The influence of baseline hemoglobin concentration on tolerance of anemia in cardiac surgery

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.

Impact of perioperative hemoglobin-related parameters on clinical outcomes in patients with spinal metastases: identifying key markers for blood management

PURPOSE

Patients with spinal metastases undergoing surgical treatment face challenges related to preoperative anemia, intraoperative blood loss, and frailty, emphasizing the significance of perioperative blood management. This retrospective analysis aimed to assess the correlation between hemoglobin-related parameters and outcomes, identifying key markers to aid in blood management.

METHODS

A retrospective review was performed to identify patients who underwent surgical treatment for spinal metastases. Hb-related parameters, including baseline Hb, postoperative nadir Hb, predischarge Hb, postoperative nadir Hb drift, and predischarge Hb drift (both in absolute values and percentages) were subjected to univariate and multivariate analyses. These analyses were conducted in conjunction with other established variables to identify independent markers predicting patient outcomes. The outcomes of interest were postoperative short-term (6-week) mortality, long-term (1-year) mortality, and postoperative 30-day morbidity.

RESULTS

A total of 289 patients were included. Our study demonstrated that predischarge Hb (OR 0.62, 95% CI 0.44-0.88, P = 0.007) was an independent prognostic factor of short-term mortality, while baseline Hb (OR 0.76, 95% CI 0.66-0.88, P < 0.001) was identified as an independent prognostic factor of long-term mortality. Additionally, nadir Hb drift (OR 0.82, 95% CI 0.70-0.97, P = 0.023) was found to be an independent prognostic factor for postoperative 30-day morbidity.

CONCLUSIONS

This study demonstrated that predischarge Hb, baseline Hb, and nadir Hb drift are prognostic factors for outcomes. These findings provide a foundation for precise blood management strategies. It is crucial to consider Hb-related parameters appropriately, and prospective intervention studies addressing these markers should be conducted in the future.

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.

Role of red blood cells in clinically relevant bleeding tendencies and complications

The multiple roles of red blood cells (RBCs) are often neglected as contributors in hemostasis and thrombosis. Proactive opportunities to increase RBC numbers, either acutely or subacutely in the case of iron deficiency, are critical as RBCs are the cellular elements that initiate hemostasis together with platelets and stabilize fibrin and clot structure. RBCs also possess several functional properties to assist hemostasis: releasing platelet agonists, promoting shear force-induced von Willebrand factor unfolding, procoagulant capacity, and binding to fibrin. Additionally, blood clot contraction is important to compress RBCs to form a tightly packed array of polyhedrocytes, making an impermeable seal for hemostasis. All these functions are important for patients having intrinsically poor capacity to cease bleeds (ie, hemostatic disorders) but, conversely, can also play a role in thrombosis if these RBC-mediated reactions overshoot. One acquired example of bleeding with anemia is in patients treated with anticoagulants and/or antithrombotic medication because upon initiation of these drugs, baseline anemia doubles the risk of bleeding complications and mortality. Also, anemia is a risk factor for reoccurring gastrointestinal and urogenital bleeds, pregnancy, and delivery complications. This review summarizes the clinically relevant properties and profiles of RBCs at various steps of platelet adhesion, aggregation, thrombin generation, and fibrin formation, including both structural and functional elements. Regarding patient blood management guidelines, they support minimizing transfusions, but this approach does not deal with severe inherited and acquired bleeding disorders where a poor hemostatic propensity is exacerbated by limited RBC availability, for which future guidance will be needed.

Association of Postoperative Drift in Hemoglobin With Mortality After Brain Tumor Craniotomy

BACKGROUND

Postoperative downward drift in hemoglobin (Hb) concentration may be associated with complications and death, even if nadir Hb remains more than the red blood cell transfusion threshold of 7 g/dL.

OBJECTIVE

To assess whether postoperative Hb drift in patients undergoing brain tumor craniotomy influences mortality in the immediate perioperative period.

METHODS

This retrospective cohort study included patients undergoing craniotomy for brain tumors. We defined no postoperative Hb decrease, mild decrease, moderate decrease, and severe decrease as postoperative Hb drift of ≤25%, 26% to 50%, 51% to 75%, and >75%, respectively. The primary outcome was 30-day mortality after craniotomy.

RESULTS

This study included 8159 patients who underwent a craniotomy for brain tumors. Compared with patients with no postoperative Hb drift, the odds of postoperative mortality at 30 days increased in patients with mild postoperative Hb drift (adjusted odds ratio [OR] 2.47, 95% CI 1.72-3.56), moderate drift (adjusted OR 6.56, 95% CI 3.42-12.59), and severe drift (adjusted OR 12.33, 95% CI 3.48-43.62). When postoperative Hb drift was analyzed as a continuous variable, for each 10% increase in Hb drift, the adjusted OR of postoperative mortality at 30 days was 1.46 (95% CI 1.31-1.63).

CONCLUSION

In patients undergoing brain tumor craniotomy, a small postoperative Hb drift was associated with increased odds of postoperative mortality at 30 days, even if the nadir Hb level remained greater than the red blood cell transfusion threshold of 7 g/dL. Future randomized clinical trials of perioperative transfusion practices may examine the effect of both nadir Hb and Hb drift.

Perioperative Management of the Patient at High-Risk for Cardiac Surgery-Associated Acute Kidney Injury

Acute kidney injury (AKI) is one of the most common major complications of cardiac surgery, and is associated with increased morbidity and mortality. Cardiac surgery-associated AKI has a complex, multifactorial etiology, including numerous factors such as primary cardiac dysfunction, hemodynamic derangements of cardiac surgery and cardiopulmonary bypass, and the possibility of a large volume of blood transfusion. There are no truly effective pharmacologic therapies for the management of AKI, and, therefore, anesthesiologists, intensivists, and cardiac surgeons must remain vigilant and attempt to minimize the risk of developing renal dysfunction. This narrative review describes the current state of the scientific literature concerning the specific aspects of cardiac surgery-associated AKI, and presents it in a chronological fashion to aid the perioperative clinician in their approach to this high-risk patient group. The evidence was considered for risk prediction models, preoperative optimization, and the intraoperative and postoperative management of cardiac surgery patients to improve renal outcomes.

Anemia Is a Risk Factor for the Development of Ischemic Stroke and Post-Stroke Mortality

BACKGROUND

anemia is known to be a risk factor for developing ischemic stroke in long-term follow-up studies, and it is also known to increase the risk of death in ischemic stroke patients. We aimed to determine the association of anemia with the risk of ischemic stroke and the risk of death after ischemic stroke.

METHODS

The study included patients from National Health Insurance Service cohort, from January 2005 to December 2015. Anemia patients were defined as those with confirmed diagnostic codes and related medications in the sample cohort, and patients under the age of 18 were excluded. To perform a comparative analysis with the control group, twice as many patients were extracted by propensity score matching. The effects of anemia on the development of ischemic stroke were analyzed.

RESULTS

A total of 58,699 patients were newly diagnosed with anemia during the study period. In anemia group, the rate of ischemic stroke occurring within 1 year was 0.550%, and the rate was 0.272% in the control group. The odds ratio of anemia related to ischemic stroke was 1.602 (95% confidence intervals (CI) 1.363-1.883). During the follow-up period, 175 out of 309 (56.6%) died in anemia group, and 130 out of 314 (41.4%) died in control group. The anemia group showed a higher risk of death than the control group (Hazard ratio 1.509, 95% CI 1.197-1.902).

CONCLUSION

Analysis of the nationwide health insurance data revealed that anemia is one of the risk factors for the development of ischemic stroke, and also an independent prognostic factor affecting post-stroke mortality.

Optimising bloodless cardiovascular surgery for Jehovah's Witnesses and beyond

Emerging evidence suggests surgical outcomes of patients undergoing cardiovascular surgery that refuse autologous transfusion is comparable to those who accept whole blood product transfusions. There are several methods that can be used to minimize blood loss during cardiovascular surgery. These methods can be categorised into pharmacological measures, including the use of erythropoietin, iron and tranexamic acid, surgical techniques, like the use of polysaccharide haemostat, and devices such as those used in acute normovolaemic haemodilution. More prospective studies with stricter protocols are required to assess surgical outcomes in bloodless cardiac surgery as well as further research into the long-term outcomes of bloodless cardiovascular surgery patients. This review summarizes current evidence on the use of pre-, intra-, and post-operative strategies aimed at the subset of patients who refuse blood transfusion, for example Jehovah's Witnesses.

Relative decrease in hemoglobin and outcomes in patients undergoing kidney transplantation surgery: A retrospective cohort study

BACKGROUND

Recent surgical literature suggests that a relative decrease in hemoglobin (ΔHb) is predictive of adverse outcomes regardless of the absolute level. We aimed to examine the association between perioperative ΔHb and kidney transplantation (KT) outcomes.

METHODS

This was a retrospective cohort study of transplant recipients, where ΔHb = [Hb0- Hb1Hb0]x 100 (Hb₀ = hemoglobin pre-KT and Hb₁ = lowest hemoglobin 24-h post-KT). The main outcome of interest was immediate graft function (IGF).

RESULTS

Of the 899 eligible patients, 38% experienced IGF, and ΔHb was associated with 36% lower odds of IGF. Also, ΔHb was associated with higher all-cause graft failure and longer length of stay but not death-censored graft failure or mortality. ΔHb ≥30% was the threshold beyond which the odds of IGF were significantly lower even if Hb₁ was ≥7 g/dL.

CONCLUSION

ΔHb is associated with inferior outcomes independent of Hb_1; whether it can be used to guide transfusion practices should be explored.

Intraoperative blood loss may be associated with myocardial injury after non-cardiac surgery

BACKGROUND

This study aimed to evaluate the association between intraoperative blood loss and myocardial injury after non-cardiac surgery (MINS), which is a severe and common postoperative complication.

METHODS

We compared the incidence of MINS based on significant intraoperative bleeding, defined as an absolute hemoglobin level < 7 g/dL, a relative hemoglobin level less than 50% of the preoperative measurement, or need for packed red cell transfusion. We also estimated a threshold for intraoperative hemoglobin level associated with MINS.

RESULTS

We stratified a total of 15,926 non-cardiac surgical patients with intraoperative hemoglobin and postoperative cardiac troponin (cTn) measurements according to the occurrence of significant intraoperative bleeding; 13,416 (84.2%) had no significant bleeding while 2,510 (15.8%) did have significant bleeding. After an adjustment with inverse probability weighting, the incidence of MINS was higher in the significant bleeding group (35.2% vs. 16.4%; odds ratio, 1.58; 95% confidence interval, 1.43-1.75; p < 0.001). The threshold of intraoperative hemoglobin associated with MINS was estimated to be 9.9 g/dL with an area under the curve of 0.643.

CONCLUSION

Intraoperative blood loss appeared to be associated with MINS. Further studies are needed to confirm these findings.

CLINICAL REGISTRATION

The cohort was registered before patient enrollment at https://cris.nih.go.kr (KCT0004244).

Management of Perioperative Iron Deficiency in Cardiac Surgery: A Modified RAND Delphi Study

BACKGROUND

Over the last decade, preoperative anemia has become recognized as a clinical condition in need of management. Although the etiology of preoperative anemia can be multifactorial, two-thirds of anemic elective surgical patients have iron deficiency anemia. At the same time, one-third of non-anemic elective surgical patients are also iron deficient.

METHODS

Modified-RAND Delphi methodology was employed to identify areas of consensus among an expert panel regarding the management of iron deficiency in patients undergoing cardiac surgery. A list of statements was sent to panel members to respond to using a five-point Likert Scale. All panel members subsequently attended a face-to-face meeting. The initial survey was presented and discussed, and panel members responded to each statement on the Likert scale again. Based on the second survey, the panel came to a consensus on recommendations.

RESULTS

The panel recommended all patients undergoing cardiac surgery be evaluated for iron deficiency, whether or not anemia is present. Evaluation should include iron studies and reticulocyte hemoglobin content. If iron deficiency is present, with or without anemia, patients should receive parenteral iron. Erythropoietin stimulating agents may be appropriate for some patients.

CONCLUSIONS

Consensus of an expert panel resulted in a standardized approach to diagnosing and managing iron deficiency in patients undergoing cardiac surgery.

Association between transfusion of blood products and acute kidney injury following cardiac surgery

BACKGROUND

Acute kidney injury (AKI) is a serious complication following cardiac surgery associated with increased mortality. Red blood cell transfusion enhances the risk of developing AKI. However, the impact of other blood products on AKI is virtually unexplored. The aim of this study was to explore if transfusion of red blood cells, fresh frozen plasma and platelets alone or in combination were associated with postoperative AKI.

METHODS

Patients undergoing elective on-pump cardiac surgery were included (n = 1960) between 2012 to 2014. Transfusion data were collected intraoperatively and until the first postoperative day. AKI was classified according to the KDIGO criteria. Data were analysed using univariate and stepwise multiple logistic regression with adjustment for clinical risk factors and complementary blood products.

RESULTS

AKI was observed in 542 patients (27.7%). In univariate analysis and following adjustment for clinical risk factors, administration of red blood cells, freshfrozen plasma and platelets were all independently associated with KDIGO stage 2-3. Following additional adjustment for complementary blood products, only red blood cell transfusion remained significantly associated with AKI. A dose-dependent association between volume of red blood cells and degree of AKI severity was observed.

CONCLUSION

Transfusion of all blood products in a dose-dependent manner increased the risk for AKI. However, in multivariate analysis combining all blood products, only red blood cell transfusion remained significantly associated with AKI development.

Acute Kidney Injury Associated with Cardiac Surgery: a Comprehensive Literature Review

Objective

To comprehensively understand cardiac surgeryassociated acute kidney injury (CSA-AKI) and methods of prevention of such complication in cardiac surgery patients.

Methods

A comprehensive literature search was performed using the electronic database to identify articles describing acute kidney injury (AKI) in patients that undergone cardiac surgery. There was neither time limit nor language limit on the search. The results were narratively summarized.

Results

All the relevant articles have been extracted; results have been summarized in each related section. CSA-AKI is a serious postoperative complication and it can contribute to a significant increase in perioperative morbidity and mortality rates. Optimization of factors that can reduce CSA-AKI, therefore, contributes to a better postoperative outcome.

Conclusion

Several factors can significantly increase the rate of AKI; identification and minimization of such factors can lead to lower rates of CSA-AKI and lower perioperative morbidity and mortality rates.

Acute kidney injury after cardiac surgery: prevalence, impact and management challenges

Acute kidney injury (AKI) is a major medical problem that is of particular concern after cardiac surgery. Perioperative AKI is independently associated with an increase in short-term morbidity, costs of treatment, and long-term mortality. In this review, we explore the definition of cardiac surgery-associated acute kidney injury (CSA-AKI) and identify diverse mechanisms and risk factors contributing to the renal insult. Current theories of the pathophysiology of CSA-AKI and description of its clinical course will be addressed in this review. Data on the most promising renal protective strategies in cardiac surgery, from well-designed studies, will be scrutinized. Furthermore, diagnostic tools such as novel biomarkers of AKI and their potential utility will be discussed.

Bioelectrical Impedance Phase Angle-Predictor of Blood Transfusion in Cardiac Surgery

OBJECTIVE

To determine whether bioelectrical impedance-derived phase angle (PA) can be a predictor of red blood cell (RBC) transfusion in patients undergoing cardiac surgery.

DESIGN

An observational retrospective study of prospectively collected data.

SETTING

Single center, tertiary referral university hospital.

PARTICIPANTS

The study sample comprised 642 adult patients undergoing elective cardiac surgery.

INTERVENTIONS

Patient demographic and clinical variables were collected. The body composition of the patients was evaluated by bioelectrical impedance analysis (BIA) the day prior to surgery. The rates of postoperative RBC transfusion were recorded.

MEASUREMENTS AND MAIN RESULTS

Among the 642 patients (67.8% men, median age of 66 [range 59-73]) included in the present study, 210 (32.7%) received at least 1 RBC unit postoperatively. Hypertension, preoperative stroke, renal failure, preoperative hemoglobin and hematocrit values, BIA-derived PA, aortic crossclamp time, and cardiopulmonary bypass (CPB) time were associated with the risk of RBC transfusion in the univariate analysis, and were included in the final multivariate regression model. Preoperative stroke (odds ratio [OR] 0.394; 95% confidence interval [CI]: 0.183-0.848; p = 0.017), preoperative hemoglobin values (OR 0.943; 95% CI: 0.928-0.960; p < 0.001), PA <15th percentile (OR 2.326; 95% CI: 1.351-4.000; p = 0.002), and CPB time (OR 1.013; 95% CI: 1.008-1.018; p < 0.001) were identified as independent predictors of RBC transfusion.

CONCLUSION

Several factors were identified to be associated significantly with postoperative RBC transfusion in patients undergoing cardiac surgery. Among the conventional predictors, the value of the BIA-derived PA was indicated as a potent prognostic tool.

Measurement of Blood Loss in Cardiac Surgery: Still Too Much

BACKGROUND

Cardiac surgery is associated with a significant decrease in hematocrit. It is unclear whether that occurs from hemodilution, loss of red cells, or both. Hematocrit is a major determinant of transfusion decisions although transfusion is associated with increased morbidity and mortality. Physicians must determine whether this anemia is the result of hemodilution or red blood cell loss as the former would be treated with packed red blood cell transfusions and the latter by diuresis. We hypothesize that the decrease in hematocrit observed in cardiac surgery is due to hemodilution.

METHODS

Blood volume (BV), plasma volume (PV), and red blood cell volume (RBCV) were measured in 54 patients undergoing coronary artery bypass graft surgery, valve surgery, or coronary artery bypass graft/valve surgery. Measurements were made preoperatively, immediately postoperatively, and 2 hours after surgery utilizing a dilution tracer method and hematocrit measurements.

RESULTS

Preoperative average BV was 6,094 mL (SD 1,904 mL), RBCV was 2,024 mL (SD 720 mL), and PV was 4,070 mL (SD 1,339 mL). Postoperative average BV was 4,834 mL (SD 1,432 mL), RBCV 1,226 mL (SD 527 mL), and PV 3,607 mL (SD 993 mL). Blood volume decreased 18% (p < 0.0001), RBCV decreased 38% (p < 0.001), and PV decreased 8% (p < 0.012). There were no significant changes between postoperative values and those 2 hours later in the cardiac surgery intensive care unit.

CONCLUSIONS

Decreases in hematocrit observed in cardiac surgery patients are due to significant red blood cell losses and not to hemodilution. Red blood cell losses averaged 38%. Plasma volume also decreased.

Percentage change in hemoglobin level and morbidity in spine surgery patients

OBJECTIVE

The aim of this study was to characterize the association between percentage change in hemoglobin (ΔHb)—i.e., the difference between preoperative Hb and in-hospital nadir Hb concentration—and perioperative adverse events among spine surgery patients.

METHODS

Patients who underwent spine surgery at the authors’ institution between December 4, 2008, and June 26, 2015, were eligible for this retrospective study. Patients who underwent the following procedures were included: atlantoaxial fusion, subaxial anterior cervical fusion, subaxial posterior cervical fusion, anterior lumbar fusion, posterior lumbar fusion, lateral lumbar fusion, excision of intervertebral disc, and excision of spinal cord lesion. Data on intraoperative transfusion were obtained from an automated, prospectively collected, anesthesia data management system. Data on postoperative hospital transfusions were obtained through an Internet-based intelligence portal. Percentage ΔHb was defined as: ([preoperative Hb − nadir Hb]/preoperative Hb) × 100. Clinical outcomes included in-hospital morbidity and length of stay associated with percentage ΔHb.

RESULTS

A total of 3949 patients who underwent spine surgery were identified. Of these, 1204 patients (30.5%) received at least 1 unit of packed red blood cells. The median nadir Hb level was 10.6 g/dl (interquartile range 8.7–12.4 g/dl), yielding a mean percentage ΔHb of 23.6% (SD 15.4%). Perioperative complications occurred in 234 patients (5.9%) and were more common in patients with a larger percentage ΔHb (p = 0.017). Hospital-related infection, which occurred in 60 patients (1.5%), was also more common in patients with greater percentage ΔHb (p = 0.001).

CONCLUSIONS

Percentage ΔHb is independently associated with a higher risk of developing any perioperative complication and hospital-related infection. The authors’ results suggest that percentage ΔHb may be a useful measure for identifying patients at risk for adverse perioperative events.

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.

Perioperative hemoglobin area under the curve is an independent predictor of renal failure after cardiac surgery. Results from a Spanish multicenter retrospective cohort study

Perioperative anemia is an important risk factor for cardiac surgery-associated acute kidney injury (CSA-AKI). Nonetheless, the severity of the anemia and the time in the perioperative period in which the hemoglobin level should be considered as a risk factor is conflicting. The present study introduces the concept of perioperative hemoglobin area under the curve (pHb-AUC) as a surrogate marker of the evolution of perioperative hemoglobin concentration. Through a retrospective analysis of prospectively collected data, we assessed this new variable as a risk factor for the development of acute kidney injury after cardiac surgery in 966 adult patients who underwent cardiac surgery with cardiopulmonary bypass, at twenty-three academic hospitals in Spain. Exclusion criteria were patients on renal replacement therapy, who needed a reoperation because of bleeding and/or with missing perioperative hemoglobin or creatinine values. Using a multivariate regression analysis, we found that a pHb-AUC <19 g/dL was an independent risk factor for CSA-AKI even after adjustment for intraoperative red blood cell transfusion (OR 1.41, p <0.05). It was also associated with mortality (OR 2.48, p <0.01) and prolonged hospital length of stay (4.67 ± 0.99 days, p <0.001)

Gender disparities in red blood cell transfusion in elective surgery: a post hoc multicentre cohort study

OBJECTIVES

A post hoc gender comparison of transfusion-related modifiable risk factors among patients undergoing elective surgery.

SETTINGS

23 Austrian centres randomly selected and stratified by region and level of care.

PARTICIPANTS

We consecutively enrolled in total 6530 patients (3465 women and 3065 men); 1491 underwent coronary artery bypass graft (CABG) surgery, 2570 primary unilateral total hip replacement (THR) and 2469 primary unilateral total knee replacement (TKR).

MAIN OUTCOME MEASURES

Primary outcome measures were the number of allogeneic and autologous red blood cell (RBC) units transfused (postoperative day 5 included) and differences in intraoperative and postoperative transfusion rate between men and women. Secondary outcomes included perioperative blood loss in transfused and non-transfused patients, volume of RBCs transfused, perioperative haemoglobin values and circulating red blood volume on postoperative day 5.

RESULTS

In all surgical groups, the transfusion rate was significantly higher in women than in men (CABG 81 vs 49%, THR 46 vs 24% and TKR 37 vs 23%). In transfused patients, the absolute blood loss was higher among men in all surgical categories while the relative blood loss was higher among women in the CABG group (52.8 vs 47.8%) but comparable in orthopaedic surgery. The relative RBC volume transfused was significantly higher among women in all categories (CABG 40.0 vs 22.3; TKR 25.2 vs 20.2; THR 26.4 vs 20.8%). On postoperative day 5, the relative haemoglobin values and the relative circulating RBC volume were higher in women in all surgical categories.

CONCLUSIONS

The higher transfusion rate and volume in women when compared with men in elective surgery can be explained by clinicians applying the same absolute transfusion thresholds irrespective of a patient's gender. This, together with the common use of a liberal transfusion strategy, leads to further overtransfusion in women.

Impact of Delta Hemoglobin on Provider Transfusion Practices and Post-operative Morbidity Among Patients Undergoing Liver and Pancreatic Surgery

BACKGROUND

Delta hemoglobin (ΔHb) is defined as the difference between the preoperative Hb and the lowest post-operative Hb level. We sought to define the impact of ΔHb relative to nadir Hb levels on the likelihood of transfusion, as well as characterize the impact of ΔHb and nadir Hb on morbidity among a large cohort of patients undergoing complex hepatopancreatobiliary (HPB) surgery.

METHODS

Patients who underwent pancreatic or hepatic resection between January 1, 2009 and June 30, 2015 at Johns Hopkins Hospital were identified. Data on the perioperative ΔHb, nadir Hb, as well as blood utilization were obtained and analyzed. Multivariable logistic regression models were used to identify the factors associated with ΔHb and the impact of ΔHb on perioperative morbidity. A Bayesian model was used to evaluate the correlation of ΔHb and nadir Hb with the likelihood of transfusion, as well as the impact on morbidity.

RESULTS

A total of 4363 patients who underwent hepatobiliary (n = 2200, 50.4 %) or pancreatic (n = 2163, 49.6 %) surgery were identified. More than one quarter of patients received at least one unit of packed red blood cells (PRBC) (n = 1187, 27.2 %). The median nadir Hb was 9.2 (IQR 7.9-10.5) g/dL resulting in an average ΔHb of 3.4 mg/dL (IQR 2.2-4.7) corresponding to 26.3 %. Both ΔHb and nadir Hb strongly influenced provider behavior with regards to use of transfusion. Among patients with the same nadir Hb, ΔHb was strongly associated with use of transfusion; among patients who had a nadir Hb ≤6 g/dL, the use of transfusion was only 17.9 % when the ΔHb = 10 % versus 49.1 and 80.9 % when the ΔHb was 30 or 50 %, respectively. Perioperative complications occurred in 584 patients (13.4 %) and were more common among patients with a higher value of ΔHb, as well as patients who received PRBC (both P < 0.001).

CONCLUSIONS

The combination of the Hb trigger with ΔHb was associated with transfusion practices among providers. Larger ΔHb values, as well as receipt of transfusion, were strongly associated with risk of perioperative complication following HPB surgery.

Clinical use of low haemoglobin density, transferrin saturation, bone marrow morphology, Perl's stain and other plasma markers in the identification of treatable anaemia presenting for cardiac surgery in a prospective cohort study

OBJECTIVES

The differential diagnosis between iron deficiency anaemia (IDA) and anaemia of chronic disease (ACD) with or without associated iron deficiency can be challenging. We assessed the use of different parameters, both classical like ferritin, transferrin saturation and stainable bone marrow iron stores, and novel markers such as low haemoglobin density (LHD) and hepcidin to help discriminate between the three entities. This would allow the detection of patients with ACD with associated iron deficiency, which could benefit from iron supplementation that would have otherwise remained undetected.

MATERIALS AND METHODS

Prospective and observational cohort study from 2012 to 2013 where 200 anaemic cardiac surgical patients were recruited and 165 were studied. Detailed blood and bone marrow analyses were performed to establish the aetiology of anaemia.

RESULTS

Seventy-four patients (44.8%) had ACD and 29 (39%) of these had an elevated LHD indicating concomitant iron deficiency. Hepcidin was inappropriately normal or increased in the IDA and ACD group. Mean hepcidin was however lower in the group with IDA (4.8 ng/mL) than in the ACD group (15.0 ng/mL; p=0.002). Median hepcidin was lower in patients with ACD and iron restriction as indicated by LHD >4% (17.5 ng/mL) than on those with no iron restriction (25.9 ng/mL; p=0.045). In patients with ACD there was no concordance between Perl's stain and LHD.

CONCLUSIONS

LHD was superior to hepcidin and bone marrow iron stores in identifying patients with ACD and associated iron deficiency, which would potentially benefit from parenteral iron therapy.

Hematological Changes in Patients Undergoing Coronary Artery Bypass Surgery: a Prospective Study

Objectives:

Removal of pro inflammatory stimuli after CABG, wound closure and the regenerative ability of the bone marrow will ensure a gradual recovery of hematological parameters. The aim of this study was to assess the hematological changes after CABG.

Materials and Methods:

A prospective cohort study included 164 consecutive patients undergoing on pump CABG surgery between January 2012 and January 2013. Patients with primary hematologic disease, emergent or urgent CABG and off-pump CABG were not included. A time line protocol was employed.

Results:

All patients survived surgery. Average values of erythrocytes, hemoglobin and hematocrit declined, to reach lower values on day 3 after surgery (-33.6 %, -33.1 %, -32.6 % versus preoperative value, p<0.001) and then gradually increased to reach normal values after one month and the preoperative values after three months. The average values of leukocytes and neutrophils increased rapidly to achieve the highest value on day 2, while the average value of lymphocytes decreased quickly to achieve lower value on day 1 after surgery (+74.7 %, +127.1 %, -52.4 % respectively from the preoperative value, p<0.001). The average platelet count decreased to the lowest value on day 2 after surgery (-26.4 % from the preoperative value, p<0.001), after which gradually increased up to +100.8 % of preoperative value on day 14 (p<0.001) and then gradually decreased to reach normal values on day 21 and preoperative values after three months.

Conclusions:

Average values of the three peripheral blood cells parameters undergo important changes after CABG, but not life threatening, and regain normal and preoperative values after 1-3 months after surgery.

Preoperative anemia does not predict complications after single-level lumbar fusion: a propensity score-matched multicenter study

STUDY DESIGN

Multicenter retrospective cohort study.

OBJECTIVE

To estimate the impact of preoperative anemia on 30-day complications in patients undergoing single-level lumbar fusion.

SUMMARY OF BACKGROUND DATA

Anemia has been widely implicated as a risk factor in various surgical procedures including elective spine surgery. No large-scale study has been performed to examine this relationship in single-level lumbar fusion surgery.

METHODS

The American College of Surgeons National Surgical Quality Improvement Program database was retrospectively reviewed to identify all patients who underwent single-level lumbar fusion procedures during 2006 to 2011. A propensity score-matching algorithm was used to match scores of anemic patients with that of nonanemic patients. Multivariate logistic regression analysis of unadjusted and propensity score-matched cohorts was performed to examine the effect of preoperative anemia on 30-day postoperative complication rates and length of hospital stay.

RESULTS

A total of 2960 patients met inclusion criteria. The propensity score-matching procedure yielded scores of 491 pairs of well-matched nonanemic and anemic patients. The multivariate analysis of propensity score-matched population found preoperative anemia to carry no significant association with any of the complications analyzed, including overall complications, medical complications, surgical complications, reoperation, mortality, or length of total hospital stay.

CONCLUSION

For patients undergoing single-level lumbar fusion, preoperative anemia is not independently associated with increased risk of 30-day complications or increased length of stay. Further studies are needed to independently validate this relationship in other spine surgical procedures.

LEVEL OF EVIDENCE

3.

Decline in serum hemoglobin in the 7 days after cardiac catheterization

OBJECTIVES

Bleeding is an established complication following cardiac catheterization and lower preoperative hemoglobin concentration is a potentially modifiable risk factor for adverse outcomes after cardiac surgery. However, typical changes in serum hemoglobin concentration after cardiac catheterization are poorly defined. The authors sought to identify the pattern of change in serum hemoglobin concentration within 7 days after cardiovascular catheterization, factors associated with this change and any association with adverse outcomes.

DESIGN

Retrospective observational study over a 1-year period.

SETTING

U.S. academic medical institution.

PARTICIPANTS

Participants were 284 adult patients with baseline hemoglobin concentration≥12 g/dL undergoing nonemergent cardiac surgery after cardiovascular catheterization via the femoral arterial route.

INTERVENTIONS

None.

MEASUREMENTS AND MAIN RESULTS

Lowest daily hemoglobin concentration was recorded where available for up to 7 days after catheterization and before surgery. Generalized estimating equations identified the pattern of change in serum hemoglobin while regression models identified factors associated with hemoglobin decline. Following cardiovascular catheterization average serum hemoglobin declined over time, reaching a nadir 1.4 g/dL (95% CI 1.0-1.8) below baseline 6 days after catheterization. A higher baseline hemoglobin concentration and lower body mass index were associated with greater maximal decline in hemoglobin concentration after catheterization. Acute preoperative hemoglobin decline was not associated with acute kidney injury (AKI) or a composite adverse outcome that may reflect organ ischemia.

CONCLUSIONS

In a cohort of patients before cardiac surgery serum hemoglobin declines during the week after cardiac catheterization, with maximal average decline observed 5 to 7 days after catheterization.

Component reductions in oxygen delivery generate variable haemodynamic and stress hormone responses

BACKGROUND

In clinical practice, global oxygen delivery (DO2) is often considered as a whole; however pathological and adaptive responses after a decrease in individual constituents of the DO2 equation (cardiac output, haemoglobin, oxyhaemoglobin saturation) are likely to be diverse. We hypothesized that an equivalent decrease in DO2 after reductions in each separate component of the equation would result in different haemodynamic, tissue oxygenation, and stress hormonal responses.

METHODS

Anaesthetized, fluid-resuscitated male Wistar rats were subjected to circulatory, anaemic, or hypoxic hypoxia (by haemorrhage, isovolaemic haemodilution, and breathing a hypoxic gas mix, respectively), produced either rapidly over 5 min or graded over 30 min, to a targeted 50% decrease in global oxygen delivery. Sham-operated animals acted as controls. Measurements were made of haemodynamics, skeletal muscle tissue oxygen tension, blood gas analysis, and circulating stress hormone levels.

RESULTS

Whereas haemorrhage generated the largest decrease in cardiac output, and the greatest stress hormone response, haemodilution had the most marked effect on arterial pressure. In contrast, rapid hypoxaemia produced a minor impact on global haemodynamics yet induced the greatest decrease in regional oxygenation. A greater degree of hyperlactataemia was observed with graded insults compared with those administered rapidly.

CONCLUSIONS

Decreasing global oxygen delivery, achieved by targeted reductions in its separate components, induces varying circulatory, tissue oxygen tension, and stress hormone responses. We conclude that not all oxygen delivery is the same; this disparity should be emphasized in classical teaching and re-evaluated in patient management.

[Patient Blood Management : three pillar strategy to improve outcome through avoidance of allogeneic blood products]

Blood transfusions are commonly viewed as life-saving interventions; however, current evidence shows that blood transfusions are associated with a significant increase of morbidity and mortality in a dose-dependent relationship. Not only explanatory models of basic research but also the results from randomized controlled trials suggest a causal relationship between blood transfusion and adverse outcome. Therefore, it can be claimed that the current state of science debunks the long held belief in the so-called life-saving blood transfusion by exposing the potential for promoting disease and death. Adherence to the precautionary principle and also the fact that blood transfusions are more costly than previously assumed require novel approaches in the treatment of anemia and bleeding. Patient Blood Management (PBM) allows transfusion rates to be dramatically reduced through correcting anemia by stimulating erythropoiesis, minimization of perioperative blood loss and harnessing and optimizing the physiological tolerance of anemia. A resolution of the World Health Assembly has endorsed PBM and therefore morbidity and mortality should be significantly reduced by lowering of the currently high blood utilization rate of allogeneic blood products in Austria, Germany and Switzerland.

Association between ischemic stroke and iron-deficiency anemia: a population-based study

Background

Very little is known about the relationship between non-sickle cell anemia and stroke. The purpose of this study is to evaluate the association of iron-deficiency anemia (IDA) with stroke based on a nationwide coverage database in Taiwan.

Methods

The case-control study subjects were obtained from the Taiwanese Longitudinal Health Insurance Database 2000. We included 51,093 subjects with stroke as cases and randomly selected 153,279 controls (3 controls per case) in this study.Separate conditional logistic regression analyses were used to calculate the odds ratio (OR) for having been previously diagnosed with IDA between cases and controls.We further analyzed the association between stroke and IDA by stroke subtype.

Results

Results showed that 3,685 study subjects (1.81%) had been diagnosed with IDA prior to the index date; of those subjects, 1,268 (2.48%) were cases and 2,417 (1.58%) were controls (p<0.001). Conditional logistic regression shows that the OR of having previously received an IDA diagnosis among cases was 1.49 (95% CI: 1.39~1.60; p < 0.01) that of controls after adjusting for monthly income, geographic region, hypertension, diabetes, coronary heart disease, atrial fibrillation, heart failure, hyperlipidemia, tobacco use disorder, and alcohol abuse/alcohol dependency syndrome. Furthermore, the adjusted OR of prior IDA for cases with ischemic stroke was found to be 1.45 (95% CI: 1.34~1.58) compared to controls. However, we did not find any significant relationship between IDA and subarachnoid/intracerebral hemorrhage even adjusting for other confounding factors (OR=1.17, 95% CI=0.97~1.40).

Conclusion

There is a significant association between prior IDA and ischemic stroke.

Factors affecting hemoglobin measurement

A review of the literature shows that current "standard" laboratory measurements for hemoglobin are subject to numerous factors that affect both accuracy and reliability. In addition, total hemoglobin concentration measurements are subject to numerous factors that affect the "true" hemoglobin value. This article discusses both the physiologic factors that influence hemoglobin levels and the technical aspects and variability among the different measurement methodologies currently available.

Can maximum surgical blood order schedule be used as a predictor of successful completion of bloodless surgery?

Background

The Soonchunhyang University Hospital Bloodless Center was established in 2000, and more than 2,000 bloodless surgeries have been performed there since. In this study, the lowest postoperative Hb/preoperative Hb (Hb_low/pre) ratio and mortality rates of patients who underwent bloodless surgery were analyzed for each maximum surgical blood order schedule (MSBOS) category to assess whether MSBOS can be used as a predictor of successful completion of bloodless surgery.

Methods

A total of 971 patients were included. MSBOS was defined as the average number of units of RBCs transfused during each elective surgery. We used the Hb_low/pre ratio as an alternative to intraoperative blood loss. Frequency of Hb_low/pre ratios ≤0.5, use of transfusion alternatives, and mortality rates were compared across MSBOS categories.

Results

Out of the 971 patients, 701 (72.2%) were categorized as type and screen (T&S), 184 (18.9%) as MSBOS 1, 64 (6.6%) as MSBOS 2, and 22 (2.3%) as MSBOS 4. Transfusion alternatives were used by 397 (40.9%) patients. The frequency of the use of simultaneous erythropoietin and iron, hemostatics, acute normovolemic hemodilution, and Cell Saver (Haemonetics corp., USA) was higher in patients in the higher MSBOS categories. Six (0.6%) patients died within 30 days of surgery. Hb_low/pre ratios tended to be lower as the level of MSBOS category increased.

Conclusions

Surgeries in the higher MSBOS categories tended to be associated with high blood loss and mortality. Active use of transfusion alternatives is recommended in patients in high MSBOS categories who are scheduled to undergo bloodless surgery.

Urinary interleukin-18 and urinary neutrophil gelatinase-associated lipocalin predict acute kidney injury following pulmonary valve replacement prior to serum creatinine

BACKGROUND

It is becoming increasingly recognized that manifestations of congenital heart disease (CHD) extend beyond the cardiovascular system. The factors contributing to renal dysfunction in patients with CHD are multifactorial, with acute kidney injury (AKI) at time of cardiac surgery playing a major role. AKI is often diagnosed based on changes in serum creatinine and estimated glomerular filtration rate (eGFR). Such measurements are often late and imprecise. Recent data indicate that urinary biomarkers interleukin-18 (IL-18) and neutrophil gelatinase-associated lipocalin (NGAL) are earlier markers of AKI. We sought to determine the efficacy of urinary IL-18 and NGAL for detecting early AKI in patients undergoing surgical pulmonary valve replacement (PVR).

METHODS

Twenty patients presenting for surgical PVR with a history of previous repair of a conotruncal anomaly were enrolled. Preoperative clinical data were measured and urine samples and serum creatinine were collected at 6, 12, 24, and 72 hours post bypass. Urine was evaluated for NGAL and IL-18. AKI was determined using the Risk, Injury, Failure, Loss and End Stage Renal Disease (RIFLE) classification system.

RESULTS

Using the RIFLE classification system, seven patients (35%) were found to have AKI defined as a drop in the eGFR or an increase in serum creatinine. All seven patients with AKI had marked increase from preoperative baseline in urine IL-18 (sixfold) and NGAL (26-fold). Using NGAL and IL-18, AKI was detected at 6 hours postoperatively, resulting in AKI being identified 12-36 hours prior to detection by conventional methods. No preoperative predictors for AKI were identified.

CONCLUSION

Both NGAL and IL-18 are early predictive biomarkers of AKI, and both increase in tandem after surgical PVR. Importantly, both rise before an increase in creatinine or a decrease in eGFR is present. Monitoring both biomarkers may allow for earlier detection and subsequent interventions to prevent AKI at time of surgery for CHD.