Transfusion Requirements in Cardiac Surgery III (TRICS III): Study Design of a Randomized Controlled Trial

Jehovah's Witness Needing Critical Care: A Narrative Review on the Expanding Arsenal

Present day Jehovah's Witness (JW) religion accounts for 8.5 million followers. A tenant feature of the JW faith is religious objection to transfusions of blood and blood products. Interpatient variability, as it pertains to blood and blood products may occur; hence, a confidential interview will determine which products individual may consent to (Marsh and Bevan, 2002). This belief and practice place great restrictions on treating medical professionals in scenarios of life-threatening anaemia and active haemorrhage. The review to follow explores the physiological and pathophysiological consequences of severe anaemia. Non-blood transfusion practices are explored, many of which are potentially lifesaving. Particular attention is drawn to the evolving science involving artificial oxygen carriers and their use in emergency situations. A greater safety profile ensures its future use amongst religious objectors to be greatly beneficial. Intravenous iron supplementation has enjoyed a lively debate within the critical care community. A review of recent systematic and meta-analysis supports its use in the ICU; however, more investigation is needed into the complementary use of hepcidin.

What drives variability in postoperative cardiac surgery transfusion rates?

OBJECTIVE

Wide interhospital variation exists in cardiac surgical postoperative transfusion rates. We aimed to compare transfusion rates at 2 hospitals and identify the institutional practice factors, unrelated to patient or operative characteristics, associated with postoperative transfusion rates.

METHODS

Records for adult patients undergoing routine cardiac surgery at 2 hospitals (H and L) from February 2020 to August 2022 were analyzed. Patient and operative characteristics, preoperative and intensive care unit hemoglobin values, and postoperative transfusion rates were compared. Transfusion indication was recorded prospectively. Propensity matching was completed to assess comparability of patient populations.

RESULTS

After propensity matching patients at H and L on age, procedure type, predicted morbidity or mortality, crossclamp time, preoperative hypertension, preoperative heart failure, and preoperative stroke, 2111 patients remained, with similar characteristics except hypertension. Matched results showed no significant differences in mortality, reoperation, or other major outcomes. Hospital H transfused 36% of patients (mean postoperative hemoglobin [Hb] 10.5) with 1483 units of packed red blood cells whereas hospital L transfused 12% of patients (mean postoperative Hb 9.4) with 198 units of packed red blood cells (P < .001). For all patients with a Hb >7.5, hospital H versus L transfused 27% versus 0.9% (P < .001). Hospital L's sole transfusion indication for pretransfusion hemoglobin trigger >7.5 was bleeding versus hospital H, which had multiple indications. When Hb concentration alone was the indication for transfusion, the threshold at hospital H was <7.5 g/dL versus <6 g/dL at hospital L.

CONCLUSIONS

Variation in transfusion rates between hospitals H and L resulted from strict adherence at hospital L to a transfusion trigger of <6 g/dL with narrow indications for transfusions above that Hb concentration.

Methemoglobin as a marker of acute anemic stress in cardiac surgery

Biological evidence supports plasma methemoglobin as a biomarker for anemia-induced tissue hypoxia. In this translational planned substudy of the multinational randomized controlled transfusion thresholds in cardiac surgery (TRICS-III) trial, which included adults undergoing cardiac surgery requiring cardiopulmonary bypass with a moderate-to-high risk of death, we investigated the relationship between perioperative hemoglobin concentration (Hb) and methemoglobin; and evaluated its association with postoperative outcomes. The primary endpoint was a composite of death, myocardial infarction, stroke, and severe acute kidney injury at 28 days. We observe weak non-linear associations between decreasing Hb and increasing methemoglobin, which were strongest in magnitude at the post-surgical time point. Increased levels of post-surgical methemoglobin were associated with a trend toward an elevated risk for stroke and exploratory neurological outcomes. Our generalizable study demonstrates post-surgical methemoglobin may be a marker of anemia-induced organ injury/dysfunction, and may have utility for guiding personalized approaches to anemia management. Clinicaltrials.gov registration NCT02042898.

Generating real-world evidence compatible with evidence from randomized controlled trials: a novel observational study design applicable to surgical transfusion research

BACKGROUND

Numerous observational studies have revealed an increased risk of death and complications with transfusion, but this observation has not been confirmed in randomized controlled trials (RCTs). The "transfusion kills patients" paradox persists in real-world observational studies despite application of analytic methods such as propensity-score matching. We propose a new design to address this long-term existing issue, which if left unresolved, will be deleterious to the healthy generation of evidence that supports optimized transfusion practice.

METHODS

In the new design, we stress three aspects for reconciling observational studies and RCTs on transfusion safety: (1) re-definition of the study population according to a stable hemoglobin range (gray zone of transfusion decision; 7.5-9.5 g/dL in this study); (2) selection of comparison groups according to a trigger value (last hemoglobin measurement before transfusion; nadir during hospital stay for control); (3) dealing with patient heterogeneity according to standardized mean difference (SMD) values. We applied the new design to hospitalized older patients (aged ≥60 years) undergoing general surgery at four academic/teaching hospitals. Four datasets were analyzed: a base population before (Base Match-) and after (Base Match+) propensity-score matching to simulate previous observational studies; a study population before (Study Match-) and after (Study Match+) propensity-score matching to demonstrate effects of our design.

RESULTS

Of 6141 older patients, 662 (10.78%) were transfused and showed high heterogeneity compared with those not receiving transfusion, particularly regarding preoperative hemoglobin (mean: 11.0 vs. 13.5 g/dL) and intraoperative bleeding (≥500 mL: 37.9% vs. 2.1%). Patient heterogeneity was reduced with the new design; SMD of the two variables was reduced from approximately 100% (Base Match-) to 0% (Study Match+). Transfusion was related to a higher risk of death and complications in Base Match- (odds ratio [OR], 95% confidence interval [CI]: 2.68, 1.86-3.86) and Base Match+ (2.24, 1.43-3.49), but not in Study Match- (0.77, 0.32-1.86) or Study Match+ (0.66, 0.23-1.89).

CONCLUSIONS

We show how choice of study population and analysis could affect real-world study findings. Our results following the new design are in accordance with relevant RCTs, highlighting its value in accelerating the pace of transfusion evidence generation and generalization.

Restrictive versus liberal transfusion in patients with diabetes undergoing cardiac surgery: An open-label, randomized, blinded outcome evaluation trial

AIM

To characterize the association between diabetes and transfusion and clinical outcomes in cardiac surgery, and to evaluate whether restrictive transfusion thresholds are harmful in these patients.

MATERIALS AND METHODS

The multinational, open-label, randomized controlled TRICS-III trial assessed a restrictive transfusion strategy (haemoglobin [Hb] transfusion threshold <75 g/L) compared with a liberal strategy (Hb <95 g/L for operating room or intensive care unit; or <85 g/L for ward) in patients undergoing cardiac surgery on cardiopulmonary bypass with a moderate-to-high risk of death (EuroSCORE ≥6). Diabetes status was collected preoperatively. The primary composite outcome was all-cause death, stroke, myocardial infarction, and new-onset renal failure requiring dialysis at 6 months. Secondary outcomes included components of the composite outcome at 6 months, and transfusion and clinical outcomes at 28 days.

RESULTS

Of the 5092 patients analysed, 1396 (27.4%) had diabetes (restrictive, n = 679; liberal, n = 717). Patients with diabetes had more cardiovascular disease than patients without diabetes. Neither the presence of diabetes (OR [95% CI] 1.10 [0.93-1.31]) nor the restrictive strategy increased the risk for the primary composite outcome (diabetes OR [95% CI] 1.04 [0.68-1.59] vs. no diabetes OR 1.02 [0.85-1.22]; P_interaction  = .92). In patients with versus without diabetes, a restrictive transfusion strategy was more effective at reducing red blood cell transfusion (diabetes OR [95% CI] 0.28 [0.21-0.36]; no diabetes OR [95% CI] 0.40 [0.35-0.47]; P_interaction  = .04).

CONCLUSIONS

The presence of diabetes did not modify the effect of a restrictive transfusion strategy on the primary composite outcome, but improved its efficacy on red cell transfusion. Restrictive transfusion triggers are safe and effective in patients with diabetes undergoing cardiac surgery.

Prolonged mechanical ventilation after cardiac surgery: substudy of the Transfusion Requirements in Cardiac Surgery III trial

PURPOSE

Prolonged mechanical ventilation (MV) is a major complication following cardiac surgery. We conducted a secondary analysis of the Transfusion Requirements in Cardiac Surgery (TRICTS) III trial to describe MV duration, identify factors associated with prolonged MV, and examine associations of prolonged MV with mortality and complications.

METHODS

Four thousand, eight hundred and nine participants undergoing cardiac surgery at 71 hospitals worldwide were included. Prolonged MV was defined based on the Society of Thoracic Surgeons definition as MV lasting 24 hr or longer. Adjusted associations of patient and surgical factors with prolonged MV were examined using multivariable logistic regression. Associations of prolonged MV with complications were assessed using odds ratios, and adjusted associations between prolonged MV and mortality were evaluated using multinomial regression. Associations of shorter durations of MV with survival and complications were explored.

RESULTS

Prolonged MV occurred in 15% (725/4,809) of participants. Prolonged MV was associated with surgical factors indicative of complexity, such as previous cardiac surgery, cardiopulmonary bypass duration, and separation attempts; and patient factors such as critical preoperative state, left ventricular impairment, renal failure, and pulmonary hypertension. Prolonged MV was associated with perioperative but not long-term complications. After risk adjustment, prolonged MV was associated with perioperative mortality; its association with long-term mortality among survivors was weaker. Shorter durations of MV were not associated with increased risk of mortality or complications.

CONCLUSION

In this substudy of the TRICS III trial, prolonged MV was common after cardiac surgery and was associated with patient and surgical risk factors. Although prolonged MV showed strong associations with perioperative complications and mortality, it was not associated with long-term complications and had weaker association with long-term mortality among survivors.

STUDY REGISTRATION

www.

CLINICALTRIALS

gov (NCT02042898); registered 23 January 2014. This is a substudy of the Transfusion Requirements in Cardiac Surgery (TRICS) III trial.

Preoperative anemia management program reduces blood transfusion in elective cardiac surgical patients, improving outcomes and decreasing hospital length of stay

BACKGROUND

Anemia is an independent risk factor for hospitalization, readmission, prolonged length of stay (LOS), diminished quality of life, and mortality. A multidisciplinary program was implemented to manage anemia preoperatively as a patient blood management (PBM) initiative.

METHODS AND MATERIALS

From March 2016 to August 2018, 240 patients were screened for anemia during their preoperative cardiovascular visit. About 52/240 (22%) were found to be anemic and met out inclusion criteria. Also, 45/52 (87%) had iron deficiency anemia and 7 (13%) had anemia without iron deficiency. A similar historical cohort of patients undergoing elective cardiovascular surgery with hemoglobin (Hb) < 12 g/dl from September 2014 to February /2016 (n = 52) served as control group. The primary outcome was perioperative red blood cell (RBC) transfusion. Secondary outcomes were date-of-surgery Hb, intensive care unit (ICU) and hospital LOS, complication rates, and transfusion cost.

RESULTS

The two most common treatments were IV iron ± folate (n = 36/45; 80%) and oral iron (n = 9/45; 20%). As compared to historical patients, study patients had significantly higher day-of-surgery Hb (10.6 ± 1.4 vs. 9.8 ± 1.3 g/dl, p < .001), lower utilization of RBC transfusion (0.86 ± 1.4 vs. 2.78 ± 2.4, p < .001), fewer days in the ICU (2.1 ± 2.0 vs. 4.0 ± 3.5, p = .002), and shorter total LOS (6.9 ± 4.8 vs. 12.9 ± 6.8, p < .0001). Study patients also showed lower overall complication rates (p < .0001). Analysis of RBC acquisition cost and transfusion cost also showed significant saving of 69% ($293 vs. $945 and $656 vs. $2116, respectively).

CONCLUSION

When corrected for type of procedures and surgeon, our pilot anemia program in elective cardiovascular surgeries showed higher day-of-surgery Hb and significant reduction in RBC transfusion rates, ICU and hospital LOS, and overall complication rates.

Influence of blood haemoglobin concentration on renal haemodynamics and oxygenation during experimental cardiopulmonary bypass in sheep

AIM

Blood transfusion may improve renal oxygenation during cardiopulmonary bypass (CPB). In an ovine model of experimental CPB, we tested whether increasing blood haemoglobin concentration [Hb] from ~7 g dL-1 to ~9 g dL-1 improves renal tissue oxygenation.

METHODS

Ten sheep were studied while conscious, under stable isoflurane anaesthesia, and during 3 hours of CPB. In a randomized cross-over design, 5 sheep commenced bypass at a high target [Hb], achieved by adding 600 mL donor blood to the priming solution. After 90 minutes of CPB, PlasmaLyte® was added to the blood reservoir to achieve low target [Hb]. For the other 5 sheep, no blood was added to the prime, but after 90 minutes of CPB, 800-900 mL of donor blood was given to achieve a high target [Hb].

RESULTS

Overall, CPB was associated with marked reductions in renal oxygen delivery (-50 ± 12%, mean ± 95% confidence interval) and medullary tissue oxygen tension (PO2 , -54 ± 29%). Renal fractional oxygen extraction was 17 ± 10% less during CPB at high [Hb] than low [Hb] (P = .04). Nevertheless, no increase in tissue PO2 in either the renal medulla (0 ± 6 mmHg change, P > .99) or cortex (-19 ± 13 mmHg change, P = .08) was detected with high [Hb].

CONCLUSIONS

In experimental CPB blood transfusion to increase Hb concentration from ~7 g dL-1 to ~9 g dL-1 did not improve renal cortical or medullary tissue PO2 even though it decreased whole kidney oxygen extraction.

Controversies in the Clinical Practice of Patient Blood Management

Patient blood management (PBM) has been proposed as a standard of care in modern perioperative medicine. PBM-related interventions usually are implemented as bundles, but randomized controlled trials on the implementation of PBM as a bundle are missing. This special article focuses on the current evidence and controversies in the clinical practice of PBM and on emerging data related to specific PBM-related interventions in patients undergoing cardiac surgery. Strong evidence for many PBM-related interventions is limited because of missing studies or the poor quality of published findings and study endpoints. Restrictive blood transfusion and timely interventions to maintain hemoglobin concentration and to reduce blood loss potentially might result in improved patient outcome, although the latter has yet to be proven.

Critical Care Society of Southern Africa adult patient blood management guidelines: 2019 Round-table meeting, CCSSA Congress, Durban, 2018

The CCSSA PBM Guidelines have been developed to improve patient blood management in critically ill patients in southern Africa. These consensus recommendations are based on a rigorous process by experts in the field of critical care who are also practicing in South Africa (SA). The process comprised a Delphi process, a round-table meeting (at the CCSSA National Congress, Durban, 2018), and a review of the best available evidence and international guidelines. The guidelines focus on the broader principles of patient blood management and incorporate transfusion medicine (transfusion guidelines), management of anaemia, optimisation of coagulopathy, and administrative and ethical considerations. There are a mix of low-middle and high-income healthcare structures within southern Africa. Blood products are, however, provided by the same not-for-profit non-governmental organisations to both private and public sectors. There are several challenges related to patient blood management in SA due most notably to a high incidence of anaemia, a frequent shortage of blood products, a small donor population, and a healthcare system under financial strain. The rational and equitable use of blood products is important to ensure best care for as many critically ill patients as possible. The summary of the recommendations provides key practice points for the day-to-day management of critically ill patients. A more detailed description of the evidence used to make these recommendations follows in the full clinical guidelines section.

COMMENCE trial (Comparing hypOtherMic teMperaturEs duriNg hemiarCh surgEry): a randomized controlled trial of mild vs moderate hypothermia on patient outcomes in aortic hemiarch surgery with anterograde cerebral perfusion

Background

Aortic arch surgery remains the only viable life-saving treatment for aortic arch disease. However, the necessity for cessation of systemic blood flow with hypothermic cardiac arrest carries substantial risk of morbidity and mortality, including poor neurological outcomes and kidney failure. While uncontrolled studies have suggested the safety of operating at warmer temperatures, significant variables remain un-investigated, supporting the need for a randomized clinical trial (RCT) to produce evidence-based guidelines for perfusion strategies in aortic surgery. This study proposes a multi-center RCT in order to compare outcomes of warmer hypothermic strategies during aortic hemiarch surgery on a composite endpoint of neurologic and acute kidney injury (AKI).

Methods/design

This is a prospective multi-center, single-blind two-arm RCT comparing mild (32 °C) versus moderate (26 °C) hypothermic cardiac arrest in patients (n = 282) undergoing hemiarch surgery with antegrade cerebral perfusion (ACP). The primary endpoint is a composite of neurological injury (incidence of transient ischemic attack and/or stroke) and Kidney Disease Improving Global Outcomes (KDIGO) stage 1 or higher AKI. Secondary outcomes include death, cardiopulmonary bypass time, bleeding, transfusion rates, prolonged mechanical ventilation, myocardial infarction, length of stay, and quality of life measures.

Patients will undergo 1:1 block randomization to each treatment arm on day of surgery. Sequence of operation will be at the surgeon’s discretion with mandatory guidelines for temperature and ACP administration. Perioperative management will occur as per enrolling center standard of care. Neurocognitive function will be assessed for neurological injury using validated neurological screening tests: NIHSS, MOCA, BI, and MRS throughout patient follow-up. Diagnosis and classification of AKI will be based on rising creatinine values as per the KDIGO criteria. Study duration for each patient will be 60 ± 14 days.

Discussion

It is hoped that performing hemiarch surgery using mild hypothermia (32 °C) and selective ACP will result in a 15% absolute risk reduction in the composite outcomes. The potential of this risk reduction will translate into improved patient outcomes, survival, and long-term financial savings to the health care system. In addition, the results of this trial will be used to create the first-ever guidelines for temperature management strategy during aortic surgery.

Trial registration

This trial is registered on ClinicalTrials.gov with the registration number NCT02860364. Registration date August 9th, 2016.

Safety of a Restrictive versus Liberal Approach to Red Blood Cell Transfusion on the Outcome of AKI in Patients Undergoing Cardiac Surgery: A Randomized Clinical Trial

BACKGROUND

Safely reducing red blood cell transfusions can prevent transfusion-related adverse effects, conserve the blood supply, and reduce health care costs. Both anemia and red blood cell transfusion are independently associated with AKI, but observational data are insufficient to determine whether a restrictive approach to transfusion can be used without increasing AKI risk.

METHODS

In a prespecified kidney substudy of a randomized noninferiority trial, we compared a restrictive threshold for red blood cell transfusion (transfuse if hemoglobin<7.5 g/dl, intraoperatively and postoperatively) with a liberal threshold (transfuse if hemoglobin<9.5 g/dl in the operating room or intensive care unit, or if hemoglobin<8.5 g/dl on the nonintensive care ward). We studied 4531 patients undergoing cardiac surgery with cardiopulmonary bypass who had a moderate-to-high risk of perioperative death. The substudy's primary outcome was AKI, defined as a postoperative increase in serum creatinine of ≥0.3 mg/dl within 48 hours of surgery, or ≥50% within 7 days of surgery.

RESULTS

Patients in the restrictive-threshold group received significantly fewer transfusions than patients in the liberal-threshold group (1.8 versus 2.9 on average, or 38% fewer transfusions in the restricted-threshold group compared with the liberal-threshold group; P<0.001). AKI occurred in 27.7% of patients in the restrictive-threshold group (624 of 2251) and in 27.9% of patients in the liberal-threshold group (636 of 2280). Similarly, among patients with preoperative CKD, AKI occurred in 33.6% of patients in the restrictive-threshold group (258 of 767) and in 32.5% of patients in the liberal-threshold group (252 of 775).

CONCLUSIONS

Among patients undergoing cardiac surgery, a restrictive transfusion approach resulted in fewer red blood cell transfusions without increasing the risk of AKI.

Association of Perioperative Transfusion with Recurrence and Survival After Resection of Distal Cholangiocarcinoma: A 10-Institution Study from the US Extrahepatic Biliary Malignancy Consortium

BACKGROUND

Perioperative allogeneic blood transfusion is associated with poor oncologic outcomes in multiple malignancies. The effect of blood transfusion on recurrence and survival in distal cholangiocarcinoma (DCC) is not known.

METHODS

All patients with DCC who underwent curative-intent pancreaticoduodenectomy at 10 institutions from 2000 to 2015 were included. Primary outcomes were recurrence-free (RFS) and overall survival (OS).

RESULTS

Among 314 patients with DCC, 191 (61%) underwent curative-intent pancreaticoduodenectomy. Fifty-three patients (28%) received perioperative blood transfusions, with a median of 2 units. There were no differences in baseline demographics or operative data between transfusion and no-transfusion groups. Compared with no-transfusion, patients who received a transfusion were more likely to have (+) margins (28 vs 14%; p = 0.034) and major complications (46 vs 16%; p < 0.001). Transfusion was associated with worse median RFS (19 vs 32 months; p = 0.006) and OS (15 vs 29 months; p = 0.003), which persisted on multivariable (MV) analysis for both RFS [hazard ratio (HR) 1.8; 95% confidence interval (CI) 1.1-3.0; p = 0.031] and OS (HR 1.9; 95% CI 1.1-3.3; p = 0.018), after controlling for portal vein resection, estimated blood loss (EBL), grade, lymphovascular invasion (LVI), and major complications. Similarly, transfusion of ≥ 2 pRBCs was associated with lower RFS (17 vs 32 months; p < 0.001) and OS (14 vs 29 months; p < 0.001), which again persisted on MV analysis for both RFS (HR 2.6; 95% CI 1.4-4.5; p = 0.001) and OS (HR 4.0; 95% CI 2.2-7.5; p < 0.001). The RFS and OS of patients transfused 1 unit was comparable to patients who were not transfused.

CONCLUSION

Perioperative blood transfusion is associated with decreased RFS and OS after resection for distal cholangiocarcinoma, after accounting for known adverse pathologic factors. Volume of transfusion seems to exert an independent effect, as 1 unit was not associated with the same adverse effects as ≥ 2 units.

Six-Month Outcomes after Restrictive or Liberal Transfusion for Cardiac Surgery

BACKGROUND

We reported previously that, in patients undergoing cardiac surgery who were at moderate-to-high risk for death, a restrictive transfusion strategy was noninferior to a liberal strategy with respect to the composite outcome of death from any cause, myocardial infarction, stroke, or new-onset renal failure with dialysis by hospital discharge or 28 days after surgery, whichever came first. We now report the clinical outcomes at 6 months after surgery.

METHODS

We randomly assigned 5243 adults undergoing cardiac surgery to a restrictive red-cell transfusion strategy (transfusion if the hemoglobin concentration was <7.5 g per deciliter intraoperatively or postoperatively) or a liberal red-cell transfusion strategy (transfusion if the hemoglobin concentration was <9.5 g per deciliter intraoperatively or postoperatively when the patient was in the intensive care unit [ICU] or was <8.5 g per deciliter when the patient was in the non-ICU ward). The primary composite outcome was death from any cause, myocardial infarction, stroke, or new-onset renal failure with dialysis occurring within 6 months after the initial surgery. An expanded secondary composite outcome included all the components of the primary outcome as well as emergency department visit, hospital readmission, or coronary revascularization occurring within 6 months after the index surgery. The secondary outcomes included the individual components of the two composite outcomes.

RESULTS

At 6 months after surgery, the primary composite outcome had occurred in 402 of 2317 patients (17.4%) in the restrictive-threshold group and in 402 of 2347 patients (17.1%) in the liberal-threshold group (absolute risk difference before rounding, 0.22 percentage points; 95% confidence interval [CI], -1.95 to 2.39; odds ratio, 1.02; 95% CI, 0.87 to 1.18; P=0.006 for noninferiority). Mortality was 6.2% in the restrictive-threshold group and 6.4% in the liberal-threshold group (odds ratio, 0.95; 95% CI, 0.75 to 1.21). There were no significant between-group differences in the secondary outcomes.

CONCLUSIONS

In patients undergoing cardiac surgery who were at moderate-to-high risk for death, a restrictive strategy for red-cell transfusion was noninferior to a liberal strategy with respect to the composite outcome of death from any cause, myocardial infarction, stroke, or new-onset renal failure with dialysis at 6 months after surgery. (Funded by the Canadian Institutes of Health Research and others; TRICS III ClinicalTrials.gov number, NCT02042898 .).