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An impressive effect of the infection with SARS-Co-19 is the impairment of oxygen uptake due to lung injury. The reduced oxygen diffusion may potentially be counteracted by an increase in oxygen affinity of hemoglobin. However, hypoxia and anemia associated with COVID-19 usually decrease oxygen affinity due to a rise in [2,3-bisphosphoglycerate]. As such, COVID-19 related changes in the oxygen dissociation curve may be critical for oxygen uptake and supply, but are hard to predict. A Pubmed search lists 14 publications on oxygen affinity in COVID-19. While some investigations show no changes, three large studies found an increased affinity that was related to a good prognosis. Exact causes remain unknown. The cause of the associated anemia in COVID-19 is under discussion. Erythrocytes with structural alterations of membrane and cytoskeleton have been observed, and virus binding to Band 3 and also to ACE2 receptors in erythroblasts has been proposed. COVID-19 presentation is moderate in many subjects suffering from sickle cell disease. A possible explanation is that COVID-19 counteracts the unfavorable large right shift of the oxygen dissociation curve in these patients. Under discussion for therapy are mainly affinity-increasing drugs.
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SESSION TITLE: Drug-Induced and Associated Critical Care Cases Posters 2 SESSION TYPE: Case Report Posters PRESENTED ON: 10/19/2022 12:45 pm - 01:45 pm INTRODUCTION: Methemoglobinemia is an increase in methemoglobin (mHb) level characterized by functional anemia and tissue hypoxia. It can be caused by congenital enzymes deficiencies, but it is usually acquired. Dapsone, an oxidizing agent, is a medication commonly associated with acquired methemoglobinemia (1). We describe the diagnosis and management of a COVID-19 patient with acquired methemoglobinemia due to Dapsone. CASE PRESENTATION: 84-year-old female with history of MPO-ANCA vasculitis with renal involvement, CKD4 and anemia of chronic disease presented with shortness of breath, lethargy and weakness. Initially, the patient was saturating (SpO2) 80% on room air and was placed on 4L nasal cannula (NC) with improvement to 92%. CT of the chest showed b/l GGOs consistent with atypical pneumonia and patient tested positive for COVID-19. About 4 months prior, she had received 2 doses of Rituximab and on high steroid therapy that was tapered to 5mg of prednisone daily. She has been on Trimethoprim/Sulfamethoxazole for PJP prophylaxis, but due to hyperkalemia the medication was stopped. After confirming no G6PD deficiency, she was started on Dapsone 100mg daily. During hospitalization, she was given dexamethasone 6 mg daily and Dapsone was continued. On hospital stay day 6, a rapid response was called after oxygen dropped to 78% while walking on 6L NC. She was placed on high flow NC 100% and SpO2 went up to 90%. An arterial blood gas (ABG) was then obtained showing pO2 of 334, oxyhemoglobin (oxyHb) of 83 and mHb of 17.4. The SpO2-PaO2 gap and elevated mHb lead to the diagnosis of Dapsone-induced methemoglobinemia. Dapsone was discontinued. Patient received a one-time dose of 1mg/kg IV of methylene blue. One hour later her dyspnea had improved and was on 3L NC. Repeat ABG showed improvement of oxyHb (98) and decreased mHb (2.2). DISCUSSION: Physiologically, mHb is less than 1% of total Hb (1) and occurs when the iron in the porphyrin group of heme is oxidized from ferrous to the ferric form (2). Ferric heme binds oxygen irreversibly causing a left shift of the oxygen-hemoglobin dissociation curve. Clinical presentation tends to correlate with mHb levels, and it varies from being asymptomatic to fatigue, dyspnea, confusion, seizure, cyanosis resistant to oxygen therapy (mHb > 15%) and death. Methylene blue is safe and can be consider when mHb level is greater than 10 to 20% (2). Methylene blue was administer to our patient given the presence of COVID (leaving patient more susceptible to medication-induced methemoglobinemia (3)) and chronic anemia which made her less likely to tolerate state of reduced oxygen delivery. CONCLUSIONS: The diagnosis of methemoglobinemia is a rare cause of hypoxemia that is often overlooked. In patients with risk factors (COVID, medication exposure) a high index of suspicion is needed when interpreting an ABG (SpO2-PaO2 gap) for correct diagnosis and appropriate treatment. Reference #1: Toker, Ibrahim, et al. "Methemoglobinemia Caused by Dapsone Overdose: Which Treatment Is Best?” Turkish Journal of Emergency Medicine, vol. 15, no. 4, Dec. 2015, pp. 182–184, 10.1016/j.tjem.2014.09.002. Accessed 31 Aug. 2020. Reference #2: Cortazzo JA, Lichtman AD. Methemoglobinemia: a review and recommendations for management. J Cardiothorac Vasc Anesth. 2014 Aug;28(4):1043-7. doi: 10.1053/j.jvca.2013.02.005. Epub 2013 Aug 13. PMID: 23953868. Reference #3: Naymagon, Leonard, et al. "The Emergence of Methemoglobinemia amidst the COVID -19 Pandemic.” American Journal of Hematology, vol. 95, no. 8, 3 June 2020, 10.1002/ajh.25868. Accessed 3 Mar. 2021. DISCLOSURES: No relevant relationships by Mileydis Alonso No relevant relationships by Samantha Gillenwater No relevant relationships by Christine Girard No relevant relationships by Sikandar Khan No relevant relationships by Jose Rivera No relevant relationships by Frederick Ross
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Background & Aim: Blood is one of the most vital resources in modern medicine. Blood transfusions have become an essential and often lifesaving procedure for accidents, during surgery, for patients with chronic disorders such as anemia, sickle cell disease, cancer, and myriad other circumstances. However, despite the rapidly growing world population, the availability of healthy blood donors is declining with aging populations. Furthermore, natural and man- made calamities often produce sudden and concentrated shocks in demand, which strains global supply chains. The COVID-19 pandemic has demonstrated this issue on a global scale by reducing the number of blood drives and donations, resulting in 39% of blood centers in the United States being left with only one- to two-day supplies, and a 50% drop of blood units collected in countries such as Zambia. Additionally, storage limitations of 42 days for donor blood limits stock availability during peak demand. Large-scale generation of universal red blood cells (RBCs) from O-ve human induced pluripotent stem cells (hiPSCs) offers the potential to alleviate blood shortages and provide a secure year-round supply. Mature iPSC-derived RBCs and reticulocytes could also find important applications in research in malaria and COVID-19 studies. (Figure Presented) Fig. 1 ( 700). Methods, Results & Conclusion: In this study, we have reprogrammed hiPSC from CD34+ O-ve cells and demonstrated the smallscale generation of high-density cultures of erythroblasts in a stirred perfusion bioreactor system. Twenty O-ve iPSC lines were derived, screened, and characterized for their ability to differentiate towards the erythroid lineage, showing high expression of mesoderm (KDR+, 64.9%), hematopoietic (CD34+/CD45+, 68.4%;CD34+/CD43+, 84.9%), and erythroid markers (CD235a+, 83,5%), and were able to undergo enucleation in vitro. Using the best clones, we were able to achieve erythroblast peak cell density of 34.7 million cells/mL with 92.2% viability in an Applikon perfusion bioreactor using an ultrasound system (Sonosep) to concentrate cells while removing waste media. This resulted in a cumulative-fold expansion of over 1,500 after 29 days of culture. Cells carried O2 effectively as demonstrated by hemoglobin dissociation curves. The perfusion culture platform paves the way for controlled high-density bioreactor culture for the generation of RBCs.
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COVID-19 hinders oxygen transport to the consuming tissues by at least two mechanisms: In the injured lung, saturation of hemoglobin is compromised, and in the tissues, an associated anemia reduces the volume of delivered oxygen. For the first problem, increased hemoglobin oxygen affinity [left shift of the oxygen dissociation curve (ODC)] is of advantage, for the second, however, the contrary is the case. Indeed a right shift of the ODC has been found in former studies for anemia caused by reduced cell production or hemolysis. This resulted from increased 2,3-bisphosphoglycerate (2,3-BPG) concentration. In three investigations in COVID-19, however, no change of hemoglobin affinity was detected in spite of probably high [2,3-BPG]. The most plausible cause for this finding is formation of methemoglobin (MetHb), which increases the oxygen affinity and thus apparently compensates for the 2,3-BPG effect. However, this "useful effect" is cancelled by the concomitant reduction of functional hemoglobin. In the largest study on COVID-19, even a clear left shift of the ODC was detected when calculated from measurements in fresh blood rather than after equilibration with gases outside the body. This additional "in vivo" left shift possibly results from various factors, e.g., concentration changes of Cl-, 2,3-BPG, ATP, lactate, nitrocompounds, glutathione, glutamate, because of time delay between blood sampling and end of equilibration, or enlarged distribution space including interstitial fluid and is useful for O2 uptake in the lungs. Under discussion for therapy are the affinity-increasing 5-hydroxymethyl-2-furfural (5-HMF), erythropoiesis-stimulating substances like erythropoietin, and methylene blue against MetHb formation.