Intensive plasma exchange in small and critically ill pediatric patients: techniques and clinical outcome.

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 112 plasma exchanges (TPE) on 11 children, 9 of whom weighed less than 20 kg and 7 of whom were critically ill. All were treated on continuous flow apparatus; seven on centrifugal systems (CS), two on a membrane filtration system (MFS), and two on 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. Immunoglobulins fell by the following amounts: IgG 43.7%, IgA 36.7%, and IgM 41% per plasma volume. Platelets fell by 20-90% (CS) and 5-7% (MFS). Vascular access was obtained by various means including Thomas shunts, dialysis catheters, and standard 16-19 gauge butterflies and angiocaths. Bleeding in patients with coagulopathies was prevented by using repeated small 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 (1 patient). Treatment outcome was successful in 8 out of 11 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.