Preoperative Clinical Factors Are Important Determinants of the Inflammatory State Before and After Heart Surgery

Hospital variation in mortality after emergent bowel resections: The role of failure-to-rescue

BACKGROUND

Hospital variation in failure-to-rescue (FTR) rates has partially explained nationwide differences in mortality after elective surgeries. To examine the role of FTR among emergency general surgery, we compared nationwide risk-adjusted mortality, complications, and FTR rates after emergent bowel resections.

METHODS

We identified patients who underwent emergent small or large bowel resections in the 2010 to 2011 Nationwide Inpatient Sample using the American Association for the Surgery of Trauma criteria. We then calculated risk-adjusted mortality rates for each hospital using multivariable logistic regressions and postestimation, which adjusted for patient age, sex, race and ethnicity, payer status, comorbidities, and hospital clustering. After excluding hospitals with fewer than 10 resections per year, we ranked the remaining hospitals by their risk-adjusted mortality rates and divided them into five quintiles. We compared both risk-adjusted complication rates and FTR rates between the top (lowest mortality) and bottom (highest mortality) quintiles.

RESULTS

We identified 21,564 emergent bowel resections, weighted to 105,925 procedures nationwide. The bottom quintile of hospitals had an overall risk-adjusted mortality rate that was 10.9 times higher than that of the top quintile of hospitals (15.3% vs. 1.4%). While risk-adjusted complication rates were similarly high for both the bottom and the top quintiles of hospitals (22.5% vs. 15.7%), the risk-adjusted FTR rates were 10.8 times higher in the bottom quintile of hospitals relative to the top quintile of hospitals (33.4% vs. 3.1%). Using larger hospital volume thresholds yielded similar findings. Furthermore, large variations existed in complication-specific FTR rates (surgical site infection [6.6%] to myocardial infarction [29.4%]).

CONCLUSION

Nationwide hospital variation in risk-adjusted mortality rates exist after emergent bowel resections. As complication rates were similar across hospitals, the significantly higher FTR rates at higher-mortality hospitals may drive this variation in mortality. System-level initiatives addressing the management of postoperative complications may improve patient care and reduce variation in outcomes.

LEVEL OF EVIDENCE

Prognostic and epidemiological study, level IV.

The Pathophysiology of Cardiac Surgery-Associated Acute Kidney Injury (CSA-AKI)

Cardiac surgery associated acute kidney injury (CSA-AKI) is a significant clinical problem. Its pathogenesis is complex and multifactorial. It likely involved at least six major injury pathways: exogenous and endogenous toxins, metabolic factors, ischemia and reperfusion, neurohormonal activation, inflammation and oxidative stress. These mechanisms of injury are likely to be active at different times with different intensity and probably act synergistically. Because of such complexity and the small number of randomised controlled investigations in this field only limited recommendations can be made. Nonetheless, it appears important to avoid nephrotoxic drugs and desirable to avoid hyperglycemia in the peri-operative period. The duration of cardiopulmonary bypass should be limited whenever possible. Off-pump surgery, when indicated, may decrease the risk of AKI. Invasive hemodynamic monitoring focussed on attention to maintaining euvolemia, an adequate cardiac output and an adequate arterial blood pressure is desirable. Echocardiography may be useful in minimizing atheroembolic complications. The administration of N-acetylcysteine to protect the kidney from oxidative stress is not recommended. There is marked lack of randomised controlled trials in this field.

Cardiac surgery as a stressor and the response of the vulnerable older adult

In an aging population, recovery and restoration of function are critical to maintaining independence. Over the past 50years, there have been dramatic improvements made in cardiac surgery processes and outcomes that allow for procedures to be performed on an increasingly older population with the goal of improving function. Although improved function is possible, major surgical procedures are associated with substantial stress, which can severely impact outcomes. Past literature has identified that frail patients, who are vulnerable to the stress of surgery, are more likely to have postoperative major adverse cardiac and cerebrovascular events (OR 4.9, 95% confidence interval 1.6, 14.6). The objective of this manuscript is to examine preoperative frailty in biological, psychological, and social domains using cardiac surgery to induce stress. We systematically searched PubMed for keywords including "cardiac surgery, frailty, and aged" in addition to the biological, psychological, and social keywords. In the biological domain, we examine the association of physiological and physical vulnerabilities, as well as, the impact of comorbidities and inflammation on negative surgical outcomes. In the psychological domain, the impact of cognitive impairment, depression, and anxiety as vulnerabilities were examined. In the social domain, social structure, coping, disparities, and addiction as vulnerabilities are described. Importantly, there is substantial overlap in the domains of vulnerability. While frailty research has largely focused on discrete physical vulnerability criteria, a broader definition of frailty demonstrates that vulnerabilities in biological, psychological, and social domains can limit recovery after the stress of cardiac surgery. Identification of vulnerability in these domains can allow better understanding of the risks of cardiac surgery and tailoring of interventions to improve outcomes.

Genetic and clinical risk factors for fluid overload following open-heart surgery

BACKGROUND

Post-operative fluid overload following cardiac surgery is associated with increased morbidity and mortality. We hypothesised that genetic variations and pre-operative clinical factors predispose some patients to post-operative fluid overload.

METHODS

Perioperative variables were collected prospectively for 1026 consecutive adults undergoing open-heart surgery at St. Olavs University Hospital, Norway from 2008-2010. Post-operative fluid overload was defined as a post-operative fluid balance/kg ≥ the 90th percentile of the study population. Genotyping was performed for 31 single-nucleotide polymorphisms related to inflammatory/vascular responses or previously associated with complications following open-heart surgery. Data were analysed using logistic regression modelling, and the findings were internally validated by bootstrapping (n = 100).

RESULTS

Homozygous carriers of the common G allele of rs12917707 in the UMOD gene had a 2.2 times greater risk of post-operative fluid overload (P = 0.005) after adjustment for significant clinical variables (age, duration of cardiopulmonary bypass, and intraoperative red cell transfusion). A genetic risk score including 14 single-nucleotide polymorphisms was independently associated with post-operative fluid overload (P = 0.001). The number of risk alleles was linearly associated with the frequency of fluid overload (odds ratio per risk allele 1.153, 95 % confidence interval 1.056-1.258). Nagelkerke's R(2) increased with 7.5% to a total of 25% for the combined clinical and genetic model. Hemofiltration did not reduce the risk.

CONCLUSION

A common variation in the UMOD gene previously shown to be related to renal function was associated with increased risk of post-operative fluid overload following cardiac surgery. Our findings support a genetic susceptibility to disturbed fluid handling following cardiac surgery.

Association between statins and infections after coronary artery bypass grafting

BACKGROUND

We determined whether pre-operative statin therapy is associated with a decrease in the incidence of infections after coronary artery bypass grafting (CABG).

METHODS

A retrospective cohort study of 6253 patients undergoing isolated CABG, from the Texas Heart Institute Database from January 1, 2000 to December 31, 2010 (3869 receiving statins and 2384 not receiving statins) was conducted. Primary outcome was the development of any postoperative infection (composite of deep-sternal wound infection, leg harvest-site infection, pneumonia, or sepsis) after CABG. Secondary outcome was the association between pre-operative statin use and individual incidence of each aforementioned infection. Logistic regression analyses were performed.

RESULTS

Incidence of any postoperative infection in patients who received statins pre-operatively was 6.5% compared to 8.3% in patients who did not receive statins. Pre-operative statin therapy was associated with a significant reduction in the primary outcome (odds ratio (OR) 0.74, 95% confidence interval (CI) 0.60-0.90) in adjusted models. Among individual secondary outcomes, pre-operative statin therapy was associated with a reduced incidence of sternal wound infections (2.5% vs. 3.2%, OR 0.6, 95% CI 0.5-0.8) and leg harvest site infections (0.6% vs. 1.3%, OR 0.46, 95% CI 0.2-0.8). Pre-operative statin therapy was not associated with a reduced incidence of pneumonia or sepsis.

CONCLUSION

Pre-operative statin use is associated with a decrease in overall incidence of post-operative infections after CABG. We propose immunomodulatory effects of statins leading to a dampening of inflammatory cascade as the cause of our findings.

Preoperative statin is associated with decreased operative mortality in high risk coronary artery bypass patients

Background

Statins are widely prescribed to patients with atherosclerosis. A retrospective database analysis was used to examine the role of preoperative statin use in hospital mortality, for patients undergoing isolated coronary artery bypass grafting (CABG.)

Methods

The study population comprised 2377 patients who had isolated CABG at Allegheny General Hospital between 2000 and 2004. Mean age of the patients was 65 ± 11 years (range 27 to 92 years). 1594 (67%) were male, 5% had previous open heart procedures, and 4% had emergency surgery. 1004 patients (42%) were being treated with a statin at the time of admission. Univariate, bivariate (Chi², Fisher's Exact and Student's t-tests) and multivariate (stepwise linear regression) analyses were used to evaluate the association of statin use with mortality following CABG.

Results

Annual prevalence of preoperative statin use was similar over the study period and averaged 40%. Preoperative clinical risk assessment demonstrated a 2% risk of mortality in both the statin and non-statin groups. Operative mortality was 2.4% for all patients, 1.7% for statin users and 2.8% for non-statin users (p < 0.07). Using multivariate analysis, lack of statin use was found to be an independent predictor of mortality in high-risk patients (n = 245, 12.9% vs. 5.6%, p < 0.05).

Conclusions

Between 2000 and 2004 less than 50% of patients at this institution were receiving statins before admission for isolated CABG. A retrospective analysis of this cohort provides evidence that preoperative statin use is associated with lower operative mortality in high-risk patients.

No clear clinical benefit of using mini-invasive extracorporeal circulation in coronary artery bypass grafting in low-risk patients

Background: Current research is engaged in innovative technologies of extracorporeal circulation (ECC) systems in an effort to eliminate negative effetcs. Some studies have shown that, due to the complexity of technical settings of mini-ECC, they invoke a weaker immune response compared to classic ECC. The clinical benefits of using these systems have not been clearly proven yet. Methods: A group of 54 patients who were indicated for elective coronary surgery were randomised into two groups — Group A (patients operated on using classic ECC - open modification) and Group B (patients operated on using mini-ECC). The concentrations of IL-6, PMN elastase and MCP-1 in both groups were monitored per- and postoperatively, along with the postoperative clinical course. Results: The groups did not differ in the basic pre- and peroperative characteristics. We recorded a lower priming for mini-ECC (p < 0.001) and significantly reduced hemodilution during ECC. There were no differences in the clinical outcome in either group. Serum concentrations of monitored markers of immune reaction towards ECC showed higher activity during standard ECC. Conclusion: New technologies used in mini-systems have proven to lower activation of the immune system, which can be monitored using kinetics of proinflammatory mediators. In spite of these comparable laboratory results, we did not find differences in short-term clinical results when comparing both these groups of low-risk patients.