THERAPEUTIC PLASMA EXCHANGE

Transcription

1 THERAPEUTIC PLASMA EXCHANGE DIRECTORATE OF NEPHROLOGY AND TRANSPLANTATION Background and Indications Therapeutic plasma exchange (TPE) is an extracorporeal blood purification technique in which plasma is separated from the cellular components. It is a recognised treatment for conditions where rapid removal of a pathogenic protein (usually antibody) is required to prevent on-going organ damage. Additional beneficial effects on the immune system include the removal of inflammatory mediators and stimulation of lymphocyte clones, with increased sensitivity to cytotoxic therapy. There are two methods in use in the health board: filtration (used in Nephrology and Critical Care), and centrifugation (used in Haematology). The information in this protocol refers to the filtration method. TPE involves the removal of 1 to 1.5 plasma volumes and replacement with a similar volume of colloid and crystalloid (usually a combination 0.9% saline, 4.5% albumin and fresh frozen plasma (FFP)/Octaplas). The prescription for an individual patient should be based on an estimate of their plasma volume (PV), rounded up to the nearest 500ml: PV = (0.07 X weight) X (1 haematocrit) ie 3 4L for an average adult undergoing a single PV exchange A single PV exchange will lower the plasma IgG concentration by 60%. An exchange equal to 1.4 X the PV will lower the concentration by 75%. However, the majority of IgG is extravascular, and re-equilibration between the extra- and intravascular compartments is relatively slow (1 3%/hour). Several treatments are therefore required at intervals of hours to remove a substantial amount of total body IgG. Immunosuppression is also given to reduce on-going production. The standard replacement fluids are 4.5% HAS (to maintain plasma oncotic pressure) and 0.9% saline in a ration of 2:1. Anticoagulation to maintain the circuit is with heparin. FFP should be included in the fluid replacement regimen for patients at high risk of bleeding. These include patients who have undergone a renal biopsy in the preceding 5 days, and those with severe pulmonary haemorrhage complicating vasculitis or anti-gbm disease. In these situations, a 1:1 ratio of 4.5% HAS:FFP or Octaplas should be used, with FFP or Octaplas as the replacement fluid in the second half of treatment (when depletion of clotting factors will be greatest). For these patients, the dose of heparin should be reduced. Complete omission of heparin may be considered, but runs the risk of clotting of the plasma exchange circuit. The replacement fluid consists of FFP or Octaplas alone in the management of thrombotic thrombocytopaenia purpura (TTP) or atypical haemolytic uraemic syndrome (ahus). Directorate of Nephrology and Transplantation Version 1 : 30/06/2017 SV Griffin, N Junglee, E Swales 1 of 6

2 The indication for TPE and treatment schedule should be documented in the patient s notes. Usual Indications and Scheduling for Plasma Exchange (Nephrology) ANCA positive vasculitis Comments Greater benefit has been demonstrated for patients with severe renal involvement, Cr >500mol/L or dialysis dependency (MEPEX trial). This recommendation may change following analysis of the PEXIVAS trial, which randomised patients with a Cr >150mol/L. Also indicated for significant pulmonary haemorrhage. Usual Schedule X5 alternate days, more prolonged if persistent pulmonary haemorrhage. Anti-GBM disease Thrombotic microangiopathy (TMA) Indication: renal disease +/- pulmonary haemorrhage. In the absence of pulmonary haemorrhage, if dialysis dependent on presentation and 100% crescents on biopsy, renal recovery is unlikely and risks of immunosuppression and TPE may outweigh benefits. TPE may be initiated whilst underlying diagnosis is clarified. If ahus definitive treatment is eculizumab. If TTP to continue daily TPE. The management of patients with TTP is coordinated by haematology. Daily X3 then alternate days, length of course determined by clinical response. A minimum of 7 exchanges is usually required. Daily treatment with 100% replacement with FFP or Octaplas. Acute antibody mediated rejection Consider DFPP as alterative treatment modality. X5 alternate days then reassess depending on response of HLA antibody. TPE may be considered for other rare conditions, including croglobulinaemic vasculitis, catastrophic antiphospholipid antibody syndrome, hyperviscosity, HELLP syndrome, and mushroom poisoning. Patients undergoing pre-transplant desensitisation for ABO or HLA incompatibility are treated with double filtration plasmapheresis (DFPP) please see separate protocol. Directorate of Nephrology and Transplantation Version 1 : 30/06/2017 SV Griffin, N Junglee, E Swales 2 of 6

3 Complications Vascular Access Haematoma, pneumothorax (internal jugular) Retroperitoneal bleed (femoral) Infection Line blocks and requires intervention Procedure Hypotension Bleeding Oedema Due to hypoalbuminaemia or over-replacement of exchange volume. Anaphylaxis May occur in response to blood products or the filter. Hypocalcaemia Hypocalcaemia is more common with the use of citrate as an anti-coagulant rather than heparin. However, FFP contains citrate 15% by volume, and if a significant quantity of FFP is used as the replacement fluid then hypocalcaemia and a metabolic alkalosis may result. Anticoagulation In the absence of FFP in the replacement fluid, a single PV exchange will deplete all clotting factors by c.60%. These then normalise over the next 6 12 hours, but if daily exchanges are performed the depletion may persist for longer. Directorate of Nephrology and Transplantation Version 1 : 30/06/2017 SV Griffin, N Junglee, E Swales 3 of 6

4 Monitoring blood tests Baseline and prior to each exchange: FBC, clotting screen (including fibrinogen), U+E s, LFT s, Ca/PO4, blood borne virus serology, G+S if replacement FFP required. Concomitant treatment All patients to be prescribed calcichew 1g bd, unless serum corrected calcium >2.5mmol/l. If serum corrected calcium <2mmol/l prior to TPE, 20ml 10% calcium gluconate made up to 50ml in 0.9% saline to be given over the duration of treatment into the venous limb of the plasma exchange circuit. If fibrinogen <1g/l prior to exchange, include 500ml FFP or Octaplas as final replacement fluid. All patients to be prescribed hydrocortisone 100mg iv and chlorpheniramine 10mg iv prn in case of allergic reaction to blood products. Intravenous immunosuppression with cyclophosphamide or CD20 blockade should be given after TPE. TPE can be repeated the day after cyclophosphamide. Following administration of CD20 blockade the next TPE should not be for at least 36 hours. Timing of dialysis TPE and haemodialysis can be carried out on alternate days. If required on the same day, haemodialysis should occur after TPE to allow for correction of fluid balance. The dose of heparin required for dialysis should be reduced to avoid excessive anticoagulation. Directorate of Nephrology and Transplantation Version 1 : 30/06/2017 SV Griffin, N Junglee, E Swales 4 of 6

5 PLASMA EXCHANGE PRESCRIPTION MODE & FLUID BALANCE PATIENT ADDRESSOGRAPH Treatment Mode: TPE TPE REPLACEMENT FLUID Total plasma exchange volume..l OCTAPLAS...units FFP...units 4.5% ALBUMIN...ml THIS MUST ALSO BE PRESCRIBED ON AN ALL WALES BLOOD TRANSFUSION PRESCRIPTION CHART AND / OR: Sodium Chloride 0.9% Synthetic Colloid: Preparation... Volume.....ml Volume.ml FLUIDS: TO PRIME CIRCUIT AND RETURN BLOOD PRESCRIBERS SIGNATURE Sodium Chloride 0.9% 500ml : To Prime Replacement Line Sodium Chloride 0.9% (x3l total) : To Prime Blood Circuit x2 1000ml Sodium Chloride 0.9% to 3rd Litre only add 5000 International Units Heparin YES / NO SODIUM CHLORIDE 0.9% 500ML : TO RETURN BLOOD Heparin 1000 units/ml : draw up 10ml Initial bolus 2000 units (2 ml) ANTICOAGULATION (HEPARIN) Maintenance infusion rate units / hr Vascath Hep-Lock with 5000 units / ml Heparin: VASCATH MANAGEMENT Volume as specified for each lumen (Red and Blue) Sodium Chloride 0.9% (2 X 20 ml) Flush Prescriber s name: Signature: Date: Directorate of Nephrology and Transplantation Version 1 : 30/06/2017 SV Griffin, N Junglee, E Swales 5 of 6

6 PLASMA EXCHANGE PRESCRIPTION FLUID AND HEP-LOCK RECORD Date / Time Drug & Batch Number Fluid & Batch Number(s) Volume Nurse 1 Nurse 2 Date/Time Hep-lock Record Nurse 1 Nurse 2 Heparin 5000 units / ml Batch No... Red lumen Volume... Blue lumen Volume... Directorate of Nephrology and Transplantation Version 1 : 30/06/2017 SV Griffin, N Junglee, E Swales 6 of 6