Immunoadsorption Versus Therapeutic Plasma Exchange. Will Fibrinogen Make the Difference

reduced and their return to baseline values may take days, even in patients with normal liver function [9] . Although a reduction of coagulation parameters in general does not necessarily imply more hemorrhagic complications [10] , a low fibrinogen concentration is definitely associated with an increased bleeding risk [11] . This bleeding diathesis is also prolonged in TPEtreated patients with extremely low and/or slowly recovering fibrinogen levels. Importantly, such a scenario cannot be predicted, which precludes timely anticipation and prevention [12] . Over the years, strategies have been developed to tackle a low fibrinogen condition after TPE providing FFP targeting a fibrinogen level above 100 mg/ dl [13] . Unlike TPE, immunoadsorption (IAS) is a blood-purification technique that enables the selective removal of immunoglobulins (Ig) from separated plasma through high-affinity adsorbers. IAS is currently used for treatment of a large variety of antibody-mediated or immunological diseases (e.g., humoral transplant rejection, lupus nephritis, multiple sclerosis) [3, 14] . In this issue of Blood Purification, Zollner et al. retrospectively compared TPE, IAS and a TPE/IAS combination in 67 patients with a broad spectrum of immunoand neuropathies [15] . All methods reduced plasma fibrinogen levels by a fixed percentage independently of pre-treatment Therapeutic plasma exchange (TPE) already has a long service record in modern medicine. Throughout the years, TPE has steadily evolved from a centrifugationbased technique essentially used in bloodbanking procedures toward an easily applicable and efficient hemofiltration-steered modality in critically ill patients [1] . In support of the benefit of TPE was its mechanistic potential to remove injurious or noxious large molecular-weight substances (i.e., auto-antibodies, immune complexes, myeloma light chains, endotoxin, and cryoglobulins) and lipids such as cholesterol or triglycerides [2] . Subsequently, indications for TPE progressively also expanded encompassing thrombotic microangiopathies (e.g., Moscowitz syndrome), specific auto-immune diseases (e.g., Guillain-Barré, Goodpasture’s, and anti-phospholipid syndrome), as well as rescue treatment of a wide variety of connective tissue and neurological disorders [3–7] . Classically, exchange is realized with human albumin to minimize potential allergic reactions induced by fresh frozen plasma (FFP) [8] . Proteins are removed from the plasma by an exchange process and by microthrombosis. In this scenario, levels of plasma constituents, including coagulation factors, at first substantially decrease and then gradually regain pre-treatment levels. However, the decrease and recovery rate of specific factors may vary. Fibrinogen levels, for instance, are markedly Published online: December 4, 2014