The impact of two radical sternectomy surgical techniques on the outcome of deep sternal wound infections.

BACKGROUND: Deep sternal wound infection (DSWI) is a rare, yet devastating complication after cardiac surgery. While the surgical treatment always implies the soft tissue and bone debridement, there is little data about this procedure. The aim of our study was to evaluate the impact of the radical sternectomy on the outcome in patients with DSWI and to identify the risk factors which could influence the result. The surgical techniques of piecemeal sternectomy and the newly developed en bloc sternectomy were also evaluated. METHODS: The study was developed as a retrospective cohort study. 86 patients with DSWI who received a radical sternal resection at our institution between March 2018 and December 2021 were included. RESULTS: The average age of the cohort was 67.3 ± 7.4 years, and 23.3% of patients were female. The average length of stay trended shorter after en bloc sternectomy (median 26 days) compared to piecemeal sternectomy (37 days). There were no significant differences between the piecemeal and en bloc sternal resection techniques. Anticoagulant and antiplatelet drugs had no significant influence on bleeding and transfusion rates. Obese patients showed an increased risk for postoperative bleeding requiring reintervention. Transfusion of packed red blood cells was significantly associated with lower hemoglobin values before surgery and ASA Class 4 compared to ASA Class 3. The in-hospital mortality was 9.3%, with female sex and reintervention for bleeding as significant risk factors. Nine patients developed an infection relapse as a chronic fistula at the level of clavicula or ribs, with ASA Class 4 as a risk factor. CONCLUSION: Radical sternectomy is a safe procedure to treat DSWI with compromised sternal bone. Both piecemeal and en bloc techniques ensure reliable results, while complications and mortality appear to be patient-related.

Microbiological study of sternal osteomyelitis after median thoracotomy - a retrospective cohort study.

INTRODUCTION: Deep sternal wound infection is a rare but feared complication of median thoracotomies and is usually caused by microorganisms from the patient's skin or mucous membranes, the external environment, or iatrogenic procedures. The most common involved pathogens are Staphylococcus aureus, Staphylococcus epidermidis and gram-negative bacteria. We aimed to evaluate the microbiological spectrum of deep sternal wound infections in our institution and to establish diagnostic and treatment algorithms. METHODS: We retrospectively evaluated the patients with deep sternal wound infections at our institution between March 2018 and December 2021. The inclusion criteria were the presence of deep sternal wound infection and complete sternal osteomyelitis. Eighty-seven patients could be included in the study. All patients received a radical sternectomy, with complete microbiological and histopathological analysis. RESULTS: In 20 patients (23%) the infection was caused by S. epidermidis, in 17 patients (19.54%) by S. aureus, in 3 patients (3.45%) by Enterococcus spp., in 14 patients (16.09%) by gram-negative bacteria, while in 14 patients (16.09%) no pathogen could be identified. In 19 patients (21,84%) the infection was polymicrobial. Two patients had a superimposed Candida spp. INFECTION: Methicillin-resistant S. epidermidis was found in 25 cases (28,74%), while methicillin-resistant S. aureus was isolated in only three cases (3,45%). The average hospital stay for monomicrobial infections was 29.93 ± 13.69 days and for polymicrobial infections was 37.47 ± 19.18 (p = 0.03). Wound swabs and tissue biopsies were routinely harvested for microbiological examination. The increasing number of biopsies was associated with the isolation of a pathogen (4.24 ± 2.22 vs. 2.18 ± 1.6, p < 0,001). Likewise, the increasing number of wound swabs was also associated with the isolation of a pathogen (4.22 ± 3.34 vs. 2.40 ± 1.45, p = 0.011). The median duration of antibiotic treatment was 24.62 (4-90) days intravenous and 23.54 (4-70) days orally. The length of antibiotic treatment for monomicrobial infections was 22.68 ± 14.27 days intravenous and 44.75 ± 25.87 days in total and for polymicrobial infections was 31.65 ± 22.29 days intravenous (p = 0.05) and 61.29 ± 41.45 in total (p = 0.07). The antibiotic treatment duration in patients with methicillin-resistant Staphylococci as well as in patients who developed an infection relapse was not significantly longer. CONCLUSION: S. epidermidis and S. aureus remain the main pathogen in deep sternal wound infections. The number of wound swabs and tissue biopsies correlates with accurate pathogen isolation. With radical surgical treatment, the role of prolonged antibiotic treatment remains unclear and should be evaluated in future prospective randomized studies.

Pathological study of sternal osteomyelitis after median thoracotomy-a prospective cohort study.

PURPOSE: Osteomyelitis of the sternum may arise either as a primary condition or secondary to median thoracotomy after cardiac surgery, with the latter being decidedly more frequent. Deep sternal wound infections appear as a complication of median thoracotomy in 0.2 to 4.4% of cases and may encompass the infection of the sternal bone. To date, there are no exhaustive histopathological studies of the sternal osteomyelitis. METHODS: Our work group developed a surgical technique to remove the complete infected sternal bone in deep sternal wound infections. We therefore prospectively examined the en bloc resected sternal specimens. Seven standard histological sections were made from the two hemisternums. RESULTS: Forty-seven sternums could be investigated. The median age of the patients in the cohort was 66 (45-81) years and there were 10 females and 37 males. Two methods were developed to examine the histological findings, with one model dividing the results in inflammatory and non-inflammatory, while the second method using a score from 0 to 5 to describe more precisely the intensity of the bone inflammation. The results showed the presence of inflammation in 76.6 to 93.6% of the specimens, depending on the section. The left manubrial sections were more prone to inflammation, especially when the left mammary artery was harvested. No further risk factors proved to have a statistical significance. CONCLUSION: Our study proved that the deep sternal wound infection may cause a ubiquitous inflammation of the sternal bone. The harvest of the left mammary artery may worsen the extent and intensity of infection.