Liberal or restrictive transfusion for VV ECMO

The findings reported in The Lancet Respiratory Medicine by Gennaro Martucci and colleagues1Martucci G Schmidt M Agerstrand C et al.Transfusion practice in patients receiving VV ECMO (PROTECMO): a prospective, multicentre, observational study.Lancet Respir Med. 2023; 11: 245-255Summary Full Text Full Text PDF Scopus (9) Google Scholar in the PROTECMO study lend further support to the purported harms of blood transfusion in patients who are undergoing venovenous extracorporeal membrane oxygenation (VV ECMO). Blood transfusions are done to enhance oxygen delivery. VV ECMO can lead to haemolysis, the release of free haemoglobin, which reduces the ability of the blood to carry oxygen and leads to abnormalities in blood viscosity, platelet aggregation, and red blood cell deformability, from which a patient can take months to recover.2Dufour N Radjou A Thuong M Hemolysis and plasma free hemoglobin during extracorporeal membrane oxygenation support: from clinical implications to laboratory details.ASAIO J. 2020; 66: 239-246Crossref PubMed Scopus (39) Google Scholar A risk of anoxia might arise because of these haemorheologic abnormalities. Could blood transfusion to achieve a higher haemoglobin level potentially correct some of these abnormalities? It is crucial to do a confirmatory study before a change in transfusion practice occurs. It is not very accurate to use haemoglobin concentration as a transfusion trigger. Red blood cell mass indexed to a patient's size might provide a more accurate indicator of a sufficient haemoglobin concentration.3Otto JM Plumb JOM Clissold E et al.Hemoglobin concentration, total hemoglobin mass and plasma volume in patients: implications for anemia.Haematologica. 2017; 102: 1477-1485Crossref PubMed Scopus (52) Google Scholar If the blood volume is normalised, this value will represent a patient's haemoglobin concentration, offering a more accurate indication of haemoglobin levels than haemoglobin concentration alone. Additionally, clinical indicators of red blood cell transfusion can be improved. Although haemoglobin level has been frequently used as an objective measure of anaemia and tissue hypoxia, cardiac output is the most important determinant of tissue oxygenation. Near-infrared spectroscopy could provide a non-invasive way to gauge cerebral tissue oxygenation.4Crispin P Forwood K Near infrared spectroscopy in anemia detection and management: a systematic review.Transfus Med Rev. 2021; 35: 22-28Crossref PubMed Scopus (4) Google Scholar, 5Kredel M Lubnow M Westermaier T et al.Cerebral tissue oxygenation during the initiation of venovenous ECMO.ASAIO J. 2014; 60: 694-700Crossref PubMed Scopus (25) Google Scholar This method is also more effective at detecting tissue oxygenation than is central venous oxygen saturation measurement, which cannot show global oxygen use. Future large clinical trials should consider the clinical utility of near-infrared spectroscopy as an individual and physiological trigger for blood transfusion compared with arbitrarily fixed haemoglobin thresholds. We declare no competing interests. We gratefully acknowledge financial support from the Talent Introduction Plan of the Lanzhou University Second Hospital (YJRCKYQDJ202102) and the Key Talent Project in Gansu Province (202117). Transfusion practice in patients receiving VV ECMO (PROTECMO): a prospective, multicentre, observational studyDuring VV ECMO, there was no universally accepted threshold for transfusion, but PRBC transfusion was invariably associated with lower mortality only when done with haemoglobin concentration of less than 7 g/dL. Full-Text PDF