The cardiac anesthesia risk evaluation score: a clinically useful predictor of mortality and morbidity after cardiac surgery

Prediction of acute kidney injury risk after cardiac surgery: using a hybrid machine learning algorithm

Background

Acute kidney injury (AKI) is a serious complication after cardiac surgery. We derived and internally validated a Machine Learning preoperative model to predict cardiac surgery-associated AKI of any severity and compared its performance with parametric statistical models.

Methods

We conducted a retrospective study of adult patients who underwent major cardiac surgery requiring cardiopulmonary bypass between November 1st, 2009 and March 31st, 2015. AKI was defined according to the KDIGO criteria as stage 1 or greater, within 7 days of surgery. We randomly split the cohort into derivation and validation datasets. We developed three AKI risk models: (1) a hybrid machine learning (ML) algorithm, using Random Forests for variable selection, followed by high performance logistic regression; (2) a traditional logistic regression model and (3) an enhanced logistic regression model with 500 bootstraps, with backward variable selection. For each model, we assigned risk scores to each of the retained covariate and assessed model discrimination (C statistic) and calibration (Hosmer–Lemeshow goodness-of-fit test) in the validation datasets.

Results

Of 6522 included patients, 1760 (27.0%) developed AKI. The best performance was achieved by the hybrid ML algorithm to predict AKI of any severity. The ML and enhanced statistical models remained robust after internal validation (C statistic = 0.75; Hosmer–Lemeshow p = 0.804, and AUC = 0.74, Hosmer–Lemeshow p = 0.347, respectively).

Conclusions

We demonstrated that a hybrid ML model provides higher accuracy without sacrificing parsimony, computational efficiency, or interpretability, when compared with parametric statistical models. This score-based model can easily be used at the bedside to identify high-risk patients who may benefit from intensive perioperative monitoring and personalized management strategies.

Supplementary Information

The online version contains supplementary material available at 10.1186/s12911-022-01859-w.

Effectiveness of Mild to Moderate Hypothermic Cardiopulmonary Bypass on Early Clinical Outcomes

Background: Intraoperative hypothermia is an integral part of cardiopulmonary bypass (CPB), and a precise degree of hypothermia may improve the early clinical outcomes of cardiac surgery. Presently, there is no agreement on an accurate, advantageous temperature range for routine use in CPB. To address this issue, we conducted a retrospective observational study to compare the effects of different hypothermic temperature ranges on primary (inotropic support, blood loss, and platelet count) and secondary (ventilation support and in-hospital stay) outcomes in patients undergoing elective cardiac surgery. Methods: Data were retrieved from the medical database of the Cardiovascular Surgery Department, King Edward Medical University, Lahore-Pakistan (a tertiary care hospital), dating from February 2015 to December 2017. Patients were divided into mild (34 °C to 36 °C), intermediate (31 °C to 33 °C), or moderate (28 °C to 30 °C) hypothermic groups. Results: Out of 275 patients, 245 (89.09%) fit the inclusion criteria. The cohort with mild hypothermic CPB temperatures presented better clinical outcomes in terms of requiring less inotropic support, less blood loss, fewer blood transfusions, improved platelet counts, shorter in-hospital stays, and required less ventilation support, when compared with other hypothermic groups. Conclusions: Mild hypothermic CPB (34 °C to 36 °C) may produce better clinical outcomes for cardiac surgery and improve the quality of health of cardiac patients.

Predicting Postoperative Complications in Cancer Patients: A Survey Bridging Classical and Machine Learning Contributions to Postsurgical Risk Analysis

Simple Summary

Structured survey on the predictive analysis of postoperative complications in oncology, bridging classic risk scores with machine learning advances, and further establishing principles to guide the design of cohort studies and the predictive modeling of postsurgical risks.

Abstract

Postoperative complications can impose a significant burden, increasing morbidity, mortality, and the in-hospital length of stay. Today, the number of studies available on the prognostication of postsurgical complications in cancer patients is growing and has already created a considerable set of dispersed contributions. This work provides a comprehensive survey on postoperative risk analysis, integrating principles from classic risk scores and machine-learning approaches within a coherent frame. A qualitative comparison is offered, taking into consideration the available cohort data and the targeted postsurgical outcomes of morbidity (such as the occurrence, nature or severity of postsurgical complications and hospitalization needs) and mortality. This work further establishes a taxonomy to assess the adequacy of cohort studies and guide the development and assessment of new learning approaches for the study and prediction of postoperative complications.

Scoring Systems for Risk Stratification in Patients Undergoing Cardiac Surgery

Cardiac surgery is associated with significant mortality rates. Careful selection of surgical candidates is, therefore, vital to optimize morbidity and mortality outcomes. Risk scores can be used to inform this decision-making process. The European System for Cardiac Operative Risk Evaluation Score and the Society of Thoracic Surgeons score are among the most commonly used risk scores. There are many other scoring systems in existence; however, no perfect scoring system exists, therefore, additional research is needed as clinicians strive toward a more idealized risk stratification model. The purpose of this review is to discuss the advantages and limitations of some of the most commonly used risk stratification systems and use this to determine what an ideal scoring system might look like. This includes not only the generalizability of available scores but also their ease of use and predictive power.

The Impact of Preoperative Risk on the Association between Hypotension and Mortality after Cardiac Surgery: An Observational Study

Background: Despite steady improvements in cardiac surgery-related outcomes, our understanding of the physiologic mechanisms leading to perioperative mortality remains incomplete. Intraoperative hypotension is an important risk factor for mortality after noncardiac surgery but remains relatively unexplored in the context of cardiac surgery. We examined whether the association between intraoperative hypotension and in-hospital mortality varied by patient and procedure characteristics, as defined by the validated Cardiac Anesthesia Risk Evaluation (CARE) mortality risk score. Methods: We conducted a retrospective cohort study of consecutive adult patients who underwent cardiac surgery requiring cardiopulmonary bypass (CPB) from November 2009–March 2015. Those who underwent off-pump, thoracic aorta, transplant and ventricular assist device procedures were excluded. The primary outcome was in-hospital mortality. Hypotension was categorized by mean arterial pressure (MAP) of <55 and between 55–64 mmHg before, during and after CPB. The relationship between hypotension and death was modeled using multivariable logistic regression in the intermediate and high-risk groups. Results: Among 6627 included patients, 131 (2%) died in-hospital. In-hospital mortality in patients with CARE scores of 1, 2, 3, 4 and 5 was 0 (0%), 7 (0.3%), 35 (1.3%), 41 (4.6%) and 48 (13.6%), respectively. In the intermediate-risk group (CARE = 3–4), MAP < 65 mmHg post-CPB was associated with increased odds of death in a dose-dependent fashion (adjusted OR 1.30, 95% CI 1.13–1.49, per 10 min exposure to MAP < 55 mmHg, p = 0.002; adjusted OR 1.18 [1.07–1.30] per 10 min exposure to MAP 55–64 mmHg, p = 0.001). We did not observe an association between hypotension and mortality in the high-risk group (CARE = 5). Conclusions: Post-CPB hypotension is a potentially modifiable risk factor for mortality in intermediate-risk patients. Our findings provide impetus for clinical trials to determine if hemodynamic goal-directed therapies could improve survival in these patients.

Clinical and prognostic differences between methicillin-resistant and methicillin-susceptible Staphylococcus aureus infective endocarditis

Background

S. aureus (SA) infective endocarditis (IE) has a very high mortality, attributed to the age and comorbidities of patients, inadequate or delayed antibiotic treatment, and methicillin resistance, among other causes. The main study objective was to analyze epidemiological and clinical differences between IE by methicillin-resistant versus methicillin-susceptible SA (MRSA vs. MSSA) and to examine prognostic factors for SA endocarditis, including methicillin resistance and vancomycin minimum inhibitory concentration (MIC) values > 1 μg/mL to MRSA.

Methods

Patients with SA endocarditis were consecutively and prospectively recruited from the Andalusia endocarditis cohort between 1984 and January 2017.

Results

We studied 437 patients with SA endocarditis, which was MRSA in 13.5% of cases. A greater likelihood of history of COPD (OR 3.19; 95% CI 1.41–7.23), invasive procedures, or recognized infection focus in the 3 months before IE onset (OR 2.9; 95% CI 1.14–7.65) and of diagnostic delay (OR 3.94; 95% CI 1.64–9.5) was observed in patients with MRSA versus MSSA endocarditis.

The one-year mortality rate due to SA endocarditis was 44.3% and associated with decade of endocarditis onset (1985–1999) (OR 8.391; 95% CI (2.82–24.9); 2000–2009 (OR 6.4; 95% CI 2.92–14.06); active neoplasm (OR 6.63; 95% CI 1.7–25.5) and sepsis (OR 2.28; 95% CI 1.053–4.9). Methicillin resistance was not associated with higher IE-related mortality (49.7 vs. 43.1%; p = 0.32).

Conclusion

MRSA IE is associated with COPD, previous invasive procedure or recognized infection focus, and nosocomial or healthcare-related origin. Methicillin resistance does not appear to be a decisive prognostic factor for SA IE.

Morbidity After cardiac surgery under cardiopulmonary bypass and associated factors: A retrospective observational study

Background

The present study aimed to assess the morbidity after cardiac surgery and identify the preoperative and intraoperative factors associated with postoperative morbidity.

Methods

A retrospective observational study was conducted including 362 adult patients aged 18–75 years who underwent open-heart surgery under cardiopulmonary bypass at Sri Jayadeva Institute of Cardiovascular Sciences and Research, Bengaluru, India, during the period from June 2016 to May 2017. Using a structured schedule, preoperative and intraoperative data were collected from the hospital's cardiac surgery database, whereas the postoperative data were collected from the intensive care unit (ICU) database and the hospital's clinical information system database.

Results

Of 362 patients, 254 (70.2%) had at least one major complication, and the most frequently occurring complication was low cardiac output state (29.8%). The ICU length of stay (LOS) was for > 2 days in 23.2% of patients, and the hospital LOS was for > 7 days in almost 60% of the patients. Multivariate logistic regression analyses revealed that gender, type of surgery, body weight, blood lactate level at ICU admission, and 12-h blood lactate level were significant predictors of complications; gender and 24-h blood lactate level were significantly associated with the prolonged ICU LOS, whereas type of surgery and 24-h blood lactate level were significantly associated with prolonged hospital LOS.

Conclusion

The appropriate patient management strategy can be tailored based on the personal attributes, surgery type, and blood lactate level for individual patients undergoing cardiac surgery to reduce the likelihood of postoperative complications, ICU LOS, and hospital LOS.

Microvolt T-wave alternans at the end of surgery is associated with postoperative mortality in cardiac surgery patients

Microvolt T-wave alternans (MTWA), which reflects electrical dispersion of repolarization, is known to be associated with arrhythmia or sudden cardiac death in high risk patients. In this study we investigated the relationship between MTWA and postoperative mortality in 330 cardiac surgery patients. Electrocardiogram, official national data and electric chart were analysed to provide in-hospital and mid-term outcome. MTWA at the end of surgery was significantly associated with in-hospital mortality in both univariate analysis (OR = 27.378, 95% CI 5.616-133.466, p < 0.001) and multivariate analysis (OR = 59.225, 95% CI 6.061-578.748, p < 0.001). Cox proportional hazards model revealed MTWA at the end of surgery was independently associated with mid-term mortality (HR = 4.337, 95% CI 1.594-11.795). The area under the curve of the model evaluating MTWA at the end of surgery was 0.764 (95% CI, 0.715-0.809) and it increased to 0.929 (95% CI, 0.896-0.954) when combined with the EuroSCORE II. MTWA positive at the end of surgery had a 60-fold increase in in-hospital mortality and a 4-fold increase in mid-term mortality. Moreover, MTWA at the end of surgery could predict in-hospital mortality and this predictability is more robust when combined with the EuroSCORE II.

Comparison of Two Major Perioperative Bleeding Scores for Cardiac Surgery Trials

Editor’s Perspective

What We Already Know about This Topic

What This Article Tells Us That Is New

Background

Research into major bleeding during cardiac surgery is challenging due to variability in how it is scored. Two consensus-based clinical scores for major bleeding: the Universal definition of perioperative bleeding and the European Coronary Artery Bypass Graft (E-CABG) bleeding severity grade, were compared in this substudy of the Transfusion Avoidance in Cardiac Surgery (TACS) trial.

Methods

As part of TACS, 7,402 patients underwent cardiac surgery at 12 hospitals from 2014 to 2015. We examined content validity by comparing scored items, construct validity by examining associations with redo and complex procedures, and criterion validity by examining 28-day in-hospital mortality risk across bleeding severity categories. Hierarchical logistic regression models were constructed that incorporated important predictors and categories of bleeding.

Results

E-CABG and Universal scores were correlated (Spearman ρ = 0.78, P &lt; 0.0001), but E-CABG classified 910 (12.4%) patients as having more severe bleeding, whereas the Universal score classified 1,729 (23.8%) as more severe. Higher E-CABG and Universal scores were observed in redo and complex procedures. Increasing E-CABG and Universal scores were associated with increased mortality in unadjusted and adjusted analyses. Regression model discrimination based on predictors of perioperative mortality increased with additional inclusion of the Universal score (c-statistic increase from 0.83 to 0.91) or E-CABG (c-statistic increase from 0.83 to 0.92). When other major postoperative complications were added to these models, the association between Universal or E-CABG bleeding with mortality remained.

Conclusions

Although each offers different advantages, both the Universal score and E-CABG performed well in the validity assessments, supporting their use as outcome measures in clinical trials.

Vasopressor magnitude predicts poor outcome in adults with congenital heart disease after cardiac surgery

BACKGROUND

High levels of vasoactive inotrope support (VIS) after congenital heart surgery are predictive of morbidity in pediatric patients. We sought to discern if this relationship applies to adults with congenital heart disease (ACHD).

METHODS

We retrospectively studied adult patients (≥18 years old) admitted to the intensive care unit after cardiac surgery for congenital heart disease from 2002 to 2013 at Mayo Clinic. Vasoactive medication dose values within 96 hours of admission were examined to determine the relationship between VIS score and poor outcome of early mortality, early morbidity, or complication related morbidity.

RESULTS

Overall, 1040 ACHD patients had cardiac surgery during the study time frame; 243 (23.4%) met study inclusion criteria. Sixty-two patients (25%), experienced composite poor outcome [including eight deaths within 90 days of hospital discharge (3%)]. Thirty-eight patients (15%) endured complication related early morbidity. The maximum VIS (maxVIS) score area under the curve was 0.92 (95% CI: 0.86-0.98) for in-hospital mortality; and 0.82 (95% CI: 0.76-0.89) for combined poor clinical outcome. On univariate analysis, maxVIS score ≥3 was predictive of composite adverse outcome (OR: 14.2, 95% CI: 7.2-28.2; P < 0.001), prolonged ICU LOS ICU LOS (OR: 19.2; 95% CI: 8.7-42.1; P < 0.0001), prolonged mechanical ventilation (OR: 13.6; 95% CI: 4.4-41.8; P < 0.0001) and complication related morbidity (OR: 7.3; 95% CI: 3.4-15.5; P < 0.0001).

CONCLUSIONS

MaxVIS score strongly predicted adverse outcomes and can be used as a risk prediction tool to facilitate early intervention that may improve outcome and assist with clinical decision making for ACHD patients after cardiac surgery.

Predictors of total morbidity burden on days 3, 5 and 8 after cardiac surgery

Background

Post-operative morbidity affects up to 36% of cardiac surgical patients. However, few countries reliably record morbidity outcome data, despite patients wanting to be informed of all the risks associated with surgery. The Cardiac Post-Operative Morbidity Score (C-POMS) is a new tool for describing and scoring (0–13) total morbidity burden after cardiac surgery, derived by noting the presence/absence of 13 morbidity domains on days 3, 5, 8 and 15. Identifying modifiable C-POMS risk factors may suggest targets for intervention to reduce morbidity and healthcare costs. Thus, we explored the association of C-POMS with previously identified predictors of post-operative morbidity.

Methods

A systematic literature review of pre-operative risk assessment models for post-operative morbidity was conducted to identify variables associated with post-operative morbidity. The association of those variables with C-POMS was explored in patients drawn from the original C-POMS study (n = 444).

Results

Seventy risk factors were identified, of which 56 were available in the study and 49 were suitable for analysis. Numbers were too few to analyse associations on D15. Thirty-three (67.3%) and 20 (40.8%) variables were associated with C-POMS on at least 1 or 2 days, respectively. Pre-operative albumin concentration, left ventricular ejection fraction and New York Heart Association functional class were associated with C-POMS on all days. Of the 16 independent risk factors, pre-operative albumin and haemoglobin concentrations and weight are potentially modifiable.

Conclusions

Different risk factors are associated with total morbidity burden on different post-operative days. Pre-operative albumin and haemoglobin concentrations and weight were independently predictive of post-operative total morbidity burden suggesting therapeutic interventions aimed at these might reduce both post-operative morbidity risk and health-care costs in patients undergoing cardiac surgery.

Electronic supplementary material

The online version of this article (doi:10.1186/s13741-017-0060-9) contains supplementary material, which is available to authorized users.

Are frailty scales better than anesthesia or surgical scales to determine risk in cardiac surgery?

BACKGROUND

In the last year there has been an increasing interest for using frailty scales for risk stratification of elderly patients undergoing major surgery. We planned to compare two frailty scales with risk scales already used in cardiac surgery, to study which of these scores have better prognostic value predicting postoperative outcome in open heart surgery.

METHODS

We conducted a prospective clinical trial, including 57 patients over 65 years. We calculated Cardiac Anesthesia Risk Evaluation score, EuroScore II, Clinical Frailty Scale, Edmonton Frail Scale for each patient and followed the postoperative complications, length of mechanical ventilation, length of stay in the intensive care unit and hospital, and in-hospital death related to these risk and frailty scores.

RESULTS

Postoperative complications occurred in 25 patients (43.9%), while four patients (7%) died with multiple organ failure. All scales had low predictability for postoperative complications, but for length of mechanical ventilation we obtained positive correlations with EuroScore II, Edmonton Frail Scale and Clinical Frailty Scale. EuroScore II can also predict the length of stay in the intensive care unit. For postoperative deaths, the highest sensitivity had EuroScore II, followed by Clinical Frailty Scale and Edmonton Frail Scale.

CONCLUSIONS

EuroScore II and the frailty scales have an increased prognostic value regarding the postoperative outcome of patients (length of mechanical ventilation and in-hospital mortality), the EuroScore II can predict the length of stay in the intensive care unit as well.

Clinical Predictions and Decisions to Perform Cardiac Surgery on High-Risk Patients

The proportion of high-risk patients undergoing cardiac surgery has increased steadily over the last two decades. Many of those patients have a catastrophic postoperative course and use hospital resources in a proportion that largely outweighs their number. Consequently, the appropriateness of invasive and intensive interventions in those patients has been questioned. If futility of care were predictable preoperatively, cardiac surgery would probably be denied to many highrisk patients. Logistic regression has been used to develop many complex predictive models to identify high-risk patients and predict their outcome; however, those models do not provide much more discrimination than clinical judgment alone. Moreover, with continuous improvement in medical care all risk models lose their calibration over time. As a result, they often overestimate the probabilities of poor outcome in the individual patients. Many high-risk cardiac surgical patients require a prolonged stay in the intensive care unit (ICU). The analysis of small cohorts of patients who had a prolonged postoperative stay in the ICU shows that 50% and 40% of them are still alive at 1- and 2-year follow-up, respectively; and most survivors report a good quality of life. Considering the limitations of predictive risk models and the satisfaction of cardiac surgical patients who survive after a prolonged ICU stay, it is reasonable to recognize that cardiac surgery should rarely be denied to high-risk patients unless technically unfeasible, and clinical predictions should have only a marginal role in the decision to operate on those patients.

Predicting outcomes: Is there utility in risk scores?

PURPOSE

This review discusses the utility of risk scores, specifically, the role of preoperative risk scores in guiding the management of surgical patients, approaches to evaluate the quality of risk scores, and limitations to consider when applying risk scores in clinical practice.

PRINCIPAL FINDINGS

This review shows how accurate predictions of perioperative risk can help inform patients and clinicians with respect to decision-making around surgery; identify patients who warrant further specialized investigations, new interventions intended to decrease risk, modifications in planned operative procedures, or intensification of postoperative monitoring; and facilitate fairer comparisons of outcomes between providers and hospitals. A preoperative risk score formally integrates several pieces of clinical information (e.g., age, comorbid disease, laboratory tests) to arrive at an overall estimate of an individual patient's expected risk for specific postoperative adverse events. A good risk score should be simple to incorporate in clinical practice, reliable when applied by different raters, and accurate at predicting postoperative risk. Several analytical methods (e.g., receiver operating characteristic curves, likelihood ratios, risk reclassification tables, observed vs predicted plots) are required to characterize the relevant domains that encompass the prognostic accuracy of a risk score. External validation is critical in determining whether the predictive accuracy of a risk score is preserved when applied to new settings, populations, or outcome events.

CONCLUSIONS

Preoperative risk scores help inform perioperative clinical decision-making. Future research must determine how estimates of preoperative risk can be updated with information from the intraoperative period, how risk information should be communicated to patients, and which interventions can improve outcomes among patients within newly identified risk strata.

Reduced Right Ventricular Function Predicts Long-Term Cardiac Re-Hospitalization after Cardiac Surgery

Background

The significance of right ventricular ejection fraction (RVEF), independent of left ventricular ejection fraction (LVEF), following isolated coronary artery bypass grafting (CABG) and valve procedures remains unknown. The aim of this study is to examine the significance of abnormal RVEF by cardiac magnetic resonance (CMR), independent of LVEF in predicting outcomes of patients undergoing isolated CABG and valve surgery.

Methods

From 2007 to 2009, 109 consecutive patients (mean age, 66 years; 38% female) were referred for pre-operative CMR. Abnormal RVEF and LVEF were considered <35% and <45%, respectively. Elective primary procedures include CABG (56%) and valve (44%). Thirty-day outcomes were perioperative complications, length of stay, cardiac re-hospitalizations and early mortaility; long-term (> 30 days) outcomes included, cardiac re-hospitalization, worsening congestive heart failure and mortality. Mean clinical follow up was 14 months.

Findings

Forty-eight patients had reduced RVEF (mean 25%) and 61 patients had normal RVEF (mean 50%) (p<0.001). Fifty-four patients had reduced LVEF (mean 30%) and 55 patients had normal LVEF (mean 59%) (p<0.001). Patients with reduced RVEF had a higher incidence of long-term cardiac re-hospitalization vs. patients with normal RVEF (31% vs.13%, p<0.05). Abnormal RVEF was a predictor for long-term cardiac re-hospitalization (HR 3.01 [CI 1.5-7.9], p<0.03). Reduced LVEF did not influence long-term cardiac re-hospitalization.

Conclusion

Abnormal RVEF is a stronger predictor for long-term cardiac re-hospitalization than abnormal LVEF in patients undergoing isolated CABG and valve procedures.

Predicting New-Onset Postoperative Atrial Fibrillation in Cardiac Surgery Patients

OBJECTIVE

To derive a simple clinical prediction rule identifying patients at high risk of developing new-onset postoperative atrial fibrillation (POAF) after cardiac surgery.

DESIGN

Retrospective analysis on prospectively collected observational data.

SETTING

A university-affiliated cardiac hospital.

PARTICIPANTS

Adult patients undergoing coronary artery bypass grafting and/or valve surgery.

INTERVENTIONS

Observation for the occurrence of new-onset postoperative atrial fibrillation.

MEASUREMENTS AND MAIN RESULTS

Details on 28 preoperative variables from 999 patients were collected and significant predictors (p<0.2) were inserted into multivariable logistic regression and reconfirmed with recursive partitioning. A total of 305 (30.5%) patients developed new-onset POAF. Eleven variables were associated significantly with atrial fibrillation. A multivariable logistic regression model included left atrial dilatation, mitral valve disease, and age. Coefficients from the model were converted into a simple 7-point predictive score. The risk of POAF per score is: 15.0%, if 0; 20%, if 1; 27%, if 2; 35%, if 3; 44%, if 4; 53%, if 5; 62%, if 6; and 70%, if 7. A score of 4 has a sensitivity of 44% and a specificity of 82% for POAF. A score of 6 has a sensitivity of 11% and a specificity of 97%. Bootstrapping with 5,000 samples confirmed the final model provided consistent predictions.

CONCLUSIONS

This study proposed a simple predictive score incorporating three risk variables to identify cardiac surgical patients at high risk of developing new-onset POAF. Preventive treatment should target patients ≥ 65 years with left atrial dilatation and mitral valve disease.

Impact of subglottic suctioning on the incidence of pneumonia after cardiac surgery: a retrospective observational study

OBJECTIVE

Continuous aspiration of subglottic secretions (CASS) has been found to decrease the incidence of pneumonia in the general intensive care unit (ICU) population, but its benefit in cardiac surgery patients is unclear. The present study aimed to determine whether the routine use of CASS in cardiac surgical patients was associated with decreased pneumonia.

DESIGN

A retrospective, single-center observational study.

SETTING

The study was conducted in a quaternary care cardiac surgery center and university research hospital.

PARTICIPANTS

4,880 patients undergoing cardiac surgery were studied.

INTERVENTIONS

The control group (no CASS) received a standard endotracheal tube and underwent surgery between April 1, 2007 and March 31, 2009. The intervention group (CASS) received a subglottic suctioning endotracheal tube and underwent surgery between June 1, 2009 and May 31, 2011. The primary outcome was the development of pneumonia, and the secondary outcomes were 30-day in-hospital mortality, ventilation time, need for tracheostomy, ICU length of stay (LOS), and hospital LOS.

MEASUREMENTS AND MAIN RESULTS

The unadjusted incidence of pneumonia was 1.9% in the CASS group and 5.6% in the control group (p<0.0001). The CASS group also had lower 30-day in-hospital mortality (2.1% v 3.3%; p = 0.007), median ventilation time (8.42 v 7.3 hours; p<0.0001), and shorter median ICU LOS (1.77 v 1.17 days; p<0.0004) compared with the control group. Tracheostomy rates and median hospital LOS did not differ between groups. After adjusting using multivariable modeling, CASS remained an independent risk predictor for pneumonia (odds ratio [OR] 0.342, 95% confidence interval [CI] 0.239-0.490) and ICU LOS (OR 0.817, 95% CI 0.718-0.931).

CONCLUSIONS

The universal implementation of CASS in a quaternary care cardiac surgical population was associated with a decreased incidence of pneumonia.

Clinical impact of mild acute kidney injury after cardiac surgery

BACKGROUND

Dialysis-dependent renal failure occurs infrequently after cardiac surgery but leads to substantial morbidity and mortality. In contrast, milder degrees of acute kidney injury (AKI), based on small increases in serum creatinine, occur frequently but the independent impact of mild AKI on outcome remains unclear.

METHODS

Between January 2010 and December 2012, 3,869 consecutive patients undergoing cardiac surgery comprised the study cohort. Acute kidney injury was defined according to the AKI Network criteria as stage I, II, or III. A nonparsimonious multivariable logistic regression model including preoperative and intraoperative variables was constructed to determine a propensity score for the development of stage I AKI followed by a greedy matching algorithm to create 1:1 propensity-matched pairs.

RESULTS

The incidence of stage I AKI in the entire cohort was 22.4%. Stage I AKI patients were more likely to be older; to have diabetes mellitus, hypertension, preoperative renal dysfunction, and poorer left ventricle function; and to require more urgent surgery and longer cardiopulmonary bypass. After propensity matching, the 833 matched pairs were similar in terms of all of the above characteristics (all p > 0.5). Within the matched cohort, AKI patients had higher mortality (2.6% versus 1.2%, p = 0.01), higher incidence of neurologic dysfunction (15.2% versus 8.1%, p < 0.001), and longer duration of mechanical ventilation (41.7 ± 125.0 versus 19.3 ± 58.6 hours, p < 0.001). Intensive care unit stay (5.2 ± 10.7 versus 2.7 ± 3.8 days, p < 0.0001), and hospital length of stay (17.9 ± 20.1 versus 14.7 ± 18.3 days, p = 0.0007) was significantly longer for matched AKI patients.

CONCLUSIONS

Patients with even mild degrees of AKI have increased mortality and morbidity compared with their matched counterparts. Interventions that prevent or mitigate AKI after cardiac surgery can yield substantial clinical benefit.

The novel regulations of MEF2A, CAMKK2, CALM3, and TNNI3 in ventricular hypertrophy induced by arsenic exposure in rats

Arsenic is a ubiquitous toxic compound that exists naturally in many sources such as soil, groundwater, and food; in which vast majority forms are arsenite (As(3+)) or arsenate (As(5+)). The mechanism of arsenic detoxification in humans still remains obscured. Epidemiologic studies documented that arsenic pollution caused black foot disease, cardiovascular diseases (hypertension, hypotension, cardiomyopathy), bladder cancer and skin cancer in many countries in which Taiwan is considered as high arsenic exposure country for long time ago. However, the effects of arsenic to cardiac functions still lacked of investigation while some studies mainly focus on inflammatory and cancer mechanisms. In the present study, we found cardiac hypertrophy signaling may be the most significant pathway for up regulated genes in arsenic exposed patients via bioinformatics approach. To verify our bioinformatics prediction, arsenic was fed orally to rats at different concentration based on previous studies in Taiwan. Using hemodynamic method as the main tool to measure the changes in blood pressure, left ventricular pressure and left ventricular contractility index, the findings suggest that highly exposure to arsenic lead to hypertension; elevated left ventricular diastolic pressure and alteration in cardiac contractility which are supposed to be the interaction between arsenic and cardiac nerves activity via the changing in calcium homeostasis. Collectively, based on our real-time PCR and western blot data strongly suggest that calcium homeostasis may also go through MEF2A, TNNI3, CAMKK2, CALM3 and cardiac hypertrophy relative signaling pathway.

Prognostic significance of biomarkers in predicting outcome in patients with coronary artery disease and left ventricular dysfunction: results of the biomarker substudy of the Surgical Treatment for Ischemic Heart Failure trials

BACKGROUND

Patients with heart failure and coronary artery disease often undergo coronary artery bypass grafting, but assessment of the risk of an adverse outcome in these patients is difficult. To evaluate the ability of biomarkers to contribute independent prognostic information in these patients, we measured levels in patients enrolled in the biomarker substudies of the Surgical Treatment for Ischemic Heart Failure (STICH) trials. Patients in STICH Hypothesis 1 were randomized to medical therapy or coronary artery bypass grafting, whereas those in STICH Hypothesis 2 were randomized to coronary artery bypass grafting or coronary artery bypass grafting with left ventricular reconstruction.

METHODS AND RESULTS

In substudy patients assigned to STICH Hypothesis 1 (n=606), plasma levels of soluble tumor necrosis factor-α receptor-1 (sTNFR-1) and brain natriuretic peptide (BNP) were highly predictive of the primary outcome variable of mortality by univariate analysis (BNP: χ(2)=40.6; P<0.0001 and sTNFR-1: χ(2)=38.9; P<0.0001). When considered in the context of multivariable analysis, both BNP and sTNFR-1 contributed independent prognostic information beyond the information provided by a large array of clinical factors independent of treatment assignment. Consistent results were seen when assessing the predictive value of BNP and sTNFR-1 in patients assigned to STICH Hypothesis 2 (n=626). Both plasma levels of BNP (χ(2)=30.3) and sTNFR-1 (χ(2)=45.5) were highly predictive in univariate analysis (P<0.0001) and in multivariable analysis for the primary end point of death or cardiac hospitalization. In multivariable analysis, the prognostic information contributed by BNP (χ(2)=6.0; P=0.049) and sTNFR-1 (χ(2)=8.8; P=0.003) remained statistically significant even after accounting for other clinical information. Although the biomarkers added little discriminatory improvement to the clinical factors (increase in c-index ≤0.1), net reclassification improvement for the primary end points was 0.29 for BNP and 0.21 for sTNFR-1 in the Hypothesis 1 cohort, and 0.15 for BNP and 0.30 for sTNFR-1 in the Hypothesis 2 cohort, reflecting important predictive improvement.

CONCLUSIONS

Elevated levels of sTNFR-1 and BNP are strongly associated with outcomes, independent of therapy, in 2 large and independent studies, thus providing important cross-validation for the prognostic importance of these 2 biomarkers.

Perioperative predictors of morbidity and mortality following cardiac surgery under cardiopulmonary bypass

BACKGROUND

Prediction of outcome after cardiac surgery is difficult despite a number of models using pre-, intra- and post-operative factors. Ideally, risk factors operating in all three phases of the patients' stay in the hospital should be incorporated into any outcome prediction model. The aim of the present study was to identify the perioperative risk factors associated with morbidity, mortality and length of stay in the recovery room (LOSR) and length of stay in the hospital (LOSH).

METHODS

Eighty-eight adults of either sex, patients undergoing elective open cardiac surgery were studied prospectively. The ability of a number of pre-, intra- and post-operative factors to predict outcome in the form of mortality, immediate morbidity (LOSR) and intermediate morbidity (LOSH) was assessed.

RESULTS

Factors associated with higher mortality were preoperative prothrombin index (PTI), American Society of Anesthesiology-Physical Status (ASA-PS) grade, Cardiac Anaesthesia Risk Evaluation (CARE) score and New York Heart Association (NYHA) class, intraoperative duration of cardiopulmonary bypass (DCPB), number of inotropes used while coming off cardiopulmonary bypass and postoperatively, Acute Physiology and Chronic Health Evaluation (APACHE) II excluding the Glassgow Comma Scale (GCS) component and the number of inotropes used. Immediate morbidity was associated with preoperative PTI, inotrope usage intra- and post-operatively and the APACHE score. Intermediate morbidity was associated with DCPB and intra- and post-operative inotrope usage. Individual surgeon influenced the LOSR and the LOSH.

CONCLUSION

APACHE score, a general purpose severity of illness score, was relatively ineffective in the postoperative period because of sedation, neuromuscular blockade and elective ventilation used in a number of these patients. The preoperative and intraoperative factors like CARE, ASA-PS grade, NYHA, DCPB and number of inotropes used influencing morbidity and mortality are consistent with the literature, despite the small size of our sample.

The development of a postoperative morbidity score to assess total morbidity burden after cardiac surgery

OBJECTIVE

To develop a tool for identifying and quantifying morbidity following cardiac surgery (cardiac postoperative morbidity score [C-POMS]).

STUDY DESIGN AND SETTING

Morbidity was prospectively assessed in 450 cardiac surgery patients on postoperative days 1, 3, 5, 8, and 15 using POMS criteria (nine postoperative morbidity domains in general surgical patients) and cardiac-specific variables (from expert panel). Other morbidities were noted as free text and included if prevalence was more than 5%, missingness less than 5%, and mean expert-rated severity-importance index score more than 8. Construct validity was assessed by expert panel review, Cronbach's alpha (internal consistency), and linear regression (predictive ability of C-POMS for length of stay [LOS]).

RESULTS

A 13-domain model was derived. Internal consistency (>0.7) on D3-D15 permits use as a summative score of total morbidity burden. Mean C-POMS scores were 3.4 (D3), 2.6 (D5), 3.4 (D8), and 3.8 (D15). Patient LOS was 4.6 days (P=0.012), 5.3 days (P=0.001), and 7.6 days (P=0.135) longer in patients with C-POMS-defined morbidity on D3, D5, D8, and D15, respectively, than in those without. For every unit increase in C-POMS summary score, subsequent LOS increased by 1.7 (D3), 2.2 (D5), 4.5 (D8), and 6.2 (D15) days (all P=0.000).

CONCLUSION

C-POMS is the first validated tool for identifying total morbidity burden after cardiac surgery. However, further external validation is warranted.

Relationship between N-terminal pro-B-type natriuretic peptide and renal function: the effects on predicting early outcome after off-pump coronary artery bypass surgery

Background

Plasma levels of N-terminal pro-B-type natriuretic peptide (NT-proBNP) provide useful prognostic predictors in patients after cardiac surgery. However, predictive accuracy of NT-proBNP levels has varied significantly according to renal dysfunction. The purpose of this study was to assess whether preoperative NT-proBNP levels could be used as predictors of early postoperative outcomes on the basis of renal function in patients undergoing off-pump coronary artery bypass surgery (OPCAB).

Methods

In 219 patients undergoing elective OPCAB, NT-proBNP and an estimated glomerular filtration rate (eGFR) were assessed preoperatively. All patients were divided into 3 groups according to tertiles of eGFR: the first (eGFR ≥ 90 ml/min/1.73 m²), the second (90 ml/min/1.73 m² > eGFR ≥ 72 ml/min/1.73 m²) and the third tertile group (eGFR < 72 ml/min/1.73 m²). End point was the composite of early postoperative complications defined as myocardial infarction, new onset atrial fibrillation, ventricular dysfunction, prolonged mechanical ventilator care (> 48 hr), prolonged ICU stay (≥ 3 days), and in hospital mortality.

Results

There was no difference in early postoperative complications among groups. A preoperative NT-proBNP level of 228 pg/ml and 302 pg/ml (sensitivity 70%, specificity 67%, P < 0.001 and sensitivity 73%, specificity 63%, P = 0.001, respectively) were optimal cut-off values predicting complicated early postoperative course in second and third tertile group, respectively.

Conclusions

Preoperative NT-proBNP levels seem to be predictive of early postoperative complications in patients with eGFR < 90 ml/min/1.73 m² undergoing OPCAB.

The Surgical Procedure Assessment (SPA) score predicts intensive care unit length of stay after cardiac surgery

OBJECTIVE

The ability to predict intensive care unit length of stay greatly facilitates triage and resource allocation for postoperative cardiac surgical patients in the intensive care unit. We developed a simple, intuitive Surgical Procedure Assessment score that integrates surgical complexity (1, low; 2, intermediate; 3, high) with patient comorbidity (A, minimal; B, substantial). We hypothesized that the Surgical Procedure Assessment score would predict intensive care unit length of stay, discriminate preoperatively between fast-track and prolonged-stay patients, and compare favorably with more complex risk scores.

METHODS

After institutional review board approval, 1201 cardiac surgical patients were preoperatively assigned a Surgical Procedure Assessment score, as well as a Parsonnet, Tuman, Tu, and Cardiac Anesthesia Risk Evaluation score. We compared these scores with regard to prediction of intensive care unit length of stay, as well as their concordance in predicting intensive care unit length of stay of less than 48 hours (fast track) and more than 7 days (prolonged stay).

RESULTS

Intensive care unit length of stay increased significantly with increasing Surgical Procedure Assessment scores (P < .01, Cuzick's test for trend). The lowest Surgical Procedure Assessment score (1A) predicted intensive care unit length of stay of less than 48 hours, and the higher Surgical Procedure Assessment scores (2B or 3) predicted intensive care unit length of stay of more than 7 days more accurately than the Parsonnet, Tuman, Tu and Cardiac Anesthesia Risk Evaluation scores.

CONCLUSIONS

The Surgical Procedure Assessment score predicts intensive care unit length of stay better than other comparable scores. It is simple, intuitive, and easily understood by all caregivers and can preoperatively discriminate fast-track from prolonged-stay patients. It is a useful tool to facilitate intensive care unit triage.

Poor performances of EuroSCORE and CARE score for prediction of perioperative mortality in octogenarians undergoing aortic valve replacement for aortic stenosis

BACKGROUND AND OBJECTIVE

Although results of cardiac surgery are improving, octogenarians have a higher procedure-related mortality and more complications with increased length of stay in ICU. Consequently, careful evaluation of perioperative risk seems necessary. The aims of our study were to assess and compare the performances of EuroSCORE and CARE score in the prediction of perioperative mortality among octogenarians undergoing aortic valve replacement for aortic stenosis and to compare these predictive performances with those obtained in younger patients.

METHODS

This retrospective study included all consecutive patients undergoing cardiac surgery in our institution between November 2005 and December 2007. For each patient, risk assessment for mortality was performed using logistic EuroSCORE, additive EuroSCORE and CARE score. The main outcome measure was early postoperative mortality. Predictive performances of these scores were assessed by calibration and discrimination using goodness-of-fit test and area under the receiver operating characteristic curve, respectively.

RESULTS

During this 2-year period, we studied 2117 patients, among whom 134/211 octogenarians and 335/1906 nonoctogenarians underwent an aortic valve replacement for aortic stenosis. When considering patients with aortic stenosis, discrimination was poor in octogenarians and the difference from nonoctogenarians was significant for each score (0.58, 0.59 and 0.56 vs. 0.82, 0.81 and 0.77 for additive EuroSCORE, logistic EuroSCORE and CARE score in octogenarians and nonoctogenarians, respectively, P < 0.05). Moreover, in the whole cohort, logistic EuroSCORE significantly overestimated mortality among octogenarians.

CONCLUSION

Predictive performances of these scores are poor in octogenarians undergoing cardiac surgery, especially aortic valve replacement. Risk assessment and therapeutic decisions in octogenarians should not be made with these scoring systems alone.

Intraoperative Hemodynamic Instability During and After Separation From Cardiopulmonary Bypass

Every year, more than 1 million patients worldwide undergo cardiac surgery. Because of the aging of the population, cardiac surgery will increasingly be offered to patients at a higher risk of complications. The consequence is a reduced physiological reserve and hence an increased risk of mortality. These issues will have a significant impact on future health care costs because the population undergoing cardiac surgery will be older and more likely to develop postoperative complications. One of the most dreaded complications in cardiac surgery is difficult separation from cardiopulmonary bypass (CPB). When separation from CPB is associated with right-ventricular failure, the mortality rate will range from 44% to 86%. Therefore, the diagnosis and the preoperative prediction of difficult separation from CPB will be crucial to improve the selection and care of patients and to prevent complications for this high-risk patient population.

Cardiac risk in patients aged >75 years with asymptomatic, severe aortic stenosis undergoing noncardiac surgery

Severe aortic stenosis (AS) is a known predictor of cardiac risk during noncardiac surgery. However, for patients with asymptomatic AS, it is unclear whether aortic valve surgery should precede noncardiac surgery. We studied 30 patients with asymptomatic, severe AS with a mean age of 78 + or - 9 years, an aortic valve area of 0.77 + or - 0.16 cm(2), a mean gradient of 50.1 + or - 9.5 mm Hg, and a peak gradient of 84 + or - 22 mm Hg. They were compared to 60 age-matched (within 2 years) and gender-matched (ratio of 1:2) patients with mild-to-moderate AS (controls). The primary end point of the study was a composite of death, myocardial infarction, heart failure, ventricular arrhythmias before dismissal, and intraoperative hypotension requiring vasopressor administration. Most patients (>75%) and controls underwent intermediate-risk surgical procedures that were similar with respect to the nature of the surgery, type of anesthesia used, and preoperative risk assessment. Combined postoperative events were more common for the patients (n = 10; 33%) than for the controls (n = 14; 23%), but the difference was not statistically significant (p = 0.06). Intraoperative hypotension requiring vasopressor use was more likely for the patients (n = 9; 30%) than for the controls (n = 10; 17%; odds ratio 2.5; p = 0.11). The perioperative myocardial infarction rates were similar for both groups (3%; p = 0.74). No deaths, heart failure events, or ventricular arrhythmias occurred in the patients and 1 death and 1 ventricular arrhythmia episode occurred in the controls. In conclusion, intermediate-to-low-risk noncardiac surgery for patients with severe, asymptomatic AS can be performed relatively safely. Intraoperative hypotension was frequent and required prompt and aggressive treatment.

Risk classification for primary knee arthroplasty

We devised a 4-group classification for primary TKA patients: C0, fit patient, simple arthritis; CI, fit patient, complex arthritis; CII, medically unfit patient with simple pattern; and CIII, unfit patient with complex arthritis. Patient fitness and arthritis complexity were based on the literature. One hundred twenty-two patients, operated on by the senior author, were retrospectively placed into one of these 4 groups. We found the following: significantly increased cumulative complication risk in CII and CIII incomparison with C0 (P < .001), increased length of stay in CII and CIII (P < .001), and similar trends between C0 and CI and between CI and CII. This system is useful in preoperative planning, risk counseling, and surgeon selection. It identifies patients with a higher risk of complications and inpatient stay.

Predicting adverse outcomes of cardiac surgery with the application of artificial neural networks

Risk-stratification models based on pre-operative patient and disease characteristics are useful for providing individual patients with an insight into the potential risk of complications and mortality, for aiding the clinical decision for surgery vs non-surgical therapy, and for comparing the quality of care between different surgeons or hospitals. Our study aimed to apply artificial neural networks (ANN) models to predict mortality and morbidity after cardiac surgery, and also to compare the efficacy of this model to that of the logistic regression model and Parsonnet score. The accuracy of the ANN, logistic regression and Parsonnet score in predicting mortality was 83.8%, 87.9% and 78.4%. The accuracy of the ANN, logistic regression and Parsonnet score in predicting major morbidity was 79.0%, 74.3% and 68.6%. The area under the receiver operating characteristic curves (AUC) of the ANN, logistic regression and Parsonnet score in predicting in-hospital mortality were 0.873, 0.852 and 0.829. The AUCs of the ANN, logistic regression and Parsonnet score in predicting major morbidity were 0.852, 0.789 and 0.727. The results showed the ANN models have the best discriminating power in predicting in-hospital mortality and morbidity among these models.

Risk scores do not predict high mortality after coronary artery bypass surgery in the presence of diastolic dysfunction

BACKGROUND

Although global postoperative mortality after on-pump coronary artery bypass grafting is approximately 3%, in some groups it can be considerably higher. Many conditions are known to increase mortality and have been included in well-known scoring systems; however, left ventricular diastolic dysfunction has not been sufficiently evaluated to identify its predictive value for mortality after coronary artery bypass grafting, nor is it integrated in currently used risk scores.

METHODS

Left ventricular filling pattern was prospectively evaluated in 191 patients scheduled for on-pump coronary artery bypass grafting. A follow-up of survival and complications was made for 30 days postoperatively. Observed mortality was compared with the mortality predicted by the scores of EuroSCORE and Parsonnet.

RESULTS

A correlation was found between diastolic function, the presence of comorbidities, and postoperative survival. There was no mortality in the group with normal filling pattern (0 of 33 patients). In the presence of an alteration of relaxation, mortality was 5 of 129 patients (3.8%); in the pseudonormal group it was 2 of 16 patients (12.5%); and in the restrictive group it was 6 of 13 patients (46.1%; p < 0.01). Parsonnet and EuroSCORE predicted a mortality of 1.5% to 1.6%, 1.5% to 2.0%, 1.5% to 2.2%, and 3.9% to 4.1% for each group, respectively. Mortality in the group with E deceleration time of 150 ms or greater was 2.8% and in the group with E deceleration time less than 150 ms was 17.3% (p < 0.01). Postoperative complications were also more frequent in the group with advanced dysfunction.

CONCLUSIONS

Severe diastolic dysfunction is a strong predictor of adverse outcome and mortality after on-pump coronary artery bypass grafting, and this high risk is not adequately predicted by EuroSCORE and Parsonnet score. Measures of diastolic function should be included in routine preoperative risk assessment.

How well do pediatric anesthesiologists agree when assigning ASA physical status classifications to their patients?

BACKGROUND

The scope and application of the American Society of Anesthesiologists Physical Status (ASA PS) classification has been called into question and interobserver consistency even by specialist anesthesiologists has been described as only fair. Our purpose was to evaluate the consistency of the application of the ASA PS amongst a group of pediatric anesthesiologists.

METHODS

We randomly selected 400 names from the active list of specialist members of the Society for Pediatric Anesthesia. Respondents were asked to rate 10 hypothetical pediatric patients and answer four demographic questions.

RESULTS

We received 267 surveys, yielding a response rate of 66.8% and the highest number of responses in any study of this nature. The spread of answers was wide across almost all cases. Only one case had a response spread of only two classifications, with the remaining cases having three or more different ASA PS classifications chosen. The most variability was found for a hypothetical patient with severe trauma, who received five different ASA PS classifications. The Modified Kappa Statistic was 0.5, suggesting moderate agreement. No significant difference between the private and academic anesthesiologists was found (P = 0.26).

CONCLUSIONS

We present the largest evaluation of interobserver consistency in ASA PS in pediatric patients by pediatric anesthesiologists. We conclude that agreement between anesthesiologists is only moderate and suggest standardizing assessment, so that it reflects the patient status at the time of anesthesia, including any acute medical or surgical conditions.