Readmission to the Intensive Care Unit Following Cardiac Surgery: A Derived and Validated Risk Prediction Model in 4,869 Patients.

OBJECTIVE: To derive and validate a clinical risk index that can predict readmission to the intensive care unit (ICU) after cardiac surgery. DESIGN: Retrospective nonrandomized study to determine the perioperative variables associated with risk of readmission to the ICU after cardiac surgery. SETTING: The study was carried out in a single university hospital. PARTICIPANTS: This was an analysis of 4,869 consecutive adult patients. INTERVENTIONS: All patients underwent cardiac surgery at a single center and were discharged to the ward from the ICU during the index surgical admission. MEASUREMENTS AND MAIN RESULTS: A total of 156 patients (3.2%) were readmitted to the ICU during their index surgical admission. Risk factors associated with readmission were identified by performing univariate analysis followed by multivariate logistic regression. The final multivariable regression model was validated internally by bootstrap replications. Nine independent variables were associated with readmission: urgency of surgery, diabetes, chronic kidney disease stage 3 to 5, aortic valve surgery, European System for Cardiac Operative Risk Evaluation, postoperative anemia, hypertension, preoperative neurological disease, and the Intensive Care National Audit and Research Centre score. Our data also showed mortality (18% v 3.2%, p < 0.0001) was significantly higher in readmitted patients. The median duration of ICU stay (7 [4-17] v 1 [1-2] days, p < 0.0001) and hospital stay (20 [12-33] v 7 [5-10] days, p < 0.0001) were significantly longer in patients who were readmitted to ICU compared to those who were not. CONCLUSION: From a comprehensive perioperative dataset, the authors have derived and internally validated a risk index incorporating 9 easily identifiable and routinely collected variables to predict readmission following cardiac surgery.

Perioperative kinetics of endocan in patients undergoing cardiac surgery with and without cardiopulmonary bypass.

INTRODUCTION: Endothelial Specific Molecule-1 or endocan is a novel biomarker associated with the development of acute lung injury (ALI) in response to a systemic inflammatory state such as trauma. Acute Respiratory Distress syndrome (ARDS), a severe form of ALI is a devastating complication that can occur following cardiac surgery due to risk factors such as the use of cardiopulmonary bypass (CPB) during surgery. In this study we examine the kinetics of endocan in the perioperative period in cardiac surgical patients. METHODS: After ethics approval, we obtained informed consent from 21 patients undergoing elective cardiac surgery (3 groups with seven patients in each group: coronary artery bypass grafting (CABG) with the use of CPB, off-pump CABG and complex cardiac surgery). Serial blood samples for endocan levels were taken in the perioperative period (T0: baseline prior to induction, T1: at the time of heparin administration, T2: at the time of protamine, T2, T3, T4 and T5 at 1, 2, 4 and 6h following protamine administration respectively). Endocan samples were analysed using the enzyme-linked immunosorbent assay (ELISA) method. Statistical analysis incorporated the use of test for normality. RESULTS: Our results reveal that an initial rise in the levels of serum endocan from baseline in all patients after induction of anaesthesia. Patients undergoing off-pump surgery have lower endocan concentrations in the perioperative period than those undergoing CPB. Endocan levels decrease following separation from CPB, which may be attributed to haemodilution following CPB. Following administration of protamine, endocan concentrations steadily increased in all patients, reaching a steady state between 2 and 6h. The baseline endocan concentrations were elevated in patients with hypertension and severe coronary artery disease. CONCLUSION: Baseline endocan concentrations are higher in hypertensive patients with critical coronary artery stenosis. Endocan concentrations increased after induction of anaesthesia and decreased four hours after separation from CPB. Systemic inflammation may be responsible for the rise in endocan levels following CPB.

Long-Term Consequences of Acute Kidney Injury After Cardiac Surgery: A Systematic Review and Meta-Analysis.

OBJECTIVES: To determine the effect of acute kidney injury (AKI) associated with cardiac surgery on long-term mortality. DESIGN: Systematic review and meta-analysis of 9 observational studies extracted from the MEDLINE and EMBASE electronic databases. SETTING: Hospitals undertaking cardiac surgery. PARTICIPANTS: The study included 35,021 cardiac surgery patients from 9 observational studies. INTERVENTIONS: None. MEASUREMENTS AND MAIN RESULTS: Nine studies including 35,021 patients reported incidence of AKI data. The median incidence of AKI was 27.75% (IQR, 16.3%-38.86%). There was significant variation in the reported incidence (range, 11.97%-54%), which can be explained by the different AKI definitions used in the included studies. Eight studies provided adjusted effect size data with 95% confidence intervals on the impact of the occurrence of postoperative AKI and long-term mortality outcomes. Occurrence of postoperative AKI is associated with a significantly increased risk of long-term mortality (HR, 1.68; 95% CI, 1.45-1.95; p<0.00001). Recovery of renal function before hospital discharge is associated with a lower long-term mortality risk (HR, 1.31; 95% CI, 1.16-1.47; p<0.00001) compared with patients who experienced persistent abnormal renal function on hospital discharge (HR, 2.71; 95% CI, 1.26-5.82; p = 0.01). CONCLUSIONS: There is wide variation in the reported incidence of AKI after cardiac surgery, reflecting the different AKI classification systems used. AKI after cardiac surgery is associated with an increased risk of long-term mortality. Patients with persistent renal dysfunction after hospital discharge carry a higher risk of AKI.

Goal-directed therapy after cardiac surgery and the incidence of acute kidney injury.

OBJECTIVE: The purpose of this study was to assess the effect of goal-directed therapy (GDT), after cardiac surgery, on the incidence of acute kidney injury (AKI). DESIGN: This is a prospective observational study designed to achieve and maintain maximum stroke volume for 8 hours, in patients after cardiac surgery. SETTING: This is a single-center study in a 15-bedded cardiothoracic intensive care unit (ICU). PARTICIPANTS: Participants are patients after coronary artery bypass grafting and/or aortic valve surgery. INTERVENTIONS: Patients in the GDT group received cardiac output monitoring and fluid challenges targeting an increase in stroke volume by at least 10%. Stroke volume maximization was maintained for a period of 8 hours from admission to the ICU. All other aspects of care were dictated by the clinical team. Patients in the standard therapy (ST) group had intravenous fluids in accordance with the routine practice of the unit. Patients were divided into the GDT and ST group dependant on availability of cardiac output monitors and allocation of nursing staff with training in GDT. Patients' data were collected prospectively in both groups. MEASUREMENTS AND MAIN RESULTS: One hundred twenty-three patients received GDT compared with 141 patients in the ST group. Both groups received similar volumes of fluid (GDT, 2905 [1367] mL vs 2704 [1393] mL; P=.09). Incidence of AKI was reduced in the GDT group (n=8 [6.5%] vs n=28 [19.9%]; P=.002). The median duration of hospital stay was 6 (4) days in the GDT group vs 7 (8) days in the ST, P=.004. CONCLUSION: Postoperative GDT in patients after cardiac surgery was associated with reduction in the incidence of AKI and a reduction in ICU and hospital duration of stay.