Automated red blood cell exchange (aRBCX) is a guideline-based treatment for patients with SCD after severe events (e.g. stroke), but often impeded by difficult venous access (VA). In July 2022, a single needle protocol (SN) for aRBCX became available for Spectra Optia (Fa. Terumo BCT). Using intermittent flow technique, portions of ca. 30 ml blood are sequentially drawn and returned until the procedure is complete. We present our experience with this protocol in two patients with SCD.
To date, patient 1 and 2 were treated with SN-aRBCX 12 and 10 times respectively. Both patients received a high-flow single lumen TidalPortTM with 9,6F catheter (Fa. Norfolk Medical). A 18G non-coring port needle (Fa. PakuMed) is used for VA.Prior to treatment, the ports routinely are declotted with Alteplase (Actilyse CathfloR 2mg). Spectra Optia is fitted with the RBCX set and the SN adapter and primed with saline and citrate according to the manufacturs instructions. The procedure usually starts with a depletion phase of up to 3% hematocrit with saline substitution, then switches to exchange mode with substitution of packed red cell concentrates (pRBC).
Venous access for treatment with double needle aRBCX (DN-aRBCX) for patient 1 was usually difficult, painful and often resulted in vasovagal reactions. Patient 2 was not eligible for DN-aRBCX because of very poor veins. Since treatment start with SN-aRBCX, venous access via port needle only has been easy and mostly pain free for both patients. Mean maximum flow rate (frmax) for patient 1 increased from 39ml/min (DN-aRBCX) to 69ml/min (SN-aRBCX), enabling higher exchange volumes/time and leading to reduced mean FRC from 32% to 24%. Mean exchange time for SN-aRBCX is 154 min. Mean frmax for patient 2 ist 56ml/min with a mean exchange time of 156 min. Because of three-weekly exchange intervals, the resulting mean FCR of 40% is sufficient to keep HbS below 30%.
The SN-procedure is a game changer for the aRBCX-treatment of patients with SCD, especially when combined with a high flow port. It is well tolerated, facilitates a sufficient exchange volume in a reasonable exchange time and alleviates the problem of painful and often insufficient venous access.
There is no conflict of interest.