Low hematocrit levels: a risk factor for long-term outcomes in patients requiring prolonged mechanical ventilation after cardiovascular surgery. A retrospective study

While low-risk patients who undergo elective surgery can tolerate low hematocrit levels, the benefits of higher hematocrit levels might outweigh the risk of transfusion in high-risk patients. Therefore, this study aimed to evaluate the effects of perioperative hematocrit levels on mortality in patients requiring prolonged mechanical ventilation (PMV) after a cardiovascular surgery. This single-center retrospective cohort study was conducted on 172 patients who underwent cardiovascular surgery with cardiopulmonary bypass or off-pump coronary artery bypass grafting and required PMV for ≥72 hours in the intensive care unit (ICU) from 2008 to 2012 at the Yokohama City University Medical Center in Yokohama, Japan. Patients were classified according to hematocrit levels on ICU admission: high (≥30%) and low (<30%) groups. Of 172 patients, 86 were included to each of the low-hematocrit and high-hematocrit groups, with median hematocrit levels (first to third quartiles) of 27.4% (25.4%–28.7%) and 33.0% (31.3%–35.5%), respectively. The difference in survival rates was significant between the two groups using the log-rank test (HR 0.55, 95% CI 0.32 to 0.95, p=0.033). Cox regression analysis revealed that ≥30% increase in hematocrit levels on ICU admission was significantly associated with decreased long-term mortality (HR 0.40, 95% CI 0.20 to 0.80, p=0.0095). Lower hematocrit levels on ICU admission was a risk factor for increased long-term mortality, and higher hematocrit levels might outweigh the risk of transfusion in patients requiring PMV after a cardiovascular surgery.

Long-term risk of adverse outcomes after acute kidney injury: a systematic review and meta-analysis of cohort studies using consensus definitions of exposure

Reliable estimates of the long-term outcomes of acute kidney injury (AKI) are needed to inform clinical practice and guide allocation of health care resources. This systematic review and meta-analysis aimed to quantify the association between AKI and chronic kidney disease (CKD), end-stage kidney disease (ESKD), and death. Systematic searches were performed through EMBASE, MEDLINE, and grey literature sources to identify cohort studies in hospitalized adults that used standardized definitions for AKI, included a non-exposed comparator, and followed patients for at least 1 year. Risk of bias was assessed by the Newcastle-Ottawa Scale. Random effects meta-analyses were performed to pool risk estimates; subgroup, sensitivity, and meta-regression analyses were used to investigate heterogeneity. Of 4973 citations, 82 studies (comprising 2,017,437 participants) were eligible for inclusion. Common sources of bias included incomplete reporting of outcome data, missing biochemical values, and inadequate adjustment for confounders. Individuals with AKI were at increased risk of new or progressive CKD (HR 2.67, 95% CI 1.99-3.58; 17.76 versus 7.59 cases per 100 person-years), ESKD (HR 4.81, 95% CI 3.04-7.62; 0.47 versus 0.08 cases per 100 person-years), and death (HR 1.80, 95% CI 1.61-2.02; 13.19 versus 7.26 deaths per 100 person-years). A gradient of risk across increasing AKI stages was demonstrated for all outcomes. For mortality, the magnitude of risk was also modified by clinical setting, baseline kidney function, diabetes, and coronary heart disease. These findings establish the poor long-term outcomes of AKI while highlighting the importance of injury severity and clinical setting in the estimation of risk.

Kidney function is associated with short-term, mid-term and long-term clinical outcome after coronary angiography and intervention

BACKGROUND

Patients with kidney dysfunction are at risk of developing ischaemic heart disease. We investigated the association between eGFR and early-, mid- and long-term clinical outcome in patients undergoing coronary angiography and intervention.

METHODS

Retrospective study on 4968 patients with complete data on eGFR, 65% male and aged 32-80 years, admitted to Danderyd University Hospital, Stockholm, Sweden for coronary angiography and intervention from 2006 to 2008. Data were censored at 0-30 days, 31-365 days and 366-1825 days of follow-up.

RESULTS

Baseline eGFR was strongly associated with all-cause mortality at all three time periods studied with each 10 ml/min per 1.73 m² increase in eGFR being associated with a ∼30% (p < .001), 25% (p = .002) and 20% (p < .001) decrease in all-cause mortality at 30, 365 and 1825 days respectively. Each 10 ml/min per 1.73 m² increase in eGFR was associated with a ∼21% (p < .001) decrease in re-hospitalisation for MI at 365 days and a 6% decrease (p = .03) at day 30 for re-vascularisation.

CONCLUSIONS

We report a strong association between kidney function and all-cause mortality at both early, mid- and long-term follow-up in patients undergoing coronary angiography and intervention, with eGFR significantly associated with MI-related mortality after one month of follow-up. Kidney function was also shown to be associated with risk for re-vascularisation at one month, indicating mostly procedural-related risk and with new MI at mid-term follow-up. Further research is warranted to explore the mechanisms linking kidney function and cardiovascular disease to improve both the short- and long-term care of these patients.

Years of Life Lost After Complications of Coronary Artery Bypass Operations

BACKGROUND

We currently have an incomplete understanding of which postoperative complications after coronary artery bypass grafting (CABG) are associated with long-term death. The purpose of this study was to find the associations between complications and attributable death.

METHODS

Prospectively collected data on patient characteristics, risk factors, and complications of patients undergoing isolated CABG with 20-year follow-up were analyzed with a Cox regression model to calculate the overall hazard of dying associated with each postoperative complication. An individual's age and hazard of dying from each complication were then used to calculate years of life lost to each complication.

RESULTS

The postoperative mortality rate was 0.79% (69 of 8,773) at 30 days, 2.85% (250 of 8,773) at 180 days, and 6.38% (560 of 8,773) at 2 years. At a median follow-up of 9.8 years, 1,891 patients (21.6%) had died. Postoperative complications occurred in 3,438 patients (39.2%). Cardiac arrest (hazard ratio, 2.153), reoperation (hazard ratio, 1.679), and new dialysis (hazard ratio, 1.64) were the complications with the greatest hazard of death. After adjusting for complication incidence and patient age, cardiac arrest (703 years), reoperation (544 years), atrial fibrillation (470 years), and prolonged mechanical ventilation (371 years) were associated with the greatest number of years of life lost.

CONCLUSIONS

Acute cardiac arrest, reoperation for other cardiac reasons, new dialysis, atrial fibrillation, and prolonged mechanical ventilation are associated with the largest increase in attributable deaths. Prevention and treatment of these complications may improve mortality rates after cardiac operations.

Existence of renal dysfunction in diabetics undergoing coronary artery bypass

INTRODUCTION

The effect of diabetes mellitus on morbidity and mortality in patients undergoing coronary artery bypass grafting has remained uncertain, and conflicting conclusions have been reported in clinical trials. Evidence suggests that coronary artery bypass in patients with diabetes mellitus carries a higher risk of stroke, renal failure, perioperative complications, and sternal wound infection. This study evaluated the frequency of acute renal dysfunction after coronary artery bypass in diabetic patients, and the associated risk factors.

METHOD

This cross-sectional observational study included 135 patients with diabetes (111 males and 24 females with a mean age 51 years and a body mass index of 27.44 kg m(-2)), who underwent elective coronary artery bypass from March 2015 to October 2015. Data were collected prospectively in 2 tertiary care centers. Renal dysfunction was assessed by serum creatinine levels preoperatively and at 24 and 48 h postoperatively.

RESULTS

Fifteen percent of patients were found to have postoperative renal dysfunction. Univariate analysis revealed that patients with increased serum creatinine preoperatively were at greater risk of developing renal dysfunction after coronary artery bypass (p = 0.00). On multivariable binary logistic regression analysis, preoperative serum creatinine level was the only independent predictor of postoperative renal dysfunction; age, body mass index, dyslipidemia, hypertension, cardiopulmonary bypass time, and aortic crossclamp time showed no significant association.

CONCLUSION

Diabetic patients with increased serum creatinine preoperatively are at greater risk of kidney damage postoperatively; therefore, these patients should be monitored and treated critically in the perioperative period.

[Mortality from postoperative complications (failure to rescue) after cardiac surgery in a university hospital]

OBJECTIVE

This study analyses the rate of post-operative complications after cardiac surgery, the incidence of the failure to rescue (FR), and the relationship between complications and survival.

METHODS

The study included a total of 2,750 adult patients operated of cardiac surgery between January 2003 and December 2009. An analysis was made of 9 post-operative complications. Multiple logistic regression analysis was used to find independent variables associated with any of the selected complications. Survival was analysed with Kaplan-Meyer survival estimates. A risk-adjusted Cox proportional regression model was used to find out which complications were associated with mid-term survival.

RESULTS

Hospital mortality rate was 1.4% (95% CI: 1.0%-1.9%). Postoperative complications rate was 38.5% (36.7%-40.4%), and FR 3.6% (2.5%-4.9%). Urgent surgery (OR = 2.03; 1.52-2.72), chronic renal failure (OR = 1.50, 95%.CI: 1.25-1.80), and age ≥70 years (OR = 1.42; 1.20-1.68) were the variables that showed the highest strength of association with the selected complications. Survival at 5 years in the group of patients without complications was 93%, and in the group of patients with complications it was 83% (P<.0001). Postoperative complications associated with mid-term survival were pneumonia (HR = 2.6, 95% CI; 1.27-5.50), acute myocardial infarction (HR = 1.9; 1.10-2.30), and acute renal failure (HR = 1.7; 1.30-2.26).

CONCLUSIONS

The incidence of complications after cardiac surgery is around 40%, and was associated with an increase in hospital mortality, although FR was very low (3.6%; 95% CI: 2.5-4.9).

Hypoalbuminemia Within Two Postoperative Days Is an Independent Risk Factor for Acute Kidney Injury Following Living Donor Liver Transplantation: A Propensity Score Analysis of 998 Consecutive Patients

OBJECTIVE

Acute kidney injury is a known major complication of liver transplantation. Previous reports have shown that hypoalbuminemia is associated with an increased risk of acute kidney injury. However, little is known about the relationship between the early postoperative albumin level and acute kidney injury after living donor liver transplantation. The aim of this study was to identify the influence of the postoperative albumin level on acute kidney injury prevalence after living donor liver transplantation.

DESIGN

A retrospective analysis.

SETTING

A tertiary care university hospital.

PATIENTS

Nine hundred and ninety-eighty patients underwent living donor liver transplantation.

INTERVENTIONS

None.

MEASUREMENTS AND MAIN RESULTS

We divided the enrolled patients into two groups: group 1 included patients whose postoperative albumin level was less than 3.0 g/dL (n = 522), and group 2 included patients with an albumin level greater than or equal to 3.0 g/dL (n = 476). The prevalence of acute kidney injury, major adverse cardiac events, hospital stay, ICU stay, 30-day mortality, and overall mortality was analyzed using inverse probability of treatment weighting and propensity-score matching (n = 249 pairs) analysis. The prevalence of acute kidney injury was higher in group 1 defined by both Acute Kidney Injury Network (after adjusting for inverse probability of treatment weighting [n = 364; 69.7%] and propensity-score matching [n = 152; 61.0%]) and Risk, Injury, Failure, Loss, and End-stage kidney disease criteria (after adjusting for inverse probability of treatment weighting [n = 419; 80.3%] and propensity-score matching [n = 190; 76.3%]). The overall mortality was higher in group 1 after adjusting for inverse probability of treatment weighting (n = 61; 11.7%) and propensity-score matching (n = 23; 9.2%). The hospital (p < 0.001) and ICU (p = 0.006) stays were significantly prolonged in group 1. Acute kidney injury was associated with ICU stay by the Acute Kidney Injury Network criteria (p = 0.034), and overall mortality was correlated with acute kidney injury by the Risk, Injury, Failure, Loss, and End-stage kidney disease criteria (p = 0.014).

CONCLUSIONS

Early postoperative hypoalbuminemia is an independent risk factor for acute kidney injury, and postoperative acute kidney injury is related to postoperative ICU stay and overall mortality after living donor liver transplantation.

Recursive and non-linear logistic regression: moving on from the original EuroSCORE and EuroSCORE II methodologies

OBJECTIVES

EuroSCORE II, despite improving on the original EuroSCORE system, has not solved all the calibration and predictability issues. Recursive, non-linear and mixed recursive and non-linear regression analysis were assessed with regard to sensitivity, specificity and predictability of the original EuroSCORE and EuroSCORE II systems.

METHODS

The original logistic EuroSCORE, EuroSCORE II and recursive, non-linear and mixed recursive and non-linear regression analyses of these risk models were assessed via receiver operator characteristic curves (ROC) and Hosmer-Lemeshow statistic analysis with regard to the accuracy of predicting in-hospital mortality. Analysis was performed for isolated coronary artery bypass grafts (CABGs) (n = 2913), aortic valve replacement (AVR) (n = 814), mitral valve surgery (n = 340), combined AVR and CABG (n = 517), aortic (n = 350), miscellaneous cases (n = 642), and combinations of the above cases (n = 5576).

RESULTS

The original EuroSCORE had an ROC below 0.7 for isolated AVR and combined AVR and CABG. None of the methods described increased the ROC above 0.7. The EuroSCORE II risk model had an ROC below 0.7 for isolated AVR only. Recursive regression, non-linear regression, and mixed recursive and non-linear regression all increased the ROC above 0.7 for isolated AVR. The original EuroSCORE had a Hosmer-Lemeshow statistic that was above 0.05 for all patients and the subgroups analysed. All of the techniques markedly increased the Hosmer-Lemeshow statistic. The EuroSCORE II risk model had a Hosmer-Lemeshow statistic that was significant for all patients (P < 0.0001), and very close to significant for isolated CABG (P = 0.05) and for isolated AVR (P = 0.06). Non-linear regression failed to improve on the original Hosmer-Lemeshow statistic. The mixed recursive and non-linear regression using the EuroSCORE II risk model was the only model that produced an ROC of 0.7 or above for all patients and procedures and had a Hosmer-Lemeshow statistic that was highly non-significant.

CONCLUSIONS

The original EuroSCORE and the EuroSCORE II risk models do not have adequate ROC and Hosmer-Lemeshow statistics to allow accurate assessment of cardiac surgeons in the modern era. A mixed recursive and non-linear regression model utilizing the EuroSCORE II risk model improves both the ROC and Hosmer-Lemeshow statistics.

Coronary artery bypass grafting: Part 1--the evolution over the first 50 years

Surgical treatment for angina pectoris was first proposed in 1899. Decades of experimental surgery for coronary artery disease finally led to the introduction of coronary artery bypass grafting (CABG) in 1964. Now that we are approaching 50 years of CABG experience, it is appropriate to summarize the advancement of CABG into a procedure that is safe and efficient. This review provides a historical recapitulation of experimental surgery, the evolution of the surgical techniques and the utilization of CABG. Furthermore, data on contemporary clinical outcomes are discussed.

The effect of patient sex on survival in patients undergoing isolated coronary artery bypass surgery receiving a radial artery

OBJECTIVES

To determine whether patient sex makes a difference to in-hospital mortality and survival in patients undergoing isolated coronary artery bypass graft surgery (CABG) receiving a radial artery graft.

METHODS

Analysis of consecutive patients on a validated prospective cardiac surgery database was performed for patients undergoing isolated CABG. Uni- and multivariate analyses were performed for in-hospital mortality and long-term survival. A propensity analysis was also performed.

RESULTS

Overall mortality was 2.1% (n = 284) for all cases, n = 13 369. Median follow-up was 7.0 (interquartile range 4.1-10.1) years. Of the cases 28.2% of males (n = 384) and 29.7% of females (n = 764) had a radial artery utilized. Univariate analysis demonstrated that in-hospital mortality was significantly lower in male patients, P < 0.001, and radial artery use was associated with increased survival in males, P < 0.0001, but not in females, P = 0.82. In male patients, multivariate analysis failed to identify the radial artery as a risk factor for in-hospital death. The radial artery was identified as a significant prognostic factor, associated with improved long-term survival (hazard ratio [HR] 0.78, 95% confidence interval [CI] 0.69-0.88, P = 0.0001). Propensity analysis confirmed this finding (HR 0.76, 95% CI 0.67-0.86, P < 0.0001). In female patients, multivariate analysis failed to identify the radial artery as a significant factor determining in-hospital mortality or long-term survival. Propensity analysis confirmed these findings.

CONCLUSION

Males derive a significant survival advantage if they receive a radial artery graft when undergoing isolated CABG. The radial artery makes no difference to long-term survival in female patients. Radial artery use does not affect in-hospital mortality regardless of patient sex.

Virchow’s triad and intestinal ischemia post cardiac surgery

Background

Intestinal ischemia is associated with a very high mortality rate. We combined the principles of Virchow’s triad to produce preoperative and postoperative models for the development of intestinal ischemia.

Methods

A single institutional study was undertaken involving 18,325 consecutive patients from April 1997 to March 2012. Univariate and multivariate analysis was performed.

Results

Mortality was 87% in 91 patients who developed bowel ischemia. Multivariate logistic regression demonstrated that age, peripheral vascular disease, intraaortic balloon pump support, female sex, and preexisting renal failure were significant determinates of intestinal ischemia preoperatively. Logistic regression demonstrated that age, peripheral vascular disease, creatine kinase-MB level, reoperation for bleeding, and blood product usage were significant determinates of intestinal ischemia postoperatively.

Conclusions

Potentially remedial causes of intestinal ischemia include blood product usage, reoperation for bleeding, and creatine kinase-MB release. Age, female sex, peripheral vascular disease, intraaortic balloon pump usage, and preexisting renal failure are fixed risk factors. Despite the continuing trend of reduced blood product usage in the field of cardiac surgery, the increase in patients’ risk factors will mean that incidences of intestinal ischemia may increase in the future.

Long-term survival of non-smokers undergoing coronary artery bypass surgery

OBJECTIVES

We sought to investigate long-term survival of non-smokers undergoing coronary artery bypass surgery (CABG).

METHODS

A prospective database of consecutive patients was retrospectively analysed and cross correlated with the UK strategic tracking service to evaluate survival after primary CABG. Univariate, multivariate and a propensity analyses were performed.

RESULTS

We analysed 13 337 primary CABG procedures. Median follow-up was 7 years. Kaplan-Meier survival curves demonstrate that non-smokers have a significantly improved long-term survival compared with ex- and current smokers, P < 0.0001. Cox regression analysis identified smoking status, age, diabetes, ejection fraction (EF), body mass index, cerebrovascular disease, dialysis, left internal mammary artery (LIMA) non-usage, postoperative creatinine kinase muscle-brain isoenzyme (CKMB), radial artery usage, preoperative rhythm, forced vital capacity (FVC) and logistic EuroSCORE as significant risk factors determining long-term survival. Propensity matching resulted in 3575 non-smokers being matched 1:1, with ex-smokers. After matching, univariate analysis demonstrated the significantly worse long-term survival of ex-smokers compared with non-smokers, P < 0.0001. Cox regression analysis identified smoking status, age, postoperative CKMB, cerebrovascular disease, dialysis, diabetes, EF, FVC, LIMA non-usage, radial artery used, sinus rhythm and logistic EuroSCORE as significant risk factors determining long-term survival. Survival by smoking status plotted at the mean of the covariates, prepropensity matching, demonstrated that non-smokers had a significantly better long-term survival than ex-smokers, P < 0.0001; however, after propensity matching, non-smokers under 65 years of age had a significantly worse long-term survival compared with ex-smokers, P < 0.0001.

CONCLUSIONS

Non-smokers under the age of 65 years of age have significantly worse long-term survival compared with ex-smokers after risk factor adjustment. We speculate that this is because ex-smokers have had the causative factor, smoking, removed, but non-smokers have not.

Statins and long-term survival after isolated valve surgery: the importance of valve type, position and procedure

OBJECTIVES

To investigate whether valve position, type and procedure are important factors in determining the beneficial effects of statin therapy with regard to long-term survival in patients undergoing isolated single valve surgery.

METHODS

A prospective single-institution cardiac surgery database was analysed. Univariate, multivariate stepwise linear, logistic and Cox regression analysis and propensity matching were performed to identify if statins were associated with increased survival post-valve surgery.

RESULTS

Overall mortality was 3.4% (n = 172) for all cases, n = 5013. The median follow-up was 5.8 years. Kaplan-Meier survival analysis indicated that statin therapy was beneficial for all patients undergoing isolated valve surgery, n = 5013, P = 0.03 and isolated aortic valve surgery, n = 3220, P = 0.03, but not isolated mitral valve surgery n = 1793, P = 0.4. Cox regression analysis of the study cohort revealed that statin therapy was a significant factors determining long-term survival in the study cohort, postisolated aortic valve replacement and postisolated biological aortic valve replacement. Statins therapy was not associated with an increased long-term survival post-mitral valve replacement or repair. Propensity matching resulted in 1555 patients receiving statins being matched 1:1 with those not receiving statins. The results after propensity matching concurred with that of the Cox regression analyses, demonstrating that statin therapy was significantly associated with reduced in-hospital mortality, hospital length of stay and postoperative creatinine kinase, muscle-brain isoenzyme release.

CONCLUSIONS

Previous publications have not distinguished valve type, position and repair as possible factors influencing statin-therapy outcomes. Statin therapy is associated with increased long-term survival postaortic valve replacement with a biological valve only. Statin therapy had no survival benefit in patients undergoing mitral valve repair or a mechanical valve replacement. A randomized trial is necessary to confirm or refute our findings.

Preoperative red cell distribution width in patients undergoing pulmonary resections for non-small-cell lung cancer

OBJECTIVES

Red cell distribution width (RDW) has been identified as an independent risk factor with regard to prognosis in patients with cardiac disease. We sought to investigate the association of RDW in patients undergoing lung resections for non-small-cell lung cancer with respect to in-hospital morbidity, mortality and long-term survival.

METHODS

Analysis of consecutive patients on a validated prospective thoracic surgery database was performed for those undergoing potentially curative resections at a single institution. Univariate and multivariate analyses were performed for postoperative invasive and non-invasive ventilation, superficial wound infections, length of hospital stay, in-hospital mortality and long-term survival.

RESULTS

Overall mortality was 1.9% for all cases (n = 917). The median follow-up was 6.8 years. Univariate analysis demonstrated that RDW has a significant effect on hospital length of stay (P < 0.001), in-hospital mortality rates (P < 0.001), postoperative invasive and non-invasive ventilation (P < 0.001), superficial wound infections (P = 0.06) and long-term survival (P < 0.0001). Multivariate analysis revealed that RDW is a significant factor determining postoperative invasive and non-invasive ventilation, superficial wound infections, length of hospital stay, in-hospital mortality and long-term survival. Confounding factor analysis revealed that in the absence of anaemia, RDW was still a significant factor in the above analysis.

CONCLUSIONS

RDW is a significant factor after risk adjustment, determining in-hospital morbidity, mortality and long-term survival in patients post-potentially curative resections for non-small-cell lung cancer. Further work is needed to elucidate the exact mechanism of RDW impact on in-hospital morbidity, mortality and long-term survival. We speculate that subtle bone marrow dysfunction may be an issue.

Red cell distribution width and coronary artery bypass surgery

OBJECTIVES

The red cell distribution width (RDW) has been identified as an independent risk factor with regard to prognosis in patients with coronary artery disease with or without heart failure. We sought to investigate the role of RDW in patients undergoing isolated coronary artery bypass graft surgery (CABG).

METHODS

Analysis of consecutive patients on a validated prospective cardiac surgery database was performed for patients undergoing isolated CABG. Univariate and multivariate analysis was performed for in hospital mortality, long-term survival, length of hospital stay, length of intensive care unit stay and creatinine kinase muscle-brain (CKMB) release.

RESULTS

Overall mortality was 2.1% for all cases, N = 8615. Median follow up was 5.8 years. Univariate analysis demonstrated that the RDW has a significant effect on CKMB release, P = 0.001, in-hospital mortality, P < 0.0001, and long-term survival, P < 0.0001, but no significant effect on the ITU length of stay, P = 0.9, or hospital length of stay, P = 0.2. Multivariate analysis revealed that the RDW was a significant factor determining in-hospital mortality and long-term survival, but had no significant effect on CKMB release, ITU or hospital length of stay. Confounding factor analysis revealed that in the absence of anaemia, the RDW was still a significant factor determining in-hospital mortality and long-term survival.

CONCLUSIONS

The RDW is a significant factor determining in-hospital mortality and long-term survival in patients undergoing isolated CABG. The mechanism of association requires further study.