Pre- and postoperative anemia, acute kidney injury, and mortality after coronary artery bypass grafting surgery: a retrospective observational study

Mitochondrial oxygenation monitoring and acute kidney injury risk in cardiac surgery: A prospective cohort study

BACKGROUND

Cardiac surgery-associated acute kidney injury (CSA-AKI) is a common complication of cardiac surgery and is associated with increased morbidity and mortality. Recent guidelines emphasize the need for new monitoring methods to facilitate targeted CSA-AKI prevention and treatment strategies. In vivo real-time measurement of mitochondrial oxygen tension (mitoPO2), could potentially fulfil this role during cardiac surgery, as suggested in our previous pilot study.

METHODS

In this prospective observational study, we investigated 75 cardiac surgery patients with an increased preoperative CSA-AKI risk. The primary aim of this study was to assess whether patients who developed CSA-AKI experienced prolonged periods of mitoPO2 < 20 mmHg during surgery. mitoPO2 was measured intraoperatively, and CSA-AKI was defined according to the Kidney Disease: Improving Global Outcomes criteria. Four additional mitoPO2 thresholds (<25, <30, <35, and < 40 mmHg) were analyzed, including the predictive capacity of all thresholds for CSA-AKI.

RESULTS

This study found that patients who developed CSA-AKI had a significantly longer intraoperative time with mitoPO2 <20 mmHg and <25, <30, <35, and <40 mmHg. Subsequently, we tested all thresholds for their association with the risk of CSA-AKI, with the <25 mmHg threshold demonstrating the highest significant odds ratio. Every minute spent below <25 mmHg increased the risk of CSA-AKI by 0.7 % (P = 0.021).

CONCLUSIONS

This study highlighted the association between mitoPO2 and the onset of CSA-AKI. Extended durations below the mitoPO2 threshold of 25 mmHg significantly correlate with an elevated CSA-AKI risk. Using mitoPO2 as a monitoring tool shows promise in potentially predicting and possibly preventing CSA-AKI when used as a treatment trigger in cardiac surgery patients.

Factors associated with acute kidney injury after on-pump coronary artery bypass grafting

BACKGROUND

Acute kidney injury (AKI) frequently occurs as a complication of cardiac surgery and cardiopulmonary bypass (CPB). Its prevalence and severity are determined by various preoperative and intraoperative factors. The aim of this study was to examine the risk factors for AKI following on-pump coronary artery bypass grafting (CABG).

METHODS

A retrospective analysis of clinical records from a single medical center was performed. The primary determinant for AKI analysis was the creatinine-level changes within the first 48 h after surgery. Records of 120 patients from a prospective cohort study were examined.

RESULTS

An AKI incidence of 26% occurred in the study cohort. The univariate analysis revealed that patients who developed AKI had notably higher EuroSCORE II values (2.00 ± 0.98 vs. 1.49 ± 0.74, p = 0.006) and higher initial levels of urea (7.62 ± 2.94 vs. 6.12 ± 1.71, p = 0.002) and creatinine (0.108 ± 0.039 vs. 0.091 ± 0.016, p = 0.003). Additionally, they exhibited a more frequent occurrence of initial albumin levels below 40 g/l (9 (34.6%) vs. 11 (14.9%) cases, p = 0.030) and a lower initial hemoglobin level (137.8 ± 13.2 g/l vs. 146.6 ± 13.6 g/l, p = 0.005) in comparison to patients without this complication. Moreover, those with AKI had a significantly longer hospital stay duration (14.3 ± 5.45 days vs. 12.6 ± 3.05 days, p = 0.048). Logistic regression indicated one risk factor, oxygen delivery during CPB, that correlated with the onset of AKI in the early postoperative period.

CONCLUSION

The prevalence of AKI was higher among patients with a higher EuroSCORE II, lower preoperative hemoglobin, increased preoperative levels of creatinine and urea, infrequent albumin levels below 40 g/L, diminished oxygen delivery during CPB, and greater need for RBC transfusion and furosemide, but it did not correlate with the duration of CPB.

Risk Factors for Acute Kidney Injury in Adult Patients Under Veno-Arterial Extracorporeal Membrane Oxygenation Support

OBJECTIVE

To investigate the incidence and risk factors of acute kidney injury (AKI) stage 3 in adult patients under veno-arterial extracorporeal membrane oxygenation (VA-ECMO) support.

DESIGN

A retrospective case-control study.

SETTING

Single center, Fuwai Hospital.

PARTICIPANTS

Adult VA-ECMO patients age ≥18 years and older treated between January 2020 and December 2022 were included.

INTERVENTIONS

The patients were grouped by whether they developed AKI Kidney Disease: Improving Global Outcomes (KDIGO) stage 3 or <3. Multivariate logistic regression was performed t"o evaluate risk factors of AKI stage 3.

MEASUREMENTS AND MAIN RESULTS

Among enrolled patients, 40 (53.3%) developed AKI stage 3. The in-hospital mortality of AKI stage 3 patients was significantly higher than that of AKI stage <3 patients (67.5% vs 34.3%; p = 0.004). Multivariate logistic regression analysis revealed that concomitant hypertension (odds ratio [OR], 0.250; 95% confidence interval [CI], 0.063, 0.987), p = 0.048), pre-ECMO hemoglobin (OR, 0.969; 95% CI, 0.947-0.992; p = 0.009), pre-ECMO lactate (OR, 1.173; 95% CI, 1.028-1.339; p = 0.018), and pre-ECMO creatinine (OR, 1.014; 95% CI, 1.003-1.025; p = 0.011) were independent risk factors for AKI stage 3.

CONCLUSIONS

This study found a high incidence (53.3%) of AKI stage 3 in adult patients with VA-ECMO support and an association with increased in-hospital mortality. Concomitant hypertension, low pre-ECMO hemoglobin, and elevated pre-ECMO lactate and pre-ECMO creatinine were independent risk factors for AKI stage 3 in patients receiving VA-ECMO. It is imperative to identify and adjust these risk factors to enhance outcomes for those supported by VA-ECMO.

Association between perioperative hemoglobin decrease and outcomes of transfusion in patients undergoing on-pump cardiac surgery: An observational study from two Chinese heart centers

Background

It is unclear how perioperative hemoglobin decrease (ΔHb) influences the balance between risks and benefits of red blood cell transfusion after cardiac surgery.

Methods

We retrospectively analyzed data on 8186 adults who underwent valve surgery and/or coronary artery bypass grafting under cardiopulmonary bypass at two large cardiology centers. We explored the potential association of ΔHb, defined relative to the preoperative level and postoperative nadir, with a composite outcome of in-hospital mortality, myocardial infarction, stroke, and acute kidney injury using multivariable logistic regression, restricted cubic spline, and piecewise-linear models.

Results

Among 6316 patients without preoperative anemia, ΔHb ≥ 50 % was associated with an elevated risk of the composite outcome [adjusted odds ratio (aOR) 1.95, 95 % confidence interval (CI) 1.81-2.35]. Among 869 patients without preoperative anemia and with ΔHb ≥ 50 %, postoperative transfusion of no more than four units of red blood cell appeared to decrease the risk of the composite outcome, whereas transfusion of more than six units increased risk. Among 5447 patients without preoperative anemia and with ΔHb < 50 %, postoperative transfusion appeared not to decrease the risk of the composite outcome. Among 1870 patients with preoperative anemia, ΔHb ≥ 30 % significantly increased the risk of the composite outcome (aOR 1.61, 95 % CI 1.23-2.10), and this risk might be moderated by postoperative transfusion of no more than four units of red blood cell, but increased by transfusion of more than six units.

Conclusions

ΔHb may influence the balance between risks and benefits of red blood cell transfusion after cardiac surgery.

Cardiac Surgery-Associated Acute Kidney Injury

AKI is a common and serious complication of cardiac surgery that has a significant impact on patient morbidity and mortality. The Kidney Disease Improving Global Outcomes definition of AKI is widely used to classify and identify AKI associated with cardiac surgery (cardiac surgery-associated AKI [CSA-AKI]) on the basis of changes in serum creatinine and/or urine output. There are various preoperative, intraoperative, and postoperative risk factors for the development of CSA-AKI which should be recognized and addressed as early as possible to expedite its diagnosis, reduce its occurrence, and prevent or ameliorate its devastating complications. Crucial issues are the inaccuracy of serum creatinine as a surrogate parameter of kidney function in the perioperative setting of cardiothoracic surgery and the necessity to discover more representative markers of the pathophysiology of AKI. However, except for the tissue inhibitor of metalloproteinase-2 and insulin-like growth factor binding protein 7 ratio, other diagnostic biomarkers with an acceptable sensitivity and specificity are still lacking. This article provides a comprehensive review of various aspects of CSA-AKI, including pathogenesis, risk factors, diagnosis, biomarkers, classification, prevention, and treatment management.

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.

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.

Prevalence and long-term implications of preoperative anemia in patients undergoing elective general surgery: a retrospective cohort study at a university hospital

OBJECTIVE

The aim of this retrospective study was to assess the prevalence of anaemia in a cohort of patients undergoing elective general surgery at a university hospital. Furthermore, the authors investigated the influence of anaemia on short-term and long-term postoperative outcome.

BACKGROUND

Awareness of the negative impact of preoperative anaemia on perioperative morbidity and mortality is rising. Anaemia is a potentially modifiable factor, and its therapy might improve patient outcome in elective surgery. Nevertheless, patients with preoperative anaemia frequently undergo elective surgery without receiving adequate preoperative treatment.

METHODS

In this single-centre cohort study, the authors analyzed 6908 adult patients who underwent elective general surgery. Patients undergoing day-clinic surgery were excluded. In all patients, preoperative haemoglobin concentration and haematocrit was available.

RESULTS

Of all patients analyzed, 32.9% were anaemic (21.0% mild, 11.8% moderate, 1.1% severe). Median time to last follow-up was 5.2 years. During the whole study period, 27.1% of patients died (1.2% died during the hospital stay); median time to death was 1.3 years. Patients with preoperative anaemia had significantly higher mortality rates ( P <0.001) and a higher probability of postoperative complications ( P <0.001). Likewise, receiving blood transfusions was associated with a higher risk of death ( P <0.001).

CONCLUSION

This retrospective single-centre analysis confirmed that preoperative anaemia is common, and is a significant risk factor for unfavourable postoperative outcome. As anaemia is a modifiable risk factor, the implementation of a patient blood management concept is crucial to reduce detrimental postoperative events associated with anaemia.

The Treatment of Coronary Artery Disease in Patients with Chronic Kidney Disease: Gaps, Challenges, and Solutions

Background

Chronic kidney disease (CKD) is associated with a high burden of coronary artery disease (CAD), which remains the leading cause of death in CKD patients. Despite the high cardiovascular risk, ACS patients with renal dysfunction are less commonly treated with guideline-based medical therapy and are less frequently referred for coronary revascularization.

Summary

The management of CAD is more challenging in patients with CKD than in the general population due to concerns regarding side effects and renal toxicity, as well as uncertainty regarding clinical benefit of guideline-based medical therapy and interventions. Patients with advanced CKD and especially those receiving dialysis have not traditionally been represented in randomized trials evaluating either medical or revascularization therapies. Thus, only scant data from small prospective studies or retrospective analyses are available. Recently published studies suggest that there are significant opportunities to substantially improve both cardiovascular and renal outcomes of patients with CAD and CKD, including new medications and interventions. Thus, the objective of this review is to summarize the current evidence regarding the management of CAD in CKD patients, in particular with respect to improvement of both cardiovascular and renal outcomes.

Key Messages

Adequate medical therapy and coronary interventions using evidence-based strategies can improve both cardiac and renal outcomes in patients with CAD and CKD.

The multifactorial dynamic perfusion index: A predictive tool of cardiac surgery associated acute kidney injury

INTRODUCTION

cardiac surgery associated acute kidney injury (CSA-AKI) has a number of preoperative and intraoperative risk factors. Cardiopulmonary bypass (CPB) factors have not yet been elucidated in a single multivariate model. The aim of this study is to develop a dynamic predictive model for CSA-AKI.

METHODS

retrospective study on 910 consecutive adult cardiac surgery patients. Baseline data were used to settle a preoperative CSA-AKI risk model (static risk model, SRM); CPB related data were assessed for association with CSA-AKI. CPB duration, nadir oxygen delivery, time of exposure to a low oxygen delivery, nadir mean arterial pressure, peak lactates and red blood cell transfusion were included in a multivariate dynamic perfusion risk (DPR). SRM and DPR were merged into a final logistic regression model (multifactorial dynamic perfusion index, MDPI). The three risk models were assessed for discrimination and calibration.

RESULTS

the SRM model had an AUC of 0.696 (95% CI 0.663-0.727), the DPR model of 0.723 (95% CI 0.691-0.753), and the MDPI model an AUC of 0.769 (95% CI 0.739-0.798). The difference in AUC between SRM and DPR was not significant (p = 0.495) whereas the AUC of MDPI was significantly larger than that of SRM (p = 0.004) and DPR (p = 0.015).

CONCLUSIONS

inclusion of dynamic indices of the quality of CPB improves the discrimination and calibration of the preoperative risk scores. The MDPI has better predictive ability than the existing static risk models and is a promising tool to integrate different factors into an advanced concept of goal-directed perfusion.

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%.

The predictive value of hematological inflammatory markers for acute kidney injury and mortality in adults with hemophagocytic Lymphohistiocytosis: A retrospective analysis of 585 patients

BACKGROUND

Hemophagocytic lymphohistiocytosis (HLH) is a rare immunological hyperactivation-related disease with a high mortality rate. The purpose of this study was to examine the relationship between complete blood count parameters and the occurrence of acute kidney injury (AKI) and mortality in patients with HLH.

METHODS

We included 585 adult patients with HLH. Logistic regression models for AKI and 28-day mortality were developed.

RESULTS

Multivariate logistic regression models revealed that hemoglobin (HB) ≤ 7.3 g/dl (adjusted OR, 1.651; 95% CI, 1.044-2.612), hemoglobin-to-red blood cell distribution width ratio (HRR) < 0.49 (adjusted OR, 1.692), neutrophil-to-lymphocyte ratio (NLR) ≥ 3.15 (adjusted OR, 1.697), and neutrophil-to-lymphocyte-platelet ratio (NLPR) ≥ 11.0 (adjusted OR, 1.608) were independent risk factors for the development of AKI. Moreover, lower platelet levels (31 × 109/L < platelets < 84 × 109/L, adjusted OR, 2.133; platelets ≤ 31 × 109/L, adjusted OR, 3.545) and higher red blood cell distribution width-to-platelet ratio (RPR) levels (0.20 < RPR < 0.54, adjusted OR, 2.595; RPR ≥ 0.54, adjusted OR, 4.307), lymphocytes ≤ 0.34 × 109/L (adjusted OR, 1.793), NLPR ≥ 11.0 (adjusted OR, 2.898), and the aggregate index of systemic inflammation (AISI) ≤ 7 (adjusted OR,1.778) were also independent risk factors for 28-day mortality. Furthermore, patients with AKI had a worse prognosis than those without AKI (P < 0.05).

CONCLUSION

In patients with HLH, hematological parameters are of great value for the early identification of patients at high risk of AKI and 28-day mortality.

Effects of intraoperative inspired oxygen fraction (FiO2 0.3 vs 0.8) on patients undergoing off-pump coronary artery bypass grafting: the CARROT multicenter, cluster-randomized trial

BACKGROUND

To maintain adequate oxygenation is of utmost importance in intraoperative care. However, clinical evidence supporting specific oxygen levels in distinct surgical settings is lacking. This study aimed to compare the effects of 30% and 80% oxygen in off-pump coronary artery bypass grafting (OPCAB).

METHODS

This multicenter trial was conducted in three tertiary hospitals from August 2019 to August 2021. Patients undergoing OPCAB were cluster-randomized to receive either 30% or 80% oxygen intraoperatively, based on the month when the surgery was performed. The primary endpoint was the length of hospital stay. Intraoperative hemodynamic data were also compared.

RESULTS

A total of 414 patients were cluster-randomized. Length of hospital stay was not different in the 30% oxygen group compared to the 80% oxygen group (median, 7.0 days vs 7.0 days; the sub-distribution hazard ratio, 0.98; 95% confidence interval [CI] 0.83-1.16; P = 0.808). The incidence of postoperative acute kidney injury was significantly higher in the 30% oxygen group than in the 80% oxygen group (30.7% vs 19.4%; odds ratio, 1.94; 95% CI 1.18-3.17; P = 0.036). Intraoperative time-weighted average mixed venous oxygen saturation was significantly higher in the 80% oxygen group (74% vs 64%; P < 0.001). The 80% oxygen group also had a significantly greater intraoperative time-weighted average cerebral regional oxygen saturation than the 30% oxygen group (56% vs 52%; P = 0.002).

CONCLUSIONS

In patients undergoing OPCAB, intraoperative administration of 80% oxygen did not decrease the length of hospital stay, compared to 30% oxygen, but may reduce postoperative acute kidney injury. Moreover, compared to 30% oxygen, intraoperative use of 80% oxygen improved oxygen delivery in patients undergoing OPCAB. Trial registration ClinicalTrials.gov (NCT03945565; April 8, 2019).

Longitudinal hemoglobin trajectories and acute kidney injury in patients undergoing cardiac surgery: a retrospective cohort study

Object

The purpose of this study was to describe the longitudinal dynamic hemoglobin trajectories in patients undergoing cardiac surgery and to explore whether they provide a broader perspective in predicting AKI compared to traditional threshold values. Additionally, the interaction of red blood cell transfusion was also investigated.

Methods

The MIMIC-IV database was searched to identify patients undergoing cardiac surgery with cardiopulmonary bypass. Group-based trajectory modeling (GBTM) was used to determine the hemoglobin trajectories in the first 72 h after ICU admission. The correlation between hemoglobin trajectories and AKI was evaluated using multivariable logistic regression and inverse probability of treatment weighting. Receiver operating characteristic (ROC) curves were created in the dataset to further validate previously reported thresholds.

Results

A total of 4,478 eligible patients were included in this study. Three hemoglobin trajectories were identified by GBTM, which were significantly different in the initial hemoglobin level and evolution pattern. Compared to the "the lowest, rising, and then declining" trajectory, patients in the "the highest, declining" and "medium, declining" trajectory groups had significantly lower AKI risk (OR 0.56; 95% CI 0.48, 0.67) and (OR 0.70; 95% CI 0.55, 0.90), respectively. ROC analysis yielded a disappointing result, with an AUC of 0.552, sensitivity of 0.25, and specificity of 0.86 when the hemoglobin threshold was set at 8 g/dl in the entire cohort. In the subgroup analysis of red blood cell transfusion, hemoglobin levels above 10 g/dl predicted higher AKI risk, and there was no correlation between hemoglobin trajectories and AKI in the non-red blood cell transfusion subgroup.

Conclusion

This study identified a hemoglobin trajectory that is associated with an increased risk of AKI after cardiac surgery. It is noteworthy that fixed hemoglobin thresholds should not be applied to all patient types. In patients receiving red blood cell transfusion, maintaining hemoglobin levels above 10 g/dl through transfusion was associated with an increased risk of AKI.

Acute kidney injury after major non-cardiac surgery: Incidence and risk factors

BACKGROUND

Acute kidney injury (AKI) is a major post-surgical complication that contributes to morbidity and mortality. AKI is welldocumented after cardiac surgery. However, less is known regarding the incidence and risk factors following major non-cardiac surgery.Globally the incidence of AKI post major surgery has been evaluated; however, there are no data available for South Africa (SA).

OBJECTIVES

To ascertain the incidence of AKI after major non-cardiac surgery at a tertiary academic SA hospital. Secondary outcomes wereto identify perioperative risk factors that are associated with an elevated risk to develop AKI in the postoperative period.

METHODS

The study was conducted at Tygerberg Hospital, a single tertiary centre in Cape Town, SA. Perioperative records of adults whounderwent major non-cardiac surgery were retrospectively collected. Variables pertaining to potential risk factors for AKI were captured,and serum creatinine levels were recorded up to 7 days postoperatively and compared with baseline measurements to determine whetherAKI had developed. Descriptive statistics along with logistic regression analysis were used to interpret results.

RESULTS

The overall incidence of AKI was 11.2% (95% confidence interval (CI) 9.8 - 12.6). Based on surgical discipline, trauma surgery(19%), followed by abdominal (18.5%) and vascular surgery (17%) had the highest incidence. Independent AKI risk factors wereidentified after multivariate analysis. These were: chronic obstructive pulmonary disease (odds ratio (OR) 2.19; 95% CI 1.09 - 4.37;p=0.005), trauma surgery (OR 3.00; 95% CI 1.59 - 5.64; p=0.001), abdominal surgery (OR 2.14; 95% CI 1.33 - 3.45; p=0.002), vascularsurgery (OR 2.42; 95% CI 1.31 - 4.45; p=0.004), urology procedures (OR 2.45; 95% CI 1.31 - 4.45; p=0.005), red blood cell transfusion(OR 1.81; 95% CI 1.21 - 2.70; p=0.004), emergency surgery (OR 1.74; 95% CI 1.15 - 2.65; p=0.009) and inotrope use (OR 2.77; 95% CI1.80 - 4.26; p<0.001).

CONCLUSION

The results of our study are in keeping with international literature regarding the incidence of AKI after major non-cardiacsurgery. The risk factor profile, however, is in several regards different from what has been found elsewhere.

Diagnosis, pathophysiology and preventive strategies for cardiac surgery-associated acute kidney injury: a narrative review

Acute kidney injury (AKI) is a common and serious complication of cardiac surgery and is associated with increased mortality and morbidity, accompanied by a substantial economic burden. The pathogenesis of cardiac surgery-associated acute kidney injury (CSA-AKI) is multifactorial and complex, with a variety of pathophysiological theories. In addition to the existing diagnostic criteria, the exploration and validation of biomarkers is the focus of research in the field of CSA-AKI diagnosis. Prevention remains the key to the management of CSA-AKI, and common strategies include maintenance of renal perfusion, individualized blood pressure targets, balanced fluid management, goal-directed oxygen delivery, and avoidance of nephrotoxins. This article reviews the pathogenesis, definition and diagnosis, and pharmacological and nonpharmacological prevention strategies of AKI in cardiac surgical patients.

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.

Aminoglycosides use has a risk of acute kidney injury in patients without prior chronic kidney disease

The outcome of acute kidney injury (AKI) as a result of aminoglycosides (AGs) use remains uncertain in patients without prior chronic kidney disease (CKD). Therefore, we explored the outcomes of AGs use on AKI episodes associated with renal recovery and progress in patients without prior CKD in Taiwan. This was a retrospective cohort study by using the Taipei Medical University Research Database from January 2008 to December 2019. 43,259 individuals without CKD who had received parenteral AGs were enrolled. The exposed and unexposed groups underwent propensity score matching for age, gender, patients in intensive care unit/emergency admission, and covariates, except serum hemoglobin and albumin levels. We identified an exposed group of 40,547 patients who used AGs (median age, 54.4 years; 44.3% male) and an unexposed group of 40,547 patients without AG use (median age, 55.7 years; 45.5% male). There was the risk for AKI stage 1 (adjusted hazard ratio [HR] 1.34; 95% confidence interval [CI] 1.00-1.79; p = 0.05) in patients that used AGs in comparison with the control subjects. Moreover, patients using AGs were significantly associated neither with the progression to acute kidney disease (AKD) stages nor with the progression to end-stage renal disease (ESRD) on dialysis. Further analyzed, there was an increased risk of AKI episodes for serum albumin levels less than 3.0 g/dL and hemoglobin levels less than 11.6 g/dL. Among patients without prior CKD, AGs-used individuals were associated with AKI risks, especially those at relatively low albumin (< 3.0 g/dL) or low hemoglobin (< 11.6 g/dL). That could raise awareness of AGs prescription in those patients in clinical practice.

Erythropoietin in Acute Kidney Injury (EAKI): a pragmatic randomized clinical trial

Background

Treatment with erythropoietin is well established for anemia in chronic kidney disease patients but not well studied in acute kidney injury.

Methods

This is a multicenter, randomized, pragmatic controlled clinical trial. It included 134 hospitalized patients with anemia defined as hemoglobin < 11 g/dL and acute kidney injury defined as an increase of serum creatinine of ≥ 0.3 mg/dL within 48 h or 1.5 times baseline. One arm received recombinant human erythropoietin 4000 UI subcutaneously every other day (intervention; n = 67) and the second received standard of care (control; n = 67) during the hospitalization until discharge or death. The primary outcome was the need for transfusion; secondary outcomes were death, renal recovery, need for dialysis.

Results

There was no statistically significant difference in transfusion need (RR = 1.05, 95%CI 0.65,1.68; p = 0.855), in renal recovery full or partial (RR = 0.96, 95%CI 0.81,1.15; p = 0.671), in need for dialysis (RR = 11.00, 95%CI 0.62, 195.08; p = 0.102) or in death (RR = 1.43, 95%CI 0.58,3.53; p = 0.440) between the erythropoietin and the control group.

Conclusions

Erythropoietin treatment had no impact on transfusions, renal recovery or mortality in acute kidney injury patients with anemia.

The trial was registered on ClinicalTrials.gov (NCT03401710, 17/01/2018).

Supplementary Information

The online version contains supplementary material available at 10.1186/s12882-022-02727-5.

Cardiac Surgery Associated AKI Prevention Strategies and Medical Treatment for CSA-AKI

Acute kidney injury (AKI) is common after cardiac surgery. To date, there are no specific pharmacological therapies. In this review, we summarise the existing evidence for prevention and management of cardiac surgery-associated AKI and outline areas for future research. Preoperatively, angiotensin-converting enzyme inhibitors and angiotensin receptor blockers should be withheld and nephrotoxins should be avoided to reduce the risk. Intraoperative strategies include goal-directed therapy with individualised blood pressure management and administration of balanced fluids, the use of circuits with biocompatible coatings, application of minimally invasive extracorporeal circulation, and lung protective ventilation. Postoperative management should be in accordance with current KDIGO AKI recommendations.

Risk factors and associated outcomes of acute kidney injury in hip fracture patients

Purpose

To assess risk factors and associated outcomes of acute kidney injury (AKI) in hip fracture patients.

Methods

Risk factors for AKI were identified by multivariate logistic regression. AKI patients were matched to patients who did not experience AKI using a validated trauma triage score. Comparative analyses between matched groups were performed.

Results

Risk factors of AKI included increasing Charlson Comorbidity Index and use of anticoagulation medications. AKI was associated with increased likelihood of medical complications and longer, more costly hospital stays.

Discussion

Patients with identified risk factors for AKI may benefit from consultation with nephrology and closer lab monitoring.

Derivation and validation of a model to predict acute kidney injury following cardiac surgery in patients with normal renal function

BACKGROUND

The study aimed to construct a clinical model based on preoperative data for predicting acute kidney injury (AKI) following cardiac surgery in patients with normal renal function.

METHODS

A total of 22,348 consecutive patients with normal renal function undergoing cardiac surgery were enrolled. Among them, 15,701 were randomly selected for the training group and the remaining for the validation group. To develop a model visualized as a nomogram for predicting AKI, logistic regression was performed with variables selected using least absolute shrinkage and selection operator regression. The discrimination, calibration, and clinical value of the model were evaluated.

RESULTS

The incidence of AKI was 25.2% in the training group. The new model consisted of nine preoperative variables, including age, male gender, left ventricular ejection fraction, hypertension, hemoglobin, uric acid, hypomagnesemia, and oral renin-angiotensin system inhibitor and non-steroidal anti-inflammatory drug within 1 week before surgery. The model had a good performance in the validation group. The discrimination was good with an area under the receiver operating characteristic curve of 0.740 (95% confidence interval, 0.726-0.753). The calibration plot indicated excellent agreement between the model prediction and actual observations. Decision curve analysis also showed that the model was clinically useful.

CONCLUSIONS

The new model was constructed based on nine easily available preoperative clinical data characteristics for predicting AKI following cardiac surgery in patients with normal kidney function, which may help treatment decision-making, and rational utilization of medical resources.

Sex-Specific Associations Between Preoperative Anemia and Postoperative Clinical Outcomes in Patients Undergoing Cardiac Surgery

BACKGROUND

Preoperative anemia is common in cardiac surgery, yet there were limited data describing the role of sex in the associations between anemia and clinical outcomes. Understanding these relationships may guide preoperative optimization efforts.

METHODS

This is an observational cohort study of adults undergoing isolated coronary artery bypass grafting or single- or double-valve surgery from 2008 to 2018 at a large tertiary medical center. Multivariable regression assessed the associations between preoperative hemoglobin concentrations and a primary outcome of postoperative acute kidney injury (AKI) and secondary outcomes of perioperative red blood cell (RBC) transfusion, reoperation, vascular complications (ie, stroke, pulmonary embolism, and myocardial infarction), and hospital length of stay (LOS). Each outcome was a single regression model, using interaction terms to assess sex-specific associations between hemoglobin and outcome.

RESULTS

A total of 4117 patients were included (57% men). Linear splines with sex-specific knots (13 g/dL in women and 14 g/dL in men) provided the best overall fit for preoperative hemoglobin and outcome relationships. In women, each 1 g/dL decrease in hemoglobin <13 g/dL was associated with increased odds of AKI (odds ratio = 1.49; 95% confidence interval [CI], [1.23-1.81]; P < .001), and there was no significant association between hemoglobin per 1 g/dL >13 g/dL and AKI (0.90 [0.56-1.45]; P = .67). The association between hemoglobin and AKI in men did not meet statistical significance (1.10 [0.99-1.22]; P = .076, per 1 g/dL decrease <14 g/dL; 1.00 [0.79-1.26]; P = .98 for hemoglobin per 1 g/dL >14 g/dL). In women, lower preoperative hemoglobin (per 1 g/dL decrease <13 g/dL) was associated with increased odds of RBC transfusion (2.90 [2.33-3.60]; P < .001), reoperation (1.27 [1.11-1.45]; P < .001) and a longer hospital LOS (multiplicative increase in geometric mean 1.05 [1.03-1.07]; P < .001). In men, preoperative hemoglobin (per 1 g/dL decrease <14 g/dL) was associated with increased odds of perioperative RBCs (2.56 [2.27-2.88]; P < .001) and longer hospital LOS (multiplicative increase in geometric mean 1.02 [1.01-1.04] days; P < .001) but not reoperation (0.94 [0.85-1.04]; P = .256). Preoperative hemoglobin per 1 g/dL >13 g/dL in women and 14 g/dL in men were associated with lower odds of RBCs transfusion (0.57 [0.47-0.69]; P < .001 and 0.74 [0.60-0.91]; P = .005, respectively).

CONCLUSIONS

Preoperative anemia was associated with inferior clinical outcomes after cardiac surgery. The associations between hemoglobin and outcomes were distinct for women and men, with different spline knot points identified (13 and 14 g/dL, respectively). Clinicians should consider data-driven approaches to determine preoperative hemoglobin values associated with increasing risk for adverse perioperative outcomes across sexes.

Predictors and Outcomes of Coronary Artery Bypass Grafting: A Systematic and Untargeted Analysis of More Than 120,000 Individuals and 1,300 Disease Traits

OBJECTIVE

To perform an untargeted data-driven analysis on the correlates and outcomes of coronary artery bypass grafting (CABG).

DESIGN

FinnGen cohort study.

SETTING

The authors collected information on up to 1,327 disease traits before and after CABG from nationwide healthcare registers.

PARTICIPANTS

A mixed population and patient sample of 127,911 individuals including 3,784 CABG patients.

INTERVENTIONS

The authors assessed the association between (1) traits and incident CABG and (2) CABG and incident traits using multivariate-adjusted Cox models.

MAIN RESULTS

Patients who underwent CABG and were in the fourth quartile of a risk score based on the top predictors of mortality had 12.2-fold increased risk of dying (95% confidence interval [CI], 10.3-14.5) compared with those in the first quartile. Cardiovascular disease (CVD) and CVD risk factors were most strongly associated with incident CABG. However, CABG was associated with death due to cardiac causes (hazard ratio [HR], 3.7; 95% CI, 3.5-4.0) or other causes (HR, 2.5; 95% CI, 2.4-2.7). CABG also was related to increased risk of several non-CVD traits, including anemia (HR, 3.4; 95% CI, 2.8-4.1), gastrointestinal disorders (HR, 2.2; 95% CI, 1.8-2.6), acute renal failure (HR, 4.2; 95% CI, 3.5-5.1), septicemia (HR, 3.6; 95% CI, 3.1-4.1), lung cancer (HR, 2.3; 95% CI, 1.9-2.8), Alzheimer's disease (HR, 2.5; 95% CI, 2.2-2.7), and chronic obstuctive pulmonary disease (HR, 2.5; 95% CI, 2.2-2.9).

CONCLUSIONS

Known CVD risk factors associate most strongly with incident CABG. However, CABG is associated with increased risk of several, somewhat unexpected, non-CVD traits. More detailed study of these links is warranted to establish potential causality and pathogenesis.

Clinical and Operative Determinants of Acute Kidney Injury after Cardiac Surgery

INTRODUCTION

Cardiac surgery-associated acute kidney injury (CSA-AKI) is associated with increased morbidity and mortality.

OBJECTIVES

We aimed to identify potentially modifiable risk factors for CSA-AKI.

METHODS

This was asingle-center retrospective cohort study of 495 adult patients undergoing cardiac surgery. AKI was diagnosed and staged using full KDIGO criteria incorporating baseline serum creatinine (SC) levels and correction of postoperative SC levels for fluid balance. We examined the association of routinely available clinical and laboratory data with AKI using multivariate logistic regression modeling.

RESULTS

A total of 103 (20.8%) patients developed AKI: 16 (15.5%) patients were diagnosed with AKI upon hospital admission, and 87 (84.5%) patients were diagnosed with CSA-AKI. Correction of SC levels for fluid balance increased the number of AKI cases to 104 (21.0%), with 6 patients categorized to different AKI stages. Univariate logistic regression analysis identified five preoperative (age, sex, diabetes mellitus, preoperative systolic pulmonary arterial pressure [PSPAP], acute decompensated heart failure) and five intraoperative predictors of AKI (age, sex, red blood cell [RBC] volume transfused, use of minimally invasive surgery, duration of cardiopulmonary bypass). When all preoperative and intraoperative variables were incorporated into one model, six predictors remained significant (age, sex, use of minimally invasive surgery, RBC volume transfused, PSPAP, duration of cardiopulmonary bypass). Model discrimination performance showed an area under the curve of 0.69 for the model including only preoperative variables, 0.76 for the model including only intraoperative variables, and 0.77 for the model including all preoperative and intraoperative variables.

CONCLUSIONS

Use of minimally invasive surgery and therapies mitigating PSPAP and intraoperative blood loss may offer protection against CSA-AKI.

Complete blood count in acute kidney injury prediction: a narrative review

Acute kidney injury (AKI) is a complex syndrome defined by a decrease in renal function. The incidence of AKI has raised in the past decades, and it is associated with negative impact in patient outcomes in the short and long term. Considering the impact of AKI on patient prognosis, research has focused on methods to assess patients at risk for developing AKI, diagnose subclinical AKI, and on prevention and treatment strategies, for which it is crucial an understanding of pathophysiology the of AKI. In this review, we discuss the use of easily available parameters found in a complete blood count to detect patients at risk for developing AKI, to provide an early diagnosis of AKI, and to predict associated patient outcomes.

Optimizing Preoperative Anemia to Improve Patient Outcomes

Anemia is a decrease in red blood cell mass, which hinders oxygen delivery to tissues. Preoperative anemia has been shown to be associated with mortality and morbidity following major surgery. The preoperative care clinic is an ideal place to start screening for anemia and discussing potential interventions in order to optimize patients for surgery. This article (1) reviews the relevant literature and highlights consequences of preoperative anemia in the surgical setting, and (2) suggests strategies for screening and optimizing anemia in the preoperative setting.

A retrospective analysis of the mixed venous oxygen saturation as the target for systemic blood flow control during cardiopulmonary bypass

Objectives:

The patient’s body surface area serves as the traditional reference for the determination of systemic blood flow during cardiopulmonary bypass (CPB). New strategies refer to different algorithms of oxygen delivery. This study reports on the mixed venous oxygen saturation (SvO2) as the target for systemic blood flow control. We hypothesise that an SvO2>75% (SvO275) is associated with better preservation of renal function and improved short-term survival.

Methods:

This retrospective, 10-year, observational study analysed 6945 consecutive cardiac surgical cases requiring CPB. Endpoints included rates of acute kidney injury (AKI) and short-term survival, also the estimated glomerular filtration rate (eGFR), lactate levels and blood transfusions.

Results:

Seventy-seven percent of the patients attained the SvO275 target. For this group, the median SvO2 was 78.1 (5.8) %, with a mean oxygen delivery of 331 (78) ml/min per m2 body surface area. Overall incidence of AKI levels (I-III): 7.5% - 2.6% - 0.6%. Incidence of eGFR (<50%): 3.9%, increasing to 6% for haemoglobin levels <80 g/L (p<0.001). Red cell transfusion was more frequent (p<0.001) within this group (30.6%) compared to levels >100 g/L (0.3%). Further, women (52.8%) were transfused more often than men (14.6%). Lactate level at weaning from CPB was 1.3 (0.7) mmol/L. The SvO275 target demonstrated a relative risk reduction of 22.5% (p=0.032) for AKI (I), increasing to 32.3% (p=0.026) for procedures extending >90 minutes. In addition, the risk for death 90-days postop was lower (p=0.039).

Conclusion:

The SvO275 target showed a decreased risk for postoperative AKI and prolonged short-term survival. Good clinical outcomes were also linked to measures of lactate and the eGFR. However, anaemia remains a risk factor for AKI.