Acute poststernotomy mediastinitis managed with debridement and closed-drainage aspiration: Factors associated with death in the intensive care unit

Deep Sternal Wound Infection Caused by Rhizopus Species After Coronary Artery Bypass Graft

Deep sternal wound infection is a rare complication of cardiac surgery that is typically caused by skin resident flora, such as species of Staphylococcus and Streptococcus. Infections caused by fungi are less common and are generally caused by Candida species. Regardless of etiology, these infections are associated with significant morbidity and mortality. We present a case of postoperative mediastinitis that occurred following a 5-vessel coronary artery bypass graft and was caused by a filamentous fungus of the Rhizopus genus. The patient was treated with serial debridement, liposomal amphotericin B, and isavuconazonium and was discharged from the hospital in stable condition. Fungal mediastinitis is a rare entity, and clinicians must maintain a high level of suspicion to make the diagnosis. A fungal cause of postoperative mediastinitis should be considered in patients with negative bacterial cultures, uncontrolled diabetes, or current immunosuppression or those who present weeks after surgery with a subacute onset of symptoms.

Review on risk factors, classification, and treatment of sternal wound infection

Sternal wound infection (SWI) is the most common complication of the median sternal incision. The treatment time is long, and the reconstruction is difficult, which causes challenges for surgeons. Plastic surgeons were often involved too late in such clinical scenarios when previous empirical treatments failed and the wound damage was relatively serious. Accurate diagnosis and risk factors against sternal wound infection need to be in focus. Classification of different types of sternotomy complications post-cardiac surgery is important for specific categorization and management. Not familiar with this kind of special and complex wound, objectively increasing the difficulty of wound reconstruction. The purpose of this comprehensive review is to review the literature, introduce various SWI risk factors related to wound nonunion, various classification characteristics, advantages and disadvantages of various wound reconstruction strategies, to help clinicians understand the pathophysiological characteristics of the disease and choose a better treatment method.

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.

Comparison of median sternotomy closure-related complication rates using orthopedic wire or suture in dogs: A multi-institutional observational treatment effect analysis

Objective

To determine and compare median sternotomy (MS) closure‐related complication rates using orthopedic wire or suture in dogs.

Study design

Multi‐institutional, retrospective observational study with treatment effect analysis.

Animals

331 client‐owned dogs, of which 68 were excluded.

Methods

Medical records of dogs with MS were examined across nine referral centers (2004–2020). Signalment, weight, clinical presentation, surgical details, complications, and outcomes were recorded. Follow‐up was performed using patient records and email/telephone contact. Descriptive statistics, treatment effect analysis and logistic regression were performed.

Results

Median sternotomy closure was performed with wire in 115 dogs and suture in 148. Thirty‐seven dogs experienced closure‐related complications (14.1%), 20 in the wire group and 17 in the suture group. Twenty‐three were listed as mild, four as moderate and 10 as severe. Treatment effect analysis showed a mean of 2.3% reduction in closure‐related complications associated with using suture versus wire (95% CI: −9.1% to +4.5%). In multivariable logistic regression, the only factor associated with increased risk of closure‐related complications was dog size (p = .01). This effect was not modified by the type of closure used (interaction term: OR = 0.99 [95% CI: 0.96/1.01]).

Conclusion

The incidence of closure‐related complication after MS was low compared to previous reports. The likelihood of developing a closure‐related complication was equivalent between sutures and wires, independent of dog size, despite a higher proportion of complications seen in larger dogs (≥20 kg).

Clinical significance

Use of either orthopedic wire or suture appear to be an appropriate closure method for sternotomy in dogs of any size.

Evaluation of a carbapenem antimicrobial stewardship program and clinical outcomes in a Japanese hospital

INTRODUCTION

Microorganisms can evolve and become resistant to antimicrobials, and this is known as antimicrobial resistance (AMR). Inappropriate use of antibiotics contributes to AMR, and antimicrobial stewardship programs have been developed to mitigate AMR. The Appropriate Use of Carbapenems Program was implemented in March 2019 in a university hospital and its effect was evaluated.

METHODS

We conducted a prospective audit and feedback on carbapenems at the time of prescription daily. Additionally, we compared a monthly survey of the total days of therapy (DOTs) per 1000 patient-days for carbapenems, piperacillin/tazobactam, and fluoroquinolones. The susceptibility of Pseudomonas aeruginosa to meropenem, piperacillin/tazobactam, and levofloxacin was tested before (January 2018 to February 2019) and after (March 2019 to December 2020) the intervention.

RESULTS

The monthly median DOTs of carbapenem usage decreased after the intervention; carbapenem use immediately declined during the intervention period. The monthly median DOTs of piperacillin/tazobactam and fluoroquinolones also decreased and continued to decline significantly after the intervention. Susceptibility of P. aeruginosa to meropenem, piperacillin/tazobactam, and levofloxacin did not change significantly during the study.

CONCLUSION

The implementation of the Appropriate Use of Carbapenems Program was effective in reducing the use of broad-spectrum antibiotics and maintaining the antibiotic susceptibility of P. aeruginosa.

Postoperative mediastinitis after cardiac surgery caused by Mycoplasma hominis: a case report

BACKGROUND

Mycoplasma hominis is a human commensal bacterium of the urogenital tract, and extragenital infection caused by M. hominis has rarely been reported. The identification of M. hominis is challenging, and surgeons are generally not aware that this bacteria can cause postoperative infection. Here, we report a rare case of postoperative mediastinitis caused by M. hominis after cardiac surgery in an immunocompetent patient.

CASE PRESENTATION

A 54-year-old man presented with pain and purulent discharge from the wound after aortic valve replacement and patent foramen ovale closure. However, Gram staining and culture of bacteria from the purulent discharge was negative, and empiric sulbactam/ampicillin therapy was not effective. This patient developed mediastinitis and rupture of a pseudoaneurysm of the ascending aorta caused by mediastinitis, and re-operation was performed. Then, postoperative mediastinitis caused by M. hominis or Ureaplasma species was suspected and bacterial cultures targeting these pathogens were performed. M. hominis was identified from abscess and tissue obtained from the surgical site and urine. A final diagnosis of postoperative mediastinitis caused by M. hominis was determined. The patient was initially treated with levofloxacin and then with minocycline for 3 weeks. The patient's clinical condition improved; the patient was transferred to another hospital.

CONCLUSION

The role of M. hominis as a cause of postoperative infection might be underestimated in cardiac surgery. M. hominis should be considered when culture-negative purulent discharge is observed or there is no response to standard empiric treatment of postoperative infections.

Characteristics and outcomes of patients with postoperative Candida versus bacterial mediastinitis: a case-matched comparative study

OBJECTIVES

Postoperative mediastinitis, a feared complication after cardiac surgery, is associated with high mortality, especially of critically ill patients. Candida species infections are rare and severe, with poorly known outcomes. We conducted a case-control study to describe the characteristics, management and outcomes of patients with postoperative Candida mediastinitis.

METHODS

This French, monocentre, retrospective study included all patients with postoperative Candida mediastinitis (January 2003-February 2020) requiring intensive care unit admission. Candida mediastinitis patients (henceforth cases) were matched 1:1 with postoperative bacterial mediastinitis (henceforth control), based on 3 factors during mediastinitis management: age >40 years, cardiac transplantation and invasive circulatory device used. The primary end point was the probability of survival within 1 year after intensive care unit (ICU) admission.

RESULTS

Forty cases were matched to 40 controls. The global male/female ratio was 2.1, with mean age at admission 47.9 ± 13.8 years. Candida species were: 67.5% albicans, 17.5% glabrata, 15% parapsilosis, 5.0% tropicalis, 2.5% krusei and 2.5% lusitaniae. The median duration of mechanical ventilation was 23, 68.8% of patients received renal replacement therapy and 62.5% extracorporeal membrane oxygenation support. The probability of survival within the first year after ICU admission was 40 ± 5.5% and was significantly lower for cases than for controls (43 ± 8% vs 80 ± 6.3%, respectively; Log-rank test: P < 0.0001). The multivariable Cox proportional hazards model retained only renal replacement therapy [hazard ratio (HR) 3.7, 95% confidence interval (CI) 1.1-13.1; P = 0.04] and Candida mediastinitis (HR 2.4, 95% CI 1.1-5.6; P = 0.04) as independently associated with 1-year mortality.

CONCLUSIONS

Candida mediastinitis is a serious event after cardiac surgery and independently associated with 1-year mortality. Further studies are needed to determine whether deaths are directly attributable to Candida mediastinitis.

Pancreatic enzymatic mediastinitis followed by total gastrectomy with splenectomy: report of two cases

BACKGROUND

Acute mediastinitis is a rare disease that rapidly progresses with a high mortality rate. Its most common cause is direct injury of the mediastinum, including iatrogenic causes such as cardiac surgery or upper endoscopy. Enzymatic mediastinitis is a rare complication of a pancreatic fistula caused by the inflammatory digestion of the parietal peritoneum spreading to the mediastinum. Here, we present two cases of enzymatic mediastinitis caused by total gastrectomy with splenectomy. One of them was successfully treated and cured after early diagnosis and transabdominal drainage.

CASE PRESENTATION

Case 1 was that of a 60-year-old man (body mass index [BMI] 27) with a medical history of diabetes and hypertension who was diagnosed with advanced gastric cancer in the upper body of the stomach. A total gastrectomy with splenectomy was performed. The patient experienced acute respiratory failure 24 h after surgery. Pulmonary embolism was suspected, so a computed tomography (CT) scan was performed; however, no relevant causes were found. Although he was immediately intubated and treated with catecholamine, he died in the intensive care unit (ICU) 40 h after surgery. Post-mortem findings revealed retroperitonitis caused by a pancreatic fistula spreading towards the mediastinum, causing severe mediastinitis; a review of the CT scan revealed pneumomediastinum. We concluded that the cause of death was enzymatic mediastinitis due to post-gastrectomy pancreatic fistula. Case 2 involved a 61-year-old man (BMI 25) with a medical history of appendicitis who was diagnosed with advanced gastric cancer at the gastric angle between the lesser curvature and the pylorus, spreading to the upper body of the stomach. A total gastrectomy with splenectomy was also performed. The patient had a high fever 3 days after the surgery, and a CT scan revealed pneumomediastinum, indicating mediastinitis. As the inflammation was below the bronchial bifurcation, we chose a transabdominal approach for drainage. The patient was successfully treated and discharged.

CONCLUSION

Acute mediastinitis caused by gastrectomy is rare. The acknowledgment of abdominal surgery as a cause of mediastinitis is important. In treating mediastinitis caused by abdominal surgery, transabdominal drainage may be a minimally invasive yet effective method if the inflammation is mainly located below the bifurcation of the trachea.

The First Case Report of Mediastinal Abscess Caused by Gemella bergeri

Most cases of mediastinal abscess occur as a postoperative complication of a thoracic surgical procedure or following trauma. The most common causative microorganism is Staphylococcus aureus, but it can be rarely caused by unusual microorganisms, such as Gemella species. These are relatively difficult-to-identify commensal microorganisms of the upper respiratory and gastrointestinal tracts and may cause several infections. A 66-year-old man was diagnosed with Gemella bergeri mediastinal abscess by the molecular detection of bacterial genes. He was successfully treated with penicillin antibiotic for eight weeks. To our knowledge, this is the first case report of mediastinal abscess caused by G. bergeri.

The Characteristics of Postoperative Mediastinitis During the Changing Phases of Cardiac Surgery

BACKGROUND

Mediastinitis is a serious complication of open heart surgery associated with high mortality, considerable health care costs, and prolonged hospital stay. We examined characteristics and incidence of mediastinitis during 29 years when indications and patient material have been in a process of change.

METHODS

This was a retrospective population-based study comprising all mediastinitis patients more than 16 years of age after open heart surgery between 1990 and 2018 from a population of 1.7 million. Patient records of 50 mediastinitis patients from 2004 to 2014 were reviewed and compared with 120 patients from 1990 to 1999.

RESULTS

Annual mediastinitis rate varied 0% to 1.5% with a decreasing trend-from a level exceeding 1.2% to approximately 0.3%-over the study period. In 2004 to 2014 patients with mediastinitis were older, more often smokers, and more often had diabetes mellitus and renal insufficiency than in 1990 to 1999. No difference in length of hospital treatment, antibiotic prophylaxis or treatment, intensive care unit treatment, or mortality was observed between 1990 to 1999 and 2004 to 2014. Coronary artery bypass graft surgery became less common and valve replacement and hybrid operations more common among operations leading to mediastinitis. Staphylococcus aureus increased (from 25% to 56%, p = .005) whereas coagulase-negative staphylococci (46% to 23%, P < .001) and gram-negative bacteria (18% to 12%, P = .033) decreased as causative agents. Surgery for mediastinitis remained similar except introduction of vacuum-assisted closure treatment.

CONCLUSIONS

The rate of mediastinitis decreased during these 29 years. No difference in 30-day mortality in mediastinitis was seen: 0.9% in 1990 to 1999 and 2% in 2004 to 2014.

Emerging trends in mediastinitis: National Veterans Health Administration experience with methicillin-resistant Staphylococcus aureus prevention

OBJECTIVES

Perioperative bacterial decolonization and prophylactic antibiotic therapy at the Veterans Affairs Health Care System have changed over the past decade. Our objectives were to identify associated changes in the microbiology of mediastinitis and to perform a contemporary survival analysis in patients with mediastinitis after isolated coronary artery bypass grafting procedure.

METHODS

From January 2006 to December 2015, 45,323 consecutive patients underwent coronary artery bypass grafting at 83 medical centers. The Veterans Affairs Health Care System nationwide administrative database was queried to identify patients with postoperative mediastinitis and obtain patient-level data. Simple descriptive statistics and multivariable logistic regression were used to analyze microbiologic data and identify risk factors for infection. Poisson regression was used to determine yearly incidence estimates. Cox proportional hazard model identified predictors of long-term survival from date of operation.

RESULTS

During the study period, 348 patients (0.78%) developed postoperative mediastinitis-with a stable rate of incidence (Cochrane-Armitage test, P = .69). Of patients with microbiologic data, 75.5% of infections (n = 188) were caused by gram-positive and 24.5% (n = 61) gram-negative organisms. The incidence of methicillin-resistant Staphylococcus aureus mediastinitis decreased during the study period (Cochrane-Armitage test, P = .013). Gram-negative mediastinitis occurred earlier than gram-positive mediastinitis (median, 15.0 vs 25.0 days; P < .0001). Patients with mediastinitis did not have increased 30-day mortality (2.0% vs 1.9%; P = .9), but had worse long-term survival compared with uninfected patients (P < .0001).

CONCLUSIONS

The incidence of methicillin-resistant S aureus mediastinitis has decreased over the past decade. Gram-negative bacteria are responsible for 1 in 4 cases of mediastinitis and infection is diagnosed earlier in the postoperative period than gram-positive mediastinitis. These findings highlight the need for efforts to prevent gram-negative and methicillin-susceptible S aureus mediastinitis.

Vacuum-Assisted Closure for the Treatment of Deep Sternal Wound Infection After Pediatric Cardiac Surgery

OBJECTIVES

Vacuum-assisted closure is being increasingly used to treat deep sternal wound infection following cardiac surgery, but most of the data refer to adults. This study investigated the safety and efficacy of vacuum-assisted closure in pediatric patients.

DESIGN

Retrospective file review.

SETTING

Tertiary pediatric medical center.

PATIENTS

All children with deep sternal wound infection treated with vacuum-assisted closure in 2003-2016.

INTERVENTIONS

Epidemiological, clinical, and microbiological data were collected from the medical records.

MEASUREMENTS AND MAIN RESULTS

The cohort included 50 patients (0.9% of cardiac patients operated during the study period) of median age 6.5 months (interquartile range, 2-12.75 mo; range, 1 wk to 14 yr) and median weight 5.1 kg (interquartile range, 4-9.75 kg). The most frequent heart defects were tetralogy of Fallot (22%) and ventricular septal defect (20%); 38% of patients had cyanotic heart disease. Deep sternal wound infections appeared a median of 10 days postoperatively (interquartile range, 7-14 d; range 3-100 d). Vacuum-assisted closure was applied a median of 13 days postoperatively (interquartile range, 10-18.5 d; range, 5-103 d) for a median duration of 10 days (interquartile range, 7-13.25 d; range, 1-21 d). Wound cultures were positive in 48 patients (96%); most isolates were Gram-positive (76%). The main bacterial pathogen was methicillin-susceptible Staphylococcus aureus (61%). Most patients were treated with cloxacillin for a median of 38 days (interquartile range, 28-42 d; range, 9-189 d). There were no statistically significant differences in clinical or treatment characteristics between bacteremic (56%) and nonbacteremic patients. Compared with older patients, infants less than 3 months old (36%) had a significantly longer hospitalization time (41 vs 25 d; p = 0.001) and higher Society of Thoracic Surgeons-European Association for Cardio-Thoracic Surgery Mortality Category (3 vs 2; p = 0.003). All cases except one (contact dermatitis) were uneventful. In 10 patients, wounds were closed surgically after vacuum-assisted closure. Two patients required a pectoralis flap, both treated before 2005. One of the two deaths was infection-related.

CONCLUSIONS

Vacuum-assisted closure is a feasible treatment option of deep sternal wound infection after pediatric cardiac surgery and was not associated with independent morbidity.

Efficacy of new multimodal preventive measures for post-operative deep sternal wound infection

BACKGROUND

Deep sternal wound infection (DSWI) is a critical complication of cardiovascular surgery. This study aimed to confirm the efficacy of new, multimodal preventive measures for post-operative DSWI.

METHODS

From January 2008 to December 2012, 1240 patients underwent cardiovascular surgery via median sternotomy at our hospital. The patients were divided into two groups according to the period in which surgery was performed: those treated before and those treated after January 2011, which was when we implemented the new preventive measures against DSWI. The preventive measures included routine use of an off-pump technique in coronary artery bypass grafting, higher body temperature of pump cases, screening and pre-operative eradication of nasal methicillin-resistant Staphylococcus aureus colonization, and use of a microbial sealant. We compared the incidence of DSWI between the two time periods. Univariate and multivariate analyses were also performed for the entire period to identify DSWI risk factors.

RESULTS

Only 1 case (0.2%) of DSWI was noted among 554 patients in the latter period while 25 patients (3.6%) experienced DSWI among the 686 patients in the earlier period (p < 0.0001). The risk factors for DSWI were body mass index (BMI) ≥ 25 kg/m² and operation time ≥ 8 h.

CONCLUSIONS

We observed a marked decrease in the incidence of DSWI after the implementation of multimodal preventive measures. The risk factors for DSWI were BMI ≥ 25 kg/m² and operation time ≥ 8 h.

A review of eleven cases of tuberculosis presenting as sternal wound abscess after open heart surgery

BACKGROUND

Sternal wound infection with Mycobacterium tuberculosis is an uncommon yet highly challenging disease that can be quite insidious with various presentations. We hereby provide a review of 10 cases in current literature and describe an additional case which illustrates the difficulties associated with diagnosis.

METHODS

We used PubMed and Google search engine to search the literature for all published papers reporting on cases of sternal M. tuberculosis infections post open-heart surgeries.

RESULTS

A total of 11 cases were presented, including a case of our own. The majority were males and were exposed to endemic areas. The average age was 59.6 ± 15.5 years. Coronary artery bypass surgery accounted for 73% of procedures and the average time to symptoms onset was 12.2 ± 16.6 months. Diabetes was the most reported non-cardiac comorbidity. Presenting symptoms varied and only 5 patients had other organs involved. Blood tests and radiographic studies were neither sensitive nor specific. M. tuberculosis culture on debrided tissues was the most sensitive test but often forgotten initially. Diagnostic delay was seen in almost all cases, often leading to unnecessary courses of antibiotics and aggressive surgical interventions. Finally, all patients responded well to anti-tuberculosis treatment, with reported treatment duration ranging from 9 to 12 months.

CONCLUSION

M. tuberculosis infection of the sternum should be suspected in late-onset sternal wound infections post open-heart surgery especially when the course is chronic and indolent.

Sepsis and Challenging Infections in the Immunosuppressed Patient in the Intensive Care Unit

In 2017, most intensive care units (ICUs) worldwide are admitting a growing population of immunosuppressed patients. The most common causes of pre-ICU immunosuppression are solid organ transplantation, hematopoietic stem cell transplantation, and infection due to human immunodeficiency virus. In this article, the authors review the most frequent infections that cause critical care illness in each of these 3 immunosuppressed patient populations.

Effect of negative pressure wound therapy followed by tissue flaps for deep sternal wound infection after cardiovascular surgery: propensity score matching analysis

OBJECTIVES

Deep sternal wound infection (DSWI) after cardiovascular surgery via median sternotomy remains a severe complication associated with a drastic decrease in the quality of life. We assessed the risk factors for in-hospital death caused by DSWI and the available treatments for DSWI.

METHODS

Between January 1991 and August 2015, we retrospectively reviewed 73 patients (51 males and 22 females, mean age 67.5 ± 10.3 years) who developed DSWI after cardiovascular surgery via median sternotomy. Pathogenic bacteria mainly comprised methicillin-resistant Staphylococcus aureus (MRSA) (49.3%). Fifteen patients (20.5%) died in hospital with DSWI. Treatment of DSWI consisted of open daily irrigation (up to 2006) or negative pressure wound therapy (NPWT) (2007 onwards), followed by primary closure or reconstruction of tissue flaps. We assessed the risk factors for in-hospital mortality from DSWI by comparing data from the 15 patients who died and the 58 survivors using propensity score matching analysis of the treatments used for DSWI.

RESULTS

Univariate analysis identified age, use of intra-aortic balloon pumping, prolonged mechanical ventilation, tracheotomy, prolonged intensive care unit stay, postoperative low output syndrome, postoperative myocardial infarction, postoperative renal failure, postoperative use of haemodialysis, postoperative pneumonia, postoperative cerebral disorder, MRSA infection, NPWT and tissue flaps as being associated with in-hospital mortality (P < 0.05). Multivariate analysis identified NPWT (odds ratio, 0.062; 95% confidence interval, 0.004-0.897; P = 0.041) and tissue flaps (odds ratio, 0.022; 95% confidence interval, 0.000-0.960; P = 0.048) as independently associated with reduced in-hospital mortality after DSWI. On comparing 22 patients receiving NPWT with 22 not on NPWT using propensity score matching, patients on NPWT had significantly lower in-hospital mortality than those without NPWT (NPWT vs non-NPWT, 5 vs 36%, P = 0.021). In DSWI infected by MRSA, NPWT significantly reduced the in-hospital mortality caused by DSWI (NPWT vs non-NPWT, 0 vs 52%, P = 0.003).

CONCLUSIONS

NPWT and tissue flaps may be favourable factors associated with reduced in-hospital mortality attributable to DSWI. NPWT as a bridge therapy to tissue flaps may play a major role in treating DSWI and improve the prognosis for patients with MRSA-infected DSWI.

A retrospective study of deep sternal wound infections: clinical and microbiological characteristics, treatment, and risk factors for complications

Deep sternal wound infection (DSWI) is a feared complication following cardiac surgery. This study describes clinical, microbiological, and treatment outcomes of DSWI and determines risk factors for complications. Of 55 patients with DSWI, 66% were male and mean age was 68.2 years. Initial sternotomy was for coronary artery bypass graft in 49% of patients. Sternal debridement at mean 25.4±18.3 days showed monomicrobial (94%), mainly Gram-positive infection. Secondary sternal wound infection (SSWI) occurred in 31% of patients, was mostly polymicrobial (71%), and was predominantly due to Gram-negative bacilli. Risk factors for SSWI were at least 1 revision surgery (odds ratio [OR] 4.8 [95% confidence interval {CI} 1.0-22.4], P=0.047), sternal closure by muscle flap (OR 4.6 [1.3-16.8], P=0.02), delayed sternal closure (mean 27 versus 14 days, P=0.03), and use of vacuum-assisted closure device (100% versus 58%, P=0.008). Hospital stay was significantly longer in patients with SSWI (69 days versus 48 days, P=0.04).

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.

Diagnostic value of ⁹⁹mTc-HMPAO-labeled leukocytes scintigraphy in suspicion of post-sternotomy mediastinitis relapse

BACKGROUND

The diagnostic value of radiolabeled white blood cells (WBCs) scintigraphy in mediastinitis is well established, but data in the specific context of relapse are lacking. The present study aimed at evaluation of the diagnostic value of WBCs scintigraphy in suspicion of mediastinitis relapse after prior surgical revision.

METHODS AND RESULTS

Multiple planar incidences of the chest were acquired 4 and 20 hours after injection of labeled WBC in 43 patients. In case of non-conclusive scintigraphy, a second scan was performed 2-3 weeks after the first one. The diagnosis of infection was based on positive bacteriological results; otherwise patients were followed up for at least 1 year. Out of 39 analyzable patients, 17 (44%) were diagnosed with mediastinitis relapse. After the first scan, 32 of 39 were correctly classified, 2 were false positive, and 5 were not conclusive. After completion of an additional scan in the latter 5 patients, 36 of 39 were correctly classified and 3 were false positive (100% sensitivity, 86% specificity, 85% positive predictive value, and 100% negative predictive value).

CONCLUSIONS

In the specific context of suspicion of mediastinitis relapse, the optimal diagnostic value was achieved by repeating the scan when the first one was not conclusive. In this context, a negative WBC scintigraphy was able to rule out infection, with potential major impact on therapeutic management in patients with poor clinical status.

High-dose continuous oxacillin infusion results in achievement of pharmacokinetics targets in critically ill patients with deep sternal wound infections following cardiac surgery

Knowledge regarding antimicrobial therapy strategies in deep sternal wound infections (DSWI) following cardiac surgery is limited. Therefore, we aimed to determine the steady-state plasma and mediastinal concentrations of oxacillin administered by continuous infusion in critically ill patients with DSWI and to compare these concentrations with the susceptibility of staphylococci recovered. A continuous infusion of oxacillin (150 to 200 mg/kg of body weight/24 h) was administered after a loading dose (50 mg/kg). Plasma and mediastinal concentrations of total and unbound oxacillin were determined 4 h after the loading dose (H4) and then at day 1 (H24) and day 2 (H48). Twelve patients were included. Nine patients exhibited bacteremia, 5 were in septic shock, 8 were positive for Staphylococcus aureus, and 4 were positive for coagulase-negative staphylococci. The median MIC (first to third interquartile range) was 0.25 (0.24 to 0.41) mg/liter. Median plasma concentrations of total and unbound oxacillin at H4, H24, and H48 were, respectively, 64.4 (41.4 to 78.5) and 20.4 (12.4 to 30.4) mg/liter, 56.9 (31.4 to 80.6) and 21.7 (6.5 to 27.3) mg/liter, and 57.5 (32.2 to 85.1) and 20 (14.3 to 35.7) mg/liter. The median mediastinal concentrations of total and unbound oxacillin at H4, H24, and H48 were, respectively, 2.3 (0.7 to 25.9) and 0.9 (<0.5 to 15) mg/liter, 29.1 (19.7 to 38.2) and 12.6 (5.9 to 19.8) mg/liter, and 31.6 (14.9 to 42.9) and 17.1 (6.7 to 26.7) mg/liter. High-dose oxacillin delivered by continuous infusion is a valuable strategy to achieve our pharmacokinetic target (4× MIC) at the site of action at H24. But concerns remain in cases of higher MICs, emphasizing the need for clinicians to obtain the MICs for the bacteria and to monitor oxacillin concentrations, especially the unbound forms, at the target site.

Evaluation of fever and infections in cardiac surgery patients

Fever following cardiac surgery is common and may be infectious or noninfectious in etiology. In this article, we review the major causes of postoperative fever while highlighting special considerations in cardiac surgery patients. We also outline a structured approach to evaluation and present an overview of diagnostic and management considerations for mediastinitis, postpericardiotomy syndrome, prosthetic valve endocarditis, aortic vascular graft infections, and ventricular assist device infections.

[Mediastinal omental flap in the treatment of post cardiac surgery mediastinitis: report of a case]

Nous rapportons le cas d'un patient diabétique et obèse, opéré d'une chirurgie de revascularisation myocardique avec l'utilisation des deux artères mammaires internes comme greffon. L'intervention s'est compliquée d'une médiastinite traitée premièrement à thorax fermé et secondairement par une épiplooplastie. Cette technique reste efficace dans les médiastinites graves et délabrantes. Tout chirurgien cardiaque et digestif doit la connaitre.

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.

Extracranial head and neck infections

This article outlines infections in the submandibular, lateral pharyngeal, retropharyngeal, danger, and prevertebral spaces, in conjunction with infections of the sinuses and mediastinum. By understanding the anatomy and pathophysiology, the reader will gain insight into the rationale for various therapeutic options.

Primary closure using Redon drains for the treatment of post-sternotomy mediastinitis

OBJECTIVES

Post-sternotomy mediastinitis is a severe complication of open heart surgery resulting in prolonged hospital stay and increased mortality. Vacuum-assisted closure is commonly used as treatment for post-sternotomy mediastinitis, but has some disadvantages. Primary closure over high vacuum suction Redon drains previously has shown to be an alternative approach with promising results. We report our short- and long-term results of Redon therapy-treated mediastinitis.

METHODS

We performed a retrospective analysis of 124 patients who underwent primary closure of the sternum over Redon drains as treatment for post-sternotomy mediastinitis in Amphia Hospital (Breda, Netherlands) and St. Antonius Hospital (Nieuwegein, Netherlands). Patient characteristics, preoperative risk factors and procedure-related variables were analysed. Duration of therapy, hospital stay, treatment failure and mortality as well as C-reactive protein and blood leucocyte counts on admission and at various time intervals during hospital stay were determined.

RESULTS

Mean age of patients was 68.7 ± 11.0 years. In 77.4%, the primary surgery was coronary artery bypass grafting. Presentation of mediastinitis was 15.2 ± 9.8 days after surgery. Duration of Redon therapy was 25.9 ± 18.4 days. Hospital stay was 32.8 ± 20.7 days. Treatment failure occurred in 8.1% of patients. In-hospital mortality was 8.9%. No risk factors were found for mortality or treatment failure. The median follow-up time was 6.6 years. One- and 5-year survivals were 86 and 70%, respectively.

CONCLUSIONS

Primary closure using Redon drains is a feasible, simple and efficient treatment modality for post-sternotomy mediastinitis.

Evaluation of risk factors for hospital mortality and current treatment for poststernotomy mediastinitis

PURPOSE

Poststernotomy mediastinitis (PSM) following cardiovascular surgery remains an intractable complication associated with considerable mortality. It is therefore necessary to assess the risk factors associated with hospital mortality and evaluate the surgical treatment options for PSM.

METHODS

We identified 59 (2.2%) patients who developed PSM after cardiovascular surgery between January 1991 and January 2010. PSM was defined as deep sternal wound infection requiring surgical treatment. In all, 31 patients were infected with methicillin-resistant Staphylococcus aureus (MRSA); and 14 patients died in hospital from PSM. A total of 51 patients were treated by simple closure or tissue flap reconstruction after débridement (traditional treatment), and 8 underwent closure or reconstruction after negative-pressure wound therapy (NPWT). The risk factors for in-hospital mortality due to PSM were analyzed by comparing the characteristics of survivors and nonsurvivors. The available surgical treatments for mediastinitis were also assessed.

RESULTS

Univariate analysis identified age, sex, pulmonary disease, MRSA infection, prolonged mechanical ventilation and prolonged intensive care unit stay as risk factors for in-hospital mortality (P < 0.05). Multiple logistic regression analysis identified MRSA infection (odds ratio 20.263, 95% confidence interval 1.580-259.814; P = 0.0208) as an independent risk factor for hospital mortality. NPWT was associated with significantly less surgical failure than traditional treatment (P = 0.0204). There were no deaths as a result of PSM in patients who underwent NPWT irrespective of the presence of MRSA infection.

CONCLUSION

MRSA infection was an independent risk factor for PSM-related in-hospital mortality. NPWT may improve the prognosis for patients with MRSA mediastinitis.

Risk factors for mortality in patients with mediastinitis after cardiac surgery

BACKGROUND

Patients with mediastinitis after cardiac surgery have higher morbidity and mortality.

AIMS

Describe the characteristics of patients with mediastinitis, determine the mortality within one month, and assess the risk factors associated with mortality.

METHODS

Retrospective cohort study including all adult patients with mediastinitis during the 2002-2006 period at the Nantes University Hospital. Multivariate analysis by logistic regression and Kaplan-Meier curve of survey were done.

RESULTS

Nearly 5574 patients were operated during the study period, with a mediastinitis incidence rate of 0.7%, 28 patients (72%) had coronary artery bypass graft. The mortality rate increased from de 12.8% during hospital stay to 20.5% within one year. Only two deaths were associated with mediastinitis. The occurrence of a co-infection was the only independent risk factor associated with mortality (OR 13, P<0.04). The instantaneous risk of death was increased by 7 in patient with co-infection, particularly mechanical ventilator-associated pneumonia (CR 1,97).

CONCLUSION

Mortality varied according to the duration of surveillance, and mediastinitis was not the major cause of death. Mechanical ventilator-associated pneumonia after mediastinitis increases the mortality and needs specific prevention.

Infectious mediastinitis after cardiovascular surgery: role of computed tomography

PURPOSE

The aim of this study was to evaluate the effectiveness of computed tomography (CT) findings in the diagnosis of mediastinitis after cardiovascular surgery with median sternotomy.

MATERIAL AND METHODS

A total of 122 patients were divided into two groups: the early group (<or=21 days after surgery) and the late group (>21 days after surgery). Among them, six patients were ultimately diagnosed with infectious mediastinitis. CT findings in each patient were evaluated. Mediastinal fluid collections or free gas bubbles were regarded as the primary findings of mediastinitis.

RESULTS

In the early group, sensitivity and specificity of the primary CT findings were 100% and 39%, respectively. In the late group, the sensitivity was 100% and the specificity 85%. Mediastinal fluid collections were observed in all six patients with mediastinitis.

CONCLUSION

Mediastinal fluid collections or free gas bubbles are not specific during the early postoperative period. However, after 2 21 days, these observations could be indicative of mediastinitis.

Treatment of postoperative sternal dehiscence with mediastinitis: twenty-four-year use of a single method

OBJECTIVE

Postoperative deep sternal wound infection with dehiscence carries a high mortality rate, a high morbidity rate, and a poor cure rate. We developed a standard protocol of care to treat this complication, achieving primary closure and cure of the infection.

METHODS

From January 1, 1981, through May 31, 2005 (24 years 5 months), we treated 114 patients with dehiscence and mediastinitis. The diagnosis was made from 4 to 56 days (mean, 14.5 days) after surgery. Mean age was 64.3 years (range, 38-84 years); 79 (69%) were obese, and 48 (42%) had diabetes. Ten had previous attempts (1-4) of repair with other methods. Treatment entailed (1) debridement without removal of bone, (2) bilateral dissection of skin and subcutaneous tissue as one layer, (3) implantation of a staggered double-tube irrigation-suction system posterior and another one anterior to the sternum, (4) lateral reinforcement of the sternum and reclosure with a double wire, and (5) a single-layer closure of the subcutaneous tissue and skin.

RESULTS

Of 114 patients, 109 (96%) had mediastinitis, positive for Staphylococcus species in 101 (92.6%). The cure rate was 98% (112/114); hospital stay was 14 days (range, 12-16 days), with no deaths.

CONCLUSIONS

Use of this standard protocol is effective and highly recommended. It spares the sternum, cures the infection, and leaves the patient physically functional without the use of soft tissue flaps.

Risk factors for 1-year mortality after postoperative mediastinitis

OBJECTIVE

Postoperative mediastinitis after median sternotomy is associated with disability and mortality. The aim of this study was to identify risk factors for mortality 1 year after postoperative mediastinitis diagnosis.

METHODS

Postoperative mediastinitis was defined as an organ-space infection involving the mediastinum and necessitating debridement. A total of 183 cases of postoperative mediastinitis were prospectively identified from infection control databases. By using univariate and multivariate analysis, clinical risk factors for 1-year mortality were identified.

RESULTS

Of 183 patients, 36 (19.7%) died within 3 months of the initial operation. Overall, 51 (33%) died during the study period (the median time to death from the date of diagnosis was 37 days [interquartile range, 11,139 days]). In multivariate analysis, independent predictors of 1-year mortality were a greater than 3-day delay in sternal closure after debridement (hazard ratio, 6.27; P < .001), age greater than 65 years (hazard ratio, 2.29; P = .015), serum creatinine level greater than 2 mg/dL before debridement (hazard ratio, 2.52; P = .019), stay in an intensive care unit before sternal debridement (hazard ratio, 5.56; P < .001), and postoperative mediastinitis due to methicillin-resistant Staphylococcus aureus (hazard ratio, 2.13; P = .02). Treatment with antibiotics with in vitro activity against the infecting pathogen within 7 days of initial debridement was associated with a decreased risk for mortality (hazard ratio, 0.40; P = .03).

CONCLUSIONS

Our data suggest that, to improve long-term survival, patients with postoperative mediastinitis should undergo sternal closure within 72 hours after sternal debridement and should receive effective antimicrobial therapy based on operative culture results.

Median Sternotomy Closure in Dogs: A Mechanical Comparison of Technique Stability

OBJECTIVE

To evaluate the mechanical properties of canine median sternotomy closure using double-loop cerclage compared with other commonly used cerclage sternotomy closure patterns.

STUDY DESIGN

Experimental study.

SAMPLE POPULATION

Forty canine cadaveric sternal segments.

METHODS

Median sternotomy-wire constructs were loaded to failure in a materials testing machine. Each construct was radiographed before and after testing. Specific wire configurations tested were: 2 single twist cerclage centered on the sternebrae, single twist figure of 8 pattern centered on the sternal synchondrosis, double twist figure of 8 pattern centered on the sternal synchondrosis, 2 double-loop cerclage centered on the sternebrae, and 1 double-loop cerclage centered on the sternal synchondrosis. Wire configurations were compared by craniocaudal translation of sternabrae on pre-test radiographs, and displacement during loading, and mode of failure, based on analysis of test video, and post-test radiographs.

RESULTS

Double-loop cerclage did not provide superior mechanical stabilization of median sternotomy. Both figure of 8 patterns had the least displacement at higher loads. Two single twists that were centered on sternebrae were least able to prevent displacement at higher loads, caused the most craniocaudal translation before testing, and fractured more often at loads < or = 200 N compared with other configurations.

CONCLUSION

Sternal wiring techniques stabilizing sternal synchondroses had the least displacement. Overall, figure of 8 cerclage appeared most suitable because they minimized displacement at high loads and facilitated accurate reduction during tensioning.

CLINICAL RELEVANCE

In closing canine sternotomy, figure of 8 cerclage may be most suitable. Double-loop cerclage centered on the sternal synchondrosis should be avoided because of wire failure at high loads.