access was obtained by various nieans including Thoinas shunts. dialysis catheters. and standard 16-19 gmge butterflies and angiocaths. Bleeding in patients with coagulopathics was prevented by using repeated sniiill boluses of heparin to maintain a clotting time of 2.5-3 minutes. Morbidity from TPE was limited to citrate toxicity ( 2 patients) and transient pulmonary edema (I patient).
Trcatnient outcome was successful in 8 out of I I patients. We have shown that if PEX is otherwise indicated. it should not be withheld solely for patient size or the complexity of concurrent medical problems.