Predictive Accuracy of a Perioperative Laboratory Test-Based Prediction Model for Moderate to Severe Acute Kidney Injury After Cardiac Surgery.

Importance: Effective treatment of acute kidney injury (AKI) is predicated on timely diagnosis; however, the lag in the increase in serum creatinine levels after kidney injury may delay therapy initiation. Objective: To determine the derivation and validation of predictive models for AKI after cardiac surgery. Design, Setting, and Participants: Multivariable prediction models were derived based on a retrospective observational cohort of adult patients undergoing cardiac surgery between January 2000 and December 2019 from a US academic medical center (n = 58 526) and subsequently validated on an external cohort from 3 US community hospitals (n = 4734). The date of final follow-up was January 15, 2020. Exposures: Perioperative change in serum creatinine and postoperative blood urea nitrogen, serum sodium, potassium, bicarbonate, and albumin from the first metabolic panel after cardiac surgery. Main Outcomes and Measures: Area under the receiver-operating characteristic curve (AUC) and calibration measures for moderate to severe AKI, per Kidney Disease: Improving Global Outcomes (KDIGO), and AKI requiring dialysis prediction models within 72 hours and 14 days following surgery. Results: In a derivation cohort of 58 526 patients (median [IQR] age, 66 [56-74] years; 39 173 [67%] men; 51 503 [91%] White participants), the rates of moderate to severe AKI and AKIrequiring dialysis were 2674 (4.6%) and 868 (1.48%) within 72 hours and 3156 (5.4%) and 1018 (1.74%) within 14 days after surgery. The median (IQR) interval to first metabolic panel from conclusion of the surgical procedure was 10 (7-12) hours. In the derivation cohort, the metabolic panel-based models had excellent predictive discrimination for moderate to severe AKI within 72 hours (AUC, 0.876 [95% CI, 0.869-0.883]) and 14 days (AUC, 0.854 [95% CI, 0.850-0.861]) after the surgical procedure and for AKI requiring dialysis within 72 hours (AUC, 0.916 [95% CI, 0.907-0.926]) and 14 days (AUC, 0.900 [95% CI, 0.889-0.909]) after the surgical procedure. In the validation cohort of 4734 patients (median [IQR] age, 67 (60-74) years; 3361 [71%] men; 3977 [87%] White participants), the models for moderate to severe AKI after the surgical procedure showed AUCs of 0.860 (95% CI, 0.838-0.882) within 72 hours and 0.842 (95% CI, 0.820-0.865) within 14 days and the models for AKI requiring dialysis and 14 days had an AUC of 0.879 (95% CI, 0.840-0.918) within 72 hours and 0.873 (95% CI, 0.836-0.910) within 14 days after the surgical procedure. Calibration assessed by Spiegelhalter z test showed P >.05 indicating adequate calibration for both validation and derivation models. Conclusions and Relevance: Among patients undergoing cardiac surgery, a prediction model based on perioperative basic metabolic panel laboratory values demonstrated good predictive accuracy for moderate to severe acute kidney injury within 72 hours and 14 days after the surgical procedure. Further research is needed to determine whether use of the risk prediction tool improves clinical outcomes.

Lack of Association between Preoperative Statin Use and Respiratory and Neurologic Complications after Cardiac Surgery.

BACKGROUND: Statins may reduce the risk of pulmonary and neurologic complications after cardiac surgery. METHODS: The authors acquired data for adults who had coronary artery bypass graft, valve surgery, or combined procedures. The authors matched patients who took statins preoperatively to patients who did not. First, the authors assessed the association between preoperative statin use and the primary outcomes of prolonged ventilation (more than 24 h), pneumonia (positive cultures of sputum, transtracheal fluid, bronchial washings, and/or clinical findings consistent with the diagnosis of pneumonia), and in-hospital all-cause mortality, using logistic regressions. Second, the authors analyzed the collapsed composite of neurologic complications using logistic regression. Intensive care unit and hospital length of stay were evaluated with Cox proportional hazard models. RESULTS: Among 14,129 eligible patients, 6,642 patients were successfully matched. There was no significant association between preoperative statin use and prolonged ventilation (statin: 408/3,321 [12.3%] vs. nonstatin: 389/3,321 [11.7%]), pneumonia (44/3,321 [1.3%] vs. 54/3,321 [1.6%]), and in-hospital mortality (52/3,321 [1.6%] vs. 43/3,321 [1.3%]). The estimated odds ratio was 1.06 (98.3% CI, 0.88 to 1.27) for prolonged ventilation, 0.81 (0.50 to 1.32) for pneumonia, and 1.21 (0.74 to 1.99) for in-hospital mortality. Neurologic outcomes were not associated with preoperative statin use (53/3,321 [1.6%] vs. 56/3,321 [1.7%]), with an odds ratio of 0.95 (0.60 to 1.50). The length of intensive care unit and hospital stay was also not associated with preoperative statin use, with a hazard ratio of 1.04 (0.98 to 1.10) for length of hospital stay and 1.00 (0.94 to 1.06) for length of intensive care unit stay. CONCLUSIONS: Preoperative statin use did not reduce pulmonary or neurologic complications after cardiac surgery.

The association between body mass index and outcome after coronary artery bypass grafting operations.

OBJECTIVES: This investigation was undertaken to analyse the association between body mass index (BMI) and morbidity after coronary artery bypass graft (CABG) operations. METHODS: The setting was a cardiovascular intensive care unit (ICU) of a tertiary medical referral centre. This was a retrospective review; patients were classified according to their BMI into five groups: underweight <18.5 kg/m(2); normal weight 18.5-24.9 kg/m(2); overweight 25-29.9 kg/m(2); Class I obesity 3034.9 kg/m(2); and Class II/III obesity >35 kg/m(2). We included patients who underwent isolated CABG between January 3, 2006 and March 8, 2011. After including only the initial operation or admission in patients with more than one operation or hospital admission and excluding patients with any missing variable, 3470 patients remained in the analyses. The primary outcomes analysed were hospital mortality and pulmonary and infection morbidities. We secondarily assessed the association between BMI category and each of the three outcomes. RESULTS: Respective mortality, and pulmonary and infection morbidity occurrence rates were: 8.7, 13.0 and 13.0% for the underweight; 2.4, 8.0 and 4.8% for the overweight; 1.8, 10.9 and 5.6% for the Class I obesity group; and 2.7, 11.1 and 5.7% for the Class II/III obesity group, vs 2.3, 7.0 and 6.2% for the normal weight group. Class I and II/III obesity patients were more likely to have pulmonary morbidity compared with the normal weight group, after adjusting for the potential confounding variables. CONCLUSIONS: Class I and Class II/III obesity (BMI ≥30 kg/m(2)) was associated with increased pulmonary morbidity after CABG operations. There was no difference in mortality or infection morbidity in any BMI group compared with the normal group.

Preoperative brain natriuretic peptide and atrial arrhythmias after coronary artery bypass graft surgery.

OBJECTIVE: To assess the association of preoperative brain natriuretic peptide with atrial arrhythmias and length of stay after cardiac surgery. DESIGN: A retrospective data analysis. SETTING: All data were collected from patients who underwent cardiac surgery at a single institution, an academic hospital, between 2005 and 2010. PARTICIPANTS: Patient data were collected from the authors' institution's Perioperative Health Documentation System of cardiac surgeries. INTERVENTIONS: None. MEASUREMENTS AND MAIN RESULTS: The major findings were that individuals with a 10-pg/mL increase in brain natriuretic peptide were 1.005 (95% CI: 1.002, 1.009) times more likely to have an atrial arrhythmia than those with no increase in brain natriuretic peptide. A brain natriuretic peptide value ≥306 pg/mL was calculated to best predict an atrial arrhythmia. Those above the threshold were 1.455 (95% CI: 1.087, 1.947) times more likely to have an atrial arrhythmia than those below the threshold. Individuals above the threshold had a median of 3 days in the intensive care unit compared to 1 day for those below the threshold, as well as median hospital stays of 11 days for those below the threshold. CONCLUSIONS: The results indicated that elevated brain natriuretic peptide was associated with increased risk of atrial arrhythmias and prolonged length of hospital stay after cardiac surgery. Identifying at-risk patients is important to guide preventative strategies for postoperative atrial arrhythmias.

Comparison of Positive End-Expiratory Pressure of 8 versus 5 cm H2O on Outcome After Cardiac Operations.

PURPOSE: Postoperative positive end-expiratory pressure (PEEP) selection in patients who are mechanically ventilated after cardiac operations often seems random. The aim of this investigation was to compare the 2 most common postoperative initial PEEP settings at our institution, 8 and 5 cm H2O, on postoperative initial tracheal intubation time (primary outcome); cardiovascular intensive care unit (CVICU); hospital length of stay (LOS); occurrence of pneumonia; and hospital mortality (secondary outcomes). MATERIALS AND METHODS: The electronic medical records of patients who were mechanically ventilated after isolated coronary artery bypass grafting (CABG) or combined CABG and valve operations were reviewed. Propensity score matching was used to compare patients with an initial postoperative PEEP setting of 8 cm H2O (n = 4722 [25.9%]) with those who had PEEP of 5 cm H2O (n = 13 535 [74.1%]) on the primary and secondary outcomes listed earlier. RESULTS: There was no difference in initial postoperative intubation time between the PEEP of 8 cm H2O and the PEEP of 5 cm H2O patient groups (mean 11.9 vs 12.0 hours [median 8.2 vs 8.8 hours], P = .89). The groups did not differ on the occurrence of pneumonia (0.43% vs 0.60%, P = .25) nor on hospital mortality (0.47% vs 0.43%, P = .76). Aspiration pneumonia occurrence approached a significant difference (0.06% vs 0.21%, P value = .052), as did CVICU LOS (mean: 47.9 vs 49.8 hours [median: 28.5 vs 28.4 hours], P = .057), but were not statistically different. There was a slight but likely clinically unimportant difference in hospital LOS (7.7 vs 7.4 days, PEEP = 8 vs 5, P < .001). CONCLUSION: Patients being mechanically ventilated after cardiac operations with an initial postoperative PEEP setting of 8 versus 5 cm H2O differed significantly only on hospital LOS but the difference was likely clinically unimportant. Thus, use of 8 cm H2O PEEP in these patients without a clinical indication, although likely not harmful, does not seem beneficial.

Dexmedetomidine sedation after cardiac surgery decreases atrial arrhythmias.

STUDY OBJECTIVE: To determine whether postoperative cardiac surgery patients who are sedated with dexmedetomidine have fewer atrial arrhythmias, and whether dexmedetomidine is associated with fewer renal and more gastrointestinal (GI) complications. DESIGN: Retrospective study. SETTING: Urban academic hospital. MEASUREMENTS: The records of 765 postoperative cardiac surgery patients who were given dexmedetomidine for postoperative sedation in the intensive care unit (ICU) were studied. Data from the hospital's Cardiac Anesthesiology database between the years 2005 and 2010 were evaluated. Records of patients whose ASA physical status was > 4 or who were < 18 years of age were excluded from the study. Patients who were and were not given dexmedetomidine were compared for postoperative sedation within three days after cardiac surgery using multivariable logistic regression, adjusting for imbalanced covariables. MAIN RESULTS: The records of 17,776 patients, including 765 cardiac patients given dexmedetomidine for postoperative sedation in the ICU, were reviewed. Patients who received postoperative dexmedetomidine had a lower risk of having atrial arrhythmias: (OR 0.74 (95% CI: 0.60, 0.91; P = 0.004). Dexmedetomidine was not associated with 30-day mortality (1.10, 0.40 - 3.02; P = 0.86), or with any of the following 30-day outcomes: surgical infection (0.72, 0.36-1.42; P = 0.34), systemic infection (1.38, 0.93 - 2.05; P = 0.11), GI complications (1.34, 0.74 - 2.42; P = 0.33), or renal complications (1.23, 0.70 - 2.15; P = 0.48). CONCLUSIONS: Dexmedetomidine use after cardiac surgery was associated with a lower incidence of atrial arrhythmias.

Low vitamin D concentration is not associated with increased mortality and morbidity after cardiac surgery.

OBJECTIVE: To determine the effect of vitamin D on postoperative outcomes in cardiac surgical patients. DESIGN: Retrospective study. SETTING: Single institution-teaching hospital. PARTICIPANTS: Adult cardiac surgical patients with perioperative 25-hydroxyvitamin D measurements. INTERVENTIONS: None. We gathered information from the Cardiac Anesthesiology Registry that was obtained at the time of the patients' visit/hospitalization. MEASUREMENTS AND MAIN RESULTS: We used data of 18,064 patients from the Cardiac Anesthesiology Registry; 426 patients with 25-hydroxyvitamin D measurements met our inclusion criteria. Association with Vitamin D concentration and composite of 11 cardiac morbidities was done by multivariate (i.e., multiple outcomes per subject) analysis. For other outcomes separate multivariable logistic regressions and adjusting for the potential confounders was used. The observed median vitamin D concentration was 19 [Q1-Q3∶12, 30] ng/mL. Vitamin D concentration was not associated with our primary composite of serious cardiac morbidities (odds ratio [OR], 0.96; 95% CI, 0.86-1.07). Vitamin D concentration was also not associated with any of the secondary outcomes: neurologic morbidity (P = 0.27), surgical (P = 0.26) or systemic infections (P = 0.58), 30-day mortality (P = 0.55), or length of initial intensive care unit (ICU) stay (P = 0.04). CONCLUSIONS: Our analysis suggests that perioperative vitamin D concentration is not associated with clinically important outcomes, likely because the outcomes are overwhelmingly determined by other baseline and surgical factors.

Lactate clearance time and concentration linked to morbidity and death in cardiac surgical patients.

BACKGROUND: Early predictors of morbidity after cardiac operations are lacking. Elevated lactate concentrations in the immediate postoperative period reflect unmet metabolic demand and may be associated with outcome. This study examined the association between early plasma lactate concentrations and outcome after cardiac operations. METHODS: As a retrospective cohort investigation, patient information was obtained from the Cardiovascular Information and the Anesthesiology Institute's patient registries. Inclusion criteria were all adult cardiac surgical patients undergoing isolated coronary artery bypass grafting or valve procedures, or coronary artery bypass grafting with a valve procedure, from January 1, 2008, to August 7, 2008 (arterial lactate values were added to the patient registry beginning January 1, 2008). RESULTS: Lactate concentrations during the initial 12 postoperative hours of a patient's stay in the cardiovascular intensive care unit were averaged (mean lactate concentration), and linear regression concentrations over time were used to predict when the lactate concentration would reach 1.5 mmol/L in individual patients (predicted lactate clearance time). We also considered the product of the mean and clearance (product value). Predicted lactate clearance time, mean lactate concentration, and product value were associated with any type of reoperation, death, and a set of composite outcomes (p < 0.001 for each). The accuracy of these indices was moderate to good, with the highest C statistic (for product value) being 0.82. CONCLUSIONS: Predicted lactate clearance time, mean lactate concentration, and product value are each associated with death, any type of reoperation, and a set of composite outcomes in patients undergoing coronary artery bypass grafting or valve operations, or both. Product value provided the best early prognostic guidance in individual patients.

Early tracheostomy is associated with improved outcomes in patients who require prolonged mechanical ventilation after cardiac surgery.

BACKGROUND: The best time to perform a tracheostomy in cardiac surgery patients who require prolonged postoperative mechanical ventilation remains unknown. The primary aim of this investigation was to determine if tracheostomy performed before postoperative day 10 improves patient outcomes. STUDY DESIGN: We conducted a retrospective review of prospectively collected patient information obtained from the Anesthesiology Institute Patient Registry on adult patients recovering from coronary artery bypass grafting and/or valve surgery. Demographic and comorbidity patient variables were obtained. Patients were divided into 2 groups based on the timing of their tracheostomy: early (less than 10 days) and late (14 to 28 days). The 2 patient groups were matched using propensity scores and compared on morbidity and in-hospital mortality outcomes. The primary outcomes measures were length of stay, morbidity, and in-hospital mortality. RESULTS: After propensity matching (n = 114 patients/group), early tracheostomy was associated with decreased in-hospital mortality (21.1% vs 40.4%, p = 0.002) and cardiac morbidity (14.0% vs 33.3%, p < 0.001), along with decreased ICU (median difference 7.2 days, p < 0.001) and hospital (median difference 7.5 days, p = 0.010) durations. The occurrence of sternal wound infection (6.0% vs 19.5%, p = 0.009) was less in the early tracheostomy group, but mediastinitis did not differ significantly (3.5% vs 7.0%, p = 0.24). CONCLUSIONS: Tracheostomy within 10 postoperative days in cardiac surgery patients who require prolonged mechanical ventilation was associated with decreased length of stay, morbidity, and mortality.

Have changes in ECMO technology impacted outcomes in adult patients developing postcardiotomy cardiogenic shock?

Extracorporeal membrane oxygenation (ECMO) technology has undergone several advancements over the last decade. We sought to compare current ECMO technology to older ones to determine how these technological improvements have impacted outcomes in patients suffering from postcardiotomy cardiogenic shock (PCS). Between 2005 and 2010, 49 patients received ECMO as support for PCS following elective cardiac surgery. Patients were divided into three groups. Group 1 (Gp 1, n = 11) patients received a Biomedicus pump with an Affinity oxygenator, Group 2 (Gp 2, n = 11) patients received a Biomedicus pump with a Quadrox D oxygenator, and Group 3 (Gp 3, n = 27) patients received a Rotaflow pump with a Quadrox D oxygenator. Groups were compared with regards to adverse events and ability to wean. Adverse event analysis showed no statistically significant difference between groups in incidence of stroke (p = 0.08), renal failure (p = 0.88), or bleeding requiring reexploration (p = 0.10). Changes in technology did little to improve weaning rates from ECMO (Gp 1 = 63.6%, Gp 2 = 45.5%, and Gp 3 = 55.6%). Similar trends were detected in hospital survival (Gp 1 = 27.3%, Gp 2 = 27.3%, and Gp 3 = 33.3%). Technology did impact oxygenator durability with Gp 1 requiring seven (63.6%) oxygenator exchanges compared to zero (0.0%) in Gp 2 and two (7.4%) in Gp 1. While advancements in ECMO technology have resulted in improved oxygenator durability, outcomes in patients requiring such support for PCS continue to be poor.

Outcome in patients who require venoarterial extracorporeal membrane oxygenation support after cardiac surgery.

OBJECTIVE: The authors analyzed hospital mortality in adult cardiac surgery patients who required postoperative venoarterial extracorporeal membrane oxygenation (ECMO) support for circulatory failure and identified perioperative patient variables associated with hospital mortality in these patients. DESIGN: A retrospective study. SETTING: A single institution, tertiary academic center. PARTICIPANTS: Adult patients requiring venoarterial ECMO support after cardiac surgery from January 1995 to December 2005 were identified from the Anesthesiology Institute Patient Registry. Twenty-two preselected patient variables were entered into a logistic regression model of hospital death. INTERVENTIONS: None. RESULTS: Two hundred thirty-three of 40,116 (0.58%) adult cardiac surgery patients required postoperative venoarterial ECMO, and among these, 149 (64%) died in the hospital. In an unadjusted analysis, older age, higher preoperative albumin, diabetes history, coronary artery bypass graft surgery, and longer total cardiopulmonary bypass (CPB) time were associated with increased hospital mortality, and a history of cardiogenic shock was associated with decreased mortality. In an adjusted logistic regression analysis, a history of cardiogenic shock and younger age were associated with decreased hospital mortality. The overall use of postoperative venoarterial ECMO in this patient population decreased since its peak in 1996. CONCLUSION: Venoarterial ECMO support after cardiac surgery was required in a small fraction of patients and was associated with very high hospital mortality; but among those requiring ECMO, mortality in these patients was lower in younger, nondiabetic patients with cardiogenic shock who had shorter CPB times. The mortality associated patient variables identified are not easily modifiable and do not appear sufficiently robust to define which patients should be selected for this potentially life-saving therapy.

The effect of postoperative gastrointestinal complications in patients undergoing coronary artery bypass surgery.

BACKGROUND: Gastrointestinal (GI) complications after coronary artery bypass graft surgery (CABG) are uncommon but associated with a disproportionate share of mortality. We thus identified variables associated with GI complications and analyzed their effect on postoperative mortality in patients undergoing isolated CABG. METHODS: Information from patients who underwent isolated CABG at our institution during a 12-year period was obtained from the Anesthesiology Institute patient registry. Patients who experienced one or more postoperative GI complication(s) during their initial intensive care unit stay were identified. Multivariable logistic regression with backward variable selection was used to determine variables associated with GI complications and to evaluate their effect on mortality. RESULTS: Among 16,043 patients who underwent isolated CABG, 213 (1.43%) had one or more GI complication(s). The main patient variables associated with postoperative GI complications included preoperative (odds ratio, 2.43; 95% confidence interval [CI], 1.39 to 4.23; p < 0.001) and intraoperative (odds ratio, 5.07; 95% CI, 3.08 to 8.35; p < 0.001) intraaortic balloon pump insertion, patient age (odds ratio, 1.65; 95% CI, 1.41 to 1.94; p < 0.001), intraoperative fresh-frozen plasma transfusion (odds ratio, 3.38; 95% CI, 2.12 to 5.41; p < 0.001), and cardiogenic shock (odds ratio, 3.04; 95% CI, 1.12 to 8.24). No difference was detected in complication rates between off-pump and on-pump CABG procedures (1.50% versus 1.30%, respectively; p = 0.63). Postoperative GI complication(s) after CABG was associated with a 12.98 times increase in mortality (p < 0.001). CONCLUSIONS: This single-center cohort study indicates that GI complications after isolated CABG remain rare with an incidence 1.43%. However, GI complications portend a significant mortality. The implications of intraoperative administration of fresh-frozen plasma and insertion of an intraaortic balloon pump deserve further investigation as they are associated with GI complications.

A propensity-matched comparison of the incidence of new-onset postoperative atrial arrhythmias in cardiac and noncardiac thoracic surgery patients.

OBJECTIVE: The primary aim of this investigation was to compare the incidence of new-onset postoperative atrial arrhythmias (POAAs) in cardiac versus noncardiac thoracic surgery patients. A subgroup analysis also was performed in the cardiac surgery patients comparing POAAs in patients who underwent cardiac surgery on and off cardiopulmonary bypass (CPB). DESIGN: This was a retrospective study using the Department of Cardiothoracic Anesthesia patient registry. All patients (n = 33,500) undergoing cardiac (n = 29,057) and noncardiac thoracic (n = 4,443) surgeries between 1993 and 2004 were identified from the patient registry. Two propensity-matched comparisons for the incidence of POAAs were made: (1) in cardiac surgery patients versus noncardiac thoracic surgery patients and (2) in patients undergoing cardiac surgery with versus without CPB. SETTING: A large metropolitan multidisciplinary clinic. PARTICIPANTS: Patients. INTERVENTION: No interventions were done because this was a retrospective study. MEASUREMENTS AND MAIN RESULTS: The cardiac patients had a significantly higher incidence of POAAs when compared with noncardiac thoracic surgery patients (11.6% v 7.5%, p < 0.001). There was no significant difference in the incidence of POAAs between patients undergoing CPB versus off-pump CPB (13.3% v 12.3%, p = 0.3). CONCLUSION: The incidence of new-onset POAAs was higher in patients undergoing cardiac surgery than in patients undergoing noncardiac thoracic surgery in propensity-matched patient groups. CPB was not associated with new-onset POAAs.

Operation timing does not affect outcome after coronary artery bypass graft surgery.

BACKGROUND: Human factors such as fatigue, circadian rhythms, scheduling, and staffing may have an impact on patient care over the course of a day across all medical specialties. Research by the transportation industry concludes that human performance is degraded by shift work, circadian rhythm disturbances, and prolonged duty. This study investigated whether the timing of coronary artery bypass graft surgery affects outcomes. METHODS: The outcomes of coronary artery bypass graft surgery patients were analyzed according to the hour of the day, day of the workweek, month, and moon phase in which the surgery started. All patients who underwent isolated coronary artery bypass graft surgery between January 1, 1993 and July 1, 2006 were considered for the study.The primary outcome measurement was a compound morbidity outcome of six variables defined by the Society of Thoracic Surgeons. These outcomes included (1) in-hospital death, (2) acute postoperative myocardial infarction, (3) neurologic morbidity, including focal or global neurologic deficits or death without awakening, (4) serious infection morbidity consisting of sepsis syndrome or septic shock, (5) new-onset renal failure requiring dialysis, and (6) postoperative ventilatory support exceeding 72 h. RESULTS: The composite morbidity and in-hospital mortality rates were 4.8% and 1.4%, respectively. The number of cases each weekday, each month of the year, and during each phase of the moon were consistent. None of the time factors significantly affected the composite morbidity outcome. CONCLUSIONS: Elective coronary artery bypass graft surgery can be scheduled throughout the workday, any day of the work week and in any month of the year without compromising outcome.

An 11-year, single-institution analysis of intra-aortic balloon pump use in cardiac surgery.

OBJECTIVES: The primary objective of this study was to analyze perioperative intra-aortic balloon pump (IABP) insertion in patients undergoing cardiac surgery in the authors' institution from 1995 to 2005 and to propose an explanation for changes in use over this period. A secondary objective was to assess patient variables associated with IABP use. DESIGN: This is a retrospective study including patients who underwent cardiac surgery between 1995 and 2005. SETTING: The Cardiothoracic Anesthesia Patient Registry of a single teaching institution was queried to obtain the required information. PARTICIPANTS: Thirty thousand two hundred sixty-nine cardiac surgery patients. INTERVENTIONS: Intra-aortic balloon pump insertion before surgery, after cardiopulmonary bypass, or in the cardiovascular intensive care unit was assessed in patients who underwent isolated coronary artery bypass graft surgery, valve surgery, or both. Select patient variables were analyzed for their association with IABP insertion. Transesophageal echocardiography (TEE) examinations, milrinone use, and mortality rates also were determined. MEASUREMENTS AND MAIN RESULTS: Among 30,269 cardiac surgery patients, 1,310 (4.32%) underwent IABP insertion. Combined preoperative, intraoperative, and postoperative IABP use decreased from 7.8% in 1995 to 3.0% in 2005. Simultaneously, the intraoperative use of milrinone increased from 4.8% to 8.8% and postoperative use increased from 5.2% to 7.8%. The number of intraoperative TEE examinations more than doubled from approximately 1,700 to 3,500. The overall mortality for patients with preoperative, intraoperative, and postoperative IABP insertion was 12.6%, 17.5%, and 47.7%, respectively. CONCLUSIONS: From 1995 to 2005, preoperative, intraoperative, and postoperative IABP use decreased by approximately 60% in cardiac surgery patients. Simultaneously, the use of TEE and milrinone each doubled. Although a cause-effect relationship cannot be established from the present study's observational data, the trends coincide and may be related.

Electrocardiographic activity before onset of postoperative atrial fibrillation in cardiac surgery patients.

BACKGROUND: Electrocardiographic (ECG) characteristics were analyzed in postoperative cardiac surgery patients in an attempt to predict development of new-onset postoperative atrial fibrillation (AF). METHODS: Nineteen ECG characteristics were analyzed using computer-based algorithms. The parameters were retrospectively analyzed from ECG signals recorded in postoperative cardiac surgery patients while they were in the cardiovascular intensive care unit (CVICU) at our institution. ECG data from 99 patients (of whom 43 developed postoperative AF) were analyzed. A bootstrap variable selection procedure was applied to select the most important ECG parameters, and a multivariable logistic regression model was developed to classify patients who did and did not develop AF. RESULTS: Premature atrial activity (PAC) was greater in AF patients (P < 0.01). Certain heart rate variability (HRV) and turbulence parameters also differed in patients who did and did not develop AF. In contrast, P-wave morphology was similar in patients with and without AF. Receiver operating curve (ROC) analysis applied to the model produced a C-statistic of 0.904. The model thus correctly classified AF patients with more than a 90% sensitivity and a 70% specificity. CONCLUSION: Among the 19 ECG parameters analyzed, PAC activity, frequency-domain HRV, and heart rate turbulence parameters were the best discriminators for postoperative AF.

Propensity matched comparison of outcomes in older and younger patients after coronary artery bypass graft surgery.

BACKGROUND: By 2050, the number of people in the United States aged 85 years and older is expected to increase from 4.2 to 20.8 million. We therefore compared outcomes after isolated coronary artery bypass grafting (CABG) in patients aged 85 years and older with those 55 to 65 years old. METHODS: Propensity matching and multivariable analysis were used to compare morbidity and mortality outcomes in 132 patients aged 85 years and older and in 5243 patients aged 55 to 65 years who underwent CABG between 1993 and 2004. Variables of interest were compared using Student t, Wilcoxon rank sum, chi(2), or Fischer exact tests, as appropriate. RESULTS: After propensity matching, each group had 122 patients who were matched on all baseline and intraoperative variables except number of intraoperative red blood cell (RBC) transfusions, which was greater in the older group. Atrial arrhythmias occurred more frequently and intensive care unit (ICU) and hospital lengths of stay (LOS) were longer in the older group. Multiple logistic regression analysis demonstrated that atrial arrhythmias and catheter-related sepsis were more common in the older group. CONCLUSIONS: Older patients received more RBC transfusions, presumably reflecting a lower threshold to transfuse older patients. Atrial arrhythmias were more common in the older group, this can account for their longer ICU and hospital LOS, which can also explain their greater incidence of catheter sepsis. The two age groups had similar mortality and morbidity. Advanced age is not associated with substantively worse outcome after CABG compared with a propensity-matched younger age group.

Automatic detection of QRS complexes in ECG signals collected from patients after cardiac surgery.

A novel automatic QRS detection algorithm that is based on a wavelet pre-filter and an adaptive threshold technique is presented. The algorithm utilizes a bi-orthogonal wavelet filter to de-noise the ECG signal. The QRS complexes are then identified by computing the first derivative of the signal and applying a set of adaptive thresholds that are not limited to a strict range. QRS complexes are identified in multiple ECG channels of a 5-lead configuration and an inter-channel comparison is performed to verify QRS locations. The algorithm was initially developed using ECG signals from Physionet website, but was later refined using ECG data collected from post cardiac surgery patients in the intensive care units. The proposed algorithm was able to detect QRS complexes with high sensitivity (>99%) and specificity (>99%) when compared to the algorithm used in Physionet ECG database. Additionally, the new algorithm can be implemented in real-time and can successfully detect QRS complexes for a wide variety of ECG shapes and characteristics often encountered in cardiac patients.

"Renal dose" dopamine is associated with the risk of new-onset atrial fibrillation after cardiac surgery.

OBJECTIVE: "Renal dose" dopamine (rDA; 1-3 microg/kg per min) is administered to patients after cardiac surgery to preserve or improve renal function. Many of these patients develop new-onset postoperative atrial fibrillation or atrial flutter (pAF) that could be related to rDA administration. The objective of this investigation was to determine whether there was an association between rDA and new-onset pAF in patients undergoing coronary artery bypass grafting with cardiopulmonary bypass (CABG). SETTING: Research hospital. SUBJECTS: The study population consisted of 1,731 patients undergoing CABG. INTERVENTIONS: CABG with and without rDA. DESIGN: After approval by the institutional review board, a retrospective study using the Cardiothoracic Anesthesia Patient Registry was undertaken to determine the association between rDA and pAF in patients undergoing CABG. Patients with a documented history of atrial fibrillation, those who required inotrope use during or after surgery, and those having valve surgery were excluded. MEASUREMENTS AND MAIN RESULTS: One-thousand seven-hundred thirty-one patients undergoing CABG during the period of January 1, 2000, through June 30, 2002, were the study population; of these, 15.0% (260/1,731) developed pAF. The incidence of pAF was 23.3 % (41/176) among patients who received rDA and 14.1% (219/1,555) among those who did not receive rDA. In the multivariable logistic regression model, patient age, gender, chronic obstructive pulmonary disease or asthma, and rDA were associated with pAF (p < .01). Receipt of rDA increased the odds of developing pAF by 74%, independent of the effect of other variables. CONCLUSIONS: Renal-dose dopamine is associated with a 1.74 odds ratio of pAF developing after CABG.