Preoperative Anemia and Outcomes in Cardiovascular Surgery: Systematic Review and Meta-Analysis

Moderate-to-Severe Preoperative Anemia is Associated with Increased Postoperative Myocardial Infarction and Mortality in Patients Undergoing Transcarotid Artery Revascularization

BACKGROUND

While preoperative anemia is prevalent among surgical patients, its impact on patients undergoing transcarotid artery revascularization (TCAR) remains poorly understood. This study aims to assess the relationship between the severity of preoperative anemia and outcomes following TCAR.

METHODS

A retrospective analysis of the Vascular Quality Initiative database (2016-2021) was performed to identify patients who underwent TCAR for carotid stenosis. Anemia was defined according to World Health Organization guidelines as a hemoglobin (Hb) level <12 g/dL in females and <13 g/dL in males. The severity of anemia was further classified as mild (Hb: 10-11.9 g/dL in females and 11-12.9 g/dL in males) or moderate to severe (Hb < 10 g/dL in females and <11 g/dL in males). Patients were stratified into three cohorts as follows, based on the presence and severity of preoperative anemia: no anemia, mild anemia, and moderate-to-severe anemia. The primary outcome was 30-day mortality. Secondary outcomes included in-hospital stroke, in-hospital death, myocardial infarction (MI), and prolonged postoperative hospitalization (>1 day). Univariable and multivariable logistic regression analyses were conducted to evaluate the association between the severity of preoperative anemia and clinical outcomes.

RESULTS

Among 21,648 patients who underwent TCAR, 4,240 (19.8%) had mild anemia, and 3,401 (15.8%) had moderate-to-severe anemia preoperatively. After adjusting for relevant clinical factors and confounders, moderate-to-severe preoperative anemia was associated with significantly increased odds of in-hospital MI (adjusted odds ratio [aOR], 2.39; 95% confidence interval [CI]: 1.53-3.74; P < 0.001), in-hospital death (aOR, 2.65; 95% CI: 1.62-4.34; P < 0.001), and 30-day mortality (aOR, 1.89; 95% CI: 1.32-2.72; P < 0.001) compared to nonanemic patients. Among patients with moderate-to-severe anemia, factors such as a history of chronic obstructive pulmonary disease (COPD) or congestive heart failure (CHF), urgent or emergent procedures, and symptomatic carotid stenosis were the strongest predictors of 30-day mortality. In contrast, mild anemia was not associated with increased odds of adverse postoperative outcomes compared to the nonanemic cohort. Preoperative anemia, regardless of severity, was not associated with an increased risk of postoperative stroke following TCAR. However, the severity of preoperative anemia was associated with a stepwise increase in the adjusted odds of prolonged hospitalization (aOR, 1.19 [mild anemia] and 1.57 [moderate-to-severe anemia]).

CONCLUSION

In this multi-institutional retrospective study of patients undergoing TCAR, moderate-to-severe preoperative anemia was independently associated with higher adjusted odds of in-hospital MI, in-hospital death, and 30-day mortality, without an increased risk of postoperative stroke. These findings highlight moderate-to-severe preoperative anemia as a potential independent prognostic marker for identifying high-risk patients. Furthermore, incorporating the severity of anemia into preoperative risk stratification may aid in tailoring perioperative cardiac assessment and optimization strategies, potentially mitigating the risk of adverse outcomes following TCAR.

Efficacy of a problem, intervention, control, and outcomes (PICO)-based perioperative blood management plan developed for patients undergoing long-segment lumbar spine posterior surgery

BACKGROUND

This study aimed to develop and evaluate the effectiveness of a perioperative blood management plan based on the problem, intervention, control, and outcomes (PICO) model for long-segment lumbar spine posterior surgery.

METHODS

In this retrospective study, 51 patients who needed long-segment posterior lumbar spine surgery at the Second Affiliated Hospital of Nantong University Department of Spinal Surgery from July 2020 to June 2022 were included in the control group, while 51 patients who needed long-segment posterior lumbar spine surgery from July 2021 to June 2022 were selected as the observation group. Patients in the control group received conventional blood management, while those in the observation group were additionally administered an evidence-based perioperative blood management plan. We compared the intervention outcomes in both the groups.

RESULTS

Patients in the observation group demonstrated significantly higher postoperative hemoglobin levels and hematocrit at various time points compared to those in the control group (P < 0.05). Intraoperative blood loss, postoperative drainage volume, and average volume of allogeneic blood transfused per recipient, as well as the number and frequency of allogeneic blood transfusions, were significantly lower in the observation group (P < 0.05). The duration of surgical drain placement and postoperative hospital stay were notably shorter in the observation group (P < 0.05). The two groups did not differ significantly in the incidence of postoperative venous thromboembolism (VTE) (P > 0.05).

CONCLUSION

The implementation of a perioperative blood management plan was effective in reducing the total blood loss and transfusion volume in the perioperative period, improving hemoglobin and hematocrit levels, facilitating earlier removal of surgical drains, and accelerating patient discharge.

How do I analyze the role of red blood cell transfusions on clinical outcome in anemic patients? Disentangling the effect of red blood cell transfusions from pre-operative anemia on post-operative outcome

BACKGROUND

Preoperative anemia is associated with worse clinical postoperative outcomes and a higher risk of receiving red blood cell (RBC) transfusions. It is challenging to disentangle the effect of preoperative anemia from the effect of receiving RBC transfusions on postoperative clinical outcomes such as length of hospital stay (LOS). When analyzing the association of preoperative anemia on LOS, it is important to be able to analyze RBC transfusions as a mediator in this relationship. In this paper, the background and application of mediation analysis is outlined as a statistical methodology in transfusion medicine research.

STUDY DESIGN AND METHODS

To explain the methodology of mediation analysis, a database from a previously reported clinical study was used (So-Osman C. et al. 2014) with anemia as the exposure variable and LOS as the primary outcome. Both the product-of-coefficients method and the change-in-coefficients method are used for mediation analysis, and linear regression models were used.

RESULTS

In the example of a simplified analysis, two-thirds of the effect could be attributed to mediation. This result was obtained by both the product-of-coefficients method and the change-in-coefficients method.

DISCUSSION

Mediation is assessed in a similar way as confounding, but the interpretation of the results is totally different. It is, therefore, of critical importance to distinguish between potential mediators and potential confounders in transfusion research. Since the calculation reported in the results is merely used as an example to show the methodology, e.g. ignoring confounding, the result should not be interpreted as scientific research data.

Impact of gender differences on optimal oxygen delivery thresholds to prevent acute kidney injury in cardiac surgeries with cardiopulmonary bypass

Background

The nadir oxygen delivery index (DO2i) during cardiopulmonary bypass (CPB) is reportedly associated with acute kidney injury (AKI) in patients undergoing cardiac surgery. However, there are few reports on the relationship between patient sex and the nadir DO2i threshold to prevent AKI. The aim of this study was to seek and evaluate the optimal DO2i threshold differences between males and females to avoid AKI during on-pump cardiac surgery.

Methods

We retrospectively analyzed a total of 430 patients who underwent cardiac surgery between March 2017 and February 2023. A receiver operating characteristic analysis and univariable and multivariable regression analyses were performed to evaluate the association between perioperative variables, including the nadir DO2i and incidence of AKI, in males and females.

Results

The nadir DO2i was significantly lower (median, 294 [interquartile range (IQR), 272-317] mL/min/m2 versus 277 [IQR, 262-295] mL/min/m2; P < .001) and cumulative time below the DO2i of 270 mL/min/m2 was longer (0.3 [IQR, 0-4.2] minutes vs 3.0 [IQR, 0-11.7] minutes; P < .001) in the female patients. However, the incidence rate of AKI was similar in males and females (15.2% [n = 39/256] vs 16.7% [n = 29/174]; P = .68). The best cut-off values of nadir DO2i for AKI were <301 mL/min/m2 (sensitivity, 82.1%; specificity, 39.5%) in males and <273 mL/min/m2 (sensitivity, 69.0%; specificity, 61.4%) in females.

Conclusions

The optimal DO2i to prevent AKI during cardiac surgery differs between males and females. Therefore, CPB management should be adjusted by sex based on the different cut-off values of nadir DO2i.

Is High-Dose Ubiquinone Therapy Before Cardiac Surgery Enough to Reduce the Incidence of Cardiac Surgery-Associated Acute Kidney Injury? A Randomized Controlled Trial

Cardiac surgery-related acute kidney injury (CS-AKI) is a decrease in kidney function after open-heart surgery, affecting up to 50% of patients. The pathophysiology of CS-AKI involves ischemia-reperfusion injury, inflammation, and oxidative stress. Ubiquinone is a potent antioxidant, and we hypothesized that it could decrease both the incidence and severity of CS-AKI. The intervention group received ubiquinone (8 mg/kg/day) divided into three daily doses, while the control group received a placebo. The primary outcome was the incidence of CS-AKI, which was manifested as an increase in creatinine ≥26.5 µmol/L or a urine output below 0.5 mL/kg/h for 6 h. Out of 73 patients, 39.7% (N = 29) developed CS-AKI, including 35.3% of the ubiquinone group and 43.6% of the placebo group (X2(1,N = 73) = 0.4931, p = 0.4825). The secondary outcomes revealed that the ubiquinone group experienced reduced postoperative bleeding, with a median (IQR) drainage of 320 mL (230-415) compared to the drainage of 420 mL (242.5-747.5) in the placebo group (t(35.84) = 2.055, p = 0.047). The median hs-TnI level in the ubiquinone group was 239.5 ng/mL (113.25-382.75) after surgery compared to a level of 366 (234.5-672.5) ng/mL in the placebo group (p = 0.024). In conclusion, there was no significant difference in the incidence of CS-AKI between groups. Postoperative hs-TnI and bleeding were significantly reduced among patients receiving ubiquinone.

Frequency and Predictors of Pneumonia After Isolated Coronary Artery Bypass Grafting (CABG): A Single-Center Study

Background: CABG is a commonly performed procedure to improve survival and quality of life in patients with coronary artery disease. Despite advances in surgical techniques and perioperative care, postoperative pneumonia remains a serious complication contributing to increased morbidity, mortality and healthcare costs. This study aims to evaluate the incidence of postoperative pneumonia (POP) and identify its risk factors in patients undergoing isolated CABG. Methods: This retrospective study analyzed 430 patients who underwent CABG between 2019 and 2024. Patient demographics, clinical characteristics, surgical details and laboratory data were collected. Statistical analysis included univariate and multivariate logistic regression to identify significant predictors of pneumonia. Results: The incidence of POP after CABG was 10% (43/430). In patients with POP, diabetes mellitus (p = 0.03) and chronic kidney disease (p = 0.048) prevalence was higher, cardiopulmonary bypass (CPB) (p = 0.01) and cross-clamp time (p = 0.003) was longer, LDH levels (p = 0.017) were higher, hemoglobin (p = 0.012) and albumin (p = 0.015) levels were lower, and lymphocyte % (p = 0.04) was lower; prevalence of COPD and length of stay (LOS) in hospital tended to be higher (both p < 0.06). Multivariate binary logistic regression identified COPD (OR 4.383, 95% CI: 1.106-17.363, p = 0.035), CPB time (OR 1.013, 95% CI: 1.001-1.025, p = 0.030) and LOS (OR 1.052, 95% CI: 1.004-1.103, p = 0.035) as independent predictors of POP. Conclusions: Postoperative pneumonia is a common complication after CABG and is strongly associated with preoperative COPD, CPB time and length of stay in hospital. These findings underline the importance of preoperative risk assessment and optimization. Early identification of high-risk patients may allow targeted strategies such as enhanced respiratory support and prophylactic antibiotics to reduce the incidence of pneumonia and improve clinical outcomes.

Unexpected impact of preoperative anemia in low-risk isolated coronary artery bypass grafting or single-valve surgical patients: Do not overlook these patients in anemia management!

OBJECTIVE

Preoperative anemia is prevalent in cardiac surgery and independently associated with increased risk for short-term and long-term mortality. The purpose of this study was to examine the effect of preoperative hematocrit (Hct) on outcomes in cardiac surgical patients and whether the effect is comparable across levels of Society of Thoracic Surgeons Predicted Risk of Mortality (STS PROM).

METHODS

The study consisted of adult, isolated coronary artery bypass grafting (CABG) or single-valve surgical patients in a statewide registry from 2011 to 2022 (N = 29,828). Regressions were used to assess effect of preoperative Hct on STS-defined major morbidity/mortality including the interaction of Hct and STS PROM as continuous variables.

RESULTS

Median age was 66 years (58-73 years), STS PROM was 1.02% (0.58%-1.99%), and preoperative Hct was 39.5% (35.8%-42.8%). The sample consisted of 78% isolated CABG (n = 23,261), 10% isolated mitral valve repair/replacement (n = 3119), 12% isolated aortic valve replacement (n = 3448), and 29% were female (n = 8646). Multivariable analyses found that greater Hct was associated with reduced risk of STS-defined morbidity/mortality (odds ratio, 0.96; P < .001). These effects for Hct persisted even after adjustment for intraoperative blood transfusion. The interaction of Hct and STS PROM was significant for morbidity/mortality (odds ratio, 1.01; P < .001). There was a stronger association between Hct levels and morbidity/mortality risk in the patients with the lowest STS risk compared with patients with the greatest STS risk.

CONCLUSIONS

Patients with lower risk had a greater association between preoperative Hct and major morbidity and mortality compared with patients with greater risk. Preoperative anemia management is essential across all risk groups for improved outcomes.

The Year in Cardiothoracic and Vascular Anesthesia: Selected Highlights from 2024

This special article is the 17th in an annual series for the Journal of Cardiothoracic and Vascular Anesthesia. The authors thank the editor in chief, Dr Kaplan, and the editorial board for the opportunity to continue this series, namely, the research highlights of the past year in the specialty of cardiothoracic and vascular anesthesiology.1 The major themes selected for 2024 are outlined in this introduction, and each highlight is reviewed in detail in the main article. The literature highlights in the specialty for 2024 begin with an update on perioperative rehabilitation and enhanced recovery in cardiothoracic surgery, with a focus on novel methods to best assess our patients in the preoperative period and the impact of implementing enhanced recovery care models on outcomes. The second major theme is focused on cardiac surgery, with the authors discussing new insights into anemia, transfusions, and coronary artery bypass grafting outcomes with a focus on gender disparities. The third theme is focused on cardiothoracic transplantation, with discussions focusing on techniques related to lung transplantation, including mechanical circulatory support. The 4th theme is focused on mechanical circulatory support, with discussions exploring advancements in left ventricular assist devices highlight the evolving landscape of mechanical circulatory support and discussion of anticoagulation practices. The fifth and final theme is an update on medical cardiology, with a focus on the outcomes of transcatheter management of regurgitant pathology, device management in heart failure, and new techniques in catheter ablation. The themes selected for this article are only a few of the diverse advances in the specialty during 2024. These highlights will inform the reader of key updates on a variety of topics, leading to improvement in perioperative outcomes for patients with cardiothoracic and vascular disease.

Perioperative Acute Kidney Injury: Diagnosis, Prediction, Prevention, and Treatment

In this review, the authors define acute kidney injury in the perioperative setting, describe the epidemiologic burden, discuss procedure-specific risk factors, detail principles of management, and highlight areas of ongoing controversy and research.

Ultrafiltration During Cardiac Surgery Requiring Cardiopulmonary Bypass and Its Effect on Acute Kidney Injury

OBJECTIVE

To explore whether ultrafiltration (UF) volume adjusted for weight is associated with an increased risk of acute kidney injury (AKI) after cardiopulmonary bypass (CPB) in cardiac surgery patients.

DESIGN

A retrospective cohort study.

SETTING

Single-center study at a tertiary academic medical center.

PARTICIPANTS

A total of 2369 adult patients (age ≥18 years) who underwent cardiac surgery with CPB between January 2018 and August 2019.

INTERVENTION

The cohort was divided into 4 groups based on weight-adjusted conventional UF volume: 0 (no UF), 0.1 to 17.9 mL, 18 to 29.9 mL, and >30 mL ultrafiltration for each kg of body weight. Demographic data, laboratory findings, comorbidities, medications, and surgical details were collected. Postoperative AKI was defined by the KDIGO (Kidney Disease: Improving Global Outcomes) staging criteria and assessed in all UF groups. The association between UF volume and AKI according to nadir hemoglobin (Hb) level and red blood cell transfusion volume was explored.

RESULTS

Postoperative AKI occurred in 840 patients (35.4%). The incidence of AKI post-CPB in patients was similar in patients with 0 mL/kg (34.4%; n = 123), 0.1 to 17.9 mL/kg (34.3%; n = 387), and 18 to 29.9 mL/kg (33.7%; n = 173) of UF volume. The patients with UF volume >30 mL/kg had a higher incidence of AKI (42.7%; n = 157; p = 0.019). For each additional 10 mL/kg increase in UF, the odds ratio (OR) of AKI was 1.14 (95% confidence interval [CI], 1.07-1.20; p < 0.001) following adjustments for preoperative covariates. However, the association was mitigated following adjustments for preoperative and intraoperative covariates (OR, 1.07; 95% CI, 0.99-1.16; p = 0.076). Although higher UF also was associated with an increased risk of AKI in patients with nadir Hb levels of 6 to 8 g/dL (adjusted OR, 1.24 and 1.22; p = 0.02), it was not significantly associated with AKI when nadir Hb was 10 to 12 g/dL. Red blood cell transfusion volume was not related to changes in AKI incidence.

CONCLUSIONS

This study suggests that conventional UF is a potential risk factor for AKI incidence following surgery with CPB. The results demonstrate an association between higher weight-adjusted ultrafiltration volume and a higher incidence of AKI. Future studies should incorporate a multicenter, prospective approach to test the generalizability of the present findings and validate modified ultrafiltration strategies that use hemodynamic variables to determine fluid removal volume.

Effect of perioperative erythropoietin on postoperative morbidity and mortality after cardiac surgery: a meta-analysis of randomized controlled trials

OBJECTIVE

Cardiac surgery is known to have high rates of perioperative red blood cell (RBC) transfusions which are associated with increased postoperative mortality and morbidity. Perioperative erythropoietin (EPO) has been suggested to lower perioperative RBC transfusions, and the effect on postoperative morbidity or mortality is unknown.

METHODS

The registered study protocol is available on PROSPERO (CRD42022314538). We searched the Pubmed, EMbase, and Cochrane CENTRAL databases for randomized controlled trials (RCT) of EPO in cardiac surgery. Outcomes were short-term mortality, acute kidney injury (AKI), re-operation, cerebrovascular accident (CVA), perioperative myocardial infarction (MI), infectious complications, and RBC transfusions. RCT studies of perioperative EPO that reported at least one prespecified outcome of interest were included.

RESULTS

A total of 21 RCT's (n = 2,763 patients) were included. Mortality analysis included 17 studies (EPO 1,272 patients, control 1,235) and showed no significant difference (risk difference (RD) 0.0004, 95%CI: -0.016, 0.009). EPO did not reduce the incidence of AKI (RD -0.006, 95% CI: -0.038, 0.026) and reoperation (RD 0.001, 95% CI: -0.013, 0.015). The incidence of CVA (RD -0.004, 95% CI: -0.015, 0.007) and perioperative MI (RD -0.008, 95% CI: -0.021, 0.005) was similar between the groups.

CONCLUSIONS

Although EPO had been proven to reduce perioperative RBC transfusions, we did not find that it reduces the incidence of postoperative short-term mortality, AKI, and reoperation. The study results support that perioperative EPO is also safe, with no rise in thrombotic events, including CVA and perioperative MI.

Return on Investment of Preoperative Anemia Management Programs in Cardiac Surgery: An Advisory From the Society of Cardiovascular Anesthesiologists Clinical Practice Improvement Committee With Endorsement by the Society for the Advancement of Patient Blood Management

Despite multiple recent guidelines recommending the diagnosis and treatment of anemia before elective cardiac surgery, few institutions have formal programs or methods in place to accomplish this. A major limitation is the perceived financial shortfall and the leadership buy-in required to undertake such an initiative. The purpose of this advisory from the Society of Cardiovascular Anesthesiologists (SCA) Clinical Practice Improvement Committee with endorsement by the Society for the Advancement of Patient Blood Management (SABM) is to provide an overview of preoperative anemia management programs with an emphasis on the associated financial implications. This advisory reviews the evidence for preoperative anemia management programs in both cardiac and noncardiac surgery, discusses options for managing preoperative anemia, provides novel financial modeling regarding the implementation of preoperative anemia management programs, and describes implementation challenges, potential solutions, and opportunities for improvement.

Use of preoperative erythropoietin-stimulating agents is associated with decreased thrombotic adverse events compared to red blood cell transfusion in surgical patients with anaemia

BACKGROUND AND OBJECTIVES

Preoperative red blood cell (RBC) transfusions increase post-operative venous thromboembolic (VTE) events. Erythropoietin-stimulating agents (ESAs) increase VTE risk in cancer patients; we aimed to assess ESA versus RBC-associated VTE risks in a broad population of surgical patients.

MATERIALS AND METHODS

We queried TriNetX Diamond Network from 2006 to 2023, comparing patients with anaemia within 3 months preoperatively who received preoperative ESAs with or without intravenous (IV) iron to patients who received preoperative RBCs. Sub-analyses included (1) all surgeries and (2) cardiovascular surgeries. We propensity score matched for demographics, comorbidities, medical services, post-treatment haemoglobin (g/dL) and, for all-surgery comparisons, surgery type. Outcomes included 30-day post-operative mortality, VTE, pulmonary embolism (PE), disseminated intravascular coagulation (DIC) and haemoglobin.

RESULTS

In our 19,548-patient cohorts, compared with preoperative RBC transfusion, ESAs without IV iron were associated with lower mortality (relative risk [RR] = 0.51 [95% confidence interval (CI), 0.45-0.59]), VTE (RR = 0.57 [0.50-0.65]) and PE (RR = 0.67 [0.54-0.84]). Post-operative haemoglobin was higher in the ESA without IV iron cohort compared with the transfusion cohort (10.0 ± 1.4 vs. 9.4 ± 1.8 g/dL, p = 0.002). Cardiac surgical patients receiving ESAs with or without IV iron had lower risk for post-operative mortality, VTE and PE (p < 0.001) than those receiving RBCs. Post-operative haemoglobin differed between patients receiving ESAs with IV iron versus RBCs (10.1 ± 1.5 vs. 9.4 ± 1.9 g/dL, p = 0.0009).

CONCLUSION

Compared with surgical patients who were transfused RBCs, ESA recipients had reduced 30-day post-operative risk of mortality, VTE, PE and DIC and increased haemoglobin levels. IV iron given with ESAs improved mortality.

Cardiac surgery-Associated acute kidney injury - A narrative review

Cardiac Surgery-Associated Acute Kidney Injury (CSA-AKI) is a serious complication seen in approximately 20-30% of cardiac surgery patients. The underlying pathophysiology is complex, often involving both patient- and procedure related risk factors. In contrast to AKI occurring after other types of major surgery, the use of cardiopulmonary bypass comprises both additional advantages and challenges, including non-pulsatile flow, targeted blood flow and pressure as well as the ability to manipulate central venous pressure (congestion). With an increasing focus on the impact of CSA-AKI on both short and long-term mortality, early identification and management of high-risk patients for CSA-AKI has evolved. The present narrative review gives an up-to-date summary on definition, diagnosis, underlying pathophysiology, monitoring and implications of CSA-AKI, including potential preventive interventions. The review will provide the reader with an in-depth understanding of how to identify, support and provide a more personalized and tailored perioperative management to avoid development of CSA-AKI.

Perioperative Patient Blood Management (excluding obstetrics): Guidelines from the French National Authority for Health

The French National Authority for Health (HAS) recently issued guidelines for patient blood management (PBM) in surgical procedures. These recommendations are based on three usual pillars of PBM: optimizing red cell mass, minimizing blood loss and optimizing anemia tolerance. In the preoperative period, these guidelines recommend detecting anemia and iron deficiency and taking corrective measures well in advance of surgery, when possible, in case of surgery with moderate to high bleeding risk or known preoperative anemia. In the intraoperative period, the use of tranexamic acid and some surgical techniques are recommended to limit bleeding in case of high bleeding risk or in case of hemorrhage, and the use of cell salvage is recommended in some surgeries with a major risk of transfusion. In the postoperative period, the limitation of blood samples is recommended but the monitoring of postoperative anemia must be carried out and may lead to corrective measures (intravenous iron in particular) or more precise diagnostic assessment of this anemia. A "restrictive" transfusion threshold considering comorbidities and, most importantly, the tolerance of the patient is recommended postoperatively. The implementation of a strategy and a program for patient blood management is recommended throughout the perioperative period in healthcare establishments in order to reduce blood transfusion and length of stay. This article presents an English translation of the HAS recommendations and a summary of the rationale underlying these recommendations.

Re-evaluating treatment thresholds in patient blood management: Female patients experience more perioperative anaemia and higher transfusion rates in major elective surgery

BACKGROUND AND OBJECTIVES

By optimizing erythropoiesis, patient blood management (PBM) programmes can reduce transfusions, lower mortality and provide cost-effective care. While definitions of anaemia have historically varied by sex, for the purposes of PBM, anaemia is defined as a haemoglobin <130 g/L. Our objective was to describe whether perioperative anaemia and transfusion rates in the PBM setting vary by sex.

MATERIALS AND METHODS

We conducted a retrospective study of the Ontario Nurse Transfusion Coordinators Program (ONTraC) database from 2018 to 2022. ONTraC collects data from 25 Ontario hospitals which together account for >70% of Ontario's provincial blood use (~400,000 units per year). We collected data on patients undergoing elective isolated coronary artery bypass graft surgery (CABG), open heart valve replacement, CABG plus valve replacement, single-knee arthroplasty and single-hip arthroplasty.

RESULTS

From 2018 to 2022, 17,700 patients were included in the ONTraC program; 47% were females (N = 8376). Across almost all years and procedures, females were found to have a significantly lower pre-operative, nadir and discharge haemoglobin as compared with males, irrespective of PBM interventions. Transfusion rates were significantly higher for females; this was most pronounced in cardiac surgery.

CONCLUSION

Females experienced more perioperative anaemia and higher transfusion rates. Historic sex-specific definitions of anaemia may contribute to a greater tolerance of anaemia in females. Prioritizing females for multimodal PBM and consistently achieving a pre-operative haemoglobin >130 g/L may reduce the amount of red blood cell (RBC) transfusions that female patients receive.

Postoperative intravenous iron to treat iron-deficiency anaemia in patients undergoing cardiac surgery: a protocol for a pilot, multicentre, placebo-controlled randomized trial (the POAM trial)

Background

Iron-deficiency anaemia, occurring in 30-40% of patients undergoing cardiac surgery, is an independent risk factor for adverse outcomes. Our long-term goal is to assess if postoperative i.v. iron therapy improves clinical outcomes in patients with preoperative iron-deficiency anaemia undergoing cardiac surgery. Before conducting a definitive RCT, we first propose a multicentre pilot trial to establish the feasibility of the definitive trial.

Methods

This internal pilot, double-blinded, RCT will include three centres. Sixty adults with preoperative iron-deficiency anaemia undergoing non-emergency cardiac surgery will be randomised on postoperative day 2 or 3 to receive either blinded i.v. iron (1000 mg ferric derisomaltose) or placebo. Six weeks after surgery, patients who remain iron deficient will receive a second blinded dose of i.v. iron according to their assigned treatment arm. Patients will be followed for 12 months. Clinical practice will not be otherwise modified. For the pilot study, feasibility will be assessed through rates of enrolment, protocol deviations, and loss to follow up. For the definitive study, the primary outcome will be the number of days alive and out of hospital at 90 days after surgery.

Ethics and dissemination

The trial has been approved by the University Health Network Research Ethics Board (REB # 22-5685; approved by Clinical Trials Ontario funding on 22 December 2023) and will be conducted in accordance with the Declaration of Helsinki, Good Clinical Practices guidelines, and regulatory requirements.

Clinical trial registration

NCT06287619.

ERAS Cardiac Society turnkey order set for patient blood management: Proceedings from the AATS ERAS Conclave 2023

OBJECTIVES

There are multiple published guidelines on comprehensive patient blood management (PBM), centered on the 3 pillars of PBM: managing preoperative anemia, minimizing blood loss, and tolerating intraoperative/postoperative anemia. We sought to create an order set to facilitate widespread implementation of evidence-based PBM for cardiac surgery patients.

METHODS

Subject matter experts were consulted to translate existing guidelines and literature into a sample turnkey order set (TKO) for PBM. Orders derived from consistent class I, class IIA, or equivalent recommendations across referenced guidelines and consensus manuscripts appear in the TKO in bold type. Selected orders that were inconsistently class I or IIA, class IIB, or supported by published evidence are presented in italic type.

RESULTS

Preoperatively, there are strong recommendations to screen and treat preoperative anemia with iron replacement and erythropoietin and to discontinue dual antiplatelet therapy if the patient can safely wait for surgery. Intraoperative orders outline the routine use of an antifibrinolytic agent, cell saver, point of care viscoelastic testing, and use of a standard transfusion algorithm. The order set also reflects strong recommendations intraoperatively and postoperatively for agreed-upon hemoglobin thresholds to consider transfusion of packed red blood cells. A hemoglobin threshold should be adopted according to local team consensus and should trigger a discussion regarding transfusion.

CONCLUSIONS

The benefit of a multidisciplinary PBM care pathway in cardiac surgery has been well established, yet implementation remains variable. Using recommendations from existing guidelines, we have created a TKO to facilitate the implementation of PBM.

Associations Between Nonanemic Iron Deficiency and Postoperative Outcomes in Cardiac Surgery: A Systematic Review and Meta-Analysis

BACKGROUND

Preoperative screening for iron deficiency is a part of patient blood management protocols. This systematic review, meta-analysis, and meta-regression reviews the association between nonanemic iron deficiency and postoperative outcomes in patients undergoing cardiac surgery. We aimed to determine whether preoperative screening for nonanemic iron deficiency should be recommended in patients undergoing cardiac surgery.

METHODS

Electronic databases MEDLINE (Ovid), Embase (Ovid), and Scopus were searched from inception until December 9, 2022. Studies were considered for inclusion if they (1) used an observational study design; (2) enrolled adult patients undergoing cardiac surgery; and (3) included an iron-deficient and iron-replete group, defined using serum ferritin and/or transferrin saturation. The primary outcome was the length of acute hospital stay. Secondary outcomes included length of intensive care unit stay, requirement for allogeneic red blood cell transfusion, number of red blood cell units transfused, days alive and at home at postoperative days 30 and 90, all-cause postoperative complications, postoperative infection, mortality, and hospital readmission. Meta-regression was performed to assess the effects of study and patient-level factors on the associations between nonanemic iron deficiency and specific outcomes. Individual study quality was assessed using the Risk of Bias in Non-Randomized Studies of Exposures (ROBINS-E) tool. The Grading of Recommendations, Assessment, Development, and Evaluations (GRADE) framework was used to determine the quality of evidence for each outcome.

RESULTS

Eight studies (2683 patients) were included. No significant association was observed between nonanemic iron deficiency and any of the primary or secondary outcomes except for an increased requirement for allogeneic red blood cell transfusion (odds ratio [OR], 1.39 [95% confidence interval, CI, 1.16-1.68; P < .001; I2 2.8%]). Meta-regression did not identify any potential sources of heterogeneity to explain variation in individual study results. The quality of evidence was rated as "low" or "very low" for all outcomes.

CONCLUSIONS

Few high-quality studies are available to assess associations between nonanemic iron deficiency and outcomes after cardiac surgery. Acknowledging these limitations, the presence of preoperative nonanemic iron deficiency was not associated with a change in the primary outcome of length of hospital stay, or any patient-centered secondary outcome compared to those without iron deficiency. There was an association with increased requirement for allogeneic red blood cell transfusion, but this did not impact the reported patient-centered outcomes.

Pre-operative anaemia-does it influence post-operative outcomes after isolated coronary artery bypass grafting?

Introduction

Preoperative anaemia is prevalent in a number of patients undergoing coronary artery bypass grafting. Studies provide conflicting results due to several reasons including variation in the threshold of haematocrit used to define anaemia. We aimed to assess the independent effect of preoperative anaemia on outcomes in patients undergoing off pump coronary artery bypass grafting (OPCAB).

Methods

In this retrospective study, patients with a hemoglobin level less than 11g/dl (haematocrit <33%) were considered to have moderate-to-severe anaemia as per the recommendations of the World Health Organization. Association between haematocrit <33% and mortality as well as adverse post-operative outcomes was assessed. Multivariable logistic regression (MLR) was carried out to assess the independent effect of haematocrit<33% on 30-day mortality and other outcomes.

Results

The study included 4957 consecutive patients undergoing isolated OPCAB surgery between 2015 and 2020. Out of 4957, 635 (12.8%) had haematocrit <33% and 4322 (81.2%) had haematocrit ≥33%. Patients with haematocrit < 33% had a 30-day mortality of 13 (2%) compared to 38 (0.9%) in patients without anaemia and had a greater requirement for blood transfusion (p<0.0001). It was also associated with an increased incidence of renal failure (p<0.0001), tracheostomy (p=.0.012) and risk of re-intubation (p=0.006). On multiple linear regression (MLR), haematocrit < 33% was not an independent predictor of 30-day mortality odds ratio (OR) 1.47, 95% confidence interval (CI) 0.745-2.917; p=0.26. It was however an important independent risk factor for blood transfusion (OR 1.80, 95% CI 1.29-2.50, p<0.001) and renal failure (OR 3.06, 95% CI 1.338-7.012, p=0.008). The receiver operating characteristic (ROC)-area under the curve (AUC) was 0.63 suggesting moderate discriminatory value of haematocrit < 33% for 30-day mortality.

Conclusion

Haematocrit < 33% is an important risk factor for adverse outcomes following isolated, primary, elective OPCAB.

Graphical Abstract

Supplementary Information

The online version contains supplementary material available at 10.1007/s12055-024-01746-1.

Implementing a Preoperative Anemia Optimization Protocol for Cardiovascular Surgery Patients: A Quality Improvement Project

BACKGROUND

Patients with anemia have poorer outcomes following cardiac surgery than do those without anemia. To improve outcomes, the Enhanced Recovery After Surgery cardiac recommendations include optimizing patients' condition, including treating anemia, before surgery.

LOCAL PROBLEM

Despite implementing Enhanced Recovery After Surgery initiatives, a midwestern cardiothoracic surgery group recognized a care gap in preoperative patients with anemia. No standardized protocol was in use.

METHODS

An anemia optimization protocol was developed for perioperative care of patients with anemia. Data from retrospective medical record review were analyzed to determine relationships between protocol use and secondary outcomes. The protocol was created using best evidence and expert consensus. Cardiac surgery and hematology specialists revised the protocol and agreed on a final version. The protocol was integrated into the consultation process for cardiac surgery patients.

RESULTS

During the implementation period, 23 of 55 patients with anemia (42%) received interventions via the anemia optimization protocol. The mean quantity of packed red blood cells transfused perioperatively per patient was 1.9 U in the protocol group and 3.5 U in the nonprotocol group. In the subgroup of patients experiencing postoperative acute kidney injury, the mean increase in creatinine level was 0.65 mg/dL in the protocol group and 1.52 mg/dL in the nonprotocol group. Four patients in the protocol group (17%) and 6 patients in the nonprotocol group (19%) experienced postoperative acute kidney injury.

CONCLUSION

Preoperative anemia is associated with poorer cardiac surgical outcomes. Incorporating the anemia optimization protocol into practice may mitigate the risk of postoperative complications for patients with anemia. Continued use of the protocol is recommended.

Analysis of Anemia, Transfusions, and CABG Outcomes in The Society of Thoracic Surgeons National Database

BACKGROUND

This study characterized the association of preoperative anemia and intraoperative red blood cell (RBC) transfusion on outcomes of elective coronary artery bypass grafting (CABG).

METHODS

Data from 53,856 patients who underwent CABG included in The Society of Thoracic Surgeons (STS) Adult Cardiac Database in 2019 were used. The primary outcome was operative mortality. Secondary outcomes were postoperative complications. The association of anemia with outcomes was analyzed with multivariable regression models. The influence of intraoperative RBC transfusion on the effect of preoperative anemia on outcomes was studied using mediation analysis.

RESULTS

Anemia was present in 25% of patients. Anemic patients had a higher STS Predicted Risk of Operative Mortality (1.2% vs 0.7%; P < .001). Anemia was associated with operative mortality (odds ratio [OR], 1.27; 99.5% CI, 1.00-1.61; P = .047), postoperative RBC transfusion (OR, 2.28; 99.5% CI, 2.12-2.44; P < .001), dialysis (OR, 1.58; 99.5% CI, 1.19-2.11; P < .001), and prolonged intensive care unit and hospital length of stay. Intraoperative RBC transfusion largely mediated the effects of anemia on mortality (76%), intensive care unit stay (99%), and hospital stay, but it only partially mediated the association with dialysis (34.9%).

CONCLUSIONS

Preoperative anemia is common in patients who undergo CABG and is associated with increased postoperative risks of mortality, complications, and RBC transfusion. However, most of the effect of anemia on mortality is mediated through intraoperative RBC transfusion.

Preoperative anaemia in distal pancreatectomy: a propensity-score matched analysis

BACKGROUND

Preoperative anaemia is a prevalent morbidity predictor that adversely affects short- and long-term outcomes of patients undergoing surgery. This analysis aimed to investigate preoperative anaemia and its detrimental effects on patients after distal pancreatectomy.

MATERIAL AND METHODS

The present study was a propensity-score match analysis of 286 consecutive patients undergoing distal pancreatectomy. Patients were screened for preoperative anaemia and classified according to WHO recommendations. The primary outcome measure was overall morbidity. The secondary endpoints were in-hospital mortality and rehospitalization.

RESULTS

The preoperative anaemia rate before matching was 34.3% (98 patients), and after matching a total of 127 patients (non-anaemic 42 vs. anaemic 85) were included. Anaemic patients had significantly more postoperative major complications (54.1% vs. 23.8%; p < 0.01), a higher comprehensive complication index (26.2 vs. 4.3; p < 0.01), and higher in-hospital mortality rate (14.1% vs. 2.4%; p = 0.04). Multivariate regression analysis confirmed these findings and identified preoperative anaemia as a strong independent risk factor for postoperative major morbidity (OR 4.047; 95% CI: 1.587-10.320; p < 0.01).

CONCLUSION

The current propensity-score matched analysis strongly considered preoperative anaemia as a risk factor for major complications following distal pancreatectomy. Therefore, an intense preoperative anaemia workup should be increasingly prioritised.

Preoperative Anemia and Postoperative Outcomes in Cardiac Surgery: A Mediation Analysis Evaluating Intraoperative Transfusion Exposures

BACKGROUND

Preoperative anemia is associated with adverse outcomes in cardiac surgery, yet it remains unclear what proportion of this association is mediated through red blood cell (RBC) transfusions.

METHODS

This is a historical observational cohort study of adults undergoing coronary artery bypass grafting or valve surgery on cardiopulmonary bypass at an academic medical center between May 1, 2008, and May 1, 2018. A mediation analysis framework was used to evaluate the associations between preoperative anemia and postoperative outcomes, including a primary outcome of acute kidney injury (AKI). Intraoperative RBC transfusions were evaluated as mediators of preoperative anemia and outcome relationships. The estimated total effect, average direct effect of preoperative anemia, and percent of the total effect mediated through transfusions are presented with 95% confidence intervals and P -values.

RESULTS

A total of 4117 patients were included, including 1234 (30%) with preoperative anemia. Overall, 437 of 4117 (11%) patients went on to develop AKI, with a greater proportion of patients having preoperative anemia (219 of 1234 [18%] vs 218 of 2883 [8%]). In multivariable analyses, the presence of preoperative anemia was associated with increased postoperative AKI (6.4% [4.2%-8.7%] absolute difference in percent with AKI, P < .001), with incremental decreases in preoperative hemoglobin concentrations displaying greater AKI risk (eg, 11.9% [6.9%-17.5%] absolute increase in probability of AKI for preoperative hemoglobin of 9 g/dL compared to a reference of 14 g/dL, P < .001). The association between preoperative anemia and postoperative AKI was primarily due to direct effects of preoperative anemia (5.9% [3.6%-8.3%] absolute difference, P < .001) rather than mediated through intraoperative RBC transfusions (7.5% [-4.3% to 21.1%] of the total effect mediated by transfusions, P = .220). Preoperative anemia was also associated with longer hospital durations (1.07 [1.05-1.10] ratio of geometric mean length of stay, P < .001). Of this total effect, 38% (22%, 62%; P < .001) was estimated to be mediated through subsequent intraoperative RBC transfusion. Preoperative anemia was not associated with reoperation or vascular complications.

CONCLUSIONS

Preoperative anemia was associated with higher odds of AKI and longer hospitalizations in cardiac surgery. The attributable effects of anemia and transfusion on postoperative complications are likely to differ across outcomes. Future studies are necessary to further evaluate mechanisms of anemia-associated postoperative organ injury and treatment strategies.

Postoperative anemia in cardiac surgery patients: a narrative review

PURPOSE

Anemia reduces the blood's ability to carry and deliver oxygen. Following cardiac surgery, anemia is very common and affects up to 90% of patients. Nevertheless, there is a paucity of data examining the prognostic value of postoperative anemia. In this narrative review, we present findings from the relevant literature on postoperative anemia in cardiac surgery patients, focusing on the incidence, risk factors, and prognostic value of postoperative anemia. We also explore the potential utility of postoperative anemia as a therapeutic target to improve clinical outcomes.

SOURCE

We conducted a targeted search of MEDLINE, Embase, and the Cochrane Database of Systematic Reviews up to September 2022, using a combination of search terms including postoperative (post-operative), perioperative (peri-operative), anemia (anaemia), and cardiac surgery.

PRINCIPAL FINDINGS

The reported incidence of postoperative anemia varied from 29% to 94% across the studies, likely because of variations in patient inclusion criteria and classification of postoperative anemia. Nonetheless, the weight of the evidence suggests that postoperative anemia is common and is an independent risk factor for adverse postoperative outcomes such as acute kidney injury, stroke, mortality, and functional outcomes.

CONCLUSIONS

In cardiac surgery patients, postoperative anemia is a common and prognostically important risk factor for postoperative morbidity and mortality. Nevertheless, there is a lack of data on whether active management of postoperative anemia is feasible or effective in improving patient outcomes.

The additive effects of anaemia and transfusion on long-term survival after coronary artery bypass surgery

OBJECTIVES

To compare the independent and combined effects of anaemia and red blood cell transfusion on late survival after isolated coronary artery bypass grafting.

METHODS

Retrospective analysis of 5243 consecutive patients undergoing primary isolated coronary artery bypass grafting, performed from 2000 to 2015, in a Portuguese Academic Hospital. We identified 1649 patients with preoperative anaemia (A+) and 1422 patients who received a perioperative transfusion (T+)-the 4 possible combinations allowed for the creation of 4 subgroups (A-/T-, A-/T+, A+/T- and A+/T+). The primary endpoint was all-cause mortality at 10 years. We employed inverse probability weighting to control for confounding variables.

RESULTS

Thirty-one percent of the patients had preoperative anaemia, and 27.0% had at least one packed red blood cell transfusion. Inverse probability weighting was effective in eliminating differences in all significant baseline characteristics. The primary endpoint of all-cause mortality at 10 years occurred in 568 patients (20.5%) in the A-/T- group, as compared with 204 (24.4%) in the A-/T+ group (hazard ratio, 1.14; 95% confidence interval, 1.00 to 1.31; P = 0.053), 358 (33.8%) in the A+/T- group (hazard ratio, 1.53; 95% confidence interval, 1.38 to 1.71; P < 0.001), 254 (43.6%) in the A+/T+ group (hazard ratio, 2.25; 95% confidence interval, 1.97 to 2.56; P < 0.001).

CONCLUSIONS

This longitudinal, population-level study emphasizes the adverse long-term outcomes of preoperative anaemia and perioperative red blood cell transfusion. It stresses the importance of an evidence-based, multimodal and multidisciplinary approach to conserving blood resources and optimizing outcomes in patients at high risk for transfusion.

Association between preoperative anemia optimization and major complications after non-cardiac surgery: a retrospective analysis

BACKGROUND

Anemia is common in the preoperative setting and associated with increased postoperative complications and mortality. However, it is unclear if preoperative anemia optimization reduces postoperative complications. We aimed to assess the association between preoperative anemia optimization and a composite endpoint of major cardiovascular, renal, and pulmonary complications and all-cause mortality within 30 days after noncardiac surgery in adult patients.

METHODS

In this retrospective analysis preoperative anemia was defined as hemoglobin concentration below 12.0 g.dl-1 in women and 13.0 g.dl-1 in men within 6 months before surgery. A propensity score-based generalized estimating equation analysis was used to determine the association between preoperative anemia optimization and the primary outcome. Moreover, mediation analysis was conducted to investigate whether intraoperative red blood cell transfusion or duration of intraoperative hypotension were mediators of the relation between anemia optimization and the primary outcome.

RESULTS

Fifty-seven hundred anemia optimized, and 8721 non-optimized patients met study criteria. The proportion of patients having any component of the composite of major complications and all-cause mortality was 21.5% in the anemia-optimized versus 18.0% in the non-optimized, with confounder-adjusted odds ratio estimate of 0.99 (95% CI 0.86‒1.15) for anemia optimization versus non-optimization, p = 0.90. Intraoperative red blood cell transfusion had a minor mediation effect on the relationship between preoperative anemia optimization and the primary outcome, whereas duration of intraoperative hypotension was not found to be a mediator.

CONCLUSION

Preoperative anemia optimization did not appear to be associated with a composite outcome of major in-hospital postoperative cardiovascular, renal, and pulmonary complications and all-cause in-hospital mortality.

Alternative blood transfusion triggers: a narrative review

BACKGROUND

Anemia, characterized by low hemoglobin levels, is a global public health concern. Anemia is an independent factor worsening outcomes in various patient groups. Blood transfusion has been the traditional treatment for anemia; its triggers, primarily based on hemoglobin levels; however, hemoglobin level is not always an ideal trigger for blood transfusion. Additionally, blood transfusion worsens clinical outcomes in certain patient groups. This narrative review explores alternative triggers for red blood cell transfusion and their physiological basis.

MAIN TEXT

The review delves into the physiology of oxygen transport and highlights the limitations of using hemoglobin levels alone as transfusion trigger. The main aim of blood transfusion is to optimize oxygen delivery, necessitating an individualized approach based on clinical signs of anemia and the balance between oxygen delivery and consumption, reflected by the oxygen extraction rate. The narrative review covers different alternative triggers. It presents insights into their diagnostic value and clinical applications, emphasizing the need for personalized transfusion strategies.

CONCLUSION

Anemia and blood transfusion are significant factors affecting patient outcomes. While restrictive transfusion strategies are widely recommended, they may not account for the nuances of specific patient populations. The search for alternative transfusion triggers is essential to tailor transfusion therapy effectively, especially in patients with comorbidities or unique clinical profiles. Investigating alternative triggers not only enhances patient care by identifying more precise indicators but also minimizes transfusion-related risks, optimizes blood product utilization, and ensures availability when needed. Personalized transfusion strategies based on alternative triggers hold the potential to improve outcomes in various clinical scenarios, addressing anemia's complex challenges in healthcare. Further research and evidence are needed to refine these alternative triggers and guide their implementation in clinical practice.

Allogeneic Blood Transfusion and Risk of Postoperative Complications in Patients with Mild and Moderate Anemia of Any Cause? A Retrospective Cohort Study in Total Revision Hip Surgery

Introduction

Patients undergoing revision total hip surgery (RTHS) have a high prevalence of mild and moderate preoperative anemia, associated with adverse outcomes. The aim of this study was to investigate the association of perioperative allogeneic blood transfusions (ABT) and postoperative complications in preoperatively mild compared to moderate anemic patients undergoing RTHS who did not receive a diagnostic anemia workup and treatment before surgery.

Methods

We included 1,765 patients between 2007 and 2019 at a university hospital. Patients were categorized according to their severity of anemia using the WHO criteria of mild, moderate, and severe anemia in the first Hb level of the case. Patients were grouped as having received no ABT, 1-2 units of ABT, or more than 2 units of ABT. Need for intraoperative ABT was assessed in accordance with institutional standards. Primary endpoint was the compound incidence of postoperative complications. Secondary outcomes included major/minor complications and length of hospital and ICU stay.

Results

Of the 1,765 patients, 31.0% were anemic of any cause before surgery. Transfusion rates were 81% in anemic patients and 41.2% in nonanemic patients. The adjusted risks for compound postoperative complication were significantly higher in patients with moderate anemia (OR 4.88, 95% CI: 1.54-13.15, p = 0.003) but not for patients with mild anemia (OR 1.93, 95% CI: 0.85-3.94, p < 0.090). Perioperative ABT was associated with significantly higher risks for complications in nonanemic patients and showed an increased risk for complications in all anemic patients. In RTHS, perioperative ABT as a treatment for moderate preoperative anemia of any cause was associated with a negative compound effect on postoperative complications, compared to anemia or ABT alone.

Discussion

ABT is associated with adverse outcomes of patients with moderate preoperative anemia before RTHS. For this reason, medical treatment of moderate preoperative anemia may be considered.

Postoperative Outcomes for Spinal Fusion Procedures in Pediatric Patients with Anemia: A Retrospective and Multivariate Analysis

BACKGROUND

Preoperative anemia is known to be associated with perioperative complications in many surgical interventions. Here, we examine the effects of preoperative anemia on peri-operative complications and postoperative outcomes in pediatric patients undergoing spinal fusion.

METHODS

Retrospective analysis was conducted using the American College of Surgeons Pediatric National Surgery Quality Improvement Program Database between 2012-2020. Current Procedural Terminology codes 22800, 22,802, 22,804, 22,840, 22,842, 22,843, and 22,844 were included to represent all primary spinal fusion procedures performed. Patients without preoperative hematocrit (HCT) levels were excluded. Classification of anemia was determined via age- and sex-adjusted HCT levels. Patient demographics, preoperative comorbidities and risk factors, and 30-day postoperative outcomes were compared between the 2 cohorts using univariate analysis. Multivariate logistic regressions were performed to determine if anemia severity was independently associated with worse postoperative outcomes.

RESULTS

A total of 30,243 pediatric patients were included in this study, with 26,621 not having preoperative anemia and 3622 having preoperative anemia. Pediatric patients with anemia have increased length of stay (LOS) (6.7 ± 9.6 vs. 5 ± 6, P < 0.001), 30-day unplanned reoperation rate (4% vs. 2.8%, P < 0.001), and total blood transfused (489.9 ± 497.8 vs. 423.4 ± 452.6, P < 0.001). Multivariate analysis supported anemia and degree of its severity as an independent predictor of increased length of stay (LOS), reoperation rate, and postoperative complications.

CONCLUSIONS

Preoperative anemia leads to worse outcomes in pediatric spinal fusion procedures. Utilizing HCT recordings could be factored into the equation for optimal patient selection and prevention of post-operative complications.

Red Blood Cell Transfusion Requirements Before and After Implementation of a Perioperative Patient Blood Management Program in Adult Patients Undergoing Cardiac Surgery. A Before and After Observational Study

OBJECTIVES

Anemia and transfusion are common in cardiac surgery patients, and are associated with significant morbidity and mortality. Multiple perioperative interventions have been described to reduce blood transfusion, but are rarely combined altogether. The aim of this study was to compare the incidence of red blood cell (RBC) transfusion in adult patients undergoing cardiac surgery before and after the implementation of a perioperative patient blood management (PBM) program.

DESIGN

Before-and-after observational study.

SETTING

Single-center French university teaching hospital.

PARTICIPANTS

Adult patients scheduled for cardiac surgery.

INTERVENTIONS

Perioperative patient blood management program including pre-, intra-, and postoperative interventions aimed at identifying and correcting anemia, minimizing blood loss during surgery, and optimizing coagulation.

MEASUREMENTS AND MAIN RESULTS

Four hundred thirty-four patients were included in the study from January 2021 to July 2022. The incidence of perioperative RBC transfusion (intraoperatively and during the first 2 postoperative days) was significantly reduced from 43% (90/213) in the pre-PBM period to 27% (60/221) in the post-PBM period (p < 0.001). The application of a PBM program was associated with a reduction in perioperative RBC transfusion by multivariate analysis (odds ratio 0.55, 95% CI 0.36-0.85, p = 0.007), and was associated with a reduction in the median number of RBC units transfused within transfused patients (p = 0.025). These effects persisted at day 30 after surgery (p = 0.029).

CONCLUSION

A perioperative PBM program in adult patients undergoing cardiac surgery was associated with a significant reduction in perioperative RBC transfusion, which persisted at day 30.

Preoperative anemia and anemia treatment in cardiac surgery: a systematic review and meta-analysis

PURPOSE

We aimed to conduct a systematic review and meta-analysis to assess the effects of anemia and anemia severity on patient outcomes in cardiac surgery and determine whether preoperative treatments confer postoperative benefit.

SOURCE

We searched four international databases for observational and randomized studies published until 1 October 2022. Study quality was assessed via Newcastle-Ottawa scores and the Cochrane Risk-of-Bias 2 tool and certainty of evidence was rated with the Grading of Recommendations, Assessment, Development and Evaluations approach. We conducted random-effects meta-analyses for our primary outcome of mortality, for secondary outcomes including length of stay (LOS) in the hospital and intensive care unit, and for postsurgical complications. As part of a secondary analysis, we analyzed short-term preoperative anemia treatments and conducted trial sequential analysis of randomized trials to assess the efficacy of these treatment programs.

PRINCIPAL FINDINGS

We included 35 studies (159,025 patients) in our primary meta-analysis. Preoperative anemia was associated with increased mortality (odds ratio [OR], 2.5; 95% confidence interval [CI], 2.2 to 2.9; P < 0.001, high certainty). Study-level meta-regression revealed lower hemoglobin levels and studies with lower proportions of male patients to be associated with increased risk of mortality. Preoperative anemia was also associated with an increase in LOS and postsurgical complications. Our secondary analysis (seven studies, 1,012 patients) revealed short-term preoperative anemia treatments did not significantly reduce mortality (OR, 1.1; 95% CI, 0.65 to 1.9; P = 0.69). Trial sequential analysis suggested that there was insufficient evidence to conclude if treatment programs yield any benefit or harm.

CONCLUSIONS

Preoperative anemia is associated with mortality and morbidity after cardiac surgery. More research is warranted to test the efficacy of current anemia treatment programs.

STUDY REGISTRATION

PROSPERO (CRD42022319431); first submitted 17 April 2023.

The Year in Coagulation and Transfusion: Selected Highlights from 2022

This is an annual review to cover highlights in transfusion and coagulation in patients undergoing cardiovascular surgery. The goal of this article is to provide readers with a focused summary of the most important transfusion and coagulation topics published in 2022. This includes a discussion covering the management of anemia and red blood cell transfusion, the management of factor Xa inhibitors, updates in coagulation testing, updates in the use of factor concentrates, advances in platelet therapy, advances in anticoagulation management of patients on extracorporeal membrane oxygenation and other forms of mechanical circulatory support, and advances in the diagnosis and management of heparin-induced thrombocytopenia.

Sex-Specific Associations Between Preoperative Hemoglobin and Outcomes After Major Noncardiac Surgery: A Retrospective Cohort Study

BACKGROUND

Preoperative anemia is an established risk factor for morbidity and mortality after surgery. Men and women have different hemoglobin concentrations and are at different risks of postoperative complications. However, sex-stratified analysis on the association between preoperative hemoglobin and outcomes after noncardiac surgery has been limited in previous studies.

METHODS

This was a retrospective cohort study of adult patients undergoing elective major noncardiac surgery in a large academic hospital. The primary outcome was a collapsed composite of postoperative mortality or cardiovascular, renal, pulmonary, and infectious complications during hospitalization. Sex-specific univariable associations between preoperative hemoglobin and the composite outcome were visualized using moving-average and cubic-spline smoothing plots. Multivariable regression models adjusting for patient demographics, comorbidities, medication uses, laboratory tests, and anesthesia/surgery features were used to estimate confounder-adjusted associations. Restricted cubic spline and piecewise linear functions were used to assess the possible nonlinear relationships between preoperative hemoglobin and the outcomes. The interaction between patient sex and hemoglobin on outcomes was assessed using a likelihood-ratio test.

RESULTS

We included 22,550 patients, with 6.7% (622 of 9268) of women and 9.7% (1293 of 13,282) of men developing the primary outcome. Lower preoperative hemoglobin was associated with a higher incidence of the primary composite outcome in both men and women. Nonlinearity for the association was not statistically significant in either women ( P = .539) or men ( P = .165). The multivariable-adjusted odds ratios per 1 g/dL increase in hemoglobin were 0.93 (95% confidence interval [CI], 0.87-0.98; P = .013) for women and 0.94 (95% CI, 0.90-0.97; P < .001) for men, with no interaction by sex ( Pinteraction = .923). No hemoglobin thresholds were confirmed at which the associations with the primary outcome changed significantly.

CONCLUSIONS

Low preoperative hemoglobin was associated with a higher risk of complications or mortality after elective noncardiac surgery in both men and women. No differences in the strength of associations between sexes were found. Further studies are needed to assess whether these associations are linear or there are sex-specific thresholds of preoperative hemoglobin concentrations below which postoperative risks begin to increase.

Implementation of a Short-term Treatment Protocol in Anemic Patients before Cardiac Surgery

BACKGROUND

 We assessed whether implementation of an immediate preoperative treatment in anemic patients could result in fewer perioperative packed red blood cell (PRBC) transfusions and improved outcomes in a real-world setting.

METHODS

 From January 1, 2020, to November 31, 2022, we implemented a perioperative protocol for anemic patients (hemoglobin (Hb) level in women <11.5 g/dL, men <12.5 g/dL), which included subcutaneous erythropoietin α, intravenous Iron, and intramuscular vitamin B12 (all given preoperatively) and per os iron and folic acid given once a day postoperatively. We retrospectively compared all patients receiving the protocol to all eligible patients who were operated upon in the 4 years prior to implementation of the protocol. Primary outcome was amount of PRBC transfusions during surgery and index admission.

RESULTS

 In the months after protocol implementation, 114 patients who received the treatment protocol were compared with 236 anemic patients in the 4 years prior to who did not receive the protocol. The treatment reduced total PRBC use (control group median 4 [2-7] units vs. treatment 2 [1-3] units, p < 0.0001) and the incidence of postoperative blood products transfusions (treatment group 58 patients, 50.88% vs. control group 177 patients, 75%, p < 0.0001). Hb prior to discharge was higher among the protocol group (treatment median 9 g/dL [8.3-9.5 g/dL] vs. control 8.6 g/dL [8.1-9.1 g/dL], p = 0.0081).

CONCLUSION

 Despite some differences compared with previously described protocols, the implementation of a perioperative treatment protocol for anemic patients was associated with a reduction in PRBC transfusion in a real-world setting.

Effect of hemoglobin and oxygen saturation on adverse outcomes in children with tetralogy of fallot: a retrospective observational study

BACKGROUND

Tetralogy of Fallot (TOF) is a common cyanotic congenital heart malformation that carries a high risk of right-to-left shunting. Anemia is characterized by decreased hemoglobin (Hb) levels that can affect tissue oxygen delivery and impact postoperative recovery in patients. Chronic hypoxia caused by right-to-left shunting of TOF could lead to compensatory increases in Hb to maintain systemic oxygen balance. This study aims to investigate whether preoperative Hb and blood oxygen saturation (SpO2) can predict adverse outcomes in children undergoing corrective surgery for TOF.

METHODS

This retrospective study included patients under 18 years of age who underwent corrective surgery for TOF at Fuwai Hospital between January 2016 and December 2018. Adverse outcomes, including in-hospital death, extracorporeal membrane oxygenation implantation, ICU stay > 30 days, and severe complications, were considered as the primary outcome. Univariable and multivariable logistic analyses were performed to identify independent risk factors for adverse outcomes. Propensity score-matched (PSM) analysis was also conducted to minimize the confounding factors.

RESULTS

A total of 596 children were included in the study, of which 64 (10.7%) experienced adverse outcomes. Hb*SpO2 < aaHb was identified as an independent risk factor for adverse outcomes (OR = 2.241, 95% CI = 1.276-3.934, P = 0.005) after univariable and multivariable logistic analyses. PSM analysis further confirmed the association between Hb*SpO2 < aaHb and adverse outcomes. Patients with Hb*SpO2 < aaHb had a significantly higher incidence of postoperative adverse outcomes, longer time of mechanical ventilation, and hospital stay, as well as higher in-hospital costs.

CONCLUSIONS

Hb*SpO2 < aaHb is significantly associated with adverse outcomes in children undergoing corrective surgery for TOF. Clinicians can use this parameter to early identify high-risk children and optimize their postoperative management.

Determining sex-specific preoperative haemoglobin levels associated with intraoperative red blood cell transfusion in cardiac surgery: a retrospective cohort study

BACKGROUND

Anaemic cardiac surgery patients are at greater risk of intraoperative red blood cell transfusion. This study questions the application of the World Health Organization population-based anaemia thresholds (haemoglobin <120 g L-1 in non-pregnant females and <130 g L-1 in males) as appropriate preoperative optimisation targets for cardiac surgery.

METHODS

A retrospective cohort study was conducted on adults ≥18 yr old undergoing cardiopulmonary bypass surgery. Logistic regression was applied to define sex-specific preoperative haemoglobin concentrations with reduced probability of intraoperative red blood cell transfusion for cardiac surgery patients.

RESULTS

Data on 4384 male and 1676 female patients were analysed. Binarily stratified multivariable logistic regression odds of receiving intraoperative red blood cell transfusion increased in cardiac surgery patients >45 yr old (odds ratio [OR] 1.84; 95% confidence interval [CI] 1.33-2.55), surgery urgency <30 days (OR 2.03; 95% CI 1.66-2.48), combined coronary artery bypass grafting and valve surgery, or other surgery types (OR 2.24; 95% CI 1.87-2.67), and female sex (OR 1.92; 95% CI 1.62-2.28). The odds decreased by 8.4% with each 1 g L-1 increase in preoperative haemoglobin (OR 0.92; 95% CI 0.91-0.92). Logistic regression predicted females required a preoperative haemoglobin concentration of 133 g L-1 and males 127 g L-1 to have a 15% probability of intraoperative transfusion.

CONCLUSIONS

The World Health Organization female anaemia threshold of haemoglobin <120 g L-1 disproportionately disadvantages female cardiac surgery patients. A preoperative haemoglobin concentration ≥130 g L-1 in adult cardiac surgery patients would minimise their overall probability of intraoperative red blood cell transfusion to <15%.

Patient blood management programmes: keeping the ball rolling

Patient blood management programmes have been endorsed by the World Health Organization and multiple medical societies. It seems important to review the progress and results of patient blood management programmes so necessary modifications or new initiatives can be added to achieve their major goals. In this issue of the British Journal of Anaesthesia, Meybohm and colleagues show that a nationwide patient blood management programme had an impact and was potentially cost-effective in centres that previously utilised large amounts of allogeneic blood transfusions. Before implementing a programme, each institution might need to identify the area(s) of deficiency with respect to established patient blood management methods, which will warrant specific focus in subsequent clinical practice reviews.

Including the patient in patient blood management: Development and assessment of an educational animation tool

BACKGROUND

Patient blood management (PBM) programs are effective at reducing transfusion-associated mortality and morbidity; however, patient engagement within the realm of PBM remains relatively unstudied. Our objectives were to develop a novel educational tool utilizing animation to educate preoperative patients about anemia and to evaluate the effectiveness of this intervention.

STUDY DESIGN AND METHODS

We created a patient-facing animation for preoperative surgical patients. The animation addressed characters' health journeys from diagnosis to treatment, addressing the role of PBM. We utilized the concept of patient activation as a means to empower patients, and developed the animation to be as accessible as possible. Post-viewing, patients provided feedback utilizing an electronic survey.

RESULTS

A final version of the animation can be found here: https://vimeo.com/495857315. A total of 51 participants viewed our animation, the majority of whom were planned to undergo joint replacement or cardiac surgery. Almost all (94%, N = 4) agreed that taking an active role in their health was the most important factor in determining their ability to function. The video was felt to be easy to understand (96%, N = 49), and 92% (N = 47) agreed that they had a better understanding of anemia and its treatment. After watching the animation, patients felt more certain that they could follow through with their PBM plan (98%, N = 50).

DISCUSSION

To the best of our knowledge, there are no other PBM-specific patient education animations. Patients enjoyed learning about PBM though animation, and patient education may lead to better uptake of PBM interventions. We hope that other hospitals will be inspired to pursue this approach.

Gastrointestinal bleeding associated to aortic valve stenosis (Heyde's syndrome): a case series and literature review

Background

The association among aortic valve stenosis, gastrointestinal bleeding, and anaemia due to arteriovenous malformations, known as Heyde's syndrome (HS), is poorly understood and controversial. Recently, acquired Type 2A von Willebrand syndrome (vWS 2A) was shown to be the most likely aetiological mechanism of anaemia.

Case summary

We report two cases of HS in whom the percutaneous replacement of the aortic valve was resolutive for iron deficiency anaemia.

Discussion

Iron deficiency anaemia and aortic stenosis are a common association in the elderly, so much that frequently; in such cases, the correction of the valvulopathy is often excluded as pre-operative anaemia is associated with higher morbidity and mortality. From this perspective, the correct diagnosis of HS is crucial to guide the decision to correct valvulopathy, as valvular substitution is resolutive for both anaemic disorders and aortic stenosis.

How Important Impact of Low Level of Hematocrit Can Be on Outcome in Patients Undergoing Off Pump Coronary Artery Bypass Surgery?

Background

Cardiosurgical patients can be often anemic, and preoperative anaemia is associated with increased postoperative complications, as well as morbidity and mortality.

Objective

The present study was conducted aiming to determine the influence of lower preoperative hematocrit values on the early postoperative recovery of patients undergoing elective off-pump coronary artery bypass grafting (OPCABG).

Methods

Our retrospective study included 150 patients who underwent elective OPCABG surgery from September 2021 to December 2022 at the Clinic for Cardiovascular Surgery University of Sarajevo. Patients were divided into two groups, anemic and non-anemic, with anemia defined as hemoglobin level <130g/l males and <120g/l females. Study observed comorbidities and early postoperative data.

Results

Overall prevalence of anemia in OPCABG patients was 36,6%, more frequent among older patients. Comorbidities as chronic obstructive pulmonary disease, hypertension, ejection fraction was quite similar in both groups, but body mass index was significantly higher in the group of patients with anemia (29.9% vs 28.4%). In early recovery period, vasopressors were more used in patients with anemia (63.6% vs 42.1%) and their doses were higher. Total drainage was higher in patients with anemia (744.45±45.72 ml vs 681.58±349.06 ml). Number of transfusions was higher in the group of patients with anemia: red blood cells (0.89±1.29 vs 0.29±0.84; p<0,05), fresh frozen plasma (0.65±1.13 vs 0.41±1.15; p<0,05) and platelets (0.11±0.57 vs 0,07±0.42; p>0,05). Duration of mechanical ventilation was longer in patients with anemia compared to non-anemic patients (623-91±259.83 minutes vs 469±191.13 minutes). Atrial fibrillation occurred more often in patients with anemia (12.7 vs 7.4%). Length of stay in the intensive care unit was without significant difference.

Conclusion

Based on our findings, patients who underwent elective OPCABG with lower than normal hematocrit, needed more blood and blood products, more vasopressor drugs in higher doses, longer mechanical ventilation, all which can prolong the patient's recovery and increase the cost of treatment.

Prognostic Implication of Preoperative Anemia in Redo Cardiac Surgery: A Single-Center Propensity-Matched Analysis

Preoperative anemia has been associated with increased morbidity and mortality after cardiac surgery, but little is known about its prognostic value in the setting of redo procedure. A retrospective, observational cohort study of prospectively collected data was undertaken on 409 consecutive patients referred for redo cardiac procedures between January 2011 and December 2020. The EuroSCORE II calculated an average mortality risk of 25.7 ± 15.4%. Selection bias was assessed with the propensity-adjustment method. The prevalence of preoperative anemia was 41%. In unmatched analysis, significant differences between the anemic and nonanemic groups emerged in the risk for postoperative stroke (0.6% vs. 4.4%, p = 0.023), postoperative renal dysfunction (29.7% vs. 15.6%, p = 0.001), a need for prolonged ventilation (18.1% vs. 7.2%, p = 0.002), and high-dosage inotropes (53.1% vs. 32.9%, p < 0.001) along with both length of ICU and hospital stay (8.2 ± 15.9 vs. 4.3 ± 5.4 days, p = 0.003 and 18.8 ± 17.4 vs. 14.9 ± 11.1, p = 0.012). After propensity matching (145 pairs), preoperative anemia was still significantly associated with postoperative renal dysfunction, stroke, and the need for high-dosage inotrope cardiac morbidity. Preoperative anemia is significantly associated with acute kidney injury, stroke, and the need for high-dosage inotropes in patients referred for redo procedures.

Development of a nomogram for predicting nosocomial infections among patients after cardiac valve replacement surgery

AIMS AND OBJECTIVES

To construct a predictive nomogram of the risk of nosocomial infections among patients after cardiac valve replacement surgery.

BACKGROUND

Nosocomial infections are a standout challenge that worsens the prognosis of patients after valve replacement surgery. However, studies on the nomogram of nosocomial infections in these patients have remained scarce.

DESIGN

A retrospective cohort study.

METHODS

Patients (n = 720) following valve replacement surgery from 2018 to 2019 were selected. LASSO regression and multivariate logistic regression were utilised to ascertain predictors of nosocomial infections. The predictive performance of the nomogram was appraised by calibration and discrimination. Decision and impact curves were used to assess the clinical utility. Internal validation was implemented via 1000 bootstrap samples to mitigate overfitting. TRIPOD guidelines were used in this study.

RESULTS

One hundred and fifty one patients (20.97%) experienced nosocomial infections following valve replacement surgery. Heart failure, preoperative anaemia, valve material, American Society of Anesthesiologists score ≥ IV, prolonged duration of surgery, duration of mechanical ventilation ≥ 24 h and indwelling nasogastric tube were predictors of nosocomial infections. Using these variables, we developed a predictive nomogram of the occurrence of nosocomial infections and the internal validation results demonstrated good discrimination and calibration of the nomogram. The clinical decision and impact curve revealed significant clinical utility.

CONCLUSIONS

The present study constructed a nomogram for predicting the risk of nosocomial infections in patients following cardiac valve replacement surgery. This nomogram may strengthen the effective screening of patients at high risk of nosocomial infections.

RELEVANCE TO CLINICAL PRACTICE

This risk warning tool can assist clinical staff in making decisions and providing individualised infection control measures for patients, which has a significant reference value for clinical practice.

NO PATIENT OR PUBLIC CONTRIBUTION

The data for this study were obtained from the hospital database, and the entire process of the study did not involve patient participation.

[Implementation of Patient Blood Management as Standard-of-Care]

Anaemia is among the most common co-morbidity in surgical patients. However, it often remains unrecognized and untreated, which results in an increased requirement for allogeneic blood products and complications. Patient Blood Management offers patient-centred and evidence-based therapies and preventive measures for anaemia. Patient Blood Management is composed of 3 main pillars: pre-operative anaemia management, blood loss reduction and the rational use of allogeneic blood products. The World Health Organization demands the implementation of Patient Blood Management measures since 2010. However, a comprehensive implementation of Patient Blood Management as a standard-of-care is still not achieved. Here, we describe the need for a comprehensive Patient Blood Management implementation and highlight several specific Patient Blood Management measures.

Haemoglobin levels and outcomes of subgroups of patients with pre-operative anaemia based on red cell size: A retrospective cohort study

BACKGROUND

Pre-operative anaemia is common and associated with adverse outcomes. We hypothesised that pre-operative anaemia would be evident more than 1 month pre-operatively, and that peri-operative changes in haemoglobin and post-operative outcomes differed between red cell size-based subsets of anaemia.

METHODS

A retrospective single-centre cohort study, including all patients 18 years and older undergoing their first surgery at Landspitali between January 2006 and December 2018 with available measurement of haemoglobin (Hb) within 30 days preceding surgery. Clinical data were compared between patients with subgroups of anaemia classified by mean corpuscular volume (MCV) into microcytic (MCV < 80 fl), normocytic (MCV 80-100 fl), and macrocytic (MCV > 100 fl) anaemia. The development of haemoglobin measurements from a nationwide database was plotted from 1 year pre-operatively to 2 years post-operatively.

RESULTS

Of 40,979 patients, 10,505 (25.6%) had pre-operative anaemia, of which 1089 (10.4%) had microcytic anaemia, 9243 (88.0%) had normocytic anaemia, and 173 (1.6%) had macrocytic anaemia. Patients within all subgroups of pre-operative anaemia had a higher degree of comorbidity and frailty burden and a low haemoglobin evident for more than 100 days pre-operatively and similar changes post-operatively. Post-operative prolonged recovery of haemoglobin was slower for macrocytic anaemia than other types of anaemia. All groups of patients with anaemia had a higher incidence of 30-day mortality, acute kidney injury, and rate of readmission compared with patients without anaemia.

CONCLUSIONS

Pre-operative anaemia is evident long prior to the procedure and its association with worse outcomes is similar regardless of red cell size.

Importance of assessing biomarkers and physiological parameters of anemia-induced tissue hypoxia in the perioperative period

Anemia is associated with increased risk of Acute Kidney Injury (AKI), stroke and mortality in perioperative patients. We sought to understand the mechanism(s) by assessing the integrative physiological responses to anemia (kidney, brain), the degrees of anemia-induced tissue hypoxia, and associated biomarkers and physiological parameters. Experimental measurements demonstrate a linear relationship between blood Oxygen Content (C_aO₂) and renal microvascular PO₂ (y = 0.30x + 6.9, r² = 0.75), demonstrating that renal hypoxia is proportional to the degree of anemia. This defines the kidney as a potential oxygen sensor during anemia. Further evidence of renal oxygen sensing is demonstrated by proportional increase in serum Erythropoietin (EPO) during anemia (y = 93.806*10^-0.02, r² = 0.82). This data implicates systemic EPO levels as a biomarker of anemia-induced renal tissue hypoxia. By contrast, cerebral Oxygen Delivery (DO₂) is defended by a profound proportional increase in Cerebral Blood Flow (CBF), minimizing tissue hypoxia in the brain, until more severe levels of anemia occur. We hypothesize that the kidney experiences profound early anemia-induced tissue hypoxia which contributes to adaptive mechanisms to preserve cerebral perfusion. At severe levels of anemia, renal hypoxia intensifies, and cerebral hypoxia occurs, possibly contributing to the mechanism(s) of AKI and stroke when adaptive mechanisms to preserve organ perfusion are overwhelmed. Clinical methods to detect renal tissue hypoxia (an early warning signal) and cerebral hypoxia (a later consequence of severe anemia) may inform clinical practice and support the assessment of clinical biomarkers (i.e., EPO) and physiological parameters (i.e., urinary PO₂) of anemia-induced tissue hypoxia. This information may direct targeted treatment strategies to prevent adverse outcomes associated with anemia.

The Prognostic Significance of Red Cell Distribution Width in Cardiac Surgery: A Systematic Review and Meta-Analysis

RED CELL DISTRIBUTION WIDTH (RDW) is a routinely available biomarker of likely erythropoietic dysfunction, which may be associated with adverse outcomes after cardiac surgery. This systematic review and meta-analysis aimed to clarify the prognostic value of RDW in patients undergoing cardiac surgery. The authors searched MEDLINE, Embase, and the Cochrane Library from inception to May 10, 2022 for studies investigating the association between elevated RDW (as defined by the authors of included studies) and adverse outcomes after cardiac surgery. Herein, the authors extracted maximally adjusted hazard ratios (HRs) and odds ratios (ORs) with associated CIs, and pooled them using random-effects inverse- variance modeling. The authors explored interstudy heterogeneity using metaregression. The authors included 26 studies involving 48,092 patients who had undergone cardiac surgery. Elevated preoperative RDW was associated with long-term mortality (pooled HR 1.63, 95% CI 1.05-2.52), short-term mortality (pooled OR 2.16, 95% CI 1.21-3.87), acute kidney injury (AKI; pooled OR 1.30, 95% CI 1.19-1.41) and postoperative atrial fibrillation (POAF; pooled OR 1.44, 95% CI 1.05-1.96). Some studies suggested a significant association between preoperative RDW elevation and neurologic complications; however, their number was insufficient for meta-analysis. The postoperative RDW levels were less consistently reported and could not be meta-analyzed. In conclusion, the authors found that elevated preoperative RDW was associated with increased short- and long-term mortality, POAF, and AKI after cardiac surgery. Further research is needed to investigate its role in the risk stratification of patients undergoing cardiac surgery.

Perioperative Anemia and Transfusions and Late Mortality in Coronary Artery Bypass Patients

BACKGROUND

Perioperative anemia and transfusions are associated with adverse operative outcomes after coronary artery bypass graft surgery (CABG). Their individual association with long-term outcomes is unclear.

METHODS

Patients aged 65 years and older who had undergone CABG and were in The Society of Thoracic Surgeons (STS) Adult Cardiac Surgery Database (n = 504,596) from 2011 to 2018 were linked to Centers for Medicare and Medicaid Service data to assess long-term survival. The association of intraoperative anemia defined by intraoperative nadir hematocrit (nHct) and red blood cell (RBC) transfusions, and their interactions, on long-term mortality were assessed with Kaplan-Meier estimates and multivariable Cox regression. Restricted cubic splines were used to explore the association between nHct as a continuous variable and long-term mortality.

RESULTS

258,398 on-pump CABG STS Adult Cardiac Surgery Database patients surviving the perioperative period were linked to Centers for Medicare and Medicaid Service claims files. Per World Health Organization criteria, 41% had preoperative anemia. Mean intraoperative nHct was 24%; RBC transfusion rate was 43.7%. Univariable analysis associated both RBC transfusion and lower nHct with worse survival. Lower nHct was only marginally associated with risk-adjusted mortality: adjusted hazard ratio (AHR) 1.04 (95% CI, 1.01-1.06) and 1.07 (95% CI, 1.00-1.14) at nHct 20% and at nHct 14%, respectively. RBC transfusion was associated with significantly higher adjusted mortality irrespective of timing of transfusion: AHR intraoperative 1.21 (95% CI, 1.18-1.27); AHR postoperative 1.26 (95% CI, 1.22-1.30); AHR both 1.46 (95% CI, 1.40-1.52) and across all levels of nHct. RBC transfusion was not associated with improved survival at any level of nHct.

CONCLUSIONS

Among Medicare CABG patients, RBC transfusions were associated with increased risk-adjusted late mortality across all levels of nHct whereas intraoperative anemia was only marginally so. Tolerance of lower intraoperative nHct than currently accepted may be preferable to transfusions.

Treatment Strategies in Anemic Patients Before Cardiac Surgery

Both preoperative anemia and the transfusion of red blood cells have been associated with increased morbidity and mortality after cardiac surgery. To reduce the need for blood transfusion during surgery and improve patient outcomes, patient blood management programs have been developed. A primary focus of patient blood management in the preoperative period is the identification, diagnosis, and treatment of preoperative anemia, as anemia is associated with an increased risk of preoperative blood transfusion. In this narrative review, the authors focus on the laboratory screening of anemia before surgery and the evidence and limitations of different treatment strategies in anemic patients scheduled for cardiac surgery. To accurately correct preoperative anemia, the timely detection and definition of the etiology of anemia before elective cardiac surgery are crucial. Multiple randomized studies have been performed using preoperative iron supplementation and/or administration of erythropoiesis-stimulating agents in patients undergoing cardiac surgery. Although preoperative iron substitution in patients with iron deficiency is recommended, the evidence of its effectiveness is limited. In patients with nonpure iron deficiency anemia, combined therapy with erythropoiesis-stimulating agents and intravenous iron is recommended. Combined therapy might effectively reduce the need for red blood cell transfusion, even if applied shortly before cardiac surgery. The therapeutic effect on morbidity and mortality remains unclear. Nonetheless, the timely preoperative assessment of anemia and determination of iron status, eventually leading to targeted therapy, should become a standard of care and might potentially improve patient outcomes.