Double filtration plasmapheresis in critical care

Many kinds of technologies have been introduced and successfully developed for therapeutic apheresis. Furthermore, several kinds of these technologies have also been applied in critical care. Double filtration plasmapheresis (DFPP), however, is rarely applied in this field in comparison with other treatments such as continuous hemofiltration, continuous hemodiafiltration, single filtration plasmapheresis, and plasma adsorption therapies. In this paper, the characteristics of the DFPP treatments for critical care are summarized. During the DFPP treatments, the patient's blood volume (BV) often decreases with time due to albumin loss induced by inadequate albumin infusion in a supplementation fluid. We examined the change of BV by a continuous hematocrit monitor, Crit-Line, during an in vivo study for 9 patients. As a result, albumin loss fairly occurred in DFPP treatments. The decrease of patient BV was induced by an oncotic pressure drop due to albumin loss and often resulted in a blood pressure drop. This is a serious problem for DFPP in critical care. We should avoid inadequate albumin infusion if the patient is suffering from these adverse effects. In order to determine the optimal concentration C(S) and volume V(S) values of a supplemented albumin solution, we introduced a variable blood volume model for albumin transport in DFPP.