Summary: As COVID–19 disease escalates globally, optimising patient outcome during this catastrophic healthcare crisis is the number one priority. The principles of patient blood management are fundamental strategies to improve patient outcomes and should be given high priority in this crisis situation. The aim of this expert review is to provide clinicians and healthcare authorities with information regarding how to apply established principles of patient blood management during the COVID–19 pandemic. In particular, this review considers the impact of the COVID–19 pandemic on blood supply and specifies important aspects of donor management. We discuss how preventative and control measures implemented during the COVID–19 crisis could affect the prevalence of anaemia, and highlight issues regarding the diagnosis and treatment of anaemia in patients requiring elective or emergency surgery. In addition, we review aspects related to patient blood management of critically ill patients with known or suspected COVID–19, and discuss important alterations of the coagulation system in patients hospitalised due to COVID–19. Finally, we address special considerations pertaining to supply‐demand and cost‐benefit issues of patient blood management during the COVID–19 pandemic.

Summary: Anaemia is common in patients with end‐stage liver disease. Pre‐operative anaemia is associated with greater mortality after major surgery. We analysed the association of pre‐operative anaemia (World Health Organization classification) with survival and complications after orthotopic liver transplantation using Cox and logistic regression models. We included patients undergoing their first orthotopic liver transplantation between 2004 and 2016. Out of 599 included patients, 455 (76%) were anaemic before transplantation. Pre‐operative anaemia was not associated with the survival of 485/599 (81%) patients to 1 year after liver transplantation, OR (95% CI ) 1.04 (0.64–1.68), p = 0.88. Pre‐operative anaemia was associated with higher rates of intra‐operative blood transfusions and acute postoperative kidney injury on multivariable analysis, OR (95% CI ) 1.70 (0.82–2.59) and 1.72 (1.11–2.67), respectively, p < 0.001 for both. Postoperative renal replacement therapy was associated with pre‐operative anaemia on univariate analysis, OR (95% CI ) 1.87 (1.11–3.15), p = 0.018.

Experimental and volunteer studies have reported pulmonary vasoconstriction during transfusion of packed red blood cells (PRBCs) stored for prolonged periods. The primary aim of this study was to evaluate whether transfusion of PRBCs stored over 21 days (standard-issue, siPRBCs) increases pulmonary artery pressure (PAP) to a greater extent than transfusion of PRBCs stored for less then 14 days (fresh, fPRBCs) in critically ill patients following cardiac surgery. The key secondary aim was to assess whether the pulmonary vascular resistance index (PVRI) increases after transfusion of siPRBCs to a greater extent than after transfusion of fPRBCs. The study was performed as a single-center, double-blinded, parallel-group, randomized clinical trial. Leukoreduced PRBCs were transfused while continuously measuring hemodynamic parameters. Systemic concentrations of syndecan-1 were measured to assess glycocalyx injury. After randomizing 19 patients between January 2014 and June 2016, the study was stopped due to protracted patient recruitment. Of 19 randomized patients, 11 patients were transfused and included in statistical analyses. Eight patients were excluded prior to transfusion, 6 patients received fPRBCs (10±3 storage days), whereas 5 patients received siPRBCs (33±4 storage days). The increase in PAP (7±3 vs. 2±2 mmHg, P = 0.012) was greater during transfusion of siPRBCs than during transfusion of fPRBCs. In addition, the change in PVRI (150±89 vs. -4±37 dyn·s·cm^-5·m², P = 0.018) was greater after transfusion of siPRBCs than after transfusion of fPRBCs. The increase in PAP correlated with the change of systemic syndecan-1 concentrations at the end of transfusion (R = 0.64,P = 0.034). Although this study is underpowered and results require verification in larger clinical trials, our findings suggest that transfusion of siPRBCs increases PAP and PVRI to a greater extent than transfusion of fPRBCs in critically ill patients following cardiac surgery. Glycocalyx injury might contribute to pulmonary vasoconstriction associated with transfusion of stored blood.

The product of the concentrations of urinary tissue inhibitor of metalloproteinases-2 and insulin-like growth factor binding protein-7 (urinary [TIMP-2] × [IGFBP-7]) has been suggested as biomarker for early detection of acute kidney injury (AKI) in various clinical settings. However, the performance of urinary [TIMP-2] × [IGFBP-7] to predict AKI has never been assessed in patients undergoing orthotopic liver transplantation (OLT). Thus, the aim of this study was to assess the early predictive value of urinary [TIMP-2] × [IGFBP-7] for the development of AKI after OLT. In this observational study, urinary [TIMP-2] × [IGFBP-7] was measured in samples from adult OLT patients. AKI was diagnosed and classified according to KDIGO criteria. Areas under the receiver operating curves (AUC) were calculated to assess predictive values of urinary [TIMP-2] × [IGFBP-7] for the development of AKI. Forty patients (mean age 55 ± 8 years) were included. Twenty-eight patients (70%) developed AKI stage 1, 2, or 3 within 48 h after OLT. Urinary [TIMP-2] × [IGFBP-7] was not predictive for AKI at the end of OLT (AUC: 0.54, CI [0.32–0.75], P = 0.72), at day 1 (AUC: 0.60, CI [0.41–0.79], P = 0.31), or day 2 after OLT (AUC: 0.63, CI [0.46–0.8], P = 0.18). Based on our results, routine clinical use of urinary [TIMP-2] × [IGFBP-7] cannot be recommended for risk assessment of AKI in patients undergoing OLT.

Numerous observations indicate that red blood cells (RBCs) affect T-cell activation and proliferation. We have studied effects of packed RBCs (PRBCs) on T-cell-receptor (TCR) signaling and the molecular mechanisms whereby (P)RBCs modulate T-cell activation. In line with previous reports, PRBCs attenuated the expression of T-cell activation markers CD25 and CD69 upon co-stimulation via CD3/CD28. In addition, T-cell proliferation and cytokine expression were markedly reduced when T-cells were stimulated in presence of PRBCs. Inhibitory activity of PRBCs required direct cell-cell contact and intact PRBCs. The production of activation-induced cellular reactive oxygen species (ROS), which act as second messengers in T-cells, was completely abrogated to levels of unstimulated T-cells in presence of PRBCs. Phosphorylation of the TCR-related zeta-chain and thus proximal TCR signal transduction was unaffected by PRBCs, ruling out mechanisms based on secreted factors and steric interaction restrictions. In large part, downstream signaling events requiring ROS for full functionality were affected, as confirmed by an untargeted mass spectrometry-based phosphoproteomics approach. PRBCs inhibited T-cell activation more efficiently than treatment with 1 mM of the anti-oxidant N-acetyl cysteine. Taken together, our data imply that inflammation-related radical reactions are modulated by PRBCs. These immunomodulating effects may be responsible for clinical observations associated with transfusion of PRBCs.

Objective: The aim of this retrospective study was to assess the prevalence of anaemia in a cohort of patients undergoing elective general surgery at a university hospital. Furthermore, the authors investigated the influence of anaemia on short-term and long-term postoperative outcome. Background: Awareness of the negative impact of preoperative anaemia on perioperative morbidity and mortality is rising. Anaemia is a potentially modifiable factor, and its therapy might improve patient outcome in elective surgery. Nevertheless, patients with preoperative anaemia frequently undergo elective surgery without receiving adequate preoperative treatment. Methods: In this single-centre cohort study, the authors analyzed 6908 adult patients who underwent elective general surgery. Patients undergoing day-clinic surgery were excluded. In all patients, preoperative haemoglobin concentration and haematocrit was available. Results: Of all patients analyzed, 32.9% were anaemic (21.0% mild, 11.8% moderate, 1.1% severe). Median time to last follow-up was 5.2 years. During the whole study period, 27.1% of patients died (1.2% died during the hospital stay); median time to death was 1.3 years. Patients with preoperative anaemia had significantly higher mortality rates (P<0.001) and a higher probability of postoperative complications (P<0.001). Likewise, receiving blood transfusions was associated with a higher risk of death (P<0.001). Conclusion: This retrospective single-centre analysis confirmed that preoperative anaemia is common, and is a significant risk factor for unfavourable postoperative outcome. As anaemia is a modifiable risk factor, the implementation of a patient blood management concept is crucial to reduce detrimental postoperative events associated with anaemia.