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Summary There has been a significant surge in admissions to critical care during the coronavirus disease 2019 (COVID‐19) pandemic. At present, the demands on blood components have not been described. We reviewed their use during the first 6 weeks of the outbreak from 3 March 2020 in a tertiary‐level critical care department providing venovenous extracorporeal membrane oxygenation (vv‐ECMO). A total of 265 patients were reviewed, with 235 not requiring ECMO and 30 requiring vv‐ECMO. In total, 50 patients required blood components during their critical care admission. Red cell concentrates were the most frequently transfused component in COVID‐19‐infected patients with higher rates of use during vv‐ECMO. The use of fresh frozen plasma, cryoprecipitate and platelet transfusions was low in a period prior to the use of convalescent plasma.

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Dear Sir, Hyperhaemolysis is most frequently described in patients with sickle cell disease, although there are cases of this event occurring in patients with thalassaemia and myelofibrosis (Grainger et al., 2001;Treleaven & Win 2004). We report a case of hyperhaemolysis in a patient with Haemoglobin H (HbH) disease, and outline our institutions approach to the management of hyperhaemolysis.A 65-year-old lady with HbH disease and baseline haemoglobin (Hb) of 85 g L −1 , presented to hospital with breathlessness which was felt to be secondary to exacerbation of her asthma. Her Hb at the time of admission was 74 g L −1 , in view of her hypoxia she was transferred to the intensive care unit where she was treated with antibiotics and transfused 4 units of red cells. Iron studies pre-transfusion revealed a serum iron of 2·5 μmol L −1 (11-29 μmol L −1 ) and transferrin saturation of 8%. She made a good recovery and was discharged home, at this time her Hb was 115 g L −1 .She presented to hospital 12 days later with general lethargy, fever, right upper quadrant discomfort and dark urine. The Hb was 77 g L −1 , bilirubin 266 (0-21 μmol L −1 ), C-reactive protein CRP 125 (0-4 mg L −1 ). She was diagnosed with cholecystitis and commenced on antibiotics. In less than 24 hours her Hb had dropped to 51 g L −1 . At this stage haematology was contacted and the provisional working diagnosis was a delayed haemolytic transfusion reaction (DHTR).Lactate dehydrogenase (LDH) was >2000 IU L −1 (240-480 IU L −1 ), reticulocyte count 68 × 10 9 L −1 (10-100 × 10 9 ) and haptoglobin was <0·08 g/L (0.3-2.0 g/L). The direct antiglobulin test (DAT) was moderately positive against IgG 3+ and anti C3d 2+. Pre-transfusion red cell immunology detected the presence of a historical anti E, post-transfusion anti-Jkb and anti-Lua were detected by indirect antiglobulin test (IAT). The eluate revealed anti-Jkb and anti-Lua by IAT. On review of the pre-transfusion units, two of four packed red cell units were phenotyped and shown to be Jkb+ve and the remaining two were Lua+ve.The Hb continued to drop and was 44 g L −1 the following day. The patient became increasingly reticulocytopenic with a reticulocyte count of 13 × 10 9 L −1 and it was felt that the DHTR had triggered hyperhaemolysis with a drop in Hb below pre-transfusion baseline.

P hiladelphia (Ph)-negative myeloproliferative neoplasms (MPN) are acquired hematologic diseases with increased production of mature blood cells. They include polycythemia vera (PV), essential thrombocythemia (ET) and myelofibrosis (MF). The most frequent molecular abnormality found in Ph negative MPN is JAK2V617F, an activating mutation of JAK2 which is responsible for constitutive signaling of various cytokine receptors. Arterial and venous thromboses are the main complications of these diseases and are responsible for high rates of morbidity and mortality. Of note there is a disproportionate incidence of thrombosis at unusual sites including splanchnic vein thrombosis. 1 Splanchnic vein thromboses (SVT) involve one or more abdominal veins, the two most frequent are Portal Vein Thrombosis (PVT) and Budd Chiari Syndrome (BCS). Pathophysiology of thrombosis in MPN is complex and involves abnormalities in blood cells, plasma factors, and endothelial cells (ECs). Several groups, using different techniques, have shown JAK2V617F expression in endothelial cells (Supplemental Fig. 1, http://links.lww.com/HS/ A79). Using laser capture microdissection, JAK2V617F was demonstrated in ECs from hepatic venules in 2 of 3 patients with PV and BCS. 2 JAK2V617F endothelial cells were demonstrated in microdissected splenic capillaries and in ECs cultured from splenic vein in patients with myelofibrosis but without SVT. 3 Although these teams performed experiments to ensure that the DNA they obtained originated from ECs, it is difficult to completely rule out a possible contamination by blood cells. Analysis of endothelial progenitor cells, specifically endothelial colony forming cells (ECFCs), is an alternative way to look for JAK2V617F ECs. Indeed, ECFCs are reported to be the only "true" endothelial progenitor cells, as they are the only ones able to generate blood vessels in vivo: they display clonogenic potential, endothelial but not myeloid cell surface markers, and pronounced postnatal vascularisation ability in vivo. 4,5 ECFCs are a unique tool to investigate endothelial molecular dysfunction in disease, as they give access to endothelial cells from patients in a non-invasive way and a promising tool for vascular regenerative approaches and gene therapy. 6 Yoder et al studied 11 JAK2V617F MPN patients and reported 3 JAK2V617F ECFCs derived from only 1 of 11 patients. Of note, this patient presented with thrombosis and later developed PV. 4 In another study, the JAK2V617F mutation was not detected in any of 75 ECFCs obtained from 57 patients with JAK2V617F MPN but no thrombosis. 7 Teofili et al reported JAK2V617F ECFCs in 5 of 22 MPN patients, all with thrombotic complications including 1 with BCS and 1 with PVT. 8 Lastly, 4 of 5 JAK2V617F-positive patients with BCS but without overt MPN had JAK2V617F ECFCs cultured from the bone marrow. 9 Taken together, these results suggest that the presence of JAK2V617F ECFCs in patients is associated with thrombosis, even in the absence of overt MPN. Our groups have previously demonstr...

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Introduction: Myeloproliferative neoplasms (MPN) account for the majority of non-cirrhotic and non-malignant Splanchnic vein thrombosis (SVT). SVT comprises extrahepatic portal vein obstruction (EHPVO), Budd-Chiari syndrome (BCS), mesenteric vein thrombosis (MVT) and splenic vein thrombosis (SpVT). 30% of EHPVO and 45% BCS are attributable to MPN. Portal hypertension (PH) is a major complication of SVT and hepatic and splenic elastography is increasingly used as a non-invasive tool for the characterization of hepatic fibrosis and PH. We had already established in 17 patients with chronic liver disease (CLD) that SS was the only predictor of clinically significant PH (CSPH) with an AUROC of 0.908, SE=0.45, p<0.0001, 95% CI 0.821-0.996, Cut-off 44.3 kPa, sensitivity 88%, specificity 85%. We wished to explore the role of tissue stiffness in characterizing splenomegaly in MPN patients with SVT. Methods: As part of an observational study of patients with MPN-SVT (Mascot study) from September 2015 we assessed 18 patients with MPN-SVT for spleen stiffness (SS) and spleen size (SSz) using point shear wave elastography (ElastoPQ Phillips Healthcare system). 14 patients had measurements at two time points 3-8 months apart (median 4.5m). Their clinical and radiologic details are presented in Table 1. SVT was diagnosed 1-16 years prior to the investigations (median 5 years). Patients were treated with LMWH and warfarin. Most patients also received Aspirin at the outset and 2/14 patients had thrombolysis in the acute phase. Review of SVT with imaging by CT/MR was undertaken at 6-12 monthly intervals. MPN was diagnosed on the basis of blood and bone marrow morphology and molecular analysis. 1 patient had CALR mutation, the others JAK2V617F mutation. Treatment included venesection, Hydroxycarbamide, Pegylated Interferon and Ruxolitinib. Results: 8/14 were male, median age 45 years. All patients had splenomegaly at baseline. All patients showed stable or improved appearances of the site of thrombus with patent TIPS on follow-up imaging. 9/14 were on MPN directed medication; median time between commencing medication and 1st SS measurement was 3 months (range -3m to 7 yrs) including 1 patient who commenced Ruxolitinib 3 months after 1st assessment but 7 months before the 2nd assessment (patient 12). In 6/14 patients SS worsened (pts 1-6, Table 1), SSz was stable or worse. 4/6 had TIPS and 4/6 had cytoreductive treatment including 2 receiving Ruxolitinib. In 6 patients SS reduced along with a reduction in SSz (pts 9-14). 2 had TIPS and 5/6 had cytoreductive treatment including 4 receiving Ruxolitinib. Patients with increasing SS over time also had microcytic erythrocytosis that persisted over the period of measurement. Patients with improving SS had improvement in the MCV leading to normal values of RBC and MCV (Fig 1). Conclusions: In this small pilot study on a cohort of well characterised MPN-SVT patients we have assessed SS and considered clinical variables affecting this. This study shows that 1. Spleen elastography provides a novel method of characterising the spleen. In patients with CLD it correlates well with clinically significant PH. 2. All patients with MPN-SVT have residual splenomegaly 3. Patients had no recurrence of the SVT after adequate anticoagulation was instituted. 4. More patients with reduction in SS received JAK2 inhibitor drugs. 5. Reduction in SS is not a consistent feature of PH reduction via TIPS. 6. Persistent microcytic erythrocytosis is seen in the patients with worsening spleen stiffness and improvement in patients with improving stiffness. 7. The dynamics of splenomegaly in these patients remains unclear. Discussion: TIPS reduces portal pressure and in PH related to CLD and thereby reduces SSz. In our patients this has not been a consistent result. Previous studies have shown a reduction in SSz with Ruxolitinib. In our patients the reduction is size and stiffness is noted in patients on Ruxolitinib/Pegylated Interferon but it is not consistent. This lack of response in some patients occurs despite normalisation /improvement of counts. The persistence of splenomegaly with abnormal stiffness in the face of TIPS and cytoreduction is puzzling and worthy of longitudinal studies using elastography which may offer valuable insights into the role and behaviour of the spleen in these disorders. Figure Figure. Disclosures Sekhar: Novartis: Research Funding.

Complex surgery associated with major hemorrhage presents particular risks for Jehovah's Witnesses who do not accept transfusion of blood products. Intraoperative use of two cell saver machines simultaneously can maximize the yield of salvaged blood from both the operative field and from washed surgical swabs and can potentially be life‐saving.