Risk factors for sternal wound infection and mid-term survival following coronary artery bypass surgery

Objective: To identify risk factors for sternal wound infection following coronary artery bypass surgery (CABG), and to compare early and mid-term survival outcome. Methods: Data were prospectively collected for 4228 patients who underwent CABG surgery between April 1997 and March 2001. One hundred and nine (2.6%) patients developed sternal wound infection. We used logistic regression to identify independent risk factors associated with post-operative sternal wound infection. Patient records were linked to the National Strategic Tracing Service, which records all deaths in the UK, to establish current vital status. Deaths occurring over time were described using Kaplan–Meier techniques. To control for differences in patient characteristics, we used Cox proportional hazards analysis to calculate adjusted hazard ratios (HR) and 95% confidence intervals (CI). Results: The results of the logistic regression analysis found that the independent predictors of sternal wound infection were obesity (odds ratio (OR) 2.0; P<0.001), New York Heart Association class ≥3 (OR 1.6; P=0.022), use of bilateral internal mammary arteries (OR 3.2; P<0.001), increasing number of grafts (OR 1.5; P<0.001), re-exploration for bleeding (OR 3.1; P=0.011), and increased duration of mechanical ventilation (for every 10 h (OR 1.12; P<0.001)). Three hundred and forty one (8.1%) deaths occurred during the study period with mean follow up of 3.2±1.3 years. The crude HR of mid-term mortality for sternal wound infection patients was 2.51 (95% CI 1.59–3.94, P<0.001). After adjustment for pre, intra and post-operative factors, the adjusted HR of mid-term mortality for sternal wound infection patients was 1.64 (95% CI 1.03–2.61, P=0.037). The adjusted freedom from death for sternal wound infections at 30 days, and 1, 2 and 4 years was 96.8, 93.7, 91.4 and 86.7%, respectively, compared with 98.1, 96.1, 94.7 and 91.7% for patients without sternal wound infections. Conclusions: In conclusion, we have identified risk factors for sternal wound infection, many of which are modifiable. We have also shown that there is a significant increase in mortality in patients with sternal wound infection during a 4-year follow-up period after CABG.     

Multivariate analysis of risk factors for deep and superficial sternal infection after coronary artery bypass grafting at a tertiary care medical center

Identification of modifiable risk factors for sternal infection is essential for the development and institution of practices that decrease the incidence of these infections. This study analyzed 4004 consecutive patients undergoing coronary artery bypass grafting performed at a single institution between January 1996 and May 2003. Specific risk factors for both superficial and deep sternal wound infection were identified by univariate and multivariate analysis. The incidence of superficial sternal wound infections was 2.2% (N = 87) while the incidence of deep sternal wound infections was 1.8% (N = 73). Risk factors for superficial sternal infection identified by multivariate analysis include increasing body mass index (BMI) (OR 1.089, 95% CI 1.057-1.122, P < 0.001), female gender (OR 1.412, 1.108-1.717, P = 0.036), active smoking (OR 1.856, 1.079-3.193, P = 0.025), utilization of bilateral internal mammary arteries (OR 7.546, 3.175-17.935, P < 0.001), and transfusion of > or =4 units of packed red blood cells postoperatively (OR 2.009, 1.158-3.485, P = 0.013). Risk factors for deep sternal infection include increasing BMI (OR 1.077, 1.042-1.114, P < 0.001), diabetes mellitus (OR 2.412, 1.376-4.231, P = 0.002), and transfusion with > or =2 units of platelets postoperatively (OR 2.787, 1.279-6.071, P = 0.010). These data suggest that cessation of smoking, improved blood glucose management, preoperative weight loss, limitation of transfusions, and discriminate use of bilateral internal mammary arteries are all practices that may decrease the incidence of postoperative wound complications following coronary revascularization.     

Is post-sternotomy percutaneous dilatational tracheostomy a predictor for sternal wound infections?

OBJECTIVE: Early post-sternotomy tracheostomy is not infrequently considered in this era of percutaneous tracheostomy. There is, however, some controversy about its association with sternal wound infections. METHODS: Consecutive patients who had percutaneous tracheostomy following median sternotomy for cardiac operation at our institution from March 1998 through January 2007 were studied, and compared to contemporaneous patients. We identified risk factors for tracheostomy, and investigated the association between percutaneous tracheostomy and deep sternal wound infection (mediastinitis) by multivariate analysis. RESULTS: Of 7002 patients, 100 (1.4%) had percutaneous tracheostomy. The procedure-specific rates were: 8.6% for aortic surgery, 2.7% for mitral valve repair/replacement (MVR), 1.1% for aortic valve replacement (AVR), and 0.9% for coronary artery bypass grafting (CABG). Tracheostomy patients differed vastly from other patients on account of older age, severe symptoms, preoperative support, lower ejection fraction, more comorbidities, more non-elective and complex operations and higher EuroScore. Risk factors for tracheostomy were New York Heart Association class III/IV (OR 6.01, 95% CI 2.28-16.23, p<0.0001), chronic obstructive pulmonary disease (OR 1.84, 95% CI 1.01-3.37, p=0.05), preoperative renal failure (OR 3.57, 95% CI 1.41-9.01, p=0.007), prior stroke (OR 3.08, 95% CI 1.75-5.42, p<0.0001), ejection fraction<0.30% (OR 2.73, 95% CI 1.23-6.07, p=0.01), and bypass time (OR 1.008, 95% CI 1.004-1.012, p<0.0001). The incidences of deep (9% vs 0.7%, p<0.0001) and superficial sternal infections (31% vs 6.5%, p<0.0001) were significantly higher among tracheostomy patients. Multivariate analysis identified percutaneous tracheostomy as a predictor for deep sternal wound infection (OR 3.22, 95% CI 1.14-9.31, p<0.0001). CONCLUSIONS: Tracheostomy, often performed in high-risk patients, may further complicate recovery with sternal wound infections, including mediastinitis, therefore, patients and timing should be carefully selected for post-sternotomy tracheostomy.     

Double crisscross sternal wiring and chest wound infections: a prospective randomized study

OBJECTIVE: We sought to assess the efficiency of 2 different sternal wiring techniques in preventing deep sternal wound infection or sternal instability. METHODS: Seven hundred patients were randomized to 2 different groups according to chest-closure techniques. Three hundred fifty patients who underwent a peristernal double crisscross wire closure were included in group X, whereas 350 patients who underwent a standard transsternal closure were included in group T. After sternal closure, the technique for wound suturing was the same for both groups, namely triple-layer sutures up to the intracutaneous skin. All data were prospectively collected and entered in our institute database. RESULTS: The 2 groups of patients were comparable for sex, age, preoperative risk factors, and operative procedures. The overall mortality rate was 4.3% in group X and 4.6% in group T. Postoperative morbidity and mortality were comparable between the 2 groups, unlike for sternal wound complications. None of the patients included in group X had superficial or deep wound complications, whereas in group T 7 (2%) patients presented with a superficial sternal wound infection, 6 (1.7%) presented with a deep chest wound infection with sternal instability requiring re-exploration (P <.05), and 3 presented with a sternal instability caused by sternum disruption without infection. Among patients with deep wound infection and sternal instability, 1 patient died, resulting in a mortality rate of 16.7%. CONCLUSIONS: The peristernal double crisscross wiring technique achieved a greater sternal stability, resulting in a lower incidence of wound infection in association with triple-layer closure of suprasternal tissues.     

Sternal closure techniques and postoperative sternal wound complications in elderly patients.

OBJECTIVE: Postoperative sternal wound complications (PSWC) including deep sternal wound infection (DSWI) and sternal dehiscence (SD) cause significant morbidity and mortality. Elderly patients with several risk factors are particularly prone to suffer PSWC. METHODS: We present (I) a subset of 86 patients, all aged > or =75 years out of 339 cardiac surgery patients prospectively randomised to receive either conventional sternal closure or a Robicsek type closure. Primary end-points were SD and DSWI; secondary end-points included a composite of clinical parameters; (II) we retrospectively assessed data of 54/5273 patients with mediastinitis regarding the influence of advanced age. In addition, we report an epidemiological overview of different sternal closure techniques. RESULTS: (I) The Robicsek technique showed an impact on SD and DSWI, and several secondary end-points: ventilator support (p=0.03), postoperative blood loss (p=0.04), and chest pain >3 days (p=0.04). (II) A total of 54/5273 (1.02%) patients developed postoperative mediastinitis. Twelve out of 54 (22%) patients died within 6 months of the initial operation. Predictors of mortality were insulin-dependent diabetes mellitus (p=0.05), renal insufficiency (p=0.01), delayed sternal closure (p=0.05), ICU-stay >10 days (p=0.01), and methicillin-resistant Staphylococcus aureus (p=0.03) or fungal infection (p=0.02). CONCLUSIONS: No statistical difference in sternal dehiscence or mediastinitis was found irrespective of whether the bilateral and longitudinal parasternal closure or the conventional peri/trans-sternal wiring technique was used, but there was an obvious, positive influence on sternal dehiscence, deep sternal wound infection, and clinical parameters. However, the study population is relatively small.     

Poststernotomy mediastinitis: a review of conventional surgical treatments, vacuum-assisted closure therapy and presentation of the Lund University Hospital mediastinitis algorithm

Poststernotomy mediastinitis, also commonly called deep sternal wound infection, is one of the most feared complications in patients undergoing cardiac surgery. The overall incidence of poststernotomy mediastinitis is relatively low, between 1% and 3%, however, this complication is associated with a significant mortality, usually reported to vary between 10% and 25%. At the present time, there is no general consensus regarding the appropriate surgical approach to mediastinitis following open-heart surgery and a wide range of wound-healing strategies have been established for the treatment of poststernotomy mediastinitis during the era of modern cardiac surgery. Conventional forms of treatment usually involve surgical revision with open dressings or closed irrigation, or reconstruction with vascularized soft tissue flaps such as omentum or pectoral muscle. Unfortunately, procedure-related morbidity is relatively frequent when using conventional treatments and the long-term clinical outcome has been unsatisfying. Vacuum-assisted closure is a novel treatment with an ingenious mechanism. This wound-healing technique is based on the application of local negative pressure to a wound. During the application of negative pressure to a sternal wound several advantageous features from conventional surgical treatment are combined. Recent publications have demonstrated encouraging clinical results, however, observations are still rather limited and the underlying mechanisms are largely unknown. This review provides an overview of the etiology and common risk factors for deep sternal wound infections and presents the historical development of conventional therapies. We also discuss the current experiences with VAC therapy in poststernotomy mediastinitis and summarize the current knowledge on the mechanisms by which VAC therapy promotes wound healing. Finally, we suggest a structured algorithm for using VAC therapy for treatment of poststernotomy mediastinitis in clinical practice.     

Poststernotomy Mediastinitis Treated by Transposition of the Greater Omentum

Due to its anatomical structure and physiological properties, omental tissue has proven to be beneficial when transposed to the thorax to treat severe mediastinal infections. Between April 1987 and July 1994, 17,005 open heart operations were performed at our institution. One hundred and forty patients who developed mediastinitis or serious wound infections postoperatively were treated by transposition of the greater omentum into the retrosternal space. These patients were compared with a control group of 100 patients operated in the same period, who did not develop infectious complications postoperatively. Significant differences were found in several risk factors, such as obesity, type, and duration of primary operation, ejection fraction < 30% (< 0.01), as well as the incidence of low cardiac output syndrome treated by insertion of an intra-aortic balloon pump (p < 0.05) However, no significant differences were observed in factors such as diabetes mellitus, emergency operation, reoperation, degree of postoperative bleeding, and duration of aortic cross-clamp time. The mortality of mediastinitis largely depended on the type of primary operation. It was 19.2% in patients who underwent coronary surgery, and 52.2% in patients who underwent transplantation (overall mortality 35.7%). Only in 2% of the patients did we find complications related to the creation of the omental pedicle and its translocation. Today, serious disturbances in sternal wound healing, especially involving mediastinitis, are rare complications in cardiac surgery. Nevertheless, they continue to be associated with high mortality and prolonged hospitalization.     

Bilateral pedicled internal thoracic artery grafting

Background: Pedicled bilateral internal thoracic artery grafting (BITA) has been discouraged in historical high-risk groups such as diabetes mellitus (DM), renal failure, old age, and obesity because of reported high incidence of mediastinitis. However, considering the fact that there are abundant short and long-term results including angiography study about the conventional pedicled grafts, it might be worthwhile reassessing the results of pedicled BITA grafting with modern techniques by a disciplined surgical team before abandoning the method. Methods: Between September 1989 and September 1999, 1371 patients underwent isolated coronary artery bypass grafting (CABG) in Kumamoto central hospital. Of these patients, 558 patients who had bilateral ITA strategy (mean age 63.0±9.2 years, 13–79) were studied. The method of harvest of ITAs is consistently the use of conventional pedicled grafts. The use of bone wax and unnecessary electrocautery injury to the periostium or cartilage were avoided as much as possible. The only change in the surgical technique in the study period is the application of the pinpoint hemostasis for the presternal tissues from August 1997 (late period). Results: In late period, there were significantly more patients with sternal sepsis risk factors such as diabetes mellitus (early: late; 19.3% vs. 34.8%, P<0.00003), and renal failure (0.3 vs. 9.7%, P<0.0001) as well as patients who had gastroepiploic artery grafting (16.9 vs 48.5%, P<0.0001) and those who required aortic non-touch technique (2.1 vs. 7.9%, P<0.001). The percentage of the patients receiving BITA grafting among the isolated CABG patients increased in the late period from 31.7% (331/1043) to 69.2% (227/328) (P<0.001), reflecting that a more aggressive approach towards bilateral ITA and arterial grafting has been taken in the late period. Overall operative mortality was 1.1% (n=6). Mediastinitis occurred in seven patients (1.3%). Of these, only one mediastinitis occurred in late period (0.4%). No mediastinitis occurred in 23 chronic renal dialysis patients. Among the 143 DM patients, there were three mediastinitis (2.1%). Of three, only one occurred in late period, yielding 1.3% mediastinitis rate. There was one mediastinitis (0.7%) among 134 elderly patients more than 70 years of age. Univariate analysis identified obesity as a risk factor for mediastinitis. And there was a trend of decreasing mediastinits in late period but did not reached a statistical significance (P<0.2). Multivariate analysis identified obesity and arteriosclerosis obliterates as independent risk factors. Neither diabetes mellitus, dialysis, female gender, nor old age were significant independent predictors of mediastinitis. Despite the significantly high percentage of high-risk patients in late group, there were no significant difference in mortality and morbidity between the two groups. Conclusion: Pedicled BITA grafting is feasible with acceptable morbidity and shouldn't be abandoned even in high-risk patients such as DM, old age, and dialysis, especially combined with pinpoint-hemostasis, avoiding excessive use of bone wax, and strict aseptic technique. These point require a surgical team familiar with these techniques to maintain adequate skills in conduit procurement.     

Mediastinitis after pediatric cardiac surgery: a 15-year experience at a single institution

BACKGROUND: The spectrum of sternal wound infections after cardiac surgery ranges from superficial infections to a deep sternal infection known as mediastinitis. Mediastinitis is a rare but clinically relevant source of postoperative morbidity and mortality in adult and pediatric patients after cardiac surgery. METHODS: We retrospectively identified all patients diagnosed with mediastinitis after cardiac surgery from January 1987 to December 2002 (17 patients/7,616 surgeries = 0.2%). Demographic data, cardiac diagnosis, cardiac surgery, hospital length of stay, associated medical diagnosis, and surgical treatment for mediastinitis were collected. RESULTS: Fifteen pediatric patients (age < 18 years) were diagnosed with mediastinitis (mean age at diagnosis 37.5 months, range 21 days to 17 years. The median postoperative day of diagnosis was 14 days (6 to 50 days). The most common organism was Staphylococcus species (n = 9). Six patients had an associated bacteremia. The median hospital length of stay for all patients was 42.5 days (range 16 to 163 days). The hospital mortality was 1 of 15 (6%). Each patient was treated with intravenous antibiotics; sternal debridement; and rectus abdominus flap reconstruction (n = 7), pectoralis muscle flap reconstruction (n = 3), omentum reconstruction (n = 1), or primary sternal closure (n = 4). Three patients have undergone redo-sternotomy with orthotopic heart transplantation, bidirectional cavopulmonary anastomosis, and replacement of a right ventricle to pulmonary artery homograft. CONCLUSIONS: Timely diagnosis, aggressive sternal debridement, and liberal use of rotational muscle flaps can potentially minimize the morbidity and mortality in pediatric postoperative cardiac patients. Subsequent redo-sternotomy has not been problematic.     

Sternal wound infections following open heart surgery – a review

Abstract

Surgical site infections (SSIs) are common complications after open heart surgery. Fortunately, most are superficial and respond to minor wound debridement and antibiotics. However, 1–3% of patients develop deep sternal wound infections that can be fatal. Late infections with sternocutaneous fistulas, are encountered less often, but represent a complex surgical problem. This evidence-based review covers etiology, risk factors, prevention and treatment of sternal SSIs following open heart surgery with special focus on advances in treatment, especially negative-pressure wound therapy.     

The concept of negative pressure wound therapy (NPWT) after poststernotomy mediastinitis – a single center experience with 54 patients

Deep sternal infections, also known as poststernotomy mediastinitis, are a rare but often fatal complication in cardiac surgery. They are a cause of increased morbidity and mortality and have a significant socioeconomic aspect concerning the health system. Negative pressure wound therapy (NPWT) followed by muscular pectoralis plasty is a quite new technique for the treatment of mediastinitis after sternotomy. Although it could be demonstrated that this technique is at least as safe and reliable as other techniques for the therapy of deep sternal infections, complications are not absent. We report about our experiences and complications using this therapy in a set of 54 patients out of 3668 patients undergoing cardiac surgery in our institution between January 2005 and April 2007.     

Epidemiology and Outcomes of Deep Surgical Site Infections Following Lung Transplantation

We conducted a retrospective study of deep surgical site infections (SSIs) among consecutive patients who underwent lung transplantation (LTx) at a single center from 2006 through 2010. Thirty‐one patients (5%) developed SSIs at median 25 days after LTx. Empyema was most common (42%), followed by surgical wound infections (29%), mediastinitis (16%), sternal osteomyelitis (6%), and pericarditis (6%). Pathogens included Gram‐positive bacteria (41%), Gram‐negative bacteria (41%), fungi (10%) and Mycobacterium abscessus, Mycoplasma hominis and Lactobacillus sp. (one each). Twenty‐three percent of SSIs were due to pathogens colonizing recipients' native lungs at time of LTx, suggesting surgical seeding as a source. Patient‐related independent risk factors for SSIs were diabetes and prior cardiothoracic surgery; procedure‐related independent risk factors were LTx from a female donor, prolonged ischemic time and number of perioperative red blood cell transfusions. Mediastinitis and sternal infections were not observed among patients undergoing minimally invasive LTx. SSIs were associated with 35% mortality at 1 year post‐LTx. Lengths of stay and mortality in‐hospital and at 6 months and 1 year were significantly greater for patients with SSIs other than empyema. In conclusion, deep SSIs were uncommon, but important complications in LTx recipients because of their diverse microbiology and association with increased mortality.     

The endogenous pathway is a major route for deep sternal wound infection.

OBJECTIVE: Deep wound infections pose an increasing problem in cardiac surgery patients. Prospective infection monitoring is thus a means of identifying possible risk factors. METHODS: Within a period of 5 months, a total of 376 adult patients, 260 men and 116 women, with a mean age of 62.6 years (range 18-88), underwent coronary bypass grafting (n=281) or other cardiac surgery procedures (n=95). Nasal cultures were taken preoperatively from every patient, as well as cultures of the wound during surgery and when dressings were changed thereafter. In addition, nasal cultures were taken from all the medical and nursing staff. To differentiate endogenous and exogenous infection pathways, DNA fingerprint analysis was performed. RESULTS: A total of 38 patients (10.1%) developed a wound infection, in 14 patients this happened to be a deep wound infection, in 24 patients a superficial one. Five sternal wound infections were associated with mediastinitis (1.3%). The occurrence of a wound infection overall resulted in prolonged hospitalization (29.4+/-24 vs. 11.9+/-6.9 days, P=0.001), but not in increased hospital mortality (4.4% vs. 3.9%). Obesity, diabetes mellitus and nasal carriage of Staphylococcus aureus proved to be independent risk factors with an odds ratio of 2.07, 2.26 and 2.28, respectively. In all but one of the sternal colonizations with S. aureus, DNA fingerprint analysis demonstrated an identical pattern of S. aureus from the patient's nose and sternum, indicating an endogenous infection pathway. Conclusions: The determination of the endogenous pathway for severe wound infection makes prevention possible by means of preoperative local S. aureus eradication.     

Bacteremia and sternal infection after coronary artery bypass grafting

Sternal wound infection remains a source of substantial morbidity and mortality after coronary artery bypass grafting. We noted an association between bacteremias and sternal wound complications in these patients. A review of 835 consecutive coronary bypass patients showed a 3.2% incidence of bacteremia and a 1.9% incidence of deep and superficial sternal wound infection. The sternal wound was the most common source of bacteremia, accounting for 59% of the infections. Coagulase-negative Staphylococcus was responsible for one half of the sternal wound infections. Often, a positive blood culture was the first manifestation of wound infection, occurring before local signs were manifest. We recommend multiple blood cultures in postoperative coronary bypass patients with pronounced fever. If no source of infection can be identified, sternal wound aspirate may be revealing. Appropriate early wound management can then be carried out, maximizing chances for good recovery.     

Are wound complications after a kidney transplant more common with modern immunosuppression?

BACKGROUND: The most common surgical complication after a kidney transplant is likely related to the wound. The purpose of this analysis was to determine the incidence of, and risk factors for, wound complications (e.g., infections, hernias) in kidney recipients and to assess whether newer immunosuppressive drugs increase the risk for such complications. METHODS: Between January 1, 1984 and September 30, 1998, we performed 2013 adult kidney transplants. Of these 2013 recipients, 97 (4.8%) developed either a superficial or a deep wound infection. Additionally, 73 (3.6%) recipients developed either a fascial dehiscence or a hernia of the wound. We used univariate and multivariate techniques to determine significant risk factors and outcomes. RESULTS: Mean time to development of a superficial infection (defined as located above the fascia) was 11.9 days posttransplant; to development of a deep infection (defined as located below the fascia), 39.2 days; and to development of a hernia or fascial dehiscence, 12.8 months. By multivariate analysis, the most significant risk factor for a superficial or deep wound infection was obesity (defined as body mass index>30 kg/m2) (RR=4.4, P=0.0001). Other significant risk factors were a urine leak posttransplant, any reoperation through the transplant incision, diabetes, and the use of mycophenolate mofetil (MMF) (vs. azathioprine) for maintenance immunosuppression (RR=2.43, P=0.0001). Significant risk factors for a hernia or fascial dehiscence were any reoperation through the transplant incision, increased recipient age, obesity, and the use of MMF (vs. azathioprine) for maintenance immunosuppression (RR=3.54, P=0.0004). Use of antibody induction and treatment for acute rejection were not significant risk factors for either infections or hernias. Death-censored graft survival was lower in recipients who developed a wound infection (vs. those who did not); it was not lower in recipients who developed an incisional hernia or facial dehiscence (vs. those who did not). CONCLUSIONS: Despite immunosuppression including chronic steroids, the incidence of wound infections, incisional hernias, and fascial dehiscence is low in kidney recipients. As with other types of surgery, the main risk factors for postoperative complications are obesity, reoperation, and increased age. However, in kidney recipients, use of MMF (vs. azathioprine) is an additional risk factor -one that potentially could be altered, especially in high-risk recipients.     

Is mediastinitis a preventable complication? A 10-year review

BACKGROUND: The incidence of mediastinitis after cardiac surgical intervention is reported to be between 0.15% and 5% and is a major cause of postoperative morbidity. A number of risk factors have been identified, most of which are not modifiable. It is our contention that this complication can be reduced to a minimum by the consistent application of good operative technique and postoperative management. METHODS: We reviewed the records of all 9,771 patients who underwent cardiac surgical procedures between 1987 and 1997. All operations were performed using a common skin preparation, draping, and antibiotic prophylaxis. Cases of mediastinitis were defined according to Centers for Disease Control and Prevention criteria and were identified from three sources: medical records database, hospital infection control, and the Society of Thoracic Surgeons database. Risk factors were assessed using chi2 and Fisher's exact tests. RESULTS: Of 24 patients identified as having deep sternal wound infection (incidence, 0.25%), 2 died (mortality rate, 8.3%), 18 required reoperation (75%), and only 4 needed pectoral muscle flaps. Statistical analysis revealed only the presence of chronic obstructive pulmonary disease as a significant risk factor (p < 0.01). Other factors, including diabetes, renal failure, smoking, sex, age, reoperation, morbid obesity, and steroid use, were not significant. The use of internal mammary arteries (single or bilateral) was not associated with mediastinitis. Postoperative complications, including prolonged ventilation, inotropic support, and the need for blood products, were not significant risk factors. The patients who developed mediastinitis were more likely to be readmitted to the hospital (p < 0.005) and more likely to require reoperation (p < 0.005). CONCLUSIONS: In a large patient series we found a low incidence of mediastinitis (0.25%) and an even lower incidence of required reoperation (0.19%). Except for the use of bone wax and the use of bilateral mammary arteries in diabetic patients, none of the previously identified risk factors are modifiable. We believe that with strict adherence to perioperative aseptic technique, attention to hemostasis, and precise sternal closure, a very low incidence of mediastinitis can be achieved.     

Deep sternal wound infection: the role of early debridement surgery

Objective: This retrospective chart review study aimed to evaluate whether a more aggressive staged approach can reduce morbility and mortality following post-cardiotomy deep sternal wound infection. Methods: Between 1979 and 2000, 14 620 patients underwent open heart surgery: mediastinitis developed in 124 patients (0.85%). Patients were divided in two groups: in 62 patients (Group A) (1979–1994) an initial attempt of conservative antibiotic therapy was the rule followed by surgical approach in case of failure; in 62 patients (Group B) (1995–2000) the treatment was staged in three phases: (1) wound debridment, removal of wires and sutures, closed irrigation for 10 days; (2) in case of failure open dressing with sugar and hyperbaric therapy (11 patients, 17%); (3) delayed healing and negative wound cultures mandated plastic reconstruction (three patients, 4%). Categorical values were compared using the Chi-square test, continuous data were compared by unpaired t-test. Results: Incidence of mediastinitis was higher in Group B (62 out of 5535; 1.3%) than in Group A (62 out of 9085; 0.7%) (P=0.007). Mean interval between diagnosis and treatment was shorter in Group B (18±6 days) than in group A (38±7 days) (P=0.001). Hospital mortality was higher in Group A (19/62; 31%) than in Group B (1 out of 62; 1.6%) (P<0.001). Hospital stay was shorter in Group B (30.5±3 days) than in group A (44±9 days) (P=0.001). In Group B complete healing was observed in all the 61 survivors: 47 cases (76%) after Stage 1; 11 (18%) after Stage 2; three (4.8%) after Stage 3. Conclusions: Although partially biased by the fact that the two compared groups draw back to different decades, this study showed that an aggressive therapeutic protocol can significantly reduce morbility and mortality of deep sternal wound infection.     

Sternal preservation: a better way to treat most sternal wound complications after cardiac surgery

Background

Postcardiotomy sternal wound complications remain challenging. The prevailing approach for deep sternal wound infection of débridement and flap coverage without osseous closure makes subsequent reoperation difficult.

Methods

An analysis of all patients undergoing cardiac surgery at a single institution between 1986 and 2001 was conducted. Prospective data collection and chart review were used to compare different treatment strategies for sternal complications.

Results

Of 5337 patients, 122 had sternal wound complications (2.2%) comprising 15 (0.3%) uninfected dehiscences (El Oakley class 1), 45 (0.8%) superficial infections (El Oakley class 2A), and 62 (1.1%) deep sternal wound infections (El Oakley class 2B). Thirty-two patients with deep sternal infection were treated by débridement, rewiring, and delayed primary closure. There were initial treatment failures in 6 patients (18.8%) and ultimate failures in 2 patients (6.3%), both of whom died. One of these patients had previously received external beam radiation after a radical mastectomy for breast cancer. Median length of stay was 32 days and median time to wound healing was 85 days. Twenty-five patients were managed by muscle flap coverage without sternal reclosure. There were 6 initial treatment failures (24%) but no ultimate failures or deaths (p = NS). Median length of stay was 31 days and median infection time was 161 days.

Conclusions

In patients with postcardiotomy deep sternal wound infection without previous chest radiation, débridement, rewiring, and delayed skin closure is effective. It offers a shorter healing time and probably makes late cardiac reoperation safer. We propose an algorithm for the management of poststernotomy complications.     

Predictors and outcomes of sternal wound complications in patients after coronary artery bypass graft surgery

We sought to assess predictors and outcomes of sternal wound complications in patients after coronary artery bypass grafting (CABG). A nested, case-control study from a 10-year hospitalization cohort with prospective data collection was conducted. Included in the cohort were patients age 18 and above undergoing CABG surgery between March 1997 and July 2003 (n = 7889). Patients who underwent any surgery other CABG were excluded. Cases were matched to controls 1:3 on year of surgery. Cases were CABG patients with sternal wound complications, which was defined as requiring antibiotics and/or topical treatment, requiring extra nursing care, dehiscence, or requiring surgical intervention (n = 89). Controls were CABG patients without sternal wound complications (n = 267). The study examined 29 risk factors and 10 outcome variables. Univariate analysis on the risk factors revealed 10 significant risk factors. Logistic regression analysis was conducted and the risk factors that significantly predicted sternal wound complications after CABG surgery included older age (odds ratio [OR] = 0.85, 95% confidence interval [CI] 0.808-0.892), previous CABG surgery (OR = 3.9, 95% CI 1.03-15.37), and in class three or four of the New York Heart Association functional class (OR = 2.8, 95% CI 1.27-6.12). There was a significant difference between CABG patients with and without sternal wound complications on nine outcome variables. Of the 29 predictors of post-CABG sternal wound infections being examined, 10 proved to be significant. Further analysis demonstrated only three variables that significantly predicted sternal wound complications. Older age, previous CABG surgery, and class three or four of the New York Heart Association functional class predispose CABG patients to sternal wound infections.     

The risk factors for deep and superficial chest surgical-site infections after coronary artery bypass graft surgery are different

OBJECTIVE: We sought to determine risk factors for deep and superficial chest wound infections after coronary artery bypass graft surgery to develop predictive models. METHODS: We retrospectively analyzed data collected on 1980 consecutive patients undergoing coronary artery bypass surgery at our institution between January 1, 1996, and June 30, 1999, by using the Society of Thoracic Surgery database. Independent risk factors for surgical-site infection were identified with multivariate logistic regression. RESULTS: There were 37 (1.9%) deep chest and 46 (2.3%) superficial chest surgical-site infections. Obese diabetic patients had a 7.7-fold increased risk of deep chest infections after controlling for intra-aortic balloon pump use (odds ratio, 3.1) and postoperative transfusion (odds ratio, 2.3). Independent risk factors for superficial surgical-site infections included obesity (odds ratio, 3.1), diabetes in persons 65 years of age or older (odds ratio, 2.7), and current smoking (odds ratio, 2.5). Use of antiplatelet drugs was associated with a lower risk of superficial infections (odds ratio, 0.4). Predicted operative mortality as a marker of severity of illness was not clearly predictive of deep or superficial surgical-site infection. Mortality in the year after the operation was increased in patients with deep chest infections compared with that seen in uninfected control subjects (8/37 [21.6%] vs 114/1612 [7.1%], P =.004) but not in patients with superficial chest infections (7/47 [15.2%] vs 114/1612 [7.1%], P =.075). CONCLUSIONS: Risk factors for deep and superficial chest surgical-site infections after coronary artery bypass surgery differ, suggesting different mechanisms of pathogenesis. Appropriate risk stratification models specific to these important outcomes must be developed.