Incidence, risk factors, and outcome of transfusion-associated circulatory overload in a mixed intensive care unit population: a nested case-control study

CE: Recognizing Transfusion-Associated Circulatory Overload

ABSTRACT

Transfusion-associated circulatory overload (TACO) is the leading cause of transfusion-related deaths in the United States, accounting for more than 30% of fatalities reported to the Food and Drug Administration between 2016 and 2020. However, TACO is widely considered to be an underdiagnosed and underreported complication of blood transfusions, and its exact incidence is unknown. One of the reasons for this is a lack of recognition of TACO and its signs and symptoms, especially as the definition of TACO has been updated twice since 2018 without full dissemination to nurses, who are responsible for bedside care of patients during and following blood transfusions. This article seeks to bridge this gap by discussing the updated definitions and signs and symptoms of TACO, as well as the management of this treatable blood transfusion reaction.

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.

Novel computational methods on electronic health record yields new estimates of transfusion-associated circulatory overload in populations enriched with high-risk patients

BACKGROUND

Transfusion-associated circulatory overload (TACO) is a severe adverse reaction (AR) contributing to the leading cause of mortality associated with transfusions. As strategies to mitigate TACO have been increasingly adopted, an update of prevalence rates and risk factors associated with TACO using the growing sources of electronic health record (EHR) data can help understand transfusion safety.

STUDY DESIGN AND METHODS

This retrospective study aimed to provide a timely and reproducible assessment of prevalence rates and risk factors associated with TACO. Novel natural language processing methods, now made publicly available on GitHub, were developed to extract ARs from 3178 transfusion reaction reports. Other patient-level data were extracted computationally from UCSF EHR between 2012 and 2022. The odds ratio estimates of risk factors were calculated using a multivariate logistic regression analysis with case-to-control matched on sex and age at a ratio of 1:5.

RESULTS

A total of 56,208 patients received transfusions (total 573,533 units) at UCSF during the study period and 102 patients developed TACO. The prevalence of TACO was estimated to be 0.2% per patient (102/total 56,208). Patients with a history of coagulopathy (OR, 1.36; 95% CI, 1.04-1.79) and transplant (OR, 1.99; 95% CI, 1.48-2.68) were associated with increased odds of TACO.

DISCUSSION

While TACO is a serious AR, events remained rare, even in populations enriched with high-risk patients. Novel computational methods can be used to find and continually surveil for transfusion ARs. Results suggest that patients with history or presence of coagulopathy and organ transplant should be carefully monitored to mitigate potential risks of TACO.

Differential impact of transfusion guidelines on blood transfusion practices within a health network

Whether clinical practice guidelines have a significant impact on practice is unclear. The effect of guideline recommendations on clinical practice often a lags behind the date of publication. We evaluated by means of a data-driven approach if and when the guidelines on red blood cell transfusions (RBCTs) issued by Swiss Smarter Medicine in 2016 had an impact on RBCTs practice within a hospital network, where awareness of guidelines was promoted mainly among internal medicine specialties. Data on RBCTs performed in a Swiss hospital network from January 2014 to April 2021 were analyzed by hospital site and specialty to assess whether guidelines led to a decrease in inappropriate RBCTs. RBCTs were defined as "inappropriate" if patients had a hemoglobin level ≥ 70 g/L without or ≥ 80 g/L with significant cardiovascular comorbidities. Changes in the rate of inappropriate transfusions were analyzed with an advanced statistical approach that included generalized additive models. Overall prior to March 2017 there were more inappropriate than appropriate RBCTs, but after October 2017 the opposite could be observed. A change-point in the time trend was estimated from transfusion data to occur in the time interval between March and October 2017. This change was mainly driven by practice changes in the medical wards, while no significant change was observed in the critical care, surgical and oncology wards. Change in practice varied by hospital site. In conclusion, our results show that a significant change in the RBCTs practice at the hospital level occurred approximately 18 months after national guidelines were issued.

Standardized reporting of pulmonary transfusion complications: Development of a model reporting form and flowchart

BACKGROUND

Pulmonary complications of blood transfusion, including transfusion-related acute lung injury (TRALI), transfusion-associated circulatory overload (TACO), and transfusion-associated dyspnea, are generally underdiagnosed and under-reported. The international TRALI and TACO definitions have recently been updated. Currently, no standardized pulmonary transfusion reaction reporting form exists and most of the hemovigilance forms have not yet incorporated the updated definitions. We developed a harmonized reporting form, aimed at improved data collection on pulmonary transfusion reactions for hemovigilance and research purposes by developing a standardized model reporting form and flowchart.

MATERIALS AND METHODS

Using a modified Delphi method among an international, multidisciplinary panel of 24 hemovigilance experts, detailed recommendations were developed for a standardized model reporting form for pulmonary complications of blood transfusion. Two Delphi rounds, including scoring systems, took place and several subsequent meetings were held to discuss issues and obtain consensus. Additionally, a flowchart was developed incorporating recently published redefinitions of pulmonary transfusion reactions.

RESULTS

In total, 17 participants completed the first questionnaire (70.8% response rate) and 14 participants completed the second questionnaire (58.3% response rate). According to the results from the questionnaires, the standardized model reporting form was divided into various subcategories: general information, patient history and transfusion characteristics, reaction details, investigations, treatment and supportive care, narrative, and transfused product.

CONCLUSION

In this article, we present the recommendations from a global group of experts in the hemovigilance field. The standardized model reporting form and flowchart provide an initiative that may improve data collected to address pulmonary transfusion reactions.

Can volume-reduced plasma products prevent transfusion-associated circulatory overload in a two-hit animal model?

BACKGROUND AND OBJECTIVES

Transfusion-associated circulatory overload (TACO) is a pulmonary transfusion complication and a leading cause of transfusion-related morbidity and mortality. Volume overload and rising hydrostatic pressure as a consequence of transfusion are seen as the central pathway leading to TACO. A possible preventative measure for TACO could be the use of low-volume blood products like volume-reduced lyophilized plasma. We hypothesize that volume-reduced lyophilized plasma decreases circulatory overload leading to a reduced pulmonary capillary pressure and can therefore be an effective strategy to prevent TACO.

MATERIALS AND METHODS

A validated two-hit animal model in rats with heart failure was used. Animals were randomized to receive 4 units of either solvent-detergent pooled plasma (SDP) as control, standard volume lyophilized plasma (LP-S) or hyperoncotic volume-reduced lyophilized plasma (LP-VR). The primary outcome was the difference between pre-transfusion and post-transfusion left ventricular end-diastolic pressure (ΔLVEDP). Secondary outcomes included markers for acute lung injury.

RESULTS

LVEDP increased in all randomization groups following transfusion. The greatest elevation was seen in the group receiving LP-VR (+11.9 mmHg [5.9-15.6]), but there were no significant differences when compared to groups receiving either LP-S (+6.3 mmHg [2.9-13.4], p = 0.29) or SDP (+7.7 mmHg [4.5-10.5], p = 0.55). There were no significant differences in markers for acute lung injury, such as pulmonary wet/dry weight ratios, lung histopathology scores or PaO₂ /FiO₂ ratio between the three groups.

CONCLUSION

Transfusion with hyperoncotic volume-reduced plasma did not attenuate circulatory overload compared to standard volume plasma and was therefore not an effective preventative strategy for TACO in this rat model.

Plasma transfusion practices: A multicentre electronic audit

BACKGROUND AND OBJECTIVES

Plasma is often transfused to patients with bleeding or requiring invasive procedures and with abnormal tests of coagulation. Chart audits find half of plasma transfusions unnecessary, resulting in avoidable complications and costs. This multicentre electronic audit was conducted to determine the proportion of plasma transfused without an indication and/or at a sub-therapeutic dose.

METHODS

Data were extracted on adult inpatients in 2017 at five academic sites from the hospital electronic chart, laboratory information systems and the Canadian Institute for Health Information Discharge Abstract Database. Electronic criteria for plasma transfusion outside recommended indications were: (1) international normalized ratio (INR) < 1.5 with no to moderate bleeding; (2) INR ≥ 1.5, with no to mild bleeding and no planned procedures; and (3) no INR before or after plasma infusion. Sub-therapeutic dose was defined as ≤2 units transfused.

RESULTS

In 1 year, 2590 patients received 6088 plasma transfusions encompassing 11,490 units of plasma occurred at the five sites. 77.7% of events were either outside indications or under-dosed. Of these, 34.8% of plasma orders had no indication identified, and 62% of these occurred in non-bleeding patients and no planned procedure with an isolated elevated INR. 70.7% of transfusions were under-dosed. Most plasma transfusions occurred in the intensive care unit or the operating room. Inter-hospital variability in peri-transfusion testing and dosing was observed.

CONCLUSION

The majority of plasma transfusions are sub-optimal. Local hospital culture may be an important driver. Electronic audits, with definitions employed in this study, may be a practical alternative to costly chart audits.

Adverse transfusion reactions and what we can do

INTRODUCTION

Transfusions of blood and blood components have inherent risks and the ensuing adverse reactions. It is very important to understand the adverse reactions of blood transfusion comprehensively for ensuring the safety of any future transfusions.

AREAS COVERED

According to the time of onset, adverse reactions of blood transfusion are divided into immediate and delayed transfusion reactions. In acute transfusion reactions, timely identification and immediate cessation of transfusion is critical. Vigilance is required to distinguish delayed responses or reactions that present non-specific signs and symptoms. In this review, we present the progress of mechanism, clinical characteristics and management of commonly encountered transfusion reactions.

EXPERT OPINION

The incidence of many transfusion-related adverse events is decreasing, but threats to transfusion safety are always emerging. It is particularly important for clinicians and blood transfusion staff to recognize the causes, symptoms and treatment methods of adverse blood transfusion reactions to improve the safety. In the future, at-risk patients will be better identified and can benefit from more closely matched blood components.

Plasma Transfusion in Septic Shock—A Secondary Analysis of a Retrospective Single-Center Cohort

In sepsis, both beneficial and detrimental effects of fresh frozen plasma (FFP) transfusion have been reported. The aim of this study was to analyze the indication for and effect of FFP transfusion in patients with septic shock. We performed a secondary analysis of a retrospective single-center cohort of all patients treated for septic shock at the interdisciplinary surgical intensive care unit (ICU) of the Heidelberg University Hospital. Septic shock was defined according to sepsis-3 criteria. To assess the effects of FFP administration in the early phase of septic shock, we compared patients with and without FFP transfusion during the first 48 h of septic shock. Patients who died during the first 48 h of septic shock were excluded from the analysis. Primary endpoints were 30- and 90-day mortality. A total of 261 patients were identified, of which 100 (38.3%) received FFP transfusion within the first 48 h after septic shock onset. The unmatched analysis showed a trend toward higher 30- and 90-d mortality in the FFP group (30 d: +7% p = 0.261; 90 d: +11.9% p = 0.061). In the propensity-matched analysis, 30- and 90-day mortality were similar between groups. Plasma administration did not influence fluid or vasopressor need, lactate levels, ICU stay, or days on a ventilator. We found no significant harm or associated benefit of FFP use in the early phase of septic shock. Finally, plasma should only be used in patients with a strong indication according to current recommendations, as a conclusive evaluation of the risk-benefit ratio for plasma transfusion in septic shock cannot be made based on the current data.

Prophylactic furosemide to prevent transfusion-associated circulatory overload: a randomized controlled study in rats

Transfusion-associated circulatory overload (TACO) is the leading cause of transfusion related morbidity and mortality. The only treatment is empirical use of furosemide. Our aim was to investigate if furosemide can prevent TACO. A randomized controlled trial was performed using a previously validated two-hit rat model for TACO. Volume incompliance was induced (first hit) in anemic, anesthetized Lewis rats. Rats were randomized to placebo, low-dose (5 mg kg-1) or high-dose (15 mg kg-1) furosemide-administered prior to transfusion (second-hit) and divided over two doses. Primary outcome was change in left-ventricular end-diastolic pressure (∆LVEDP) pre- compared to post-transfusion. Secondary outcomes included changes in preload, afterload, contractility and systemic vascular resistance, as well as pulmonary outcomes. Furosemide treated animals had a significantly lower ∆LVEDP compared to placebo (p = 0.041), a dose-response effect was observed. ∆LVEDP in placebo was median + 8.7 mmHg (IQR 5.9-11), + 3.9 (2.8-5.6) in the low-dose and 1.9 (- 0.6 to 5.6) in the high-dose group. The effect of furosemide became apparent after 15 min. While urine output was significantly higher in furosemide treated animals (p = 0.03), there were no significant changes in preload, afterload, contractility or systemic vascular resistance. Furosemide rapidly and dose-dependently decreases the rise in hydrostatic pulmonary pressure following transfusion, essential for preventing TACO.

Oncology Patients Who Develop Transfusion-Associated Circulatory Overload: An Observational Study

BACKGROUND

Transfusion-associated circulatory overload (TACO) is a largely preventable transfusion complication that results in significant morbidity and mortality. Cancers, related treatments, and comorbidities are among the factors that can predispose patients to TACO, but currently there are limited data on this topic in the literature.

METHODS

We collected data retrospectively from the electronic health records of 93 adult patients with cancer who met Centers for Disease Control and Prevention (CDC) criteria for TACO from July 1, 2019, through October 31, 2020. The parameters we studied included demographics, comorbidities, treatment modalities, transfusion practices, and outcomes. We summarized data by means and ranges for continuous variables, and proportions for categorical variables.

RESULTS

During the study period, the incidence of TACO among oncology patients was 0.84 per 1000 transfusions (95% CI, 0.68-1.02), representing 6.6% of all reactions. This percentage is high, compared with 1%-6% among other populations. Unique characteristics such as hematology malignancy (75.3%), receipt of cardiotoxic chemotherapy (87.1%), pneumonia (57.0%), preexisting oxygen use (59.1%), dyspnea (62.4%), hypertension (55.9%), renal insufficiency (46.2%), daily use of corticosteroids (43.0%), daily use of diuretics (40.9%), daily use of beta-blockers (36.6%), and elevated NT-proBNP (33.3%) were frequently observed in these group of oncology patients.

CONCLUSIONS

Our study indicates that oncology patients have unique factors that may lead to diagnosis of TACO. Developing appropriate guidelines that apply to oncology patients, in addition to those set forth by the CDC, should be considered. Implementation by ordering healthcare providers of a tools that can predict TACO can help in early recognition and mitigation of TACO.

Clinical Benefits of Early Concurrent Use of Cryoprecipitate and Plasma Compared With Plasma Only in Bleeding Trauma Patients

OBJECTIVES

The effectiveness of cryoprecipitate (Cryo) in trauma has not been well established; the benefits of Cryo might have been overestimated in previous studies since the difference in the total amount of administered clotting factors was not considered. We aimed to evaluate the benefits of the concurrent use of Cryo in combination with fresh frozen plasma (FFP) for bleeding trauma patients.

DESIGN

Retrospective cohort study.

SETTING

The American College of Surgeons Trauma Quality Improvement Program database between 2015 and 2019.

PATIENTS

Patients who received greater than or equal to 5 units of packed RBCs and at least 1 unit of FFP within the first 4 hours after arrival to a hospital were included and dichotomized according to whether Cryo was used within the first 4 hours of hospital arrival.

INTERVENTION

None.

MEASUREMENTS AND MAIN RESULTS

The outcomes of patients treated with Cryo and FFP were compared with those treated with FFP only using propensity score-matching analysis. The dose of administered clotting factors in each group was balanced. The primary outcome was inhospital mortality, and the secondary outcome was the occurrence rate of adverse events. A total of 24,002 patients (Cryo+FFP group: 6,018; FFP only group: 17,984) were eligible for analysis, of whom 4,852 propensity score-matched pairs were generated. Significantly lower inhospital mortality (1,959 patients [40.4%] in the Cryo+FFP group vs 2,142 patients [44.1%] in the FFP only group; odds ratio [OR], 0.86; 95% CI, 0.79-0.93) was observed in the Cryo+FFP group; no significant difference was observed in the occurrence rate of adverse events (1,857 [38.3%] vs 1,875 [38.6%]; OR, 1.02; 95% CI, 0.94-1.10). Several sensitivity analyses showed similar results.

CONCLUSIONS

Cryo use combined with FFP was significantly associated with reduced mortality in bleeding trauma patients. Future randomized controlled trials are warranted to confirm these results.

Autologous red blood cell transfusion does not result in a more profound increase in pulmonary capillary wedge pressure compared to saline in critically ill patients: A randomized crossover trial

Background and Objectives

Transfusion‐associated circulatory overload (TACO) is a major cause of severe transfusion‐related morbidity. Transfusion of red blood cells (RBCs) has been shown to induce hydrostatic pressure overload. It is unclear which product‐specific factors contribute. We set out to determine the effect of autologous RBC transfusion versus saline on pulmonary capillary wedge pressure (PCWP) change.

Materials and Methods

In a randomized crossover trial, patients who had undergone coronary bypass surgery were allocated to treatment post‐operatively in the intensive care unit with either an initial 300 ml autologous RBC transfusion (salvaged during surgery) or 300 ml saline infusion first, followed by the other. Primary outcome was the difference in PCWP change. Secondary outcome measures were the difference in extra‐vascular lung water index (EVLWI) and pulmonary vascular permeability index (PVPI).

Results

Change in PCWP was not higher after autologous RBC transfusion compared to saline (ΔPCWP 0.3 ± 0.4 vs. 0.1 ± 0.4 mmHg). ΔEVLWI and ΔPVPI were significantly decreased after autologous RBC transfusion compared to saline (ΔEVLWI −1.6 ± 0.6 vs. 0.2 ± 0.4, p = 0.02; ΔPVPI −0.3 ± 0.1 vs. 0.0 ± 0.1, p = 0.01). Haemodynamic variables and colloid osmotic pressure were not different for autologous RBC transfusion versus saline.

Conclusion

Transfusion of autologous RBCs did not result in a more profound increase in PCWP compared to saline. RBC transfusion resulted in a decrease of EVLWI and PVPI compared to saline. Our data suggest that transfusing autologous RBCs may lead to less pulmonary oedema compared to saline. Future studies with allogeneic RBCs are needed to investigate other factors that may mediate the increase of PCWP, resulting in TACO.

Differential effects of speed and volume on transfusion-associated circulatory overload: A randomized study in rats

BACKGROUND AND OBJECTIVES

Transfusion-associated circulatory overload (TACO) is the primary cause of transfusion-related mortality. Speed and volume of transfusion are major risk factors. The aim of this study was to investigate the interaction of red blood cell (RBC) transfusion speed and volume on the development of TACO.

MATERIALS AND METHODS

A validated model for TACO in anaemic Lewis rats with an acute myocardial infarction was used. The effect on pulmonary hydrostatic pressure of one, two or four units of packed RBCs transfused in either 30 or 60 min was evaluated (3.3-26.6 ml·kg-1 ·hr-1 ). Pulmonary capillary pressure was measured as left ventricular end-diastolic pressure (LVEDP). Cardiac stress biomarkers atrial natriuretic-peptide (ANP) and N-terminal pro-brain natriuretic peptide (NT-proBNP) were measured 1-h post-transfusion.

RESULTS

Thirty animals were included (n = 5 per group). Transfusion of RBCs increased LVEDP in a volume-dependent manner (ΔLVEDP [mmHg]: -0.95, +0.50, +6.26, p < 0.001). Fast transfusion increased overall ΔLVEDP by +3.5 mmHg and up to +11.8 mmHg in the four units' group (p = 0.016). Doubling transfusion speed increased ΔLVEDP more than doubling volume in the larger volume groups. No difference in ANP or NT-proBNP were seen in high transfusion volume or groups.

CONCLUSION

Transfusion volume dose-dependently increased LVEDP, with speed of transfusion rapidly elevating LVEDP at higher transfusion volumes. ANP and NT-proBNP were not impacted by transfusion volume or speed in this model. TACO is seen as purely volume overload, however, this study emphasizes that limiting transfusion speed, as a modifiable risk factor, might aid in preventing TACO.

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.

A Concise Synopsis of Current Literature and Guidelines on the Practice of Plasma Transfusion

Evidence-based indications for plasma transfusion are limited, and much of the clinical practice relies on expert opinion. This article highlights key studies, meta-analyses, and guidelines for plasma transfusion in adults. The goal is to limit non-evidence-based plasma transfusion that is outside of clinical guideline, because as with all transfusions, the administration of plasma is not without risk. Any intended potential benefit must be appraised against the real risks associated with transfusion. Moving forward, the practice of plasma transfusion would benefit greatly from randomized controlled trials to update and expand the existing guidelines.

The recipe for TACO: A narrative review on the pathophysiology and potential mitigation strategies of transfusion-associated circulatory overload

Transfusion associated circulatory overload (TACO) is one of the leading causes of transfusion related morbidity and mortality. TACO is the result of hydrostatic pulmonary edema following transfusion. However, up to 50% of all TACO cases appear after transfusion of a single unit, suggesting other factors, aside from volume, play a role in its pathophysiology. TACO follows a two-hit model, in which the first hit is an existing disease or comorbidity that renders patients volume incompliant, and the second hit is the transfusion. First hit factors include, amongst others, cardiac and renal failure. Blood product factors, setting TACO apart from crystalloid overload, include colloid osmotic pressure effects, viscosity, pro-inflammatory mediators and storage lesion byproducts. Differing hemodynamic changes, glycocalyx injury, endothelial damage and inflammatory reactions can all contribute to developing TACO. This narrative review explores pathophysiological mechanisms for TACO, discusses related therapeutic and preventative measures, and identifies areas of interest for future research.

A survey of patient blood management for patients undergoing cardiac surgery in nine European countries

STUDY OBJECTIVE

To describe and compare patient blood management (PBM) practices in cardiac surgery in nine European countries and identify the main risk factors for bleeding or transfusion according to the surveyed centres.

DESIGN

We set up an online survey to evaluate PBM practices in two clinical scenarios, risk factors for bleeding or transfusion, and previous experience with antifibrinolytics.

SETTING

This survey was completed by European anesthesiologists in 2019.

PATIENTS

No patients were included in the survey.

INTERVENTION

None.

MEASUREMENTS

We evaluated the degree of implementation of PBM practices in patients undergoing cardiac surgery.

MAIN RESULTS

Ninety-eight of 177 responses (38%) were complete with variable response rates by country. In a non-emergent situation, no respondents would transfuse red cells preoperatively in an anaemic patient, while cell salvage (89%) and antifibrinolytics (82%) would almost always be used. Optimization of Hemoglobin level (36%) and use of off-pump techniques (34%), minimally invasive surgery (25%) and relatively recently-developed CPB technologies such as mini-bypass (32%) and autologous priming (38%), varied greatly across countries. In an emergent clinical situation, topical haemostatic agents would frequently be used (61%). Tranexamic acid (72%) and aprotinin (20%) were the main antifibrinolytics used, with method of administration and dose varying markedly across countries. Five factors were considered to increase risk of bleeding or transfusion by at least 90% of respondents: pre-operative anaemia, prior cardiac surgery, clopidogrel 5 days or less before surgery, use of other P2Y12 inhibitors at any point, and thrombocytopenia <100.10⁹ platelets/mm³.

CONCLUSION

PBM guidelines are not universally implemented in European cardiac surgery centres or countries, resulting in discrepancies in techniques and products used for a given clinical situation.

Frequency and timing of all-cause deaths in visits involving suspected transfusion reactions, and the significance of cardiopulmonary disturbances

BACKGROUND/OBJECTIVES

Transfusion reactions (TRs) may cause or contribute to death. Cardiopulmonary TRs are distressing, and collectively account for most transfusion fatalities, though the degree to which they alter survival more broadly is unclear. Deaths (and their timing) after TRs may provide further insights.

MATERIALS/METHODS

Adult (tri-hospital network) haemovigilance data (2013-2016) recorded referrals with conclusions ranging from unrelated to transfusion (UTR) to entities such as: septic TRs, serologic/haemolytic reactions, transfusion-associated circulatory overload (TACO), transfusion-associated dyspnoea (TAD), transfusion-related acute lung injury (TRALI), allergic transfusion reaction (ATR), and others. For (in- or out-patient) visits involving suspected TRs (VISTRs), all-cause mortalities (% [95% confidence interval]) and associated time-to-death (TTD) (median days, [interquartile range]) were compared. Diagnoses were defined inclusively (possible-to-definite) or strictly (probable-to-definite).

RESULTS

Of 1144 events, rank order VISTR mortality following (possible-to-definite) TRs, and associated TTDs, were led by: DHTR 33% [6-19], 1 death at 123d; TRALI 32% [15-54], 6 deaths: 3d [2-20]; BaCon 21% [14-31], 17 deaths: 10d [3-28]; TACO 18% [12-26], 23 deaths: 16d [6-28]; TAD 17% [11-26]: 18 deaths, 6d [3-12]. Higher-certainty TRs ranked similarly (DHTR 50% [9-91]; BaCon 29% [12-55], 4 deaths: 12d [3-22]; and TACO 25% [16-38], 15 deaths: 21d [6-28]). VISTR mortality after TACO or TRALI significantly exceeded ATR (3·3% [2·4-5·8], P < 0·00001) but was not different from UTR events (P = 0·3).

CONCLUSIONS

Only half of cardiopulmonary TRs constituted high certainty diagnoses. Nevertheless, cardiopulmonary TRs and suspected BaCon marked higher VISTR mortality with shorter TTDs. Short (<1 week) TTDs in TAD, BaCon or TRALI imply either contributing roles in death, treatment refractoriness and/or applicable TR susceptibilities in the dying.

Impact of Perioperative Massive Transfusion on Long Term Outcomes of Liver Transplantation: a Retrospective Cohort Study

Background: Liver transplantation (LT) is associated with a significant risk of intraoperative hemorrhage and massive blood transfusion. However, there are few relevant reports addressing the long-term impacts of massive transfusion (MT) on liver transplantation recipients. Aim: To assess the effects of MT on the short and long-term outcomes of adult liver transplantation recipients. Methods: We included adult patients who underwent liver transplantation at West China Hospital from January 2011 to February 2015. MT was defined as red blood cell (RBC) transfusion of ≥10 units within 48 hours since the application of LT. Preoperative, intraoperative and postoperative information were collected for data analyzing. We used one-to-one propensity-matching to create pairs. Kaplan-Meier survival analysis was used to compare long-term outcomes of LT recipients between the MT and non-MT groups. Univariate and multivariate logistic regression analyses were performed to evaluate the risk factors associated with MT in LT. Results: Finally, a total of 227 patients were included in our study. After propensity score matching, 59 patients were categorized into the MT and 59 patients in non-MT groups. Compared with the non-MT group, the MT group had a higher 30-day mortality (15.3% vs 0, p=0.006), and a higher incidence of postoperative complications, including postoperative pulmonary infection, abdominal hemorrhage, pleural effusion and severe acute kidney injury. Furthermore, MT group had prolonged postoperative ventilation support (42 vs 25 h, p=0.007) and prolonged durations of ICU (12.9 vs 9.5 d, p<0.001) stay. Multivariate COX regression indicated that massive transfusion (OR: 2.393, 95% CI: 1.164-4.923, p=0.018) and acute rejection (OR: 7.295, 95% CI: 2.108-25.246, p=0.02) were significant risk factors affecting long-term survivals of LT patients. The 1-year and 3-year survival rates patients in MT group were 82.5% and 67.3%, respectively, while those of non-MT group were 93.9% and 90.5%, respectively. The MT group exhibited a lower long-term survival rate than the non-MT group (HR: 2.393, 95% CI: 1.164-4.923, p<0.001). Finally, the multivariate logistic regression revealed that preoperative hemoglobin <118 g/L (OR: 5.062, 95% CI: 2.292-11.181, p<0.001) and intraoperative blood loss ≥1100 ml (OR: 3.212, 95% CI: 1.586-6.506, p = 0.001) were the independent risk factor of MT in patients undergoing LT. Conclusion: Patients receiving MT in perioperative periods of LT had worse short-term and long-term outcomes than the non-MT patients. Massive transfusion and acute rejection were significant risk factors affecting long-term survivals of LT patients, and intraoperative blood loss of over 1100 ml was the independent risk factor of MT in patients undergoing LT. The results may offer valuable information on perioperative management in LT recipients who experience high risk of MT.

Plasma Transfusion Practice in Adult Surgical Patients: Systematic Review of the Literature

Background

Plasma transfusions are most commonly used therapeutically for bleeding or prophylactically in non-bleeding patients prior to invasive procedures or surgery. Although plasma transfusions generally seem to decline, plasma usage for indications that lack evidence of efficacy prevail.

Summary

There is wide international, interinstitutional, and interindividual variance regarding the compliance with guidelines based on published references, supported by appropriate testing. There is furthermore a profound lack of evidence from randomized controlled trials comparing the effect of plasma transfusion with that of other therapeutic interventions for most indications, including massive bleeding. The expected benefit of a plasma transfusion needs to be balanced carefully against the associated risk of adverse events. In light of the heterogeneous nature of bleeding conditions and their rapid evolvement over time, fibrinogen and factor concentrate therapy, directed at specific phases of coagulation identified by alternative laboratory assays, may offer advantages over conventional blood product ratio-driven resuscitation. However, their outcome benefit has not been demonstrated in well-powered prospective trials. This systematic review will detail the current evidence base for plasma transfusion in adult surgical patients.

Using arterial-venous oxygen difference to guide red blood cell transfusion strategy

Background

Guidelines recommend a restrictive red blood cell transfusion strategy based on hemoglobin (Hb) concentrations in critically ill patients. We hypothesized that the arterial-venous oxygen difference (A-V O_2diff), a surrogate for the oxygen delivery to consumption ratio, could provide a more personalized approach to identify patients who may benefit from transfusion.

Methods

A prospective observational study including 177 non-bleeding adult patients with a Hb concentration of 7.0–10.0 g/dL within 72 h after ICU admission. The A-V O_2diff, central venous oxygen saturation (ScvO₂), and oxygen extraction ratio (O₂ER) were noted when a patient’s Hb was first within this range. Transfusion decisions were made by the treating physician according to institutional policy. We used the median A-V O_2diff value in the study cohort (3.7 mL) to classify the transfusion strategy in each patient as “appropriate” (patient transfused when the A-V O_2diff > 3.7 mL or not transfused when the A-V O_2diff ≤ 3.7 mL) or “inappropriate” (patient transfused when the A-V O_2diff ≤ 3.7 mL or not transfused when the A-V O_2diff > 3.7 mL). The primary outcome was 90-day mortality.

Results

Patients managed with an “appropriate” strategy had lower mortality rates (23/96 [24%] vs. 36/81 [44%]; p = 0.004), and an “appropriate” strategy was independently associated with reduced mortality (hazard ratio [HR] 0.51 [95% CI 0.30–0.89], p = 0.01). There was a trend to less acute kidney injury with the “appropriate” than with the “inappropriate” strategy (13% vs. 26%, p = 0.06), and the Sequential Organ Failure Assessment (SOFA) score decreased more rapidly (p = 0.01). The A-V O_2diff, but not the ScvO₂, predicted 90-day mortality in transfused (AUROC = 0.656) and non-transfused (AUROC = 0.630) patients with moderate accuracy. Using the ROC curve analysis, the best A-V O_2diff cutoffs for predicting mortality were 3.6 mL in transfused and 3.5 mL in non-transfused patients.

Conclusions

In anemic, non-bleeding critically ill patients, transfusion may be associated with lower 90-day mortality and morbidity in patients with higher A-V O_2diff.

Trial registration

ClinicalTrials.gov, NCT03767127. Retrospectively registered on 6 December 2018.

Volume incompliance and transfusion are essential for transfusion-associated circulatory overload: a novel animal model

BACKGROUND

Transfusion‐associated circulatory overload (TACO) is the predominant complication of transfusion resulting in death. The pathophysiology is poorly understood, but inability to manage volume is associated with TACO, and observational data suggest it is different from simple cardiac overload due to fluids. We developed a two‐hit TACO animal model to assess the role of volume incompliance (“first‐hit”) and studied whether volume overload (“second‐hit”) by red blood cell (RBC) transfusion is different compared to fluids (Ringer's lactate [RL]).

MATERIALS AND METHODS

Male adult Lewis rats were stratified into a control group (no intervention) or a first hit: either myocardial infarction (MI) or acute kidney injury (AKI). Animals were randomized to a second hit of either RBC transfusion or an equal volume of RL. A clinically relevant difference was defined as an increase in left ventricular end‐diastolic pressure (ΔLVEDP) of +4.0 mm Hg between the RBC and RL groups.

RESULTS

In control animals (without first hit) LVEDP was not different between infusion groups (Δ + 1.6 mm Hg). LVEDP increased significantly more after RBCs compared to RL in animals with MI (Δ7.4 mm Hg) and AKI (Δ + 5.4 mm Hg), respectively. Volume‐incompliant rats matched clinical TACO criteria in 92% of transfused versus 25% of RL‐infused animals, with a greater increase in heart rate and significantly higher blood pressure.

CONCLUSION

To our knowledge, this is the first animal model for TACO, showing that a combination of volume incompliance and transfusion is essential for development of circulatory overload. This model allows for further testing of mechanistic factors as well as therapeutic approaches.

Transfusion-related Acute Lung Injury in the Perioperative Patient

Transfusion-related acute lung injury is a leading cause of death associated with the use of blood products. Transfusion-related acute lung injury is a diagnosis of exclusion which can be difficult to identify during surgery amid the various physiologic and pathophysiologic changes associated with the perioperative period. As anesthesiologists supervise delivery of a large portion of inpatient prescribed blood products, and since the incidence of transfusion-related acute lung injury in the perioperative patient is higher than in nonsurgical patients, anesthesiologists need to consider transfusion-related acute lung injury in the perioperative setting, identify at-risk patients, recognize early signs of transfusion-related acute lung injury, and have established strategies for its prevention and treatment.

Risk factors, management and prevention of transfusion-related acute lung injury: a comprehensive update

Introduction: Despite mitigation strategies that include the exclusion of females from plasma donation or the exclusion of females with a history of pregnancy or known anti-leukocyte antibody, transfusion-related acute lung injury (TRALI) remains a leading cause of transfusion-related morbidity and mortality. Areas covered: The definition of TRALI is discussed and re-aligned with the new Berlin Diagnostic Criteria for the acute respiratory distress syndrome (ARDS). The risk factors associated with TRALI are summarized as are the mitigation strategies to further reduce TRALI. The emerging basic research studies that may translate to clinical therapeutics for the prevention or treatment of TRALI are discussed. Expert opinion: At risk patients, including the genetic factors that may predispose patients to TRALI are summarized and discussed. The re-definition of TRALI employing the Berlin Criteria for ARDS will allow for increased recognition and improved research into pathophysiology and mitigation to reduce this fatal complication of hemotherapy.

Transfusion reactions and cognitive aids

PURPOSE OF REVIEW

Although the overall safety of blood transfusion is high, adverse events do still occur. Much research on transfusion reactions was done in nonperioperative patients. Fortunately, important contributions to the perioperative literature have been made in the last several years, specifically in the areas of transfusion-associated circulatory overload and transfusion-related acute lung injury (TRALI).

RECENT FINDINGS

An unfavorable reaction occurs in as many as 1% of transfusions overall, although the risk of death with each unit given is between 0.002 and 0.0005%. Specific, modifiable factors exist, however, of which the anesthesiologist should be aware. A 2017 article by Clifford et al. is the first to examine risk factors and outcomes for transfusion-associated circulatory overload in a high-risk noncardiac surgery population undergoing anesthesia and surgery. In recent years, limiting plasma donors to males only resulted in an approximately 50% decrease in TRALI.

SUMMARY

The current article explores new research on the topics of transfusion-associated circulatory overload and transfusion-related lung injury.

Transfusion-associated circulatory overload and transfusion-related acute lung injury

Transfusion-associated circulatory overload (TACO) and transfusion-related acute lung injury (TRALI) are syndromes of acute respiratory distress that occur within 6 hours of blood transfusion. TACO and TRALI are the leading causes of transfusion-related fatalities, and specific therapies are unavailable. Diagnostically, it remains very challenging to distinguish TACO and TRALI from underlying causes of lung injury and/or fluid overload as well as from each other. TACO is characterized by pulmonary hydrostatic (cardiogenic) edema, whereas TRALI presents as pulmonary permeability edema (noncardiogenic). The pathophysiology of both syndromes is complex and incompletely understood. A 2-hit model is generally assumed to underlie TACO and TRALI disease pathology, where the first hit represents the clinical condition of the patient and the second hit is conveyed by the transfusion product. In TACO, cardiac or renal impairment and positive fluid balance appear first hits, whereas suboptimal fluid management or other components in the transfused product may enable the second hit. Remarkably, other factors beyond volume play a role in TACO. In TRALI, the first hit can, for example, be represented by inflammation, whereas the second hit is assumed to be caused by antileukocyte antibodies or biological response modifiers (eg, lipids). In this review, we provide an up-to-date overview of TACO and TRALI regarding clinical definitions, diagnostic strategies, pathophysiological mechanisms, and potential therapies. More research is required to better understand TACO and TRALI pathophysiology, and more biomarker studies are warranted. Collectively, this may result in improved diagnostics and development of therapeutic approaches for these life-threatening transfusion reactions.

Transfusion-Associated Circulatory Overload: A Clinical Perspective

For 30 years, transfusion-associated circulatory overload (TACO) has been recognized as a serious transfusion complication. Currently, TACO is the leading cause of transfusion-related morbidity and mortality worldwide which occurs in 1% to 12% of at-risk populations. Despite an incomplete understanding of the underlying pathophysiology, TACO is defined as a collection of signs and symptoms of acute pulmonary edema due to circulatory overload occurring within 6 to 12 hours of transfusion. In the past decade, large observational cohort studies resulted in better insight into the associated transfusion risk factors leading to the development of TACO. In this clinical review, we critically analyze the pathogenesis of TACO, associated risk factors, clinical presentation, diagnostic modalities, and treatment options to guide clinicians with early detection of this syndrome and intervention to improve clinical outcomes. Future research should focus on better understanding of the pathogenesis to help advance the field of volume kinetics and endothelial barrier function.

The Pathogenic Involvement of Neutrophils in Acute Respiratory Distress Syndrome and Transfusion-Related Acute Lung Injury

The acute respiratory distress syndrome (ARDS) is a serious and common complication of multiple medical and surgical interventions, with sepsis, pneumonia, and aspiration of gastric contents being common risk factors. ARDS develops within 1 week of a known clinical insult or presents with new/worsening respiratory symptoms if the clinical insult is unknown. Approximately 40% of the ARDS cases have a fatal outcome. Transfusion-related acute lung injury (TRALI), on the other hand, is characterized by the occurrence of respiratory distress and acute lung injury, which presents within 6 h after administration of a blood transfusion. In contrast to ARDS, acute lung injury in TRALI is not attributable to another risk factor for acute lung injury. 'Possible TRALI', however, may have a clear temporal relationship to an alternative risk factor for acute lung injury. Risk factors for TRALI include chronic alcohol abuse and systemic inflammation. TRALI is the leading cause of transfusion-related fatalities. There are no specific therapies available for ARDS or TRALI as both have a complex and incompletely understood pathogenesis. Neutrophils (polymorphonuclear leukocytes; PMNs) have been suggested to be key effector cells in the pathogenesis of both syndromes. In the present paper, we summarize the literature with regard to PMN involvement in the pathogenesis of both ARDS and TRALI based on both human data as well as on animal models. The evidence generally supports a strong role for PMNs in both ARDS and TRALI. More research is required to shed light on the pathogenesis of these respiratory syndromes and to more thoroughly establish the nature of the PMN involvement, especially considering the heterogeneous etiologies of ARDS.