Hemostatic effects of therapeutic plasma exchange: A concise review

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.

In hospitalized patients undergoing therapeutic plasma exchange, major bleeding prevalence depends on the bleeding definition: An analysis of The Recipient Epidemiology and Donor Evaluation Study-III

BACKGROUND

Major bleeding in patients undergoing therapeutic plasma exchange (TPE) has been studied in large databases; but without standardizing bleeding definitions. Therefore, we used standardized definitions to evaluate major bleeding in hospitalized patients undergoing TPE using public use data files from the Recipient Epidemiology and Donor Evaluation Study-III (REDS-III).

STUDY DESIGN AND METHODS

In a retrospective cross-sectional analysis, we identified TPE-treated adults in a first inpatient encounter. We evaluated major bleeding prevalence using (1) International Classification of Diseases (ICD) or Current Procedural Terminology (CPT) codes, (2) packed red blood cell (PRBC) transfusion, or (3) hemoglobin (Hgb) decline. Patients with major bleeding prior to their first TPE were excluded from the analysis.

RESULTS

Among 779 patients undergoing TPE, major bleeding by at least one of the three bleeding definitions occurred in 135 patients (17.3%). For each of the ICD/CPT, PRBC, and Hgb definitions, the prevalence of major bleeding was 2.8% (n = 31), 7.4% (n = 81), and 5.4% (n = 59), respectively. Only 3.7% of bleeds (5/135) were captured by all three definitions and 19.3% (26/135) exclusively by any two pairwise definitions. The addition of PRBC transfusion and Hgb decline to ICD/CPT code definitions increased bleeding prevalence threefold.

CONCLUSION

Among hospitalized adults undergoing TPE in the REDS-III study, the prevalence of major bleeding was 17.3%. The addition of PRBC and Hgb decline to ICD codes increased bleeding prevalence threefold. Future studies are needed to develop validated models that identify patients at risk for major bleeding during TPE.

Clinical application of regional citrate anticoagulation for membrane-based therapeutic plasma exchange in children with liver failure

Background

Regional citrate anticoagulation (RCA) is being used more commonly in children for continuous renal replacement therapy. Few reports describe the application of membrane-based therapeutic plasma exchange (mTPE) with RCA in children with liver failure (LF).

Aims

To explore the application of RCA-mTPE in children with LF.

Methods

We retrospectively analyzed data from children with LF who underwent RCA-mTPE in the Children's Hospital of Chongqing Medical University's pediatric intensive care unit. We used the total to ionized calcium ratio (T/iCa) > 2.5 as the diagnostic criteria for citrate accumulation (CA). The patients were divided into two groups according to the occureence of CA at the end of RCA-mTPE (CA group: T/iCa > 2.5; NCA group: T/iCa ≤ 2.5). To evaluate the clinical safety and efficacy of RCA-mTPE, the following data from medical records were assessed and compared between groups: clinical characteristics, reasons for LF, RCA-mTPE parameters and duration, laboratory findings, and complications.

Results

In total, 92 RCA-mTPE treatments were administered to 21 children with LF over 3.8 ± 0.9 h. The following mean values were determined: blood flow rate (QB) = 2.8 ml/kg/min, 4% sodium citrate dose/blood flow rate ratio (QCi/QB) = 1.1(QCi,ml/kg/h); plasma dose/body weight ratio(QP/BW) = 18.5 (QP, ml/kg/h); 10% calcium gluconate dose/blood flow rate ratio (QCa/QB) = 0.2(QCa, ml/kg/h). The mean concentration of iCa in vitro was 0.38 ± 0.07 mmol/L. Citrate accumulation was recorded after 34 (37%) treatments. Hypocalcemia occurred in 11 (12%) and 7 (7.6%) treatments, during and after mTPE, respectively. Three hypotensive and one convulsive events, related to hypocalcemia, and two clotting events occurred during RCA-mTPE. After RCA-mTPE, the patients' pH, HCO3- and Na+ levels, and T/iCa were significantly increased and the total bilirubin (TB), conjugated bilirubin (DB), prothrombin time (PT), activated partial thromboplastin time (APTT), alanine aminotransferase (ALT), aspartate aminotransferase (AST),and ammonia levels were significantly decreased. The TB, DB, and lactic acid levels, before RCA-mTPE, were significantly higher in the CA group than in the NCA group, but there were no significance between the two groups in QB/BW, QCi/QB, and QP/BW, mTPE duration, and estimated amount of citrate metabolized.

Conclusions

Children with LF undergoing RCA-mTPE are at risk of hypocalcemia. With proper protocol adjustment, however, RCA-mTPE can be used safely and effectively in these patients.

Research priorities for therapeutic plasma exchange in critically ill patients

Therapeutic plasma exchange (TPE) is a therapeutic intervention that separates plasma from blood cells to remove pathological factors or to replenish deficient factors. The use of TPE is increasing over the last decades. However, despite a good theoretical rationale and biological plausibility for TPE as a therapy for numerous diseases or syndromes associated with critical illness, TPE in the intensive care unit (ICU) setting has not been studied extensively. A group of eighteen experts around the globe from different clinical backgrounds used a modified Delphi method to phrase key research questions related to "TPE in the critically ill patient". These questions focused on: (1) the pathophysiological role of the removal and replacement process, (2) optimal timing of treatment, (3) dosing and treatment regimes, (4) risk-benefit assumptions and (5) novel indications in need of exploration. For all five topics, the current understanding as well as gaps in knowledge and future directions were assessed. The content should stimulate future research in the field and novel clinical applications.

Effect on haemostasis of different replacement fluids during therapeutic plasma exchange—A comparative multicentre observational study

INTRODUCTION

Therapeutic plasma exchange (TPE) is used for several chronic conditions with little evidence on the efficacy and safety of different choice of replacement fluid. Measurement of haemostasis, particularly in vitro thrombin generation, could play a role in determining the immediate efficacy of different fluid replacement.

AIM

To determine the impact of different TPE replacement fluid regimens on haemostatic assays.

METHODS

Prospective observational multi-centre cohort study in adult patients 18 years and older evaluating haemostatic changes between four different TPE regimens: (1) 5% human albumin solution (Alb) only, (2) 50:50 mix of 5% Alb + modified gelatin, (3) 70:30 mix of 5% Alb and normal saline (NS), and (4) solvent-detergent, virus-inactivated fresh frozen plasma (FFP) (either alone or combined with other fluids). Twenty-one haemostasis variables were analysed (procoagulant, anticoagulant and fibrinolytic factors) pre and post TPE sessions, including in vitro thrombin generation. Linear mixed modelling and canonical discriminant analyses were used to examine the effect of TPE fluid type on haemostatic variables.

RESULTS

A total of 31 patients with up to 5 TPE sessions each (131 sessions in total) were enrolled. Out of 21 markers analysed using linear mixed modelling, the main effects of fluid type were found to be significant for 19 markers (P < 0.05), excluding plasminogen activator inhibitor-1 antigen and thrombin-anti-thrombin. Multivariate Analysis of Variance showed significant differences between the fluid types (Wilks' lambda = 0.07; F_63,245.61  = 5.50; P < 0.0001) and this was supported by a canonical discriminant analysis, which identified the 4 most discriminating markers for fluid types as thrombin generation (lag-time, time-to Peak), fibrinogen and Factor V. In our analyses, the effect of FFP on haemostasis was significantly greater compared with other fluid types. Of the non-FFP fluids, 5% Alb + NS had a lower effect on haemostasis compared to other fluid types (Alb and modified gelatin + 5% Alb).

CONCLUSION

Thrombin generation and fibrinogen discriminated better the effect of different TPE fluids on haemostasis and should be considered as potential markers to evaluate the immediate haemostatic effect of TPE procedures. The use of NS as a TPE replacement fluid had a distinctive impact on thrombin generation and fibrinogen responses compared to other non-FFP fluids.