Liberal or restrictive transfusion after cardiac surgery

The Effects of Residual Pump Blood on Patient Plasma Free Haemoglobin Levels Post Cardiac Surgery

At the end of cardiopulmonary bypass, there are invariably several hundred millilitres of residual pump blood in the reservoir, which can either be re-transfused or discarded. The objective of this prospective observational study was to investigate the quality of the residual pump blood, focusing on plasma free haemoglobin (pfHb) and blood cell counts. Fifty-one consecutive patients were included in the study. Forty-nine units of residual pump blood and 58 units of transfused red blood cell (RBC) concentrates were analysed. The mean preoperative pfHb of the patients was 0.057 ± 0.062 g/l, which increased gradually to 0.55 ± 0.36 g/l on arrival in the intensive care unit postoperatively. On the first postoperative day, the mean pfHb had returned to within the normal range. Our data showed that haemoglobin, haematocrit, and erythrocyte counts of residual pump blood were approximately 40% of the values in standardised RBC concentrates. Plasma free haemoglobin was significantly higher in residual pump blood compared to RBC concentrates, and nearly twice as high as the pfHb in patient blood samples taken contemporaneously. Our findings indicate that residual pump blood pfHb levels are markedly higher compared to patients' blood and RBC concentrates, but that its administration does not significantly increase patients' pfHb levels.

Are lower levels of red blood cell transfusion more cost-effective than liberal levels after cardiac surgery? Findings from the TITRe2 randomised controlled trial

OBJECTIVE

To assess the incremental cost and cost-effectiveness of a restrictive versus a liberal red blood cell transfusion threshold after cardiac surgery.

DESIGN

A within-trial cost-effectiveness analysis with a 3-month time horizon, based on a multicentre superiority randomised controlled trial from the perspective of the National Health Service (NHS) and personal social services in the UK.

SETTING

17 specialist cardiac surgery centres in UK NHS hospitals.

PARTICIPANTS

2003 patients aged >16 years undergoing non-emergency cardiac surgery with a postoperative haemoglobin of <9 g/dL.

INTERVENTIONS

Restrictive (transfuse if haemoglobin <7.5 g/dL) or liberal (transfuse if haemoglobin <9 g/dL) threshold during hospitalisation after surgery.

MAIN OUTCOME MEASURES

Health-related quality of life measured using the EQ-5D-3L to calculate quality-adjusted life years (QALYs).

RESULTS

The total costs from surgery up to 3 months were £17 945 and £18 127 in the restrictive and liberal groups (mean difference is -£182, 95% CI -£1108 to £744). The cost difference was largely attributable to the difference in the cost of red blood cells. Mean QALYs to 3 months were 0.18 in both groups (restrictive minus liberal difference is 0.0004, 95% CI -0.0037 to 0.0045). The point estimate for the base-case cost-effectiveness analysis suggested that the restrictive group was slightly more effective and slightly less costly than the liberal group and, therefore, cost-effective. However, there is great uncertainty around these results partly due to the negligible differences in QALYs gained.

CONCLUSIONS

We conclude that there is no clear difference in the cost-effectiveness of restrictive and liberal thresholds for red blood cell transfusion after cardiac surgery.

TRIAL REGISTRATION NUMBER

ISRCTN70923932; Results.

Restrictive versus Liberal Transfusion Strategy in the Perioperative and Acute Care Settings

Background

Blood transfusions are associated with morbidity and mortality. However, restrictive thresholds could harm patients less able to tolerate anemia. Using a context-specific approach (according to patient characteristics and clinical settings), the authors conducted a systematic review to quantify the effects of transfusion strategies.

Methods

The authors searched MEDLINE, EMBASE, CENTRAL, and grey literature sources to November 2015 for randomized controlled trials comparing restrictive versus liberal transfusion strategies applied more than 24 h in adult surgical or critically ill patients. Data were independently extracted. Risk ratios were calculated for 30-day complications, defined as inadequate oxygen supply (myocardial, cerebral, renal, mesenteric, and peripheral ischemic injury; arrhythmia; and unstable angina), mortality, composite of both, and infections. Statistical combination followed a context-specific approach. Additional analyses explored transfusion protocol heterogeneity and cointerventions effects.

Results

Thirty-one trials were regrouped into five context-specific risk strata. In patients undergoing cardiac/vascular procedures, restrictive strategies seemed to increase the risk of events reflecting inadequate oxygen supply (risk ratio [RR], 1.09; 95% CI, 0.97 to 1.22), mortality (RR, 1.39; 95% CI, 0.95 to 2.04), and composite events (RR, 1.12; 95% CI, 1.01 to 1.24—3322, 3245, and 3322 patients, respectively). Similar results were found in elderly orthopedic patients (inadequate oxygen supply: RR, 1.41; 95% CI, 1.03 to 1.92; mortality: RR, 1.09; 95% CI, 0.80 to 1.49; composite outcome: RR, 1.24; 95% CI, 1.00 to 1.54—3465, 3546, and 3749 patients, respectively), but not in critically ill patients. No difference was found for infections, although a protective effect may exist. Risk estimates varied with successful/unsuccessful transfusion protocol implementation.

Conclusions

Restrictive transfusion strategies should be applied with caution in high-risk patients undergoing major surgery.

Massive haemorrhage in liver transplantation: Consequences, prediction and management

From its inception the success of liver transplantation has been associated with massive blood loss. Massive transfusion is classically defined as > 10 units of red blood cells within 24 h, but describing transfusion rates over a shorter period of time may reduce the potential for survival bias. Both massive haemorrhage and transfusion are associated with increased risk of mortality and morbidity (need for dialysis/surgical site infection) following liver transplantation although causality is difficult to prove due to the observational design of most trials. The blood loss associated with liver transplantation is multifactorial. Portal hypertension secondary to cirrhosis results in extensive collateral circulation, which can bleed during hepatectomy particular if portal pressures are increased. Avoiding volume loading and maintenance of a low central venous pressure together with the use of vasopressors have been shown to reduce blood loss and transfusion during liver transplantation, but may increase the risk of renal impairment post-operatively. Coagulation defects may be present pre-transplant, but haemostasis is often re-balanced due to a deficit in both pro- and anti-coagulation factors. Further derangement of haemostasis may develop in the anhepatic and neohepatic phases due to absent hepatic metabolic function, hyperfibrinolysis and platelet sequestration in the donor liver. Point-of-care tests of coagulation such as the viscoelastic tests rotation thromboelastometry/thromboelastometry allow and more accurate and rapid assessment of these derangements in coagulation and guide the use of factor replacement and antifibrinolytics. Transfusion protocols guided by these tests have been shown to reduce transfusion rates compared with conventional coagulation tests, but have not shown improvements in mortality or morbidity. Pre-operative factors associated with massive transfusion include previous surgery, re-do transplantation, the aetiology and severity of liver disease. Intra-operatively the use of piggy-back technique and avoiding veno-veno bypass has been shown to reduced blood loss.

Clinical Decision Support Reduces Overuse of Red Blood Cell Transfusions: Interrupted Time Series Analysis

BACKGROUND

Red blood cell transfusion is the most common procedure in hospitalized patients in the US. Growing evidence suggests that a sizeable percentage of these transfusions are inappropriate, putting patients at significant risk and increasing costs to the health care system.

METHODS

We performed a retrospective quasi-experimental study from November 2008 until November 2014 in a 576-bed tertiary care hospital. The intervention consisted of an interruptive clinical decision support alert shown to a provider when a red blood cell transfusion was ordered in a patient whose most recent hematocrit was ≥21%. We used interrupted time series analysis to determine whether our primary outcome of interest, rate of red blood cell transfusion in patients with hematocrit ≥21% per 100 patient (pt) days, was reduced by the implementation of the clinical decision support tool. The rate of platelet transfusions was used as a nonequivalent dependent control variable.

RESULTS

A total of 143,000 hospital admissions were included in our analysis. Red blood cell transfusions decreased from 9.4 to 7.8 per 100 pt days after the clinical decision support intervention was implemented. Interrupted time series analysis showed that significant decline of 0.05 (95% confidence interval [CI], 0.03-0.07; P < .001) units of red blood cells transfused per 100 pt days per month was already underway in the preintervention period. This trend accelerated to 0.1 (95% CI, 0.09-0.12; P < .001) units of red blood cells transfused per 100 pt days per month following the implementation of the clinical decision support tool. There was no statistical change in the rate of platelet transfusion resulting from the intervention.

CONCLUSIONS

The implementation of an evidence-based clinical decision support tool was associated with a significant decline in the overuse of red blood cell transfusion. We believe this intervention could be easily replicated in other hospitals using commercial electronic health records and a similar reduction in overuse of red blood cell transfusions achieved.

Motivating Factors and Potential Deterrents to Blood Donation in High School Aged Blood Donors

Background. To ensure an adequate supply of blood, collection centers must design campaigns that successfully recruit and maintain an active donor pool. Understanding factors that motivate and deter individuals from donating may help centers develop targeted recruitment campaigns. These factors among high school aged blood donors have not yet been fully investigated. Study Design and Methods. A voluntary, anonymous survey was administered to student donors at high school mobile blood drives. The survey instrument asked the students to rate several potential motivating factors in their importance in the decision to donate blood and several potential deterring factors in their future decision whether or not to donate blood again. The survey also asked the students to rate the desirability of several potential incentives. Results. Motivating factors that reflected prosocial, empathetic, and altruistic thoughts and beliefs were rated highly by students. Pain from phlebotomy was most commonly chosen as potential deterrent. Movie tickets and cookies/snacks at the drive were rated as the most attractive incentives. Conclusion. High school aged blood donors are similar to other donor groups in their expressed motives for donating blood. This group may be unique in the factors that deter them from donating and in their preferences for different incentives.

The Case for a Conservative Approach to Blood Transfusion Management in Cardiac Surgery

Limiting blood transfusion in cardiac operations is a well-meaning goal of perioperative care. Potential benefits include decreasing morbidity and limiting procedural costs. It is difficult to identify transfusion as the cause of adverse outcomes. The need for transfusion may identify a sicker patient population at greater risk for a worse outcome that may or may not be related to the transfusion. We reviewed the indications for and adverse effects of blood transfusion in patients undergoing cardiac procedures to provide a balanced approach to management of blood resources in this population. We reviewed current literature, including systematic reviews and practice guidelines, to synthesize a practice management plan in patients having cardiac operations. Several prospective randomized studies and large population cohort studies compared a postoperative restrictive transfusion policy to a more liberal policy and found very little difference in outcomes but decreased costs with a restrictive policy. Evidence-based practice guidelines and implementation standards provide robust intervention plans that can limit harmful effects of transfusion and provide safe and effective procedure outcomes. A restrictive transfusion policy seems to be safe and effective but does not necessarily provide better outcome in most patient cohorts. The implications of these findings suggest that many discretionary transfusions could be avoided. A subset of high-risk patients could undoubtedly benefit from a more liberal transfusion policy, but the definition of high risk is ill defined.

Design of Major Randomized Trials: Part 3 of a 4-Part Series on Statistics for Clinical Trials

This paper provides practical guidance on the fundamentals of design for major randomized controlled trials. Topics covered include the choice of patients, choice of treatment and control groups, choice of primary and secondary endpoints, methods of randomization, appropriate use of blinding, and determination of trial size. Insights are made with reference to contemporary major trials in cardiology.

Transfusion Thresholds, Quality of Life, and Current Approaches in Myelodysplastic Syndromes

Hemoglobin thresholds and triggers for blood transfusions have changed over the years moving from a higher to a lower level. This review article summarizes the current evidence of transfusion thresholds in the hospitalized as well as in the outpatient setting and particularly in myelodysplasia. Fatigue is the main reported symptom in this group of patients and current clinical trials are looking for a more liberal approach of red cell transfusion and the effect on quality of life as opposed to the restrictive strategy used in the critical care setting. Practical considerations, the cost effectiveness of this strategy in addition to the possible complications, and the use of quality of life questionnaires have also been reviewed.

Impact of retained blood requiring reintervention on outcomes after cardiac surgery

OBJECTIVES

Evacuation of shed blood from around the heart and lungs is a critical requirement for patients in early recovery after cardiac surgery. Incomplete evacuation of shed blood can result in retained blood, which may require subsequent reinterventions to facilitate recovery. The purpose of this study was to determine the incidence of retained blood requiring reintervention and examine the impact on outcomes.

METHODS

We performed a cross-sectional, observational study of all adult patients undergoing cardiac surgery between 2006 and 2013. Subjects who required an intervention to remove blood, blood clot, or bloodily fluid were attributed to the retained blood group. These patients were compared with those not presenting with any of the defined criteria for retained blood. Multivariate regression was performed to account for confounders.

RESULTS

Of 6909 adult patients who underwent cardiac surgery, 1316 (19%) presented with a retained blood-related condition. Retained blood was associated with increased in-hospital mortality (odds ratio [OR], 4.041; 95% confidence interval [CI], 2.589-6.351, P < .001) and a length of stay more than 13 days in the hospital (OR, 3.853; 95% CI, 2.882-5.206; P < .001) and 5 days in the intensive care unit (OR, 4.602; 95% CI, 3.449-6.183; P < .001). The OR for a time of ventilation greater than 23 hours was 3.596 (95% CI, 2.690-4.851; P < .001) and for incidence of renal replacement therapy was 4.449 (95% CI, 3.188-6.226; P < .001).

CONCLUSIONS

Postoperative retained blood is a common outcome and associated with higher in-hospital mortality, longer intensive care unit and hospital stay, and higher incidence of renal replacement therapy. Further research is needed to validate these results and explore interventions to reduce these complications.

Potential Strategies to Prevent Ventilator-associated Events

The Centers for Disease Control and Prevention (CDC) released ventilator-associated event (VAE) definitions in 2013. The new definitions were designed to track episodes of sustained respiratory deterioration in mechanically ventilated patients after a period of stability or improvement. More than 2,000 U.S. hospitals have reported their VAE rates to the CDC, but there has been little guidance to date on how to prevent VAEs. Existing ventilator-associated pneumonia prevention bundles are unlikely to be optimal insofar as pneumonia accounts for only a minority of VAEs. This review proposes a framework and potential intervention set to prevent VAEs on the basis of studies of VAE epidemiology, risk factors, and prevention. Work to date suggests that the majority of VAEs are caused by four conditions: pneumonia, fluid overload, atelectasis, and acute respiratory distress syndrome. Interventions that minimize ventilator exposure and target one or more of these conditions may therefore prevent VAEs. Potential strategies include avoiding intubation, minimizing sedation, paired daily spontaneous awakening and breathing trials, early exercise and mobility, low tidal volume ventilation, conservative fluid management, and conservative blood transfusion thresholds. Interventional studies have thus far affirmed that minimized sedation, paired daily spontaneous awakening and breathing trials, and conservative fluid management can reduce VAE rates and improve patient-centered outcomes. Further studies are needed to evaluate the impact of the other proposed interventions, to identify additional modifiable risk factors for VAEs, and to measure whether combining strategies into VAE prevention bundles confers additional benefits over implementing one or more of these interventions in isolation.

The European guideline on management of major bleeding and coagulopathy following trauma: fourth edition

BACKGROUND

Severe trauma continues to represent a global public health issue and mortality and morbidity in trauma patients remains substantial. A number of initiatives have aimed to provide guidance on the management of trauma patients. This document focuses on the management of major bleeding and coagulopathy following trauma and encourages adaptation of the guiding principles to each local situation and implementation within each institution.

METHODS

The pan-European, multidisciplinary Task Force for Advanced Bleeding Care in Trauma was founded in 2004 and included representatives of six relevant European professional societies. The group used a structured, evidence-based consensus approach to address scientific queries that served as the basis for each recommendation and supporting rationale. Expert opinion and current clinical practice were also considered, particularly in areas in which randomised clinical trials have not or cannot be performed. Existing recommendations were reconsidered and revised based on new scientific evidence and observed shifts in clinical practice; new recommendations were formulated to reflect current clinical concerns and areas in which new research data have been generated. This guideline represents the fourth edition of a document first published in 2007 and updated in 2010 and 2013.

RESULTS

The guideline now recommends that patients be transferred directly to an appropriate trauma treatment centre and encourages use of a restricted volume replacement strategy during initial resuscitation. Best-practice use of blood products during further resuscitation continues to evolve and should be guided by a goal-directed strategy. The identification and management of patients pre-treated with anticoagulant agents continues to pose a real challenge, despite accumulating experience and awareness. The present guideline should be viewed as an educational aid to improve and standardise the care of the bleeding trauma patients across Europe and beyond. This document may also serve as a basis for local implementation. Furthermore, local quality and safety management systems need to be established to specifically assess key measures of bleeding control and outcome.

CONCLUSIONS

A multidisciplinary approach and adherence to evidence-based guidance are key to improving patient outcomes. The implementation of locally adapted treatment algorithms should strive to achieve measureable improvements in patient outcome.

AAGBI guidelines: the use of blood components and their alternatives 2016

Blood transfusion can be life-saving. Anaesthetists regularly request and administer blood components to their patients. All anaesthetists must be familiar with indications and appropriate use of blood and blood components and their alternatives, but close liaison with haematology specialists and their local blood sciences laboratory is encouraged. Considerable changes in approaches to optimal use of blood components, together with the use of alternative products, have become apparent over the past decade, leading to a need to update previous guidelines and adapt them for the use of anaesthetists working throughout the hospital system.

Transfusion practices and infectious risks

Transfusion-transmitted infections remain among the most-feared complications of allogeneic blood transfusion. Thanks to several strategies including donor screening and deferral, blood testing and pathogen inactivation, their risks have reached all-time low levels, particularly in developed nations. Nonetheless, new and emerging infections remain a threat that is likely to exacerbate in the coming years with continued globalization and climate change. More effective strategies of pathogen inactivation and more vigilant horizon screening are hoped to abate the risk. Additionally, allogeneic transfusion has repeatedly been shown to be associated with worsening of outcomes in patients, including the documented increased risk of infections (often nosocomial) in recipients of transfusions. The underlying mechanism is likely to be related to immunosuppressive effects of allogeneic blood, iron content, and bacterial contamination. This issue is best addressed by more judicious and evidence-based use of allogeneic blood components to ensure the potential benefits outweigh the risks.

Effect of restrictive versus liberal transfusion strategies on outcomes in patients with cardiovascular disease in a non-cardiac surgery setting: systematic review and meta-analysis

OBJECTIVE

To compare patient outcomes of restrictive versus liberal blood transfusion strategies in patients with cardiovascular disease not undergoing cardiac surgery.

DESIGN

Systematic review and meta-analysis.

DATA SOURCES

Randomised controlled trials involving a threshold for red blood cell transfusion in hospital. We searched (to 2 November 2015) CENTRAL, Medline, Embase, CINAHL, PubMed, LILACS, NHSBT Transfusion Evidence Library, ClinicalTrials.gov, WHO International Clinical Trials Registry Platform, ISRCTN Register, and EU Clinical Trials Register. Authors were contacted for data whenever possible.

TRIAL SELECTION

Published and unpublished randomised controlled trials comparing a restrictive with liberal transfusion threshold and that included patients with cardiovascular disease.

DATA EXTRACTION AND SYNTHESIS

Data extraction was completed in duplicate. Risk of bias was assessed using Cochrane methods. Relative risk ratios with 95% confidence intervals were presented in all meta-analyses. Mantel-Haenszel random effects models were used to pool risk ratios.

MAIN OUTCOME MEASURES

30 day mortality, and cardiovascular events.

RESULTS

41 trials were identified; of these, seven included data on patients with cardiovascular disease. Data from a further four trials enrolling patients with cardiovascular disease were obtained from the authors. In total, 11 trials enrolling patients with cardiovascular disease (n=3033) were included for meta-analysis (restrictive transfusion, n=1514 patients; liberal transfusion, n=1519). The pooled risk ratio for the association between transfusion thresholds and 30 day mortality was 1.15 (95% confidence interval 0.88 to 1.50, P=0.50), with little heterogeneity (I(2)=14%). The risk of acute coronary syndrome in patients managed with restrictive compared with liberal transfusion was increased (nine trials; risk ratio 1.78, 95% confidence interval 1.18 to 2.70, P=0.01, I(2)=0%).

CONCLUSIONS

The results show that it may not be safe to use a restrictive transfusion threshold of less than 80 g/L in patients with ongoing acute coronary syndrome or chronic cardiovascular disease. Effects on mortality and other outcomes are uncertain. These data support the use of a more liberal transfusion threshold (>80 g/L) for patients with both acute and chronic cardiovascular disease until adequately powered high quality randomised trials have been undertaken in patients with cardiovascular disease.

REGISTRATION

PROSPERO CRD42014014251.

Trial protocol for a randomised controlled trial of red cell washing for the attenuation of transfusion-associated organ injury in cardiac surgery: the REDWASH trial

Introduction

It has been suggested that removal of proinflammatory substances that accumulate in stored donor red cells by mechanical cell washing may attenuate inflammation and organ injury in transfused cardiac surgery patients. This trial will test the hypotheses that the severity of the postoperative inflammatory response will be less and postoperative recovery faster if patients undergoing cardiac surgery receive washed red cells compared with standard care (unwashed red cells).

Methods and analysis

Adult (≥16 years) cardiac surgery patients identified at being at increased risk for receiving large volume red cell transfusions at 1 of 3 UK cardiac centres will be randomly allocated in a 1:1 ratio to either red cell washing or standard care. The primary outcome is serum interleukin-8 measured at 5 postsurgery time points up to 96 h. Secondary outcomes will include measures of inflammation, organ injury and volumes of blood transfused and cost-effectiveness. Allocation concealment, internet-based randomisation stratified by operation type and recruiting centre, and blinding of outcome assessors will reduce the risk of bias. The trial will test the superiority of red cell washing versus standard care. A sample size of 170 patients was chosen in order to detect a small-to-moderate target difference, with 80% power and 5% significance (2-tailed).

Ethics and dissemination

The trial protocol was approved by a UK ethics committee (reference 12/EM/0475). The trial findings will be disseminated in scientific journals and meetings.

Trial registration number

ISRCTN 27076315.

'Blood doping' from Armstrong to prehabilitation: manipulation of blood to improve performance in athletes and physiological reserve in patients

Haemoglobin is the blood’s oxygen carrying pigment and is encapsulated in red blood corpuscles. The concentration of haemoglobin in blood is dependent on both its total mass in the circulation (tHb-mass) and the total plasma volume in which it is suspended. Aerobic capacity is defined as the maximum amount of oxygen that can be consumed by the body per unit time and is one measure of physical fitness. Observations in athletes who have undergone blood doping or manipulation have revealed a closer relationship between physical fitness (aerobic capacity) and total haemoglobin mass (tHb-mass) than with haemoglobin concentration ([Hb]). Anaemia is defined by the World Health Organisation (WHO) as a haemoglobin concentration of <130 g/L for men and <120 g/L for women. Perioperative anaemia is a common problem and is associated with increased mortality and morbidity following surgery. Aerobic capacity is also associated with outcome following major surgery, with less fit patients having a higher incidence of mortality and morbidity after surgery. Taken together, these observations suggest that targeted preoperative elevation of tHb-mass may raise aerobic capacity both directly and indirectly (by augmenting preoperative exercise initiatives- ‘prehabilitation’) and thus improve postoperative outcome. This notion in turn raises a number of questions. Which measure ([Hb] or tHb-mass) has the most value for the description of oxygen carrying capacity? Which measure has the most utility for targeting therapies to manipulate haemoglobin levels? Do the newer agents being used for blood manipulation (to increase tHb-mass) in elite sport have utility in the clinical environment? This review explores the literature relating to blood manipulation in elite sport as well as the relationship between perioperative anaemia, physical fitness and outcome following surgery, and suggests some avenues for exploring this area further.