Continuous Intraoperative Cefazolin Infusion May Reduce Surgical Site Infections During Cardiac Surgical Procedures: A Propensity-Matched Analysis.

OBJECTIVES: The authors sought to determine whether an institutional transition from intermittent to continuous dosing of intraoperative antibiotics in cardiac surgery affected surgical site infection (SSI) outcomes. DESIGN: A retrospective chart review utilizing propensity matching. SETTING: A single academic, tertiary care hospital. PARTICIPANTS: One thousand one hundred seventy-nine patients undergoing coronary artery bypass grafting (CABG) and/or cardiac valvular surgery between April 2013 and November 2014 who received perioperative cefazolin. INTERVENTIONS: By method of cefazolin administration, patients were divided into an "intermittent-dosing" (ID) group and a "continuous-infusion" (CI) group. MEASUREMENTS AND MAIN RESULTS: Of the 1,179 patients who underwent cardiac surgery during the study period, 1:1 propensity score matching yielded 399 patients in each group. Rates of diabetes (33.6% ID v 33.8% CI, p = 0.94), coronary artery bypass (62.3% v 61.4%, p = 0.66), and bilateral internal mammary artery harvesting (6.0% v 8.3%, p = 0.22) were similar between groups. SSIs occurred in more ID patients than CI patients (2.3% v 0.5%, p = 0.03). This difference was driven by decreases in extremity and conduit harvest site SSIs (1.8% v 0.3%, p = 0.03), as there were no episodes of mediastinitis, and superficial sternal SSI rates did not differ (0.5% v 0.3%, p = 0.56). There also were significantly fewer episodes of pneumonia in the CI group (6.0% v 2.3%, p = 0.008). Intensive care unit and total lengths of stay did not differ. Thirty-day mortality was 2.8% in both groups (p = 1.00). CONCLUSIONS: As compared to ID regimens, CI cefazolin infusion may reduce post-cardiac surgery infectious complications. Further study in larger patient populations is needed.

Development and Validation of a Score to Predict the Risk of Readmission After Adult Cardiac Operations.

BACKGROUND: The purpose of this study was to develop and validate a risk score for readmissions after cardiac operations. METHODS: Adults surviving to discharge after cardiac operations at a single institution from 2008 to 2013 were randomly divided 3:1 into training and validation cohorts. The primary outcome was readmission within 30 days of discharge. A multivariable model was constructed in the training cohort incorporating variables associated with 30-day readmission in univariate logistic regression. Points were assigned to predictors in the multivariable model proportional to their odds ratios. RESULTS: Among 5,193 patients undergoing cardiac operations and surviving to discharge, the 30-day readmission rate was 10.3% (n = 537). The most common reasons for readmission were volume overload (24%; n = 131) and infection (21%; n = 113). The risk score incorporated 5 multivariable predictors and was out of 20 possible points. The predicted rate of 30-day readmission based on the training cohort ranged from 5.9% (score = 0) to 54.7% (score = 20). Patients were categorized as low (score = 0; readmission 5.7%), moderate (score 1-7; readmission 11.0%), and high risk (score >7; readmission 24.2%) (p < 0.001). Thirty-day readmission rates based on these score categories were similar in the validation cohort (low 6.4%, moderate 11.0%, high 17.4%; p < 0.001). There was a robust correlation between predicted rates of readmission in the training cohort based on the composite risk score and actual rates of readmission in the validation cohort (r = 0.95; p < 0.001). CONCLUSIONS: We developed and validated a risk score for readmission after cardiac operations that may have utility in targeting interventions and modifying risk factors in high-risk populations.

Outcomes in Patients Bridged With Univentricular and Biventricular Devices in the Modern Era of Heart Transplantation.

BACKGROUND: Biventricular support before orthotopic heart transplantation (OHT) has been shown to adversely affect short- and long-term outcomes, but the comparative effect of support type is largely unknown. This study determined the comparative effect of univentricular and biventricular support on survival in bridged patients after OHT. METHODS: The United Network of Organ Sharing database was queried for adult patients bridged to OHT with a univentricular (left ventricular assist device [LVAD]), biventricular (biventricular assist device [BiVAD]), or total artificial heart ([TAH]) device between 2004 and 2012. Unconditional and conditional survivals were compared with the Kaplan-Meier method. Cox proportional hazards regression models were constructed to determine the risk-adjusted influence of support type on death. RESULTS: Of the 4,177 patients identified, 3,457 (20.4%), 575 (3.4%), and 145 (0.9%) were bridged with an LVAD, BiVAD, and TAH, respectively. Unadjusted 30-day, 1-year, and 5-year estimated survival was greater in LVAD patients than in the BiVAD and TAH cohorts. After risk-adjustment, BiVAD and TAH were associated with an increased risk of death at all time points. Unadjusted and adjusted 5-year survival, conditional on 1-year survival, was worse, however, in only TAH patients. CONCLUSIONS: Patients with biventricular failure bridged to OHT with a TAH or BiVAD experience worse short- and long-term survival comparison with those with an LVAD. This difference is most likely due to an increase in early death and depends on the type of BiVAD device implanted.

Modified Model for End-Stage Liver Disease eXcluding INR (MELD-XI) Score Predicts Early Death After Pediatric Heart Transplantation.

BACKGROUND: We sought to determine the ability of the Model for End-Stage Liver Disease eXcluding INR (MELD-XI) to predict short-term and long-term outcomes in pediatric patients undergoing orthotopic heart transplant. METHODS: The United Network for Organ Sharing Database was queried for all pediatric patients (aged 1 to 18 years) undergoing orthotopic heart transplant from 2000 to 2012. The logarithmic relationship between the serum creatinine and bilirubin was used to calculate the MELD-XI score. Lowess smoothing plots were referenced, and a score threshold of 12.2 was used to stratify patients into low (75%) and high (25%) MELD-XI cohorts. Patient-specific characteristics, intraoperative variables, and postoperative outcomes were compared between the two cohorts. Differences in survival at 30 days, 1 year, and 5 years between the MELD-XI cohorts were estimated by the Kaplan-Meier method. Cox proportional hazards modeling was used to determine the risk-adjusted effect of a high MELD-XI score on death. RESULTS: After patients with missing MELD-XI scores were excluded, 2,939 patients met the inclusion criteria. Unconditional 30-day (93.1% vs 98.0%, p < 0.001), 1-year (85.9% vs 92.9%, p < 0.001), and 5-year (71.2% vs 79.5%, p < 0.001) survivals were significantly worse in the high-score cohort. However, 1-year survival excluding 90-day deaths (94.9% vs 95.8%, p = 0.29) and 5-year survival excluding 1-year deaths (82.8% vs 85.6%, p = 0.09) were statistically equivalent. When modeled as a categoric variable, a high MELD-XI score was an independent predictor of death at 30 days (hazard ratio, 2.86; 95% confidence interval, 1.84 to 4.45; p < 0.001), 1 year (hazard ratio, 1.88; 95% confidence interval, 1.42 to 2.48, p < 0.001), and 5 years (hazard ratio, 1.41; 95% confidence interval, 1.19 to 1.77; p < 0.001). For every 1-point increase in the MELD-XI score, mortality increased 11% at 30 days, 7% at 1 year, and 4% at 5 years (p < 0.001). The MELD-XI was not predictive of conditional mortality at 1 year or 5 years. CONCLUSIONS: The MELD-XI scoring system can be used in pediatric orthotopic heart transplant to identify patients at risk for poor outcomes. Because long-term survival is largely driven by early death, renal insufficiency and congestive hepatopathy should be optimized before transplant.

Nadir Oxygen Delivery on Bypass and Hypotension Increase Acute Kidney Injury Risk After Cardiac Operations.

BACKGROUND: Acute kidney injury (AKI) continues to complicate cardiac operations. We sought to determine whether nadir oxygen delivery (DO2) on cardiopulmonary bypass (CPB) was a risk factor for AKI while also accounting for other postoperative factors. METHODS: Using propensity scoring, we matched 85 patients who developed AKI after cardiac operations on CPB with 85 control patients who did not. We analyzed the following variables through midnight on postoperative day 1 (POD1): DO2, antibiotics, blood products and vasopressors (intraoperatively and postoperatively), and hemodynamic variables. RESULTS: Univariable analysis revealed AKI patients had lower nadir DO2 on CPB (208 vs 230 mL O2/min/m(2) body surface area, p = 0.03), lower intensive care unit admission blood pressure gradient across the kidney (mean arterial pressure minus central venous pressure; 60 vs 68 mm Hg; p < 0.001), a greater proportion of patients with mean arterial pressure of less than 60 mm Hg for more than 15 minutes in the postoperative period (70% vs 42%, p < 0.001), a greater chance of having a cardiac index of less than 2.2 (74% vs 49%, p = 0.02), and greater total vasopressor use through the end of POD1 (5.2 vs 2.3 mg, p = 0.002). On multivariable analysis, predictors of AKI were a DO2 on CPB of less than 225 mL O2/min/m(2) (odds ratio, 2.46; 95% confidence interval, 1.21 to 5.03; p = 0.01) and postoperative mean arterial pressure of less than 60 mm Hg for more than 15 minutes (odds ratio, 3.96; 95% confidence interval, 1.92 to 8.20; p < 0.001). An average postoperative pressor dose greater than 0.03 µg/kg/min did not reach significance (odds ratio, 1.98; 95% confidence interval, 0.95 to 4.11; p = 0.07). CONCLUSIONS: Postoperative hypotension on POD0 or POD1 and low DO2 on CPB both independently increase the AKI risk in cardiac surgical patients.

MELD-XI Score Predicts Early Mortality in Patients After Heart Transplantation.

BACKGROUND: The aim of this study was to determine the utility of the Model for End-Stage Liver Disease Excluding INR (MELD-XI) in predicting early outcomes (30 days and 1 year) and late outcomes (5 years) in patients after orthotopic heart transplantation (OHT). METHODS: The United Network for Organ Sharing database was queried for all adult patients (aged ≥ 18 years) undergoing OHT from 2000 to 2012. A MELD-XI was calculated and the population stratified into score quartiles. Early and late survivals were compared among the MELD-XI cohorts. Multivariable Cox proportional hazards models were constructed to determine the capacity of MELD-XI (when modeled both as a categoric and a continuous variable) to predict 30-day, 1-year, and 5-year mortality. Conditional models were also designed to determine the effect of early mortality on long-term survival. RESULTS: A total of 22,597 patients were included for analysis. The MELD-XI cutoff scores were established as follows: low (≤ 10.5), low-intermediate (10.6 to 12.6), intermediate-high (12.7 to 16.4), and high (>16.4). The high MELD-XI cohort experienced statistically worse 30-day, 1-year, and 5-year unconditional survivals when compared with patients with low scores (p < 0.001). Similarly, a high MELD-XI score was also predictive of early and late mortality (p < 0.001) after risk adjustment. There was, however, no difference in 5-year survival between the high score and low score cohorts after accounting for 1-year deaths. Subanalysis of patients bridged to transplant with a continuous-flow left ventricular assist device demonstrated similar findings. CONCLUSIONS: This is the first known study to examine the relationship between a high MELD-XI score and outcomes in patients after OHT. Patients with hepatic or renal dysfunction before OHT should be closely monitored and aggressively optimized as early mortality appears to drive long-term outcomes.

A Novel Risk Score to Predict Dysphagia After Cardiac Surgery Procedures.

BACKGROUND: Although the exact cause of dysphagia after cardiac operations is unknown, timely diagnosis is critical to avoid a devastating aspiration event. Accordingly, we sought to generate the risk of dysphagia in cardiac surgery (RODICS) score to identify patients at risk for its development after heart surgery. METHODS: All adult heart surgery patients at our institution between January 2011 and March 2012 were analyzed. A videofluoroscopic swallow study stratified patients into two groups based on the presence or absence of dysphagia. Covariates (p < 0.20) were included in a multivariable model to determine the strongest independent predictors of postoperative dysphagia. Based on the relative odds ratios of significant variables, the RODICS score was generated. Risk cohorts were then created based on easily applicable, whole-integer score cutoffs. RESULTS: During the study period, 115 of 1,314 patients (8.8%) undergoing heart surgery were diagnosed with clinically significant dysphagia. The 38-point RODICS score comprises seven patient-specific characteristics and perioperative factors. The low risk (less than 4), intermediate risk (5 to 9), and high risk (more than 9) cohorts had postoperative dysphagia rates of 3.0%, 6.8%, and 21.6%, respectively (p < 0.001). The intermediate-risk cohort (odds ratio 2.3, 95% confidence interval: 1.33 to 4.27, p = 0.01) and high-risk cohort (odds ratio 8.9, 95% confidence interval: 5.22 to 15.32, p < 0.001) were at significantly higher risk of dysphagia developing. The RODICS score demonstrated excellent discriminatory ability (area under the curve 0.75). CONCLUSIONS: The incidence and impact of dysphagia after open cardiac operations is significant. This novel scoring system could lead to prompt identification of patients at high risk for postoperative dysphagia and potentially minimize the complications of aspiration.

A novel risk score that incorporates recipient and donor variables to predict 1-year mortality in the current era of lung transplantation.

BACKGROUND: In this study we sought to construct a novel scoring system to pre-operatively stratify a patient's risk of 1-year mortality after lung transplantation (LTx) based on recipient- and donor-specific characteristics. METHODS: The UNOS database was queried for adult (≥18 years) patients undergoing LTx between May 1, 2005 and December 31, 2012. The population was randomly divided in a 4:1 fashion into derivation and validation cohorts. A multivariable logistic regression model for 1-year mortality was constructed within the derivation cohort. Points were then assigned to independent predictors (p < 0.05) based on relative odds ratios. Risk groups were established based on score ranges. RESULTS: During the study period, 9,185 patients underwent LTx and the 1-year mortality was 18.0% (n = 1,654). There was a similar distribution of variables between the derivation (n = 7,336) and validation (n = 1,849) cohorts. Of the 14 covariates included in the final model, 9 were ultimately allotted point values (maximum score = 70). The model exhibited good predictive strength (c = 0.65) in the derivation cohort and demonstrated a strong correlation between the observed and expected rates of 1-year mortality in the validation cohort (r = 0.87). The low-risk (score 0 to 11), intermediate-risk (score 12 to 21) and high-risk (score ≥22) groups had a 10.8%, 17.1% and 32.0% risk of mortality (p < 0.001), respectively. CONCLUSIONS: This is the first scoring system that incorporates both recipient- and donor-related factors to predict 1-year mortality after LTx. Its use could assist providers in the identification of patients at highest risk for poor post-transplant outcomes.

The Effect of Institutional Volume on Complications and Their Impact on Mortality After Pediatric Heart Transplantation.

BACKGROUND: This study evaluated the potential association of institutional volume with survival and mortality subsequent to major complications in a modern cohort of pediatric patients after orthotopic heart transplantation (OHT). METHODS: The United Network of Organ Sharing database was queried for pediatric patients (aged ≤18 years) undergoing OHT between 2000 and 2010. Institutional volume was defined as the average number of transplants completed annually during each institution's active period and was evaluated as categoric and as a continuous variable. Logistic regression models were used to determine the effect of institutional volumes on postoperative outcomes, which included renal failure, stroke, rejection, reoperation, infection, and a composite complication outcome. Cox modeling was used to analyze the risk-adjusted effect of institutional volume on 30-day, 1-year, and 5-year mortality. Kaplan-Meier estimates were used to compare differences in unconditional survival. RESULTS: A total of 3,562 patients (111 institutions) were included and stratified into low-volume (<6.5 transplants/year, 91 institutions), intermediate-volume (6.5 to 12.5 transplants/year, 12 institutions), and high-volume (>12.5 transplants/year, 8 institutions) tertiles. Unadjusted survival was significantly different at 30 days (p = 0.0087) in the low-volume tertile (94.2%; 95% confidence interval, 92.7% to 95.4%) compared with the high-volume tertile (96.8%; 95% confidence interval, 95.7% to 97.7%). No difference was observed at 1 or 5 years. Risk-adjusted Cox modeling demonstrated that low-volume institutions had an increased rate of mortality at 30 days (hazard ratio, 1.91; 95% confidence interval, 1.02 to 3.59; p = 0.044), but not at 1 or 5 years. High-volume institutions had lower incidences of postoperative complications than low-volume institutions (30.3% vs 38.4%, p < 0.001). Despite this difference in the rate of complications, survival in patients with a postoperative complication was similar across the volume tertiles. CONCLUSIONS: No association was observed between institutional volume and adjusted or unadjusted long-term survival. High-volume institutions have a significantly lower rate of postoperative complications after pediatric OHT. This association does not correlate with increased subsequent mortality in low-volume institutions. Given these findings, strategies integral to the allocation of allografts in adult transplantation, such as regionalization of care, may not be as relevant to pediatric OHT.

The influence of institutional volume on the incidence of complications and their effect on mortality after heart transplantation.

BACKGROUND: The aim of this study was to determine whether institutional volume influenced the effect of postoperative complications on short-term and long-term survival after orthotopic heart transplantation (OHT). METHODS: The United Network for Organ Sharing database was queried for adult patients (aged ≥18 years) undergoing OHT between 2000 and 2010. Average institutional volume was calculated during the study period and modeled as a categoric and as a continuous variable. Postoperative complications included rejection, dialysis dependence, infection, stroke, reoperation, and a composite event. Kaplan-Meier estimates and Cox regression modeling were performed for each complication to categorize the unadjusted and adjusted influence of institutional volume on survival. RESULTS: The analysis included 19,849 OHT recipients who were stratified into low-volume (≤14.5 per year), intermediate-volume (14.5-26.5 per year), and high-volume (>26.5 per year) tertiles. The overall incidences of postoperative complications were 10.2% for rejection, 7.8% for dialysis dependence, 12.0% for reoperation, 24.1% for infection, and 2.3% for stroke. Recipients in low-volume institutions experienced more complications after OHT than high-volume institutions (43.4% vs 36.2%; p < 0.001). Survival after the composite complication outcome was significantly worse at 90 days, 1 year, and 5 years in the low-volume cohort. After risk adjustment, low institutional volume (when modeled as a continuous and as a categoric variable) was also independently predictive of mortality at each time point. As expected, survival at 5 years in patients without a postoperative complication (81%; 95 confidence interval [CI], 80.0%-82.8%) was statistically greater (p < 0.001) than those with 1 (72.8%; 95% CI, 69.9%-75.5%), 2 (59.8%; 95% CI, 54.4%-64.8%), or 3 (39.9%; 95% CI, 31.6%-48.2%) complications. CONCLUSIONS: Postoperative complications after OHT have a greater incidence and effect on short-term and long-term survival at low-volume institutions. Accordingly, best practice guidelines established at high-volume institutions could better equip lower-volume hospitals to manage these events in hopes of optimizing transplant outcomes.