Risk factors for mortality in patients with mediastinitis after cardiac surgery

Development of a risk score to predict occurrence of deep sternal dehiscence requiring operative debridement

OBJECTIVE

Severe deep sternal wound (DSW) complications after cardiac surgery are a source of cost, morbidity, and mortality. Our objective was to develop and validate a clinical risk score for predicting risk of DSW requiring operative bone debridement, the most severe form of sternal dehiscence.

METHODS

A retrospective review was conducted of patients who underwent open cardiac surgery at a single institution between October 2007 and March 2019. Primary outcome was DSW requiring sternal bone debridement. Potential risk factors were screened using Least Absolute Shrinkage and Selection Operator (LASSO) and significant covariates were included in a logistic regression prediction model. Interval validation was performed using 10-fold cross-validation. A novel sternal wound dehiscence risk score was derived from the relative parameterization estimates.

RESULTS

One hundred thirty-four of 8403 patients (1.6%) were identified as having a DSW. Female sex (odds ratio [OR], 2.75; 95% CI, 2.58-2.93), body mass index (OR, 1.0946; 95% CI, 1.09-1.09), percent glycated hemoglobin (OR, 1.31; 95% CI, 1.28-1.33), peripheral vascular disease (OR, 2.38; 95% CI, 2.2005-2.5752), smoking (OR, 1.66; 95% CI, 1.53-1.79) and elevated creatinine level (OR, 1.20; 95% CI, 1.18-1.22) were independent predictors of DSW. Patients were categorized as minimal risk (0%-1%), low risk (2%-3%), intermediate risk (4%-7%), and high risk (9%-64.0%) on the basis of risk score.

CONCLUSIONS

This risk stratification model for DSW requiring operative debridement might provide individualized estimates of risk, and guide counseling and potential risk mitigation strategies.

The role of negative pressure wound therapy in the treatment of poststernotomy mediastinitis in Asians: A single-center, retrospective cohort study

Introduction

Poststernotomy mediastinitis (PSM) is a critical and life-threatening complication that can arise after cardiac surgery. The aim of this study was to evaluate and compare the outcomes of negative pressure wound therapy (NPWT) and conventional methods in the management of mediastinitis following heart surgery with a focus on Asian populations.

Methods

For this retrospective study, we included and evaluated a total of 34 patients who had undergone cardiac operations between January 2011 and September 2021 and developed PSM. The patients were divided into two groups, the NPWT group (n = 16, 47.1%) and the conventional treatment group (n = 18, 52.9%), and compared.

Results

The two groups showed no significant differences in terms of patient characteristics, PSM wound classification based on the El Oakley classification, and wound closure methods, but there was a higher incidence of diabetes mellitus in the NPWT group. With regard to mediastinal cultures, a higher prevalence of Staphylococcus epidermidis was observed in the NPWT group. However, we found no significant differences between the two groups regarding the time interval from diagnosis to wound closure, hospitalization duration, and re-exploration rate. Notably, the NPWT group exhibited a significantly higher in-hospital mortality rate than the conventional treatment group (p = 0.024).

Conclusions

Our findings suggest that the use of NPWT might not lead to improved medical outcomes for patients with PSM when compared to conventional treatment methods. As a result, it becomes imperative to exercise great care when choosing patients for NPWT. To obtain more definitive and conclusive results and identify the most appropriate cases for NPWT, conducting larger randomized clinical trials is necessary.

Risk factors for 1-year mortality after postoperative deep sternal wound infection

BACKGROUND AND AIMS

A deep sternal wound infection is a life-threatening complication after cardiac surgery. This study was conducted to describe the mortality associated with postoperative deep sternal wound infections after cardiac surgery and to find risk factors linked to increased mortality in 1 year follow-up.

MATERIAL AND METHODS

A total of 7973 open-heart surgeries were performed at Tampere University Hospital. Deep sternal wound infection patients were identified, their 1-year mortality status was recorded, and the related risk factors were analyzed.

RESULTS

We detected a total of 129 (1.6%) postoperative deep sternal wound infection patients. The 1-year mortality associated with a postoperative deep sternal wound infection was 20.2%. No preoperative or perioperative, statistically significant factors associated with increased 1-year mortality were found. A prolonged stay in an intensive care unit after surgery as well as stroke, delirium, wound secretion, and co-infection were associated with increased 1-year mortality.

CONCLUSION

The risk factors found for increased 1-year mortality were all postoperative. The quality of surgical treatment as well as precise postoperative care and evaluation remain the most important factors to decrease later mortality due to deep sternal wound infections.

Monitoring the Impact of Aggressive Glycemic Intervention during Critical Care after Cardiac Surgery with a Glycemic Expert System for Nurse-Implemented Euglycemia: The MAGIC GENIE Project

A novel, multi-dimensional protocol named GENIE has been in use for intensive insulin therapy (IIT, target glucose <140 mg/dL) in the surgical intensive care unit (SICU) after open heart surgery (OHS) at VA Pittsburgh since 2005. Despite concerns over increased mortality from IIT after the publication of the NICE-SUGAR Trial, it remains in use, with ongoing monitoring under the MAGIC GENIE Project showing that GENIE performance over 12 years (2005-2016) aligns with the current consensus that IIT with target blood glucose (BG) <140 mg/dL is advisable only if it does not provoke severe hypoglycemia (SH). Two studies have been conducted to monitor glucometrics and outcomes during GENIE use in the SICU. One compares GENIE (n = 382) with a traditional IIT protocol (FORMULA, n = 289) during four years of contemporaneous use (2005-2008). The other compares GENIE's impact overall (n = 1404) with a cohort of patients who maintained euglycemia after OHS (euglycemic no-insulin [ENo-I], n = 111) extending across 12 years (2005-2016). GENIE performed significantly better than FORMULA during contemporaneous use, maintaining lower time-averaged glucose, provoking less frequent, severe, prolonged, or repetitive hypoglycemia, and achieving 50% lower one-year mortality, with no deaths from mediastinitis (0 of 8 cases vs 4 of 9 on FORMULA). Those benefits were sustained over the subsequent eight years of exclusive use in OHS patients, with an overall one-year mortality rate (4.2%) equivalent to the ENo-I cohort (4.5%). The results of the MAGIC GENIE Project show that GENIE can maintain tight glycemic control without provoking SH in patients undergoing OHS, and may be associated with a durable survival benefit. The results, however, await confirmation in a randomized control trial.

Deep sternal wound infection - latissimus dorsi flap is a reliable option for reconstruction of the thoracic wall

Background

At present, data describing patients’ long-term outcomes, quality of life, and survival after deep sternal wound infection are rarely available.

The purpose of our study was to evaluate functional outcome and patient well-being after debridement and reconstruction of the sternal defect using a pedicled latissimus dorsi flap following deep sternal wound infection (DSWI).

Methods

This retrospective analysis reviewed 106 cases of DSWI after open-heart surgery treated between May 1, 2012, and May 31, 2015. The parameters of interest were demographic and medical data, including comorbidity and mortality. Follow-up consisted of physical examination of the patients using a specific shoulder assessment, including strength tests and measurements of pulmonary function.

Results

The population consisted of 69 (65%) male and 37 (35%) female patients. Their average age at the time of plastic surgery was 69 years (range: 35–85). The 30-day mortality was 20% (n = 21); after one-year, mortality was 47% (n = 50), and at follow-up, it was 54% (n = 58).

Heart surgery was elective in 45 cases (42%), urgent in 31 cases (29%) and for emergency reasons in 30 cases (28%). The preoperative European System for Cardiac Operative Risk Evaluation (EuroSCORE) averaged 16.3 (range: 0.88–76.76).

On the dynamometer assessment, a value of 181 Newton (N) (±97) could be achieved on the donor side, in contrast to 205 N (±91) on the contralateral side.

The inspiratory vital capacity of the lung was reduced to an average of 70.58% (range: 26–118), and the forced expiratory volume in 1 s was decreased to an average of 69.85% (range: 38.2–118).

Conclusions

Given that only small adverse effects in shoulder function, strength, and pulmonary function were observed, the latissimus dorsi flap appears to be a safe and reliable option for the reconstruction of the sternal region after DSWI.

Exceptional association of two species of bacteria causing mediastinitis: Haemophilus influenzae (H. influenzae) and Aggregatibacter aphrophilus (A. aphrophilus)

BACKGROUND

Post cardiac surgery mediastinitis is the major infectious complication, despite the development of surgical techniques and the application of strict preventive measures. The Haemophilus influenzae mediastinitis is very rare. The mediastinitis caused by the association between Haemophilus influenzae and Aggregatibacter aphrophilus has never been described to our knowledge.

CASE PRESENTATION

We report the case of an exceptional combination of Haemophilus influenzae and Aggregatibacter aphrophilus in a patient operated for single bypass which is complicated by mediastinitis the 10th day after the surgical act.

CONCLUSION

The conclusion to be drawn from this work is to think in unusual seeds in case of mediastinitis post cardiac surgery for the elaboration of recommendations for antibiotic prophylaxis.

Bacteriuria is not associated with surgical site infection in patients undergoing cardiovascular surgery

BACKGROUND

Despite absence of evidence, in practice, asymptomatic bacteriuria is perceived as a risk factor for surgical site infection (SSI) among patients with cardiac surgery. We aimed to identify whether an association exists between the preoperative presence of asymptomatic bacteriuria or urinary tract infection and SSI in patients undergoing cardiovascular surgery.

METHODS

This is an analytical study with a retrospective cohort of patients undergoing coronary revascularization or valve replacement surgery. We identified cases of bacteriuria, urinary tract infection, and cardiovascular SSI and adjusted the results according to exposure to antibiotics and known risk factors for SSI using a multivariate logistic regression analysis.

RESULTS

A total of 840 patients were included in the study, of whom 33 (3.9%) had asymptomatic bacteriuria and 13 (1.5%) had urinary tract infections. The incidence of SSI was 9.5% (80 patients), with 2.3% of cases having mediastinitis. In the multivariate analysis, asymptomatic bacteriuria (relative risk, 0.83; 95% confidence interval, 0.26-2.56; P = .74) and urinary tract infection (relative risk, 2.54; 95% confidence interval, 0.60-10.69; P = .20) were not risk factors for SSI. Traditional risk factors were found to increase the risk of SSI.

CONCLUSIONS

The presence of bacteriuria is not a risk factor for presenting SSI in cardiovascular surgery. Screening with urinalysis or urine culture would not be recommended for patients undergoing cardiac surgery.

Sternal Wound Infection after Cardiac Surgery: Management and Outcome

Background

Sternal Wound Infection (SWI) is a severe complication after cardiac surgery. Debridement associated with primary closure using Redon drains (RD) is an effective treatment, but data on RD management and antibiotic treatment are scarce.

Methods

We performed a single-center analysis of consecutive patients who were re-operated for SWI between 01/2009 and 12/2012. All patients underwent a closed drainage with RD (CDRD). Patients with endocarditis or those who died within the first 45 days were excluded from management analysis. RD fluid was cultured twice weekly. Variables recorded were clinical and biological data at SWI diagnosis, severity of SWI based on criteria for mediastinitis as defined by the Centers for Disease Control (CDC), antibiotic therapy, RD management and patient’s outcome.

Results

160 patients developed SWI, 102 (64%) fulfilled CDC criteria (CDC+) and 58 (36%) did not (CDC- SWI). Initial antibiotic treatment and surgical management were similar in CDC+ and CDC- SWI. Patients with CDC+ SWI had a longer duration of antibiotic therapy and a mortality rate of 17% as compared to 3% in patients with CDC- SWI (p = 0.025). Rates of superinfection (10% and 9%) and need for second reoperation (12% and 17%) were similar. Failure (death or need for another reoperation) was associated with female gender, higher EuroScore for prediction of operative mortality, and stay in the ICU.

Conclusion

In patients with SWI, initial one-stage surgical debridement with CDRD is associated with favorable outcomes. CDC+ and CDC- SWI received essentially the same management, but CDC+ SWI has a more severe outcome.

Methicillin-resistant Staphylococcus aureus infection: an independent risk factor for mortality in patients with poststernotomy mediastinitis

OBJECTIVE

The mortality rate of patients with poststernotomy mediastinitis remains very high. The aim of this study was to identify the risk factors associated with mortality in these patients.

SUBJECTS AND METHODS

Surveillance of sternal surgical-site infections including mediastinitis was carried out for adult patients undergoing a sternotomy between 2004 and 2012. Criteria from the US Centers for Disease Control and Prevention were used to make the diagnosis. All data on patients with a diagnosis of mediastinitis who were included in the study and on mortality risk factors were obtained from the hospital database and then analyzed using SPPS 16.0 for Windows.

RESULTS

Of the 19,767 patients undergoing open heart surgery, 117 (0.39%) had poststernotomy mediastinitis; 32% of these 117 died. The independent risk factors for mortality were methicillin-resistant Staphylococcus aureus (MRSA) [odds ratio (OR) 12.11 and 95% confidence interval (CI) 3.15-46.47], intensive-care unit stays >48 h after the first operation (OR 11.21 and 95% CI 3.24-38.84) and surgery that included valve replacement (OR 6.2 and 95% CI 1.44-27.13). The mortality rate decreased significantly, dropping from 38% (34/89) between 2004 and 2008 to 14% (4/28) between 2009 and 2012 (p = 0.018).

CONCLUSION

In this study, elimination of MRSA from the hospital setting decreased the rate of mortality in patients with poststernotomy mediastinitis.