Transfusion in the mechanically ventilated patient

Targeting mast cell activation alleviates anti-MHC I antibody and LPS-induced TRALI in mice by pharmacologically blocking the TLR3 and MAPK pathway

Transfusion-related lung injury (TRALI) poses a significant risk following blood transfusion and remains the primary cause of transfusion-related morbidity and mortality, primarily driven by the activation of immune cells through anti-major histocompatibility complex class I (anti-MHC I) antibody. However, it remains to be defined how immune microenvironmental cue contributes to TRALI. Here, we uncover that activated mast cells within the immune microenvironment promote lung inflammation and injury in antibody-mediated TRALI, both in vitro and in vivo. This was demonstrated by co-culturing lipopolysaccharide (LPS)-pretreated mast cell line with anti-MHC I antibody and establishing a "two-hit" TRALI mouse model through intratracheal injection of LPS followed by tail-vein injection of anti-MHC I antibody. Importantly, mast cell-deficient KitW-sh/W-sh mice exhibited markedly reduced lung inflammation and injury responses in antibody-mediated TRALI compared with wild-type mice. Mechanistically, activation of toll-like receptor 3 (TLR3)/mitogen-activated protein kinase (MAPK) signaling pathway in mast cells contributes to the enhanced production of proinflammatory factors. These excessive proinflammatory factors produced by activated mast cells contribute to lung inflammation and injury in antibody-mediated TRALI. Pharmacologically targeting the TLR3/MAPK pathway to inhibit mast cell activation normalizes the proinflammatory microenvironment and alleviates lung inflammation and injury in the preclinical TRALI mouse model. Overall, we find that activation of mast cells via the TLR3/MAPK pathway contributes to lung inflammation and injury in antibody-mediated TRALI, providing novel insights into its underlying mechanisms. Furthermore, targeting activated mast cells and the associated pathway offers potential therapeutic strategies for antibody-mediated TRALI.

LASSO-Based Machine Learning Algorithm for Prediction of PICS Associated with Sepsis

Introduction

This study aims to establish a comprehensive, multi-level approach for tackling tropical diseases by proactively anticipating and managing Persistent Inflammation, Immunosuppression, and Catabolism Syndrome (PICS) within the initial 14 days of Intensive Care Unit (ICU) admission. The primary objective is to amalgamate a diverse array of indicators and pathogenic microbial data to pinpoint pivotal predictive variables, enabling effective intervention specifically tailored to the context of tropical diseases.

Methods

A focused analysis was conducted on 1733 patients admitted to the ICU between December 2016 and July 2019. Utilizing the Least Absolute Shrinkage and Selection Operator (LASSO) regression, disease severity and laboratory indices were scrutinized. The identified variables served as the foundation for constructing a predictive model designed to forecast the occurrence of PICS.

Results

Among the subjects, 13.79% met the diagnostic criteria for PICS, correlating with a mortality rate of 38.08%. Key variables, including red-cell distribution width coefficient of variation (RDW-CV), hemofiltration (HF), mechanical ventilation (MV), Norepinephrine (NE), lactic acidosis, and multiple-drug resistant bacteria (MDR) infection, were identified through LASSO regression. The resulting predictive model exhibited a robust performance with an Area Under the Curve (AUC) of 0.828, an accuracy of 0.862, and a specificity of 0.977. Subsequent validation in an independent cohort yielded an AUC of 0.848.

Discussion

The acquisition of RDW-CV, HF requirement, MV requirement, NE requirement, lactic acidosis, and MDR upon ICU admission emerges as a pivotal factor for prognosticating PICS onset in the context of tropical diseases. This study highlights the potential for significant improvements in clinical outcomes through the implementation of timely and targeted interventions tailored specifically to the challenges posed by tropical diseases.

Intravenous Senescent Erythrocyte Vaccination Modulates Adaptive Immunity and Splenic Complement Production

Targeted delivery of vaccines to the spleen remains a challenge. Inspired by the erythrophagocytotic process in the spleen, we herein report that intravenous administration of senescent erythrocyte-based vaccines profoundly alters their tropism toward splenic antigen-presenting cells (APCs) for imprinting adaptive immune responses. Compared with subcutaneous inoculation, intravenous vaccination significantly upregulated splenic complement expression in vivo and demonstrated synergistic antibody killing in vitro. Consequently, intravenous senescent erythrocyte vaccination produces potent SARS-CoV-2 antibody-neutralizing effects, with potential protective immune responses. Moreover, the proposed senescent erythrocyte can deliver antigens from resected tumors and adjuvants to splenic APCs, thereby inducing a personalized immune reaction against tumor recurrence after surgery. Hence, our findings suggest that senescent erythrocyte-based vaccines can specifically target splenic APCs and evoke adaptive immunity and complement production, broadening the tools for modulating immunity, helping to understand adaptive response mechanisms to senescent erythrocytes better, and developing improved vaccines against cancer and infectious diseases.

Transfusion of female blood in a rat model is associated with red blood cells entrapment in organs

Transfusion of red blood cells (RBCs) has been associated with adverse outcomes. Mechanisms may be related to donor sex and biological age of RBC. This study hypothesized that receipt of female blood is associated with decreased post-transfusion recovery (PTR) and a concomitant increased organ entrapment in rats, related to young age of donor RBCs. Donor rats underwent bloodletting to stimulate production of new, young RBCs, followed by Percoll fractionation for further enrichment of young RBCs based on their low density. Control donors did not undergo these procedures. Male rats received either a (biotinylated) standard RBC product or a product enriched for young RBCs, derived from either male or female donors. Controls received saline. Organs and blood samples were harvested after 24 hours. This study found no difference in PTR between groups, although only the group receiving young RBCs from females failed to reach a PTR of 75%. Receipt of both standard RBCs and young RBCs from females was associated with increased entrapment of donor RBCs in the lung, liver, and spleen compared to receiving blood from male donors. Soluble ICAM-1 and markers of hemolysis were higher in recipients of female blood compared to control. In conclusion, transfusing RBCs from female donors, but not from male donors, is associated with trapping of donor RBCs in organs, accompanied by endothelial activation and hemolysis.

Transfusion increased skin blood flow when initially low in volume-resuscitated patients without acute bleeding

Background

Alterations in skin blood flow is a marker of inadequate tissue perfusion in critically ill patients after initial resuscitation. The effects of red blood cell transfusions (RBCT) on skin perfusion are not described in this setting. We evaluated the effects of red blood cell transfusions on skin tissue perfusion in critically ill patients without acute bleeding after initial resuscitation.

Methods

A prospective observational study included 175 non-bleeding adult patients after fluid resuscitation requiring red blood cell transfusions. Using laser Doppler, we measured finger skin blood flow (SBF) at skin basal temperature (SBFBT), together with mean arterial pressure (MAP), heart rate (HR), hemoglobin (Hb), central venous pressure (CVP), lactate, and central or mixed venous oxygen saturation before and 1 h after RBCT. SBF responders were those with a 20% increase in SBFBT after RBCT.

Results

Overall, SBFBT did not significantly change after RBCT [from 79.8 (4.3-479.4) to 83.4 (4.9-561.6); p = 0.67]. A relative increase equal to or more than 20% in SBFBT after RBCT (SBF responders) was observed in 77/175 of RBCT (44%). SBF responders had significantly lower SBFBT [41.3 (4.3-279.3) vs. 136.3 (6.5-479.4) perfusion units; p < 0.01], mixed or central venous oxygen saturation (62.5 ± 9.2 vs. 67.3% ± 12.0%; p < 0.01) and CVP (8.3 ± 5.1 vs. 10.3 ± 5.6 mmHg; p = 0.03) at baseline than non-responders. SBFBT increased in responders [from 41.3 (4.3-279.3) to 93.1 (9.8-561.6) perfusion units; p < 0.01], and decreased in the non-responders [from 136.3 (6.5-479.4) to 80.0 (4.9-540.8) perfusion units; p < 0.01] after RBCT. Pre-transfusion SBFBT was independently associated with a 20% increase in SBFBT after RBCT. Baseline SBFBT had an area under receiver operator characteristic of 0.73 (95% CI, 0.68-0.83) to predict SBFBT increase; A SBFBT of 73.0 perfusion units (PU) had a sensitivity of 71.4% and a specificity of 70.4% to predict SBFBT increase after RBCT. No significant differences in SBFBT were observed after RBCT in different subgroup analyses.

Conclusion

The skin blood flow is globally unaltered by red blood cell transfusions in non-bleeding critically ill patients after initial resuscitation. However, a lower SBFBT at baseline was associated with a relative increase in skin tissue perfusion after RBCT.

Transfusion-associated adverse events incidence and severity after the implementation of an active hemovigilance program with 24 h follow-up. A prospective cohort study

BACKGROUND

Hemovigilance (HV) is usually based on voluntary reports (passive HV). Our aim is to ascertain credible incidence, severity, and mortality of transfusion-associated adverse events (TAAEs) using an active HV program.

STUDY DESIGN AND METHODS

Prospective cohort study to estimate transfusion risk after 46,488 transfusions in 5830 patients, using an active HV program with follow-up within the first 24 h after transfusion. We compared these results to those with the previously established passive HV program during the same 30 months of the study. We explored factors associated with the occurrence of TAAEs using generalized estimating equations models.

RESULTS

With the active HV program TAAEs incidence was 57.3 (95% CI, 50.5-64.2) and mortality 1.1 (95% CI, 0.13-2.01) per 10,000 transfusions. Incidence with the new surveillance model was 14.0 times higher than with the passive. Most events occurred when transfusions had already finished (60.2%); especially pulmonary events (80.4%). Three out of five deaths and 50.3% of severe TAAEs were pulmonary. In the multivariate analysis surgical patients had half TAAEs risk when compared to medical patients (OR, 0.53; 95% CI, 0.34-0.78) and women had nearly twice the risk of a pulmonary event compared to men (OR, 1.84; 95% CI, 1.03-3.32). Patient's age, blood component type, or blood component shelf-life were unrelated to TAAEs risk.

DISCUSSION

Active hemovigilance programs provide additional data which may lead to better recognition and understanding of TAAEs and their frequency and severity.

Acute respiratory distress syndrome: causes, pathophysiology, and phenotypes

Acute respiratory distress syndrome (ARDS) is a common clinical syndrome of acute respiratory failure as a result of diffuse lung inflammation and oedema. ARDS can be precipitated by a variety of causes. The pathophysiology of ARDS is complex and involves the activation and dysregulation of multiple overlapping and interacting pathways of injury, inflammation, and coagulation, both in the lung and systemically. Mechanical ventilation can contribute to a cycle of lung injury and inflammation. Resolution of inflammation is a coordinated process that requires downregulation of proinflammatory pathways and upregulation of anti-inflammatory pathways. The heterogeneity of the clinical syndrome, along with its biology, physiology, and radiology, has increasingly been recognised and incorporated into identification of phenotypes. A precision-medicine approach that improves the identification of more homogeneous ARDS phenotypes should lead to an improved understanding of its pathophysiological mechanisms and how they differ from patient to patient.

RBC Transfusion in Venovenous Extracorporeal Membrane Oxygenation: A Multicenter Cohort Study

OBJECTIVES

In the general critical care patient population, restrictive transfusion regimen of RBCs has been shown to be safe and is yet implemented worldwide. However, in patients on venovenous extracorporeal membrane oxygenation, guidelines suggest liberal thresholds, and a clear overview of RBC transfusion practice is lacking. This study aims to create an overview of RBC transfusion in venovenous extracorporeal membrane oxygenation.

DESIGN

Mixed method approach combining multicenter retrospective study and survey.

SETTING

Sixteen ICUs worldwide.

PATIENTS

Patients receiving venovenous extracorporeal membrane oxygenation between January 2018 and July 2019.

INTERVENTIONS

None.

MEASUREMENTS AND MAIN RESULTS

The primary outcome was the proportion receiving RBC, the amount of RBC units given daily and in total. Furthermore, the course of hemoglobin over time during extracorporeal membrane oxygenation was assessed. Demographics, extracorporeal membrane oxygenation characteristics, and patient outcome were collected. Two-hundred eight patients received venovenous extracorporeal membrane oxygenation, 63% male, with an age of 55 years (45-62 yr), mainly for acute respiratory distress syndrome. Extracorporeal membrane oxygenation duration was 9 days (5-14 d). Prior to extracorporeal membrane oxygenation, hemoglobin was 10.8 g/dL (8.9-13.0 g/dL), decreasing to 8.7 g/dL (7.7-9.8 g/dL) during extracorporeal membrane oxygenation. Nadir hemoglobin was lower on days when a transfusion was administered (8.1 g/dL [7.4-9.3 g/dL]). A vast majority of 88% patients received greater than or equal to 1 RBC transfusion, consisting of 1.6 U (1.3-2.3 U) on transfusion days. This high transfusion occurrence rate was also found in nonbleeding patients (81%). Patients with a liberal transfusion threshold (hemoglobin > 9 g/dL) received more RBC in total per transfusion day and extracorporeal membrane oxygenation day. No differences in survival, hemorrhagic and thrombotic complication rates were found between different transfusion thresholds. Also, 28-day mortality was equal in transfused and nontransfused patients.

CONCLUSIONS

Transfusion of RBC has a high occurrence rate in patients on venovenous extracorporeal membrane oxygenation, even in nonbleeding patients. There is a need for future studies to find optimal transfusion thresholds and triggers in patients on extracorporeal membrane oxygenation.

Transfusion strategies in bleeding critically ill adults: a clinical practice guideline from the European Society of Intensive Care Medicine

PURPOSE

To develop evidence-based clinical practice recommendations regarding transfusion practices and transfusion in bleeding critically ill adults.

METHODS

A taskforce involving 15 international experts and 2 methodologists used the GRADE approach to guideline development. The taskforce addressed three main topics: transfusion support in massively and non-massively bleeding critically ill patients (transfusion ratios, blood products, and point of care testing) and the use of tranexamic acid. The panel developed and answered structured guideline questions using population, intervention, comparison, and outcomes (PICO) format.

RESULTS

The taskforce generated 26 clinical practice recommendations (2 strong recommendations, 13 conditional recommendations, 11 no recommendation), and identified 10 PICOs with insufficient evidence to make a recommendation.

CONCLUSIONS

This clinical practice guideline provides evidence-based recommendations for the management of massively and non-massively bleeding critically ill adult patients and identifies areas where further research is needed.

Measuring potassium level in packed red blood cells before using: Word of caution for congenital cardiac surgery

BACKGROUND AND AIM OF THE STUDY

Transfusion-associated hyperpotassemia is a serious complication of packed red blood cell (PRBC) transfusion after congenital cardiac surgery. Our study aimed to identify risk factors and potential preventive measures of transfusion-associated hyperpotassemia in neonates and infants after congenital cardiac surgery.

METHODS

Pediatric patients who underwent congenital cardiac surgery and need transfusion were enrolled in this prospective study. The potassium concentration of PRBC was checked from the sample taken from the segment. The volume of transfusion, age of PRBC, potassium concentration of unit were recorded. The estimated increment of potassium level in patients after PRBC transfusion was calculated.

RESULTS

Seventy-four individual patients, 95 distinct transfusions, 112 blood products were evaluated. The mean age of the blood unit was 3.8 ± 1.4 days. The mean potassium concentration in the PRBCs was 9.9 ± 2.4 mmol/L. A weak correlation was observed between the potassium value of the PRBC and the age of PRBC (p = 0.049, r = 0.2, y = 0.24 × x + -0.68). There was a weak correlation between the potassium value of PRBCs and the age of the unit (p < 0.001, r = 0.37, y = 2.8 × x + -3.6).

CONCLUSIONS

Before transfusion, even PRBC is fresh, measuring the potassium level of PRBC and the potassium that will be given to the pediatric patient with transfusion can prevent transfusion-related hyperpotassemia and related complications. Otherwise, high potassium levels, which may be overlooked despite being fresh, may cause serious complications, even cardiac arrest, especially in neonates and infants.

Transfusion-related respiratory complications in intensive care: A diagnosis challenge

Transfusion-related respiratory complications can be challenging to diagnose especially in mechanically-ventilated patients in the intensive care unit (ICU) due to the concurrent respiratory symptoms associated with the patients' primary diagnoses. In this narrative review, transfusion-related respiratory complications, including transfusion-associated dyspnea (TAD), transfusion-related acute lung injury (TRALI), transfusion-associated circulatory overload (TACO), and transfusion-related allergic reaction (TRAR), are briefly presented in light of the recent consensus or experts' definitions; and the diagnosis issues for ICU patients are discussed. Acute respiratory failure occurring during, or within 6 to 24hours, of transfusion might be a transfusion-related respiratory complication. The recent updated definitions for TRALI and TACO should assist clinicians to differentiate between possible diagnoses. The issues for ICU clinicians are first to recognize the acute respiratory deterioration and the possible causality between the deterioration and blood transfusion and secondly to make the proper diagnosis. This remains challenging for mechanically-ventilated patients. Clinical assessment to identify ICU patients at particular risk of transfusion-related respiratory complications and non-invasive investigation tools could be beneficial and may help to remind clinicians to be alert to the link between transfusion and worsening of respiratory symptoms in these vulnerable critically ill patients.

Factors Influencing Implementation of Blood Transfusion Recommendations in Pediatric Critical Care Units

Purpose: Risks of red blood cell transfusion may outweigh benefits for many patients in Pediatric Intensive Care Units (PICUs). The Transfusion and Anemia eXpertise Initiative (TAXI) recommendations seek to limit unnecessary and potentially harmful transfusions, but use has been variable. We sought to identify barriers and facilitators to using the TAXI recommendations to inform implementation efforts. Materials and Methods: The integrated Promoting Action on Research Implementation in Health Services (iPARIHS) framework guided semi-structured interviews conducted in 8 U.S. ICUs; 50 providers in multiple ICU roles completed interviews. Adapted Framework analysis, a form of content analysis, used the iPARIHS innovation, recipient, context and facilitation constructs and subconstructs to categorize data and identify patterns as well as unique informative statements. Results: Providers perceived that the TAXI recommendations would reduce transfusion rates and practice variability, but adoption faced challenges posed by attitudes around transfusion and care in busy and complex units. Development of widespread buy-in and inclusion in implementation, integration into workflow, designating committed champions, and monitoring outcomes data were expected to enhance implementation. Conclusions: Targeted activities to create buy-in, educate, and plan for use are necessary for TAXI implementation. Recognition of contextual challenges posed by the PICU environment and an approach that adjusts for barriers may optimize adoption.