1. Choose initial anticoagulation mode: The decision algorithm for selecting the mode of anticoagulation is shown in Figure 1.
· If anticoagulation is required due to underlying pathology we maintain the corresponding anticoagulation method according to the indication.
· If anticoagulation is not required due to underlying pathology, the risk of bleeding is evaluated.
· If there is not bleeding risk we initiate anticoagulation with our usual initial regimen: unfractionated sodium heparin.
· If there is bleeding risk:
o In cases of severe thrombocytopenia (<50,000) and/or high risk of bleeding, EPT can be performed without heparin (in these cases, ensure that the filtration fraction does not exceed 10%-15%). It can also be performed directly with citrate.
o If platelet count is between 50,000-75,000 and/or there is mild coagulopathy (PA<75% and/or aPTT >45secs) EPT can be performed with epoprostenol or citrate.
o If platelet count is above 75,000 and there is normal coagulation we can use sodium heparin.
· If two sets clot within 24 hours, we will follow the following sequential procedure: increase the dose of sodium heparin, add epoprostenol or switch to regional anticoagulation with citrate.
· The indications for the use of citrate anticoagulation would be:
o Patients with thrombocytopenia <50,000.
o Patients with high risk of bleeding (surgery in the previous 24 hours, recent or spontaneous bleeding, etc.)
o Patients with thrombocytopenia between 50,000-70,000 and/or Prothrombin <75% and/or TTPA> 45 sec.
o All patients with normal coagulation in whom filter durations are not achieved 24 hours with the usual protocol (heparin alone or in combination with epoprostenol).
o Patients with contraindications for the use of heparin (induced antibodies, etc.) if the option of epoprostenol alone does not achieve filter durations >24 hours.
2. Proceed according to the chosen anticoagulation system:
· Sodium heparin: dose of 500 IU/hour (10,000 IU in 40 ml of 0.9% Saline in a specific syringe for the Prismaflex/Prismax monitor). Set the heparin pump rate at 2 ml/h, which can be increased up to 3 ml/h.
· Epoprostenol: the procedure for this anticoagulation is the following:
o Dilute a vial of the new Epoprostenol in 250ml of 0.9% saline solution.
o Place the saline with epoprostenol, with an infusion pump, in the afferent branch (arterial) of the circuit; as close as possible to the patient's outlet, and always pre-blood pump of the circuit (use the Y piece used for primming. NEVER use three-way valves).
o Start at a rate of 5 mL/min, and increase by 5 mL every 5 minutes until reaching the treatment dose; usually 21 mL/h.
o Since the saline with epoprostenol is introduced into the hemofilter circuit with an external pump, the volume provided (500ml, under normal conditions) must be considered in the patient's fluid balance.
o It is based on the placement of a CITRATE infusion pump in the pre-pump arterial branch at a flow rate proportional to the blood flow, replenishing the decrease in ionic calcium by placing a second CALCIUM infusion pump in the venous branch (after the bubble catcher) at a flow rate proportional to the ultrafiltration.
o A citrate concentration between 2.5 and 6 mmol/L is required to prolong coagulation time above 100%. We will achieve real regional anticoagulation of the EPT circuits by scheduling the infusion of citrate close to the arterial branch of the vascular access, which will be reversed when the blood returns from the patient and the citrate is metabolized. Currently, it can be done with the Prismaflex/Prismax monitors (all our monitors have updated software) using a specific line for calcium (from the syringe pump on the monitor itself).
o The following parameters will be set:
· CITRATE FLOW: 2-4 mmol/L (we start at 3 by default).
· CALCIUM FLOW: 30-200% (we start at 100% by default).
o The assembly scheme for citrate EPT is shown in Figure 2.
o We will start with a blood flow of 140 ml/min; dialysis flow of 1500 ml/h; substitution fluid flow of 300 ml/h.
o It should be noted that the dose of citrate used in each case is a substitution dose. Therefore, we usually only maintain a small dose to maintain fluid in the air/blood interface of the bubble catcher.
o Calcium adjustment: ionic calcium in the circuit (post-filter venous sampling) must be determined 5 min after initiation (to confirm that the system is functioning correctly) and subsequently per shift, along with a blood gas test to assess the pH of the circuit and the patient (GEM). Corrections will be made based on the calcium levels of the circuit and the patient, according to Table 2.
o Changes in blood flow and/or ultrafiltration will automatically vary the citrate and calcium flows to maintain the ratio. With Prismaflex-Prismax sysstems, the citrate infusion is done with the PBP pump. For calcium, which uses the monitor's syringe pump, use the Y-piece used for primming; place it on the catheter return line (blue line).
o We must use specific fluids for this therapy (specific palette instead of EDT fluid storage): RegiocitR(Citrate 18 mmol/L) on the PBP scale; and BiphozylR (balanced fluid, calcium-free and with phosphate -2 mEq/L- and magnesium -1.5 mEq/L-) on the dialysis and replacement scales. The specific characteristics of the fluids that we use are detailed in Table 1.
3. Monitoring of complications: This topic will be further discussed in the Troubleshooting section.