Red Blood Cell Transfusion Guided by Hemoglobin Only or Integrating Perfusion Markers in Patients Undergoing Cardiac Surgery: A Systematic Review and Meta-Analysis With Trial Sequential Analysis
Antonio Putaggio, Stefano Tigano, Alessandro Caruso, Luigi La Via, Filippo Sanfilippo
Abstract
ObjectiveStrategies for red blood cell (RBC) transfusion in patients undergoing cardiac surgery have been traditionally anchored to hemoglobin (Hb) targets. A more physiological approach would consider markers of organ hypoperfusion.DesignWe conducted a systematic review and meta-analysis with trial sequential analysis of randomized controlled trials (RCTs).SettingCardiac surgery.ParticipantsAdult patients.InterventionRBC transfusion targeting only Hb levels compared with strategies combining Hb values with markers of organ hypoperfusion.Measurements and main resultsPrimary outcomes were number of RBC units transfused, number of patients transfused at least once, and average number of transfusions. Secondary outcomes were postoperative complications, intensive care (ICU) and hospital length of stay, and mortality. Only two RCTs were included (n=257 patients),both used central venous oxygen saturation (ScvO2) as marker of organ hypoperfusion (cut-off: <70% or ≤65%). A transfusion protocol combining Hb and ScvO2 reduced the overall number of RBC units transfused (RR:1.57 [1.33;1.85];p<0.0001, I2=0%) and number of patients transfused at least once (RR:1.33 [1.16;1.53];p<0.0001, I2=41%), but not the average number of transfusions (MD:0.18 [-0.11;0.47];p=0.24, I2=66%), with moderate certainty of evidence. Mortality (RR:1.29, [0.29;5.77];p=0.73, I2=0%), ICU length-of-stay (MD:-0.06 [-0.58;0.46]; p=0.81, I2=0%), hospital length-of-stay (MD:-0.05 [-1.49;1.39];p=0.95, I2=0%) and all postoperative complications were not affected.ConclusionsIn adult patients undergoing cardiac surgery, a restrictive protocol integrating Hb values with a marker of organ hypoperfusion (ScvO2) reduces both the number of RBC units transfused and the number of patients transfused at least once, without apparent signals of harm. These findings are preliminary and warrants further multicentric research.