Intraoperative Anemia and Single Red Blood Cell Transfusion During Cardiac Surgery: An Assessment of Postoperative Outcome Including Patients Refusing Blood Transfusion

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.

Optimizing Safety and Success: The Advantages of Bloodless Cardiac Surgery. A Systematic Review and Meta-Analysis of Outcomes in Jehovah's Witnesses

Transfusions are extremely frequent after cardiac surgery, and they have a considerable economic burden and impact on outcomes. Optimal patient blood management could play a fundamental role in reducing the rate of transfusion and Jehovah's Witnesses (JW) represent the ideal surrogate study population. This meta-analysis compares outcomes of JWs and non-JWs' patients undergoing cardiac surgery, assessing the safety of a bloodless cardiac surgery. A scoping review was conducted using a search strategy for studies assessing outcomes of JW undergoing cardiac surgery. The primary outcome was perioperative mortality, and a random-effects meta-analysis was performed. Ten studies were included in our meta-analysis, involving 780 JW patients refusing any type of transfusion ("JW") and 1182 patients accepting transfusion if needed ("non-JW"). 86% of non-JW patients received at least 1 transfusion. There was no significant difference in terms of perioperative mortality (OR 0.91; 95% CI 0.55-1.52; p = 0.72). The volume blood loss was significantly less in the JW (p = 0.001), while the rate of reoperation for bleeding was also lower, but not statistically significative, in the JW (p = 0.16). Both preoperative and postoperative hemoglobin and hematocrit were significantly higher in the JW. Therefore, we concluded that bloodless cardiac surgery is safe and early outcomes are similar between JW and non-JW patients: optimal patient blood management is fundamental in guarantying these results. Further studies are needed to assess if a limitation of transfusion could have a positive long-term impact on outcomes.

Management of Combined Cardiac Surgery Using Cardiopulmonary Bypass With Acute Normovolemic Hemodilution in a Jehovah's Witness: A Case Report

Combined cardiac surgery under cardiopulmonary bypass (CPB) has a high risk of requiring blood transfusion. Performing this surgery on Jehovah's Witnesses (JWs) is challenging as they strictly refuse allogeneic blood transfusions due to their religious beliefs. A 73-year-old female JW patient underwent combined surgery involving coronary artery bypass grafting and mitral valvuloplasty under CPB. Preoperative hematopoiesis maintained the hemoglobin (Hb) level at >12 g/dL preoperatively; the Hb level was maintained at >7 g/dL during CPB for effective acute normovolemic hemodilution (ANH). Compared with the values obtained immediately after CPB weaning, the Hb level and coagulation functions (measured using viscoelastic tests) improved after autologous transfusion at the end of the surgery. When cardiac surgery under CPB is performed on JWs, ANH can be useful for maintaining postoperative Hb levels and coagulation factors. Sufficient preoperative hematopoiesis and determination of an appropriate volume for intraoperative ANH may be important for effective ANH.

Short and long-term outcomes after cardiac surgery in Jehovah's Witnesses patients: a case-control study

Cardiac surgery in Jehovah's Witnesses (JW) patients who refuse blood transfusion is challenging requiring dedicated strategies. We aimed to analyze non-selected JW patients undergoing cardiac surgery and to compare with matched controls both perioperative outcomes and long-term survival. We retrospectively analyzed JW patients undergoing cardiac surgery from January 2016 to March 2021 and compared them with matched controls. The primary outcome was a composite of in-hospital perioperative adverse events and in-hospital mortality. The secondary outcome was all-cause mortality at long-term follow-up. A total of 113 JW patients and 113 controls were included. Baseline clinical characteristics, including laboratory parameters were comparable. Overall, there were no statistical differences between JW vs controls in terms of in-hospital mortality (2.7% vs 1.8%, p = 1.00) but mortality was remarkably high (40%) in JW patients with post-op hemoglobin < 8 g/dl. Logistic regression analysis found that the JW group was not associated with a higher occurrence of the composite outcome (adjusted odds ratio 0.91, 95% confidence interval [CI] 0.54-1.57). After a median follow-up of 1397 [IQR 922.7-1723.5] days, JW patients were not associated with a significantly higher all-cause mortality (adjusted hazard ratio 0.77, 95% CI 0.24-2.42). Cardiac surgery can be safely performed in non-anemic JW patients despite the refusal of blood transfusions. Favorable clinical outcomes can be achieved by the use of specific perioperative strategies for bloodless surgery with no differences as compared to control patients except in JW patients with a very low level of post-operative hemoglobin not supported by immediate transfusions.

Outcomes of cardiac surgery in Jehovah's Witness patients: A review

OBJECTIVE

To review current literature evidence on outcomes of cardiac surgery in Jehovah's Witness patients.

METHODS

A comprehensive electronic literature search was done from 2010 to 20th August 2020 identifying articles that discussed optimisation/outcomes of cardiac surgery in Jehovah's Witness either as a solo cohort or as comparative to non-Jehovah's Witnesses. No limit was placed on place of publication and the evidence has been summarised in a narrative manner within the manuscript.

RESULTS

The outcomes of cardiac surgery in Jehovah's Witness patients has been described, and also compared, to non-Witness patients within a number of case reports, case series and comparative cohort studies. Many of these studies note no significant differences between outcomes of the two groups for a number of variables, including mortality. Pre-, intra and post-operative optimisation of the patients by a multidisciplinary team is important to achieve good outcomes.

CONCLUSION

The use of a bloodless protocol for Jehovah's Witnesses does not appear to significantly impact upon clinical outcomes when compared to non-Witness patients, and it has even been suggested that a bloodless approach could provide advantages to all patients undergoing cardiac surgery. Larger cohorts and research across multiple centres into the long term outcomes of these patients is required.

[Gastrointestinal complications after on-pump cardiac surgery]

OBJECTIVE

To determine the incidence and independent predictors of gastrointestinal complications (GICs) following on-pump cardiac surgery.

MATERIAL AND METHODS

We retrospectively analyzed data of 9559 adults who underwent cardiac surgery in 2012-2017. Two groups of patients were distinguished: group 1 - 47 (0.5%) patients with abdominal complications followed by urgent surgery; group 2 - 9512 (95.5%) patients without complications or effective therapy.

CONCLUSION

1. Predictors of gastrointestinal complications: age >65 years, previous AF (p=0.011) and multifocal atherosclerosis (p=0.016), LV EF <40% (p=0.039), aortic cross-clamping time > 90 min (p=0.021), intraoperative blood loss over 600 ml (p=0.002), postoperative serum creatinine >140 μmol/l (p=0.005), mechanical ventilation >24 hours (p=0.023).

2. Reduced hemodilution during CPB, warm blood cardioplegia, higher perioperative values of Hb, Ht and IDO2 during cardiopulmonary bypass can prevent ischemic injury of abdominal organs during prolonged cardiac surgery.

Spinal Cord Protection of Aorto-Iliac Bypass in Open Repair of Extent II and III Thoracoabdominal Aortic Aneurysm

BACKGROUND

Spinal cord injury (SCI) is one of the serious complications of thoracoabdominal aortic aneurysm (TAAA) repair. Cardiopulmonary bypass (CPB) and left heart bypass (LHB) are well-established extracorporeal circulatory assistance methods to increase distal aortic perfusion and prevent spinal cord ischaemia in TAAA repair. Aorto-iliac bypass, a new surgical adjunct offering distal aortic perfusion without the need of complex perfusion skills, was developed as a substitute for CPB and LHB. However, its spinal cord protective effect is unknown.

METHODS

The perioperative data of 183 patients who had elective open Crawford extent II and III TAAA repair at our aortic centre from July 2011 to May 2019 were retrospectively analysed. Spinal cord protection was compared between the aorto-iliac bypass group (n=106) and the extracorporeal circulatory assistance group (n=77 [65 CPB, 12 LHB]), and the risk factors for SCI in these patients were explored.

RESULTS

Eleven (11) patients had postoperative SCI: five (6.5%) in the extracorporeal circulatory assistance group (four with CPB and one with LHB), and six (5.7%) in the aorto-iliac bypass group. The incidence of SCI was 6.0% (11/183 cases). There was no difference between the aorto-iliac bypass group and the extracorporeal circulatory assistance group (p=1.0), while operation time, proximal aortic clamp time, intercostal artery clamp time, and length of intensive care unit stay were all increased in the latter group. Multivariate logistic regression analysis showed that cerebrospinal fluid pressure (odds ratio [OR], 1.270; 95% confidence interval [CI], 1.092-1.478 [p=0.002]) and lowest haemoglobin on the first postoperative day (OR, 0.610; 95% CI, 0.416-0.895 [p=0.011]) were the independent predictors of SCI in TAAA repair.

CONCLUSIONS

Spinal cord protection of aorto-iliac bypass is comparable to that of CPB and LHB in open TAAA repair.

Guidelines for enhanced recovery after cardiac surgery. Consensus document of Spanish Societies of Anesthesia (SEDAR), Cardiovascular Surgery (SECCE) and Perfusionists (AEP)

The ERAS guidelines are intended to identify, disseminate and promote the implementation of the best, scientific evidence-based actions to decrease variability in clinical practice. The implementation of these practices in the global clinical process will promote better outcomes and the shortening of hospital and critical care unit stays, thereby resulting in a reduction in costs and in greater efficiency. After completing a systematic review at each of the points of the perioperative process in cardiac surgery, recommendations have been developed based on the best scientific evidence currently available with the consensus of the scientific societies involved.

Single-unit vs multiple-unit transfusion in hemodynamically stable postpartum anemia: a pragmatic randomized controlled trial

BACKGROUND

The American Academy of Blood Banks recommends single-unit red cell transfusion protocols across medicine to reduce transfusion complications and the use of a scarce resource. There are minimal data regarding single-unit protocols in obstetrics.

OBJECTIVE

We aimed to compare single-unit vs multiple-unit transfusion protocols for treatment of hemodynamically stable postpartum anemia.

STUDY DESIGN

We performed a randomized trial comparing initial transfusion with 1 unit of packed red blood cells (single-unit protocol) to 2 units of packed red blood cells (multiple-unit protocol) from March 2018 to July 2019. Women who required transfusion >6 hours postpartum were approached for consent. Unstable vital signs, hemoglobin level <5 g/dL, hemoglobinopathy, and cardiomyopathy were exclusion criteria for enrollment. Hemoglobin assessment and standardized clinical evaluation were performed 4 to 6 hours posttransfusion; additional packed red blood cells were given if indicated. The primary outcome was total units transfused. Secondary outcomes included length of stay, endometritis, wound separation or infection, venous thromboembolism, and intensive care unit admission within 30 days postpartum. Breastfeeding, depression, maternal attachment, and fatigue scores were assessed at 4 to 9 weeks postpartum. A total of 66 women were required to detect a 20% reduction in units transfused with a single-unit protocol (power=80%; α=0.05).

RESULTS

A total of 66 women were randomized (33 per arm). There were no differences between groups in demographic or clinical characteristics, including delivery mode, blood loss, and randomization hemoglobin levels. The mean number of units transfused was lower in the single-unit protocol than in the multiple-unit protocol (1.2 U vs 2.1 U; P<.001). Only 18.2% of women in the single-unit arm required additional packed red blood cells. At posttransfusion assessment, women in the single-unit arm had lower hemoglobin levels (7.8 g/dL vs 8.7 g/dL; P<.001), but there were no differences in vital signs or symptoms between groups. There were also no differences in length of stay, 30-day complications, or 4 to 9 week postpartum outcomes.

CONCLUSION

In women with hemodynamically stable postpartum anemia, a single-unit protocol avoided a second unit of packed red blood cells in >80% of women without significant impact on morbidity. Our work supports the use of single-unit initial transfusion in this population.

Is there any connection between method of priming extracorporeal circuit and cerebral oximetry results?

Objectives. To compare the influence of different priming techniques on cerebral oximetry results during CPB in adult patients.

Methods. This study is a single-center retrospective review of data collected from adult patients who underwent isolated CABG with CPB between January and December, 2016. The patients were divided into two standardized groups with the sole difference between them being the method of priming CPB circuit: the first one was the group where we used our modified retrograde method of priming (n = 45) and the second one was the group with standard priming (n = 45). Hematocrit, hemoglobin, cerebral oxygenation were evaluated at the following points: beginning of the operation, start of CPB, cross clamping, 15, 30, 45 minutes and the end of CPB and the end of operation.

Results. In the first group indices of cerebral oximetry were higher comparing to the second group at list of the 45 minutes of CPB (р < 0,001). For the first 15 minutes of CPB hematocrit was also higher in the first group. Priming volume and the need for blood transfusion or ultrafiltration were also smaller in the first group.

Conclusion. Modified priming technique allows to maintain higher indices of cerebral oximetry, decreases volume overload and the need for blood transfusion comparing to standard technique.

Intra-operative red blood cell transfusion and mortality after cardiac surgery

Background

Anemia in cardiac surgery patients has been associated with poor outcomes. Transfusion of red blood cells during surgery is common practice for perioperative anemia, but may come with risks. Little is known about the association between intra-operative transfusion and mortality in patients undergoing cardiac surgery.

Methods

Single centre historical cohort study in 2933 adult patients undergoing coronary surgery with or without aortic valve replacement from June 2011 until September 2014. To estimate the odds ratio for mortality in patients receiving intra-operative transfusion, a propensity score based logistic regression analysis was performed.

Results

Intra-operative transfusion was associated with a more than three-fold increased risk of 30-day mortality. Patients in the highest quartile of probability of transfusion were older (age 75 vs 66; P <  0.001), had a higher EuroSCORE (6 vs 3; P <  0.001), had lower preoperative hemoglobin levels (7.6 vs 8.9 mmol/l; P < 0.001), had combined surgery more often (CABG + AVR in 33.4% of cases vs 6.6% (P < 0.001) and a longer duration of surgery (224 vs 188 min; P < 0.001). The association between intra-operative transfusion and mortality persisted after adjustment for these risk factors (adjusted OR 2.6; P = 0.007).

Conclusions

Intra-operative transfusion of red blood cells was found to be associated with increased mortality in adults undergoing coronary surgery. Preoperative patient optimization may improve perioperative outcomes by reducing the likelihood of requiring transfusion and thus its associated risk.

Risk Factors Associated with Perioperative Myocardial Infarction in Major Open Vascular Surgery

BACKGROUND

Among patients undergoing noncardiac surgery, major vascular surgery is associated with a high risk of perioperative myocardial infarction (MI). Currently, there are no perioperative MI risk calculators accounting for intraoperative and postoperative risk factors in vascular surgery patients. We aimed to investigate specific risk factors for perioperative MI after major open vascular surgery to determine which patients are at highest risk of MI and the association of perioperative MI with perioperative transfusion.

METHODS

This statewide, retrospective cohort study analyzed risk factors for perioperative MI in major open vascular surgery between July 2012 and December 2015 using the Michigan Surgical Quality Collaborative, a multicenter quality collaborative. Patients were identified using current procedure terminology codes including open abdominal aortic aneurysm repairs (oAAA), aortobifemoral bypasses (AFB), and lower extremity bypasses (LEB). Rates of myocardial infarction were described for each procedure. A priori, preoperative, intraoperative, and postoperative variables were evaluated using univariate and multivariable statistics after adjusting for intraoperative factors including anesthesia type, intraoperative blood loss, intraoperative transfusion, and intraoperative vasopressor medications.

RESULTS

A total of 3,689 patients underwent major open vascular surgery, including 375 oAAA, 392 AFB, and 2,922 LEB procedures. The overall incidence of MI was 2.4%, varying from 1.8% for aortobifemoral bypass, 2.4% for lower extremity bypass, and 3.7% for open abdominal aortic aneurysm repair. Although preoperative risk factors for myocardial infarction included age, American Society of Anesthesiologists score, diabetes, coronary artery disease, congestive heart failure, use of beta blocker, lower preoperative hematocrit, and surgical priority (urgent/emergent cases), after adjusting for intraoperative risk factors, all preoperative risk factors were not significant with the exception of surgical priority. After adjusting for intraoperative factors, only surgical priority (odds ratio [OR] = 1.70, 95% confidence interval [CI] [1.01-2.85], P < 0.001) and postoperative transfusion (OR = 2.65, 95% CI [1.59-4.44], P < 0.001) was associated with myocardial infarction, and higher nadir hematocrit was inversely associated with myocardial infarction (OR = 0.89, 95% CI [0.85-0.94], P < 0.001).

CONCLUSIONS

Among vascular surgery patients undergoing major open vascular surgery, surgical priority was the only preoperative risk factors independently associated with MI, and only postoperative variables such as nadir hematocrit and postoperative transfusion were associated with MI. This suggests minimizing intraoperative blood loss and prioritizing early intraoperative transfusion may be the potential targets for process improvement.

The Effect of Blood Transfusion on Outcomes in Aortic Surgery

The use of blood transfusion in cardiac surgery varies widely. The beneficial effects of blood products are offset by an increase in morbidity and mortality. Despite multiple studies showing an association between blood product exposure and adverse short- and long-term events, it is difficult to determine causality. Nevertheless, the implication is sufficient to warrant the search for alternative strategies to reduce the use of blood products while providing a standard of care that optimizes postoperative outcomes. Aortic surgery, in particular, is associated with an increased risk of bleeding requiring a blood transfusion. There is a paucity of evidence within aortic surgery regarding the deleterious effects of blood products. Here, we review the current evidence regarding patient outcomes after blood transfusion in cardiac surgery, with special emphasis on aortic surgery.