Comparison between Automated Erythrocytopharesis (AECP) and Manual Exchange Transfusion (M-Ex)) in Reducing Hb-S and in Recovery of Acute Chest Syndrome and Other Acute Presentations of Sickle Cell Disease Patients
Authors: Ahmed Said Yousuf , Saleh Sameh M. , Hameed Mohamed Shefan , Ragheb Ahmed M. , Abbas Telal M. , Fadel AbdelMunim , Hassan Siddiq , Baden Hussein S. , Tayeb Khaled I , Bakshi Nasir , El Yamany Ghaleb , Alotaibi Sultan Bejad 
Published: October 2019

Abstract
Background:
Sickle Cell Disease represents a national health problem in Saudi Arabia with close to 150 thousands of the population are afflicted with the disease. Patients are frequently admitted with life threatening complications like Acute chest syndrome (ACS), Hyperhemolysis (HH), pneumonia, thromboembolism including pulmonary Artery Thrombosis (PAT) or severe protracted painful vasoocclusive crises (VOC). Rapid lowering of Hemoglobin S helps in reducing sickling and in alleviating such complications and allowing rapid recovery. Exchange transfusion is the fastest way to remove pathogenetic sickling red blood cells and reducing Hb S level to a safe level. It can be done manually (Mex) or via Automated Erythrocytopharesis machine (AECP). In this study we compared manual exchange to AECP in achieving the targeted lowering of Hb S and in accelerating clinical recovery.
Patients and Methods:
Patients included are sickle cell disease patients (HbSS, HbSC, Hb S/thal) admitted to the ER of a central Hospital. Indications of exchange were: acute chest syndrome, acute severe painful vaso-occlusive crises refractory to standard ER protocol of analgesia, stroke, priapism, Hyperhemolysis, and acute pulmonary embolism.
P value of significance was calculated using student t-test comparing between median Hb S achieved after manual exchange vs AECP.
To assess the rapidity of reversal of desaturation in acute chest syndrome patients, the cumulative incidence of reversal of desaturation and normalization of Oxygen saturation on room air were plotted against time at 0 time of the start of exchange, 2 hours,4 , 12, 24, 48 and 72 hours/discharge (D/C)
Results:
Table 1 shows clinic-biological characteristics of patients who underwent exchange transfusion. A total of 230 patients-admissions were registered between Dec 1. 2017 to July 27, 2018 for painful VOC to ER; 51 (32%) had clinical indications for exchange (ACS 25, Stroke / fits 1, priapism 1, pulmonary artery thrombosis 1, Hyperhemolysis with VOC (n:7) , VOC with HLH (n:1), and the remaining with "refractory" painful VOC with or without infection. One patient died immediately at the time of arrival to ER before starting any standard resuscitative measures .
Exchange transfusion was indicated and done for 53 (23%); 12 (22,6%) AECP and the remaining (77.4%) had Manual Exchange.
The median Hb S after manual exchange was 44 % (range 31-74%) which was unsatisfactory and way higher than the targeted level while Automated ECP reached down satisfactorily to a median of 31%(range 8%-50%) ; 67% of whom achieved it with only one session. No mortalities or major procedure related complication reported with manual or automated ECP. Procedurally, 3 patients needed 2 automated sessions and 1 patient used 2 kits for one session. Manual exchange could not achieve the target Hemoglobin S level below or around 30% due to logistic and technical difficulties and sometimes patients' refusal while Automated ECP reached to a mean Hb s level of 28%( range 8%-50%) and nearly two thirds (67%) reached to as low as 31% Hb S level with only one session of Automated ECP and was associated with rapid improvement of the oxygenation within the first 2 hours of the procedure.
Conclusions:
Erythrocytopharesis (Automated RBC exchange) is effective, quick and safe procedure that is life saving for many patients with ACS and is associated with less difficulties and complications if compared with the manual exchange. Because SCA is a national problem in Saudi Arabia and acute chest syndrome and other acute major complications comprehensively kill SCD patients, Automated Erythocytopharesis should be available nation-wide like dialysis machines at all large hospitals in all cities and should be distributed according to the prevalence of SCA in the area or location.

Disclosures
No relevant conflicts of interest to declare.