A lower fibrinogen threshold does not lead to increased bleeding risk in patients receiving therapeutic plasma exchange: A prospective single-center analysis

BACKGROUND

Plasma exchange (PLEX) therapy is indicated for several disorders. The 5% albumin is often used as a sole replacement fluid during most PLEX. However, each 1.0 plasma volume exchange depletes coagulation factors by ~65%. Although most coagulation factors recover to hemostatic levels within 24 h post-PLEX, fibrinogen requires 48-72 h to recover. Fibrinogen is the key coagulation protein for hemostasis. Therefore, fibrinogen is often monitored during the acute course of PLEX, and plasma is supplemented to prevent bleeding if fibrinogen is <100 mg/dL.

STUDY DESIGN AND METHODS

We conducted a prospective, single-center, observational study to evaluate bleeding risk in adults who received an acute course of PLEX with a fibrinogen level of 80-100 mg/dL without plasma supplementation during the procedure or before central venous catheter removal. The study group was compared to patients with plasma fibrinogen >100 mg/dL.

RESULTS

Among the 275 patients who received 1406 PLEXes, 62 patients (23%) who underwent 323 PLEXes met the inclusion criteria, and only 2 (3%) patients had bleeding while on oral anticoagulants. In contrast, out of 275 patients, 143 (52%) with fibrinogen levels >100 mg/dL received 751 PLEX treatments, and bleeding occurred in 2 (1%) while on low-molecular-weight heparin.

CONCLUSIONS

Our findings suggest that a pre-procedure fibrinogen threshold of 80-100 mg/dL without plasma supplementation does not increase bleeding risk unless patients were on anticoagulation.

Therapeutic Plasma Exchange Versus FcRn Inhibition in Autoimmune Disease

Therapeutic plasma exchange (TPE or PLEX) is used in a broad range of autoimmune diseases, with the goal of removing autoantibodies from the circulation. A newer approach for the selective removal of immunoglobulin G (IgG) antibodies is the use of therapeutic molecules targeting the neonatal Fc receptor (FcRn). FcRn regulates IgG recycling, and its inhibition results in a marked decrease in circulating autoantibodies of the IgG subtype. The difference between FcRn inhibition and PLEX is often questioned. With anti-FcRn monoclonal antibodies (mAbs) and fragments only recently entering this space, limited data are available regarding long-term efficacy and safety. However, the biology of FcRn is well understood, and mounting evidence regarding the efficacy, safety, and potential differences among compounds in development is available, allowing us to compare against nonselective plasma protein depletion methods such as PLEX. FcRn inhibitors may have distinct advantages and disadvantages over PLEX in certain scenarios. Use of PLEX is preferred over FcRn inhibition where removal of antibodies other than IgG or when concomitant repletion of missing plasma proteins is needed for therapeutic benefit. Also, FcRn targeting has not yet been studied for use in acute flares or crisis states of IgG-mediated diseases. Compared with PLEX, FcRn inhibition is associated with less invasive access requirements, more specific removal of IgG versus other immunoglobulins without a broad impact on circulating proteins, and any impacts on other therapeutic drug levels are restricted to other mAbs. In addition, the degree of IgG reduction is similar with FcRn inhibitors compared with that afforded by PLEX. Here we describe the scientific literature regarding the use of PLEX and FcRn inhibitors in autoimmune diseases and provide an expert discussion around the potential benefits of these options in varying clinical conditions and scenarios.

State of the Evidence: Drug Removal via Apheresis

Therapeutic apheresis refers to a diversity of procedures in which specific hematologic components (e.g., plasma, erythrocytes, leukocytes, etc.) with pathological associations are removed from circulation (with possible replacement) in order to treat a variety of disease processes. As pharmacologic agents also circulate with these components, their removal is sometimes incidental, or in the scenario of drug toxicity, a therapeutic goal. The corpus of published manuscripts on this subject has grown immensely over the past few decades; however, the breadth of diseases, methods, and drugs that co-exist in this space make it challenging to generate generalizable evidence regarding drug removal via apheresis. This review discusses factors worth considering when interpreting literature-reported data on drug removal by apheresis with examples from several notable studies and highlights topics in need of evidential improvement and growth as our palette of therapeutic agents continues to expand.

Therapeutic plasma exchange in the intensive care unit: Rationale, special considerations, and techniques for combined circuits

Therapeutic plasma exchange (TPE) is an extracorporeal blood purification technique with proven efficacy in a variety of conditions, including in the intensive care setting. It is not uncommon for a critically ill patient to require more than one extracorporeal procedure in addition to TPE. This review focuses on the combination of TPE with other extracorporeal circuits in a critical care setting via a single vascular access (either in-series, parallel, or a hybrid mode) which is often referred to as performing procedures "in tandem." Authors performed literature review via pubmed.gov using search terms: plasma exchange, plasmapheresis, apheresis, tandem circuits, combined circuits, critical care, ICU, CRRT, hemodialysis, and ECMO. Thirty-eight English-language, peer-reviewed papers were appraised that satisfied the content of this review on techniques for combining circuits with plasma exchange, as well as describing the advantages of tandem procedures and potential complications that can arise. Performing these procedures simultaneously can be advantageous in reducing total procedure and staffing time, avoiding placement of additional central lines, reducing overall need for anticoagulation, and limiting multiple blood primes in certain populations. However, the described combined circuits are complex, associated with higher complications, and require a skilled team to understand and mitigate the potential complications associated with these combined procedures.

Dialysis and Extracorporeal Therapies for Enhanced Elimination of Toxic Ingestions and Poisoning

Poisoning and toxic ingestions cause significant morbidity and mortality worldwide. Extracorporeal therapies such as dialysis, haemoperfusion and plasma exchange are selectively applied to patients with severe intoxications unresponsive to standard interventions and can be lifesaving. Extracorporeal therapies are a complex but fundamental aspect of the practice of nephrology. Without high-quality evidence to guide implementation, an understanding of toxicokinetics and the physiochemical principles of the enhanced elimination techniques is especially important. This review provides a comphrensive, user-friendly outline of the application of extracorporeal therapy in the poisoned patient.

Plasma exchange in the intensive care unit: a narrative review

In this narrative review, we discuss the relevant issues of therapeutic plasma exchange (TPE) in critically ill patients. For many conditions, the optimal indication, device type, frequency, duration, type of replacement fluid and criteria for stopping TPE are uncertain. TPE is a potentially lifesaving but also invasive procedure with risk of adverse events and complications and requires close monitoring by experienced teams. In the intensive care unit (ICU), the indications for TPE can be divided into (1) absolute, well-established, and evidence-based, for which TPE is recognized as first-line therapy, (2) relative, for which TPE is a recognized second-line treatment (alone or combined) and (3) rescue therapy, where TPE is used with a limited or theoretical evidence base. New indications are emerging and ongoing knowledge gaps, notably regarding the use of TPE during critical illness, support the establishment of a TPE registry dedicated to intensive care medicine.

Therapeutic Plasma Exchange in the Critically Ill Patient: Technology and Indications

Therapeutic plasma exchange (TPE) is frequently the most common Apheresis Medicine technique used for extracorporeal therapy of a wide variety of renal, neurological, hematological, and other clinical indications. Many of these clinical indications require intensive care during critical illness. Conventional TPE uses one of two main technical methods to achieve the goal of removing known disease mediators from the plasma: using centrifugal forces to separate and remove components of blood, or a membrane filtration method that separates plasma from the cellular components of blood. The following review discusses the basic principles of TPE, the technological aspects, and relevant clinical scenarios encountered in the intensive care unit, including relevant guidelines and recommendations from the American Society for Apheresis.

Drug Dosing in Patients Undergoing Therapeutic Plasma Exchange

Therapeutic plasma exchange (TPE) is an extracorporeal process in which a large volume of whole blood is taken from the patient's vein. Plasma is then separated from the other cellular components of the blood and discarded while the remaining blood components may then be returned to the patient. Replacement fluids such as albumin or fresh-frozen plasma may or may not be used. TPE has been used clinically for the removal of pathologic targets in the plasma in a variety of conditions, such as pathogenic antibodies in autoimmune disorders. TPE is becoming more common in the neurointensive care space as autoimmunity has been shown to play an etiological role in many acute neurological disorders. It is important to note that not only does TPE removes pathologic elements from the plasma, but may also remove drugs, which may be an intended or unintended consequence. The objective of the current review is to provide an up-to-date summary of the available evidence pertaining to drug removal via TPE and provide relevant clinical suggestions where applicable. This review also aims to provide an easy-to-follow clinical tool in order to determine the possibility of a drug removal via TPE given the procedure-specific and pharmacokinetic drug properties.

Variability in international normalized ratio and activated partial thromboplastin time after injury are not explained by coagulation factor deficits

BACKGROUND

Conventional coagulation assays (CCAs), prothrombin time (PT)/international normalized ratio (INR) and activated partial thromboplastin time (aPTT), detect clotting factor (CF) deficiencies in hematologic disorders. However, there is controversy about how these CCAs should be used to diagnose, treat, and monitor trauma-induced coagulopathy. Study objectives were to determine whether CCA abnormalities are reflective of deficiencies of coagulation factor activity in the setting of severe injury.

METHODS

Patients without previous CF deficiency within a prospective database at an ACS-verified Level I trauma center had CF activity levels, PT/INR, aPTT, and fibrinogen levels measured upon emergency department arrival from 2014 to 2017. Linear regression assessed how CF activity explained the aPTT and PT/INR variation. Prolonged CCA values were set as INR greater than 1.3 and aPTT greater than 34 seconds. CF deficiency was defined as less than 30% activity, except for fibrinogen, defined as less than 150 mg/dL.

RESULTS

Sixty patients with a mean age of 35.8 (SD, 13.6) years and median New Injury Severity Score of 32 (interquartile range, 12-43) were included; 53.3% sustained blunt injuries, 23.3% required massive transfusion, and mortality was 11.67%. Overall, 44.6% of the PT/INR variance and 49.5% of the aPTT variance remained unexplained by CF activity. Deficiencies of CFs were: common pathway, 25%; extrinsic pathway, 1.7%; and intrinsic pathway, 6.7%. The positive predictive value for CF deficiencies were: (1) PT/INR greater than 1.3:4.4% for extrinsic pathway, 56.5% for the common pathway; (2) aPTT greater than 34 seconds:16.7% for the intrinsic pathway, 73.7% for the common pathway.

CONCLUSION

Almost half of the variances of PT/INR and aPTT were unexplained by CF activity. Prolonged PT/INR and aPTT were poor predictors of deficiencies in the intrinsic or extrinsic pathways; however, they were indicators of common pathway deficiencies.

LEVEL OF EVIDENCE

Prognostic, level III.

Plasma exchange in catastrophic antiphospholipid syndrome

Plasma exchange is a well-established therapeutic procedure commonly used in many autoimmune disorders. The beneficial effects of plasma exchange are thought to occur through the elimination of pathogenic mediators found in plasma, including autoantibodies, complement components, and cytokines. The catastrophic antiphsopholipid syndrome (CAPS) is a life-threatening variant of the antiphospholipid syndrome (APS) where several thrombosis take place in a short period of time in patients with circulating antiphospholipid antibodies. The triple therapy with anticoagulation, corticosteroids and plasma exchange or intravenous immunoglobulins has been proposed in CAPS. CAPS is a rare disease precluding the conduction of formal clinical trials. However, the observation of a better clinical course of patients who received this treatment supports their use. Plasma exchange has become an established therapeutic procedure in CAPS but there are no studies regarding the better approach and thus its use relies on the experience of the physicians in charge. The current article aims to review potential mechanisms of action of plasma exchange and the technical aspects of this procedure and will focus on its current role in CAPS, the experience published in treating this condition and the treatment protocol that we use in our institution.

[What are the indications for rescue procedures? : Systemic rheumatic diseases in the intensive care unit]

Schwere, organ- oder lebensbedrohliche Manifestationen entzündlicher rheumatischer Erkrankungen, wie z. B. eine diffuse alveoläre Hämorrhagie im Rahmen einer Kleingefäßvaskulitis, sprechen nicht immer ausreichend oder mit zeitlicher Verzögerung auf eine immunsuppressive Therapie an. Bei einem drohenden oder bereits eingetretenen Organversagen besteht dann nicht selten die Notwendigkeit, die immunsuppressive Therapie auf der Intensivstation um rasch wirksame Rescue-Therapieverfahren zu ergänzen. Aufgrund der Seltenheit vieler rheumatischer Erkrankungen ist die Evidenz zum Einsatz von Rescue-Therapieverfahren wie der Plasmapherese, der extrakorporalen Membranoxygenierung (ECMO) oder der Gabe von intravenösen Immunglobulinen (IVIG) für viele Indikationen eher gering. Der Einsatz der Plasmapherese wird bei einer akuten Anti-GBM(glomeruläre Basalmembran)-Erkrankung (Goodpasture Syndrom) oder einem katastrophalen Antiphospholipidantikörpersyndrom (CAPS) als sinnvoll angesehen. Eine ECMO-Therapie kann bei persistierender respiratorischer Insuffizienz trotz mechanischer Beatmung als Folge einer diffusen alveolären Hämorrhagie oder eines Acute-Respiratory-Distress-Syndroms (ARDS) anderer Ursache erwogen werden. Eine Gabe von IVIG ist bei einer akuten kardialen Beteiligung im Rahmen einer Kawasaki-Erkrankung indiziert und kann beim CAPS sowie bei therapierefraktären Myositiden erwogen werden.

Effect of plasma exchange on antifactor Xa activity of enoxaparin and serum levetiracetam levels

PURPOSE

The effect of therapeutic plasma exchange (TPE) on antifactor Xa activity in a patient treated with enoxaparin and levetiracetam is reported.

SUMMARY

A 52-year-old woman was treated with levetiracetam and prophylactic enoxaparin while receiving TPE to manage respiratory failure due to anti-MDA5 antibody-associated interstitial lung disease (ILD) with dermatomyositis. Due to a scant amount of evidence regarding the management of these medications in TPE, therapeutic monitoring principles were used to assess the effect TPE had on these medications. A pre-TPE antifactor Xa activity level and levetiracetam serum assay, a post-TPE antifactor Xa activity level and levetiracetam serum assay, levetiracetam serum assays at 1 and 6 hours after the patient received her next dose, and a levetiracetam assay of the waste plasma from the TPE were collected for therapeutic drug monitoring and pharmacokinetic calculations. Utilizing standard population pharmacokinetic data, the expected antifactor Xa activity without TPE was 0.14 IU/mL. This concentration was significantly higher than the undetectable concentration (<0.1 IU/mL) that was drawn immediately after TPE, suggesting significant removal of antifactor Xa activity. The measured levetiracetam level did not significantly differ from the expected post-TPE levetiracetam level that was calculated using patient-specific pharmacokinetic data.

CONCLUSION

In a patient receiving TPE to manage anti-MDA5 antibody ILD associated with dermatomyositis and a prior seizure, TPE significantly altered enoxaparin antifactor Xa activity as evidenced by the undetectable antifactor Xa activity level drawn after TPE. Alternatively, TPE had a minimal effect on the clearance of levetiracetam as evidenced by the post-TPE level and fraction elimination of only 5% of total body stores.

Developments in the use of plasma exchange and adjunctive therapies to treat immune-mediated thrombotic thrombocytopenic purpura

Introduction: Immune-mediated thrombotic thrombocytopenic purpura (iTTP) is a life-threatening disease characterized by a severe functional deficit in the von-Willebrand cleaving protease ADAMTS13, due to autoantibody production. The once-dismal prognosis of the disease has been changed by the discovery of the dramatic efficiency of therapeutic plasma exchange (TPE). Areas covered: This review focuses on the history and recent developments in the use of TPE for iTTP with a special emphasis on the consequences for TPE practice of the recent introduction of new highly effective immunosuppressive strategies and anti-von Willebrand factor (vWF) therapies. Expert opinion: Although TPE still represents the cornerstone, emergency treatment of iTTP, their duration, and associated complications could be dramatically reduced in the future by the systematic addition of early immunosuppression using corticosteroids and rituximab as well as an anti-vWF therapy with caplacizumab.

Effects of therapeutic plasma exchange on anticoagulants in patients receiving therapeutic anticoagulation: a systematic review

Therapeutic plasma exchange (TPE) removes coagulation proteins, but its impact on therapeutic anticoagulation is unknown. We performed a systematic review of the literature to determine the coagulation effects of TPE in patients receiving systemic anticoagulation. We searched MEDLINE, CINAHL, EMBASE, and Web of Science until June 2018 for studies combining controlled vocabulary and keywords related to therapeutic plasma exchange, plasmapheresis, anticoagulants, and therapy. The primary outcome was the effect of TPE on anti-Xa activity, activated partial thromboplastin time (aPTT), or international normalized ratio (INR). The secondary outcome was reports of post-TPE bleeding or thrombosis. A total of 1830 references were screened and eight studies identified. Our selected studies (five case reports and three case series) involved 23 patients and evaluated the effects of seven anticoagulants. Six studies of unfractionated heparin, low-molecular-weight heparins, and direct oral anticoagulants demonstrated an anti-Xa level decline. Two studies of unfractionated heparin and low-molecular-weight heparins showed an aPTT increase. One study of warfarin showed a post-TPE INR increase. Reports of post-TPE bleeding occurred in two patients and thrombosis in one. In patients receiving therapeutic anticoagulation, TPE is associated with anti-Xa activity decline and aPTT and INR increase. These coagulation changes do not appear to significantly increase bleeding or thrombotic risk. Our data suggest the need for prospective studies to investigate the true clinical impact of TPE on therapeutic anticoagulation.

The management of anticoagulation in patients undergoing therapeutic plasma exchange: A concise review

We surveyed multiple apheresis centers represented by the authors for their clinical approach to the management of anticoagulation issues during therapeutic plasma exchange (TPE). We present the results of their practices and a review of the pertinent literature. As plasma is removed during TPE, replacement with all or partial non-plasma-containing fluids (eg, 5% albumin) may lead to significant changes in hemostasis. These changes are amplified in patients who are receiving anticoagulation. We discuss various anticoagulants as well as the monitoring and adjustment of anticoagulation before, during, and after TPE. No single guideline can be applied, but rather, patients must be monitored individually, taking into account their often complex clinical conditions and medication profiles.

Therapeutic Plasma Exchange and Its Impact on Drug Levels: An ACLPS Critical Review

OBJECTIVES

To examine and summarize the current literature on the effects of therapeutic plasma exchange on medication levels.

METHODS

Literature review was performed via searches of the Cochrane Database and PubMed-MEDLINE (1996 to August 2016) looking for all case reports, case series, and human randomized controlled trials involving therapeutic plasma exchange (TPE)-associated drug removal.

RESULTS

Approximately 60 peer-reviewed articles were identified with the majority being case reports; no randomized controlled trials were identified. These reports and the authors' own experiences were used to derive practical guidance regarding the effect of TPE on circulating drug levels.

CONCLUSIONS

There were several limitations with existing studies, many of which relate to procedural and/or clinical properties of patients undergoing TPE. As such, additional studies are needed before definitive guidelines can be established. There is clear need for development of consensus and additional investigations in this domain.