Major sternal wound infection after open-heart surgery: a multivariate analysis of risk factors in 2,579 consecutive operative procedures

The protective effect of topical rifamycin treatment against sternal wound infection in diabetic patients undergoing on-pump coronary artery bypass graft surgery

Objectives

The aim of this study was to investigate the protective effect of topical rifamycin SV treatment against sternal wound infection (SWI) in diabetic patients undergoing on-pump coronary artery bypass graft (CABG) surgery.

Methods

One hundred and fifty-nine diabetic patients who were scheduled to undergo isolated on-pump CABG surgery were included. Eight were excluded for various reasons. Of the 151 patients, 51 were on insulin therapy and 100 were on oral anti-diabetics. The risk of mediastinitis was assessed using the American College of Cardiology/American Heart Association 2004 guideline update for CABG surgery. According to the risk scores, patients were divided into two comparable groups: the rifamycin group (n = 78) received topical rifamycin treatment after on-pump CABG surgery, and the control group (n = 73) received no topical treatment.

Results

Deep sternal wound infection (mediastinitis) was not observed in either group (0/78 vs 0/73, p = 1.0). No superficial sternal wound infection was observed in the rifamycin group, however, it did occur in one patient in the control group (0/78 vs 1/73, p = 0.303). Wound culture was performed and coagulase-negative staphylococci were observed. The infection regressed on initiation of antibiotic therapy against isolated bacteria and the patient was discharged after a full recovery.

Conclusion

Although the difference in rate of superficial sternal wound infection (SSWI) in the rifamycin and control groups was not statistically significant, locally applied rifamycin SV during closure of the sternum in the CABG operation may have had a protective affect against SWI.

Drainage days-an independent risk factor for serious sternal wound infections after cardiac surgery: a case control study

BACKGROUND

Postoperative sternal wound infections are a potentially devastating complication following cardiac surgery. The aim of our study was to determine risk factors associated with patients' baseline characteristics and peri- and postoperative management for the development of surgical site infections (SSIs) after cardiac surgery involving sternotomy.

METHODS

Since 2009 the University Hospital of Basel, a tertiary care center in Switzerland, has participated in the national SSI-surveillance program by conducting postdischarge surveillance. We conducted a nested case-control study involving 30 consecutive patients with an organ/space SSI after cardiac surgery and 60 control patients.

RESULTS

Receipt of antibiotics before operation (odds ratio [OR], 1.20; 95% confidence interval [CI], 1.02-1.41; P = .032), decreased albumin levels (OR, 0.87; 95% CI, 0.76-0.99; P = .040, respectively), time on extracorporal circulation (OR, 1.02; 95% CI, 1.00-1.03; P = .012), number of drainages (OR, 9.15; 95% CI, 2.01-41.76; P = .004), length of drain retention (OR, 1.44; 95% CI, 1.10-1.90; P = .009), and resuscitation (OR, 7.30; 95% CI, 1.53-34.71; P = .012) were associated with SSIs. Incidence density drainage days-accounting for both number of drains and length of retention-were the only independent risk factor (OR, 1.12; 95% CI, 1.02-1.11; P = .018).

CONCLUSIONS

Retention of drainages in the operative site longer than 48 hours was the only independent risk factor for the development of organ/space sternal wound infections after cardiac surgery.

Single-stage repair of the anterior chest wall following sternal destruction complicated by mediastinitis

PURPOSE

Although various techniques have been described, the ideal reconstructive procedure for treating massive sternal fragmentation and necrosis is still a matter of debate. Sometimes, reconstruction is so challenging that repetitive operations are required, particularly when complicated by mediastinitis and sternal osteomyelitis.

METHODS

Five patients (three males, two females, median age 66) with severe osteomyelitis and sternal destruction after receiving myocardial revascularization underwent partial or radical sternal resection, omental flap transposition, titanium mesh implantation and rectus abdominis muscle flap transposition. The final procedure involved single-stage closure.

RESULTS

One patient died 9 days after the final procedure due to pneumonia and septicemia. The other patients received antibiotics for at least 6 weeks postoperatively. The mean hospital stay was 36 days. Optimal wound healing was observed, with acceptable cosmetic disorders.

CONCLUSIONS

Although lateral sternal support is the first-line surgical treatment for sternal dehiscence, performing primary closure of complicated defects is often impossible. Aggressive treatment modalities are required in such cases for anterior chest wall defects. This technique provides the ability to perform rigid and stable sternal closure in complicated cases.

Poststernotomy mediastinitis and the role of broken steel wires: retrospective study

OBJECTIVE

Mediastinitis is a severe complication of cardiac surgery. Sternal instability is concomitantly present in most cases. Broken steel wires may cause sternal instability. In this study, the role of broken steel wires in sternal closure was evaluated in patients who developed poststernotomy mediastinitis.

METHODS

Preoperative, perioperative, and postoperative data of patients who underwent thoracic surgery between 1996 and 2006 were retrieved from the SUMMIT registry database. Patients needing reoperation for mediastinitis were identified. Patients' charts and chest radiographs from initial surgery to reoperation for mediastinitis were reviewed.

RESULTS

Forty-five patients developed postoperative mediastinitis needing reoperation (0.6%). Because of loss to follow-up, 31 patients were evaluated. Eight patients (25.8%) presented fractured steel wires. Most of the broken steel wires (87.5%) manifested at the cranial site of figure-of-eight configurations. In the patients without broken steel wires, mediastinitis manifested after 14 days compared with 38 days in the patients with broken wires. Time until mediastinitis was not significantly different (P = 0.229). The mean time until steel wire disruption was 14 days (range, 4-48 days).

CONCLUSIONS

Broken steel wires were observed before mediastinitis became manifest. Fracturing occurred mainly at the cranial site of figure-of-eight configurations. The results of the present study emphasize that closure technique plays a prominent role in the development of mediastinitis. Because mediastinitis is associated with an increased risk for early morbidity, attention should be paid to patients presenting with broken steel wires. New techniques for median sternotomy closure are needed that are less prone to mechanical fatigue than are steel wires.

Comparison of straight median sternotomy and interlocking sternotomy with respect to biomechanical stability

AIM: To increase the stability of sternotomy and so decrease the complications because of instability.

METHODS: Tests were performed on 20 fresh sheep sterna which were isolated from the sterno-costal joints of the ribs. Median straight and interlocking sternotomies were performed on 10 sterna each, set as groups 1 and 2, respectively. Both sternotomies were performed with an oscillating saw and closed at three points with a No. 5 straight stainless-steel wiring. Fatigue testing was performed in cranio-caudal, anterio-posterior (AP) and lateral directions by a computerized materials-testing machine cycling between loads of 0 to 400 N per 5 s (0.2 Hz). The amount of displacement in AP, lateral and cranio-caudal directions were measured and also the opposing bone surface at the osteotomy areas were calculated at the two halves of sternum.

RESULTS: The mean displacement in cranio-caudal direction was 9.66 ± 3.34 mm for median sternotomy and was 1.26 ± 0.97 mm for interlocking sternotomy, P < 0.001. The mean displacement in AP direction was 9.12 ± 2.74 mm for median sternotomy and was 1.20 ± 0.55 mm for interlocking sternotomy, P < 0.001. The mean displacement in lateral direction was 8.95 ± 3.86 mm for median sternotomy and was 7.24 ± 2.43 mm for interlocking sternotomy, P > 0.001. The mean surface area was 10.40 ± 0.49 cm² for median sternotomy and was 16.8 ± 0.78 cm² for interlocking sternotomy, P < 0.001. The displacement in AP and cranio-caudal directions is less in group 2 and it is statistically significant. Displacement in lateral direction in group 2 is less but it is statistically not significant. Surface area in group 2 is significantly wider than group 1.

CONCLUSION: Our test results demonstrated improved primary stability and wider opposing bone surfaces in interlocking sternotomy compared to median sternotomy. This method may provide better healing and less complication rates in clinical setting, further studies are necessary for its clinical implications.

External validity of the Society of Thoracic Surgeons risk stratification tool for deep sternal wound infection after cardiac surgery in a UK population

OBJECTIVES

Deep sternal wound infection (DSWI) is a devastating complication of cardiac surgery, with a historical incidence of 0.4-5%. Predicting which patients are at higher risk of infection may help instituting various preventive measures. Risk calculations for mortality have been used as surrogates to estimate the risk of deep sternal wound infection, with limited success. The Society of Thoracic Surgeons (STS) 2008 Risk Calculator modelled the risk of DSWI for cardiac surgical patients, but it has not been validated since its publication. We sought to assess the external validity of the STS-estimated risk of DSWI in a United Kingdom (UK) population.

METHODS

Using our prospectively captured database, we retrospectively calculated the risk of DSWI for 14 036 patients undergoing valve, coronary artery bypass grafts or combined procedures between February 2001 and March 2010. DSWI was identified according to the Centre for Disease Control and Prevention definition. The receiver operator characteristic (ROC) curve was employed to test the performance of the model using the area under the ROC curve (AUROC). The calibration of the model was interrogated using the Hosmer-Lemeshow test for Goodness of Fit.

RESULTS

A total of 135 (0.95%) patients developed DSWI. Although there was a statistically significant difference in the calculated risk of patients who contracted DSWI (0.44% ± 0.01) vs those who did not (0.28% ± 0.00, P < 0.0001), the AUROC of 0.699 (95% confidence interval: 0.6522-0.7414) denoted a modest discriminatory power, with the Hosmer-Lemeshow Goodness of Fit statistic (P < 0.001) suggesting poor calibration. A risk-adjusted modifier improved the calibration (P = 0.08).

CONCLUSIONS

The STS risk calculator lacks adequate discriminatory power for estimating the isolated risk of developing deep sternal wound infection in a UK population. The discrimination is similar to the tool's validation c-statistic and may have a place in an integrated calculator.

Transdiaphragmatic omental harvest: a simple, efficient method for sternal wound coverage

BACKGROUND

The greater omentum is easily harvested for coverage of sternal wounds without muscle sacrifice. Its major disadvantage is a laparotomy incision with potential bowel injury, adhesions, or hernia. Over the past 20 years, the authors' technique has evolved to use a transdiaphragmatic opening for omental harvest when possible.

METHODS

The authors performed a retrospective cohort analysis of 140 consecutive patients undergoing omental flap harvest for treatment of sternal wounds following median sternotomy. Patients were divided into two groups by access incision: laparotomy incision (n = 80) versus a transdiaphragmatic opening (n = 60).

RESULTS

The authors found that both techniques provided reliable closure of sternal wounds, but the transdiaphragmatic approach was faster, with less blood loss. There was no significant difference in rates of ventral hernias. We had only one bowel injury (laparotomy group) and no postoperative abdominal bleeding or small bowel obstruction.

CONCLUSION

Transdiaphragmatic omental harvest provides safe and efficient coverage of deep sternal wounds without a laparotomy incision.

Blood transfusion for lower extremity bypass is associated with increased wound infection and graft thrombosis

BACKGROUND

Packed RBC transfusion has been postulated to increase morbidity and mortality after cardiac/general surgical operations, but its effects after lower extremity bypass (LEB) have not been studied extensively.

STUDY DESIGN

Using the Vascular Study Group of New England's database (2003-2010), we examined 1,880 consecutive infrainguinal LEB performed for critical limb ischemia. Perioperative transfusion was categorized as 0 U, 1 to 2 U, and ≥3 U. Cohort frequency group matching was used to compare groups of patients receiving 1 to 2 U and 0 U with patients receiving ≥3 U using age, coronary artery disease, diabetes, urgency, and indication of revascularization. Primary end points were perioperative mortality, wound infection, and loss of primary graft patency at discharge, as well as 1-year mortality and loss of primary graft patency.

RESULTS

In the study cohort, 1,532 LEBs (81.5%) received 0 U, 248 LEBs (13.2%) received 1 to 2 U, and 100 LEBs (5.3%) received ≥3 U transfusion. In the study cohort and group frequency matched cohort, transfusion was associated with significantly higher perioperative wound infection (0 U:4.8% vs 1 to 2 U: 6.5% vs ≥3 U: 14.0%; p = 0.0004) and graft thrombosis at discharge (4.5% vs 7.7% vs 15.3%; p < 0.0001). At 1 year, there were no differences in infection or graft patency. In multivariate analysis, transfusion was independently associated with increased perioperative wound infection in the study cohort and group frequency matched cohort (1 to 2 U vs 0 U: adjusted odds ratio [OR] = 1.4; 95% CI, 0.8-2.5; p = 0.263; ≥3 U vs 0 U: OR = 3.5; 95% CI, 1.8-6.7; p = 0.0002; overall p = 0.002) and increased graft thrombosis at discharge (1 to 2 U vs 0 U: OR = 2.1; 95% CI, 1.2-3.6; p = 0.01; ≥3 U vs 0 U: OR = 4.8; 95% CI, 2.5-9.2; p < 0.0001, overall p < 0.0001).

CONCLUSIONS

Perioperative transfusion in patients undergoing LEB is associated with increased perioperative wound infection and graft thrombosis. From this observational study, it appears transfusion does not have major consequences during mid-term follow-up, but the presumed benefits of blood replacement should be weighed carefully because of the increased risk of perioperative complications with transfusion.

Preoperative hospital length of stay as a modifiable risk factor for mediastinitis after cardiac surgery

Background

As high-risk cardiac patients frequently remain within hospital while waiting for surgery, the aim of the present study was to determine the role of preoperative length of hospital stay on mediastinitis, and also, to assess contemporary risk factors for this complication.

Methods

The source population consisted of 6653 consecutive patients undergoing coronary bypass surgery, valve surgery, or both between September 2000 and September 2009 at a single tertiary care hospital. A retrospective cohort analysis was used to assess the effect of 18 preoperative variables, including length of stay, on mediastinitis.

Results

Mediastinitis developed in 108 patients (1.6%) resulting in an in-hospital mortality rate of 13.9%. Independent predictors of mediastinitis included obesity (2.59, CI 1.58-4.23), COPD (2.44, CI 1.55-3.84), diabetes (2.16, CI 1.44-3.24), and impaired estimated glomerular filtration rate. Preoperative hospital stay was also found to be an independent risk factor leading to a 15% increased risk of mediastinitis per week of stay. The primary wound pathogen was coagulase negative staphylococcus (82%) followed by multi-flora isolates (49%), but was unrelated to hospital stay.

Conclusions

In addition to the traditional risk factors, prolonged preoperative hospital stay is also a significant and potentially modifiable predictor for the development of mediastinitis following cardiac surgery. All efforts should be made to minimize the delay in operating on hospitalized patients awaiting heart surgery.

Temporal trends in the incidence of surgical site infections in patients undergoing coronary artery bypass graft surgery: a population-based cohort study, 1993 to 2008

OBJECTIVE

To determine the incidence of and temporal trends in surgical site infections (SSIs) in patients undergoing coronary artery bypass graft (CABG) surgery.

METHODS

A population-based cohort study was conducted to describe the epidemiologic features of SSI in Olmsted County, Minnesota, between January 1, 1993, and December 31, 2008, using the Rochester Epidemiology Project. Period-specific incidence rates (in-hospital or within 30 days outside the hospital) were calculated. Logistic regression analysis was used to adjust for potential confounders that could affect temporal trends in SSI incidence rates.

RESULTS

During the 16-year study, of 1424 residents of Olmsted County who underwent CABG surgery, 1189 (83%) had isolated CABG and 235 (17%) had combined CABG and valve surgery. The overall SSI incidence rate was 7.0% (95% confidence interval [CI], 5.7%-8.4%). The incidence rate of superficial sternal SSI was 2.0% (95% CI, 1.2%-2.7%) and of deep sternal SSI was 1.5% (95% CI, 0.9%-2.2%). The leg harvest site infection rate was 3.6% (95% CI, 2.6 %-4.5%). The incidence rate decreased over time with a statistically significant linear trend. The adjusted odds ratio (95% CI) of SSI showed a decreasing linear trend: 0.39 (0.19-0.81) vs 0.50 (0.27-0.93) vs 0.83 (0.48-1.42) vs reference for 2005-2008 vs 2001-2004 vs 1997-2000 vs 1993-1996.

CONCLUSION

In this population-based surveillance study of patients undergoing CABG surgery, the incidence of SSI decreased markedly between 1993 and 2008 in patients in Olmsted County. The factors responsible for this decrease are the focus of ongoing investigations.

Introduction to chest wall reconstruction: anatomy and physiology of the chest and indications for chest wall reconstruction

The chest wall functions as a protective cage around the vital organs of the body, and significant disruption of its structure can have dire respiratory and circulatory consequences. The past several decades have seen a marked improvement in the management and reconstruction of complex chest wall defects. Widespread acceptance of muscle and musculocutaneous flaps such as the latissimus dorsi, pectoralis major, serratus anterior, and rectus abdominis has led to a sharp decrease in infections and mortality. Successful reconstructions are dependent upon a detailed knowledge of the functional anatomy and blood supply of the chest and the underlying pathophysiology of a particular disease process. This article will provide an overview of key principles and evidence-based approaches to chest wall reconstruction.

Evolution in the treatment of mediastinitis: single-center experience

This study aimed to evaluate our 30-year experience in the treatment of deep sternal wound infection after cardiac surgery. Between 1979 and 2009, deep sternal wound infections occurred in 200 of 22,366 (0.89%) patients who underwent sternotomy. The study population was divided into 3 groups. In group A (62 patients; 1979–1994), an initial attempt at conservative antibiotic therapy was the rule, followed by surgery in case of failure. In group B (83 patients; 1995–2002), the treatment was in 3 steps: wound debridement and closed irrigation for 10 days; in case of failure, open dressing with sugar and hyperbaric treatment; delayed healing and negative wound cultures mandated plastic reconstruction. In group C (2002–2009), the treatment was based on early surgical debridement, vacuum application, and reconstruction using pectoralis muscle flap. Hospital mortality in group A was significantly higher than that in groups B and C. Hospital stay, time for normalization of white blood cell count and C reactive protein, and time for defervescence were significantly shorter in group C. In our experience, early surgical debridement and vacuum application followed by plastic reconstruction provided a satisfactory rate of healing and a good survival rate.

Mediastinitis after coronary artery bypass grafting risk factors and long-term survival

BACKGROUND

Mediastinitis is a severe complication of coronary artery bypass grafting. The aim of the present study was to determine incidence of mediastinitis, its risk factors, and its effect on early and long-term survival.

METHODS

The study has a dual design, a case-control, and a retrospective cohort, using a source population of 18,532 consecutive patients who underwent coronary artery bypass grafting from January 1989 to December 2000. The closing date was February 1, 2008. Median follow-up was 10.3 (range 8.1 to 18.9) years. Patients with mediastinitis were compared with a random control group without mediastinitis issued from the same source population in a ratio 1:4. The crude effect of mediastinitis was estimated using rate ratio and 95% confidence limits. Adjustment for multiconfounders was done with the Cox model. A logistic model was used to pinpoint risk factors of mediastinitis. Calibration and discrimination of a prognostic model was done.

RESULTS

One hundred seven patients (0.6%) developed mediastinitis. Diagnosis was made 12 (9 to 19) days postoperatively. Independent risk factors of mediastinitis using the logistic model were advanced age, male gender, left main stenosis, body mass index 30 kg/m(2) or greater, chronic obstructive pulmonary disease, diabetes, and increased amount of blood transfusion. There was no increased risk of early mortality (odds ratio = 0.58; 95% confidence interval 0.13 to 2.61) (p = 0.48) but there was increased risk of morbidity (intraaortic balloon pump, ventricular and supraventricular arrhythmia, stroke, inotrope, and myocardial infarction). Follow-up had a median observation time of 10.3 years. Survival for patients with mediastinitis was 49.5 +/- 5.0% versus 71.0 +/- 2.2% for controls (p < 0.01). Analysis of specific death causes documented that cardiac deaths were significantly more frequent in mediastinitis patients than in control patients. When controlling for the confounding effect of the other variables (age, cardiopulmonary bypass time, body mass index, chronic obstructive pulmonary disease), the hazard ratio associated with mediastinitis on long-term mortality was 1.59, 95% confidence limits (1.16 and 2.70) (p = 0.003).

CONCLUSIONS

The incidence of mediastinitis in 18,532 patients undergoing coronary artery bypass grafting surgery was low. The major preventable risk factor of mediastinitis was amount of blood transfusion. Mediastinitis had an excess risk of early morbidity and was associated with a significant reduced long-term survival. Most deaths were considered to be cardiac.

Postoperative Care of the Cardiac Surgical Patient

The subspecialty of interventional cardiology began in 1977. Since then, the discipline of interventional cardiology has matured rapidly, particularly with regards to ischemic heart disease. As a result, more patients are undergoing percutaneous catheter interventional therapy for ischemic heart disease and fewer patients are undergoing surgical myocardial revascularization. Those patients referred for surgical revascularization are generally older and have more complex problems. Furthermore, as the population ages more patients are referred to surgery for valvular heart disease. The result of these changes is a population of surgical patients older and sicker than previously treated.

A case of postcardiac injury syndrome presenting as acute mediastinitis

A 41-year-old man sought evaluation at the emergency department for pain in the anterior chest that had been ongoing for approximately 35 hours. The electrocardiogram showed marked ST segment elevation in the precordial leads. Cardiac biomarker levels were elevated. He subsequently underwent coronary angioplasty and stenting of the left anterior descending artery using two sirolimus-eluting stents. The following day, the patient complained of severe pain in his chest and shoulders. Computed tomography (CT) of the chest showed small gas bubbles around the aortic wall and mild pericardial thickening with subtle air densities, suggesting acute mediastinitis. With an impression of postcardiac injury syndrome and acute mediastinitis, he was treated with intravenous antibiotics and oral ibuprofen. Two days later, the patient had subjective improvement and the friction rub was no longer heard.

[The association of VAC® therapy, titanium plates osteosynthesis and bilateral pectoral muscle flaps in the management of postoperative mediastinitis in an obese and diabetic patient]

Postoperative mediastinitis is one of the most worrisome complications after heart surgery. Until now there is no universally accepted strategy in the management of this infectious complication. Recently, various novel techniques like negative pressure therapy and titanium plates sternal reconstruction have allowed a dramatic decrease of mortality and morbidity after mediastinitis. We report the case of a diabetic patient suffering from morbid obesity who developed a severe postoperative mediastinitis after a coronary artery bypass; she was successfully treated by combining negative pressure therapy, titanium plates osteosynthesis and bilateral pectoral muscle flaps.

Vacuum-assisted closure and bilateral pectoralis muscle flaps for different stages of mediastinitis after cardiac surgery

PURPOSE

To assess the results of bilateral pectoralis major muscle flaps (BPMMF) and vacuum-assisted closure (VAC) at different stages of postcardiac surgery mediastinitis.

METHODS

Of 65 patients with a deep sternal wound infection (DSWI) after cardiac surgery, 33 with a stable sternum were treated with VAC (59.3 +/- 11.7 years of age) and 32 with an unstable sternum or osteomyelitis (63.3 +/- 9.8 years of age) were treated with early BPMMF and continuous irrigation. Delayed BPMMF reconstruction was necessary in six VAC patients.

RESULTS

The overall incidence of DSWI was 1.04% within the study period. Deep sternal wound infection was diagnosed 15.9 +/- 10.8 days (range 5-62 days) after surgery. Diabetes was more common in the BPMMF group than in the VAC group (P = 0.046). Hospital mortality after treatment was 4.6% (n = 3) overall. Causes of death were septic multiorgan failure and respiratory failure. The infective pathogens were methicillin-resistant Staphylococcus aureus (MRSA; n = 2) and Acinetobacter species (n = 1). The median hospital stay was 29 days (range 15-110 days). After 6 months, only one recurrent sternal infection had occurred in the VAC group.

CONCLUSIONS

Early BPMMF is an effective surgical treatment for DSWI in patients with an unstable sternum and osteomyelitis. VAC may be considered for patients without osteomyelitis but a stable sternum, or as adjuvant therapy in patients with comorbidity.

Our experience using the vertical rectus abdominis muscle flap for reconstruction in 12 patients with dehiscence of a median sternotomy wound and mediastinitis

The vertical rectus abdominis (VRAM) flap has been used for reconstruction of sternal defects, particularly in the inferior third, since it was first described 20 years ago. We describe 12 patients with mediastinitis or chronic sternal osteomyelitis after sternotomy treated between 1994 and 1997, nine performed at the Royal Hospitals Trust, London. Sternal osteomyelitis and mediastinitis after median sternotomy is an uncommon (0.4%-8.4%) but often fatal condition. Vascularised pedicles are the treatment of choice, and VRAM flaps were used in all cases. We report good long-term outcome with a follow up of 2-5 years, and no long-term morbidity relating to the VRAM reconstruction. We had only one partial failure of a flap. The operations were largely done in hospitals away from the plastic surgical unit in extremely sick patients, which illustrates the importance of multidisciplinary management to reduce hospital stay, mortality, and morbidity. We argue that early involvement of plastic surgical specialists in the treatment of sternal dehiscence is essential to ensure a successful outcome.

Immediate versus delayed one-stage sternal débridement and pectoralis muscle flap reconstruction of deep sternal wound infections

BACKGROUND

The management of postoperative deep sternal wound infection varies widely based on the discretion of the cardiovascular surgeon and the plastic surgeon.

METHODS

Analysis of patients with deep sternal wound infection undergoing one-step radical sternal débridement and muscle flap reconstruction by a single plastic surgeon from 1986 to 2008 was conducted. Two groups of patients were identified. The immediate group was referred soon after diagnosis of sternal wound infection and without any débridement. The delayed group was referred much later after undergoing an extended management by their cardiovascular surgeon. Retrospective review was performed to compare morbidity, mortality, and length of stay between the two groups.

RESULTS

There were a total of 583 patients with deep sternal wound infection. Of the 497 patients referred immediately, 22 (4.4 percent) patients required mechanical ventilation for an average of 4 days, eight (1.6 percent) required tracheotomy, 13 (2.6 percent) developed stage III/IV pressure sores, 24 (4.8 percent) developed major wound dehiscence, zero (0 percent) required skin grafting, average length of stay was 4.7 days, and five died (1 percent). Of the 86 patients with a delayed referral, 40 (46.5 percent) required mechanical ventilation for an average of 18.3 days, 31 (36 percent) required tracheotomy, 20 (23.3 percent) developed stage III/IV pressure sores, 12 (14 percent) developed major wound dehiscence, nine (10.5 percent) required skin grafts, the average length of stay was 19.3 days, and four died (4.7 percent).

CONCLUSION

Patients with deep sternal wound infection following sternotomy benefit from one-step radical sternal débridement and muscle flap(s) reconstruction, as it results in a significant decrease in morbidity, mortality, and length of stay.

Sternal osteomyelitis: long-term results after pectoralis muscle flap reconstruction

BACKGROUND

Reports regarding long-term follow-up including quality-of-life assessment, pulmonary function, and donor-site morbidity after operative treatment for sternal osteomyelitis are rare.

METHODS

Data for 69 consecutive patients were acquired from patients' charts and contact with patients and general practitioners, with special reference to treatment and clinical course. Twenty-four patients were interviewed and physically examined (mean follow-up, 4 years; range, 1 to 9 years). Fifteen of the patients underwent pulmonary function tests, cine magnetic resonance imaging, and pectoralis strength testing using a dynamometer to record butterfly arm compressive movements. Statistical analysis was performed to identify factors influencing wound healing and survival.

RESULTS

Mortality rates were 10.1 percent at 30 days, 18.5 percent at 1 year, and 27.0 percent at 5 years (n = 69). In 36.2 percent of the patients, wound-healing difficulties requiring reoperation occurred. Independent of the extent of sternal resection, dynamic pulmonary function values were decreased compared with normal values (n = 15). Dynamometer assessment revealed decreases of 1.5 percent in dynamic maximum strength, 9.7 percent in maximum isometric strength, and 47.2 percent in strength endurance compared with the healthy age-matched control group. Magnetic resonance imaging showed no sign of recurrent osteomyelitis (n = 15). Muscle function was preserved in 93 percent of the patients. Eighty-three percent of the interviewed patients considered their general condition better and 17 percent considered it worse than before the treatment (n = 24).

CONCLUSIONS

Pectoralis muscle transfer represents a safe and simple procedure. Although strength loss and pain are considerable, quality of life is improved significantly. Pulmonary function impairment is most likely not exclusively attributable to the muscle transfer or the sternum resection.

Epidemiology of deep sternal wound infection in cardiac surgery

OBJECTIVES

The aim of this study was to investigate the incidence and predictors of deep sternal wound infection (DSWI) in a contemporary cohort of patients undergoing cardiac surgery. The early and late outcomes of patients with this complication also were analyzed.

DESIGN

A retrospective study of consecutive patients undergoing cardiac surgery using a computerized database based on the New York State Department of Health registry. Data collection was performed prospectively.

SETTING

A university hospital (single institution).

PARTICIPANTS

Five thousand seven hundred ninety-eight patients who underwent cardiac surgery between January 1998 and December 2005 including isolated coronary artery bypass graft (CABG) (n = 2,749, 47%), single- or multiple-valve surgery (n = 1,280, 22%), combined valve and CABG procedures (n = 934, 16%), and surgery involving the ascending aorta or the aortic arch (n = 835, 15%).

INTERVENTIONS

None.

MEASUREMENTS AND MAIN RESULTS

The overall incidence of DSWI was 1.8% (n = 106). The highest rate of DSWI occurred after combined valve/CABG surgery (2.4%, n = 22) and aortic procedures (2.4%, n = 19). Multivariate analysis revealed 11 predictors of DSWI: obesity (odds ratio [OR] = 2.2), previous myocardial infarction (OR = 2.1), diabetes (OR = 1.7), chronic obstructive pulmonary disease (OR = 2.3), preoperative length of stay >3 days (OR = 1.9), aortic calcification (OR = 2.7), aortic surgery (OR = 2.4), combined valve/CABG procedures (OR = 1.9), cardiopulmonary bypass time (OR = 1.8), re-exploration for bleeding (OR = 6.3), and respiratory failure (OR = 3.2). The mortality rate was 14.2% (n = 15) versus 3.6% (n = 205) in the control group (p < 0.001). One- and 5-year survival after DSWI were significantly decreased (72.4% +/- 4.4% and 55.8% +/- 5.6% v 93.8% +/- 0.3% and 82.0% +/- 0.6%, p < 0.001).

CONCLUSION

DSWI remains a rare but devastating complication and is associated with significant comorbidity, increased hospital mortality, and reduced long-term survival.

Aggressive treatment using muscle flaps or omentopexy in infections of the sternum and anterior mediastinum following sternotomy

OBJECTIVE

To evaluate the impact of an aggressive treatment approach using muscle flaps or omentopexy in infections of the sternum and anterior mediastinum following sternotomy on mortality, as compared to that of a conservative treatment approach.

METHODS

Data were collected prior to, during and after the surgical procedures. Group A (n = 44) included patients submitted to conservative treatment-debridement together with resuture or continuous irrigation with polyvinylpyrrolidone-iodine solutions, or even with second-intention wound healing (retrospective data). Group B (n = 9) included patients in whom infection was not resolved with conservative treatment, and who therefore underwent aggressive treatment (intermediate phase). Group C (n = 28) included patients primarily submitted to aggressive treatment (prospective data).

RESULTS

Postoperative hospital stays were shorter in the patients submitted to aggressive treatment (p < 0.046). There were 7 deaths in group A, 1 in group B, and 2 in group C. However, the classical level of significance of alpha = 0.05 was not reached.

CONCLUSION

Aggressive treatment also proved to be effective when the infection was not resolved with conservative treatment. These findings demonstrate that the proposed treatment provides excellent results.

Sternotomy wounds: rectus flap versus modified pectoral reconstruction

BACKGROUND

Infected sternotomy wounds occur in 0.5 to 8.4 percent of open heart operations. They are complex problems, with a mortality rate of 8.1 to 14.8 percent despite flap closure. For closure, the pectoralis major flap has had considerable success. However, in providing coverage to the lower third of the sternum, it may be deficient. Modifications to improve closure have included a rectus flap or an anterior rectus fascia extension to the pectoralis flap.

METHODS

This retrospective study of 130 consecutive sternotomy wounds compares 41 bilateral pectoralis major muscle flaps with a modified anterior rectus fascia extension against 56 rectus abdominis muscle flaps alone in addressing the lower third of the sternum following dehiscence.

RESULTS

Pectoralis flaps with rectus fascia extension and rectus flaps have similar success, postoperative course, and morbidity and mortality rates. The pectoralis flaps with rectus fascia extensions prevented superior dehiscence, but this modification does not eliminate dehiscence of the distal third of the sternum.

CONCLUSIONS

The rectus muscle alone proved superior in coverage to the inferior sternum. Sternal wounds should be covered preferentially by a pectoralis flap to cover a superior infection and by a rectus flap if the dehiscence is localized to the distal third.

Sternal closure reinforced with rib heads: a novel technique for prevention and treatment of sternal dehiscence

BACKGROUND

When a sternotomy cannot be performed at the midline and/or there is infection at the operation site, sternotomy revision can cause problems that increase the mortality and morbidity of the patients. There is no agreement on the best treatment method. In this paper we present a modified wiring technique.

METHODS

This technique consisted of wrapping wires twice around each rib head and placing standard circumferential wire sutures, thus providing full stability by decreasing the load on the sternum using only steel wires. The study group included 23 patients with sternal dehiscence because of inappropriate sternotomy (n = 10) and/or mediastinitis (n = 13). Two mediastinal tubes were placed for irrigation in 13 patients with mediastinitis and/or wound infection, and mobilization and interposition of omentum as an axial graft was performed in 2 patients. Irrigation and antibiotherapy were continued for 4 to 6 weeks.

RESULTS

Complete wound healing was obtained in all patients. Twenty-two patients treated with this technique survived. One patient died on postoperative 42nd day because of renal insufficiency and multi-organ failure.

CONCLUSION

Early and aggressive debridement of infected and necrotic tissue, irrigation, and antibiotics are necessary for successful treatment, but we believe that the most important factor is full stabilization of the sternal tissue with minimal use of foreign stabilization material. Despite the limited number of cases, we suggest that our stabilization technique seems to be successful in achieving full stabilization even in infected and fragile sternal bony tissue in patients with sternal dehiscence and/or inappropriate sternotomy.

Article Commentary: Strategies in the Prevention and Management of Ventilator-Associated Pneumonia

Ventilator-associated pneumonia (VAP) is a leading cause of morbidity and mortality in the intensive care unit. Prevention of VAP is possible through the use of several evidence-based strategies intended to minimize intubation, the duration of mechanical ventilation, and the risk of aspiration of oropharyngeal pathogens. Current data favor the quantitative analysis of lower respiratory tract cultures for the diagnosis of VAP, accompanied by the initiation of broad-spectrum empiric antimicrobial therapy based on patient risk factors for infection with multi-drug-resistant pathogens and data from unit-specific antibiograms. Eventual choice of antibiotic and duration of therapy are selected based on culture results and patient stability, with an emphasis on minimization of unnecessary antibiotic use.

Use of both internal thoracic arteries in diabetic patients increases deep sternal wound infection

BACKGROUND

Use of both internal thoracic arteries has been limited in diabetic patients fearing an increased incidence of deep sternal wound infection. We analyzed this concern by querying The Society of Thoracic Surgeons Database.

METHODS

Diabetic patients who had isolated coronary artery bypass graft surgery during 2002 to 2004 were included if they had no prior bypass surgery, two or more distal bypasses, and a left internal thoracic artery bypass. Group B (both internal thoracic arteries) was compared with group L (left internal thoracic artery only).

RESULTS

The incidence of deep sternal wound infection for all patients undergoing isolated first-time bypass surgery was less than 1%. Of these, 120,793 patients met criteria for inclusion: group B, 1.4% (1732); and group L, 98.6% (119,061). Group B had a higher crude (unadjusted) deep sternal wound infection rate of 2.8% (49) versus 1.7% (1969; p = 0.0005) in group L, with an estimated odds ratio of 2.23 (95% confidence interval, 1.69 to 2.96). Group B had a similar crude mortality rate of 1.7% (30) versus 2.3% (2785; p = NS) in group L, with an estimated odds ratio of 1.110 (95% CI, 0.78 to 1.59; p = NS). Patients in group B were younger, mostly male, had a lower serum creatinine level, and were more often current smokers; less commonly, they were insulin dependent, diagnosed with pulmonary or vascular disease, or on dialysis. Other risk factors for deep sternal would infection included female gender, insulin dependence, peripheral vascular disease, recent infarction, body mass index exceeding 35 kg/m2, and use of blood products.

CONCLUSIONS

There is a significant increase in the incidence of deep sternal would infection in diabetic patients. This is further increased with the use of both internal thoracic arteries with no apparent short-term mortality difference.

Mediastinitis after more than 10,000 cardiac surgical procedures

BACKGROUND

Poststernotomy mediastinitis as a complication is rare but disastrous. We assessed incidence, predisposing factors for, and outcome from, mediastinitis after cardiac surgery.

METHODS

We studied 10,713 consecutive patients who underwent open-heart surgery from 1990 to 1999 in a tertiary care university hospital using data prospectively recorded in the hospital discharge register, operating room log, and the hospital's cardiothoracic surgery unit register. Those cases with possible mediastinitis were identified from the hospital infection register and discharge register. Patients' charts were reviewed and cases of mediastinitis confirmed based on criteria of the Centers for Disease Control and Prevention.

RESULTS

The overall rate of mediastinitis was 1.1% (120 cases), and higher in coronary artery bypass surgery than in valvular surgery (1.2 vs 0.8%). No trend in incidence was detectable, although surgical patients became progressively older (mean age, 59 to 65 years, p < 0.01), and the proportion of women (from 25% to 31%; p < 0.01) and of patients with American Society of Anesthesiologists score over 3 (from 10% to 81%, p < 0.01) both increased. The rate of mediastinitis was almost twice as high in men (1.2% vs 0.7%, p < 0.01). In three body mass index (BMI) categories (<25, 25 to 30, and >30 kg/m2), rates of mediastinitis were 0.5%, 1.0%, and 1.8%. In multivariate analysis adjusted for age, sex, year, operation type, and perfusion time, the only predictor for mediastinitis was BMI.

CONCLUSIONS

Mediastinitis is not diminishing. Larger populations at risk, for example proportions of overweight patients, reinforce the importance of surveillance and pose a challenge in focusing preventive measures.

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.

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.

Chronic encapsulated mediastinal abscess presenting with remote cutaneous fistulization 12 years after redo aortic valve replacement for prosthetic valve endocarditis

Chronic encapsulated mediastinal abscess is an unusual complication of previous open heart surgery. We report on the case of a 79 year old male who presented with epigastric fistulization of an encapsulated anterior mediastinal abscess 12 years after a redo aortic valve replacement for prosthetic valve endocarditis. The encapsulated abscess and its complex branching tracts and the cutaneous fistula were excised completely except the thin longitudinal strip of the ascending aorta which formed part of the posterior wall of the infected tract. This was covered with transposed greater omentum based on right gastroepiploic artery pedicle. Patient remains fit and well 2 years after his operation.

This report is unusual on account of the length of the interval between previous heart surgery and the infective complication, the presumed dormancy of the abscess for as long as 12 years, the complex course, branching tracts and the contents of the abscess, the remote fistulization of the abscess at a distant anatomical site and, finally, the principle of successfully covering an infected tract which formed the adventia of the ascending aorta with pedicled omentum in the hope of avoiding an ascending aortic replacement in a frail 79 year old man.

In the entire English language literature, this report represents the longest interval between a heart operation and a sternal or mediastinal abscess

Anemia management program reduces transfusion volumes, incidence of ventilator-associated pneumonia, and cost in trauma patients

BACKGROUND

Strategies to restrict transfusions are gaining acceptance in critical care. We implemented an anemia management program (AMP) for trauma patients in the Surgical Intensive Care Unit. AMP was based on a transfusion trigger of 7 g/dL hemoglobin once hemodynamic sufficiency was achieved. We hypothesized that AMP would decrease the transfusion of packed red blood cells (PRBCs) and cost without detriment in clinical outcomes.

METHODS

Transfusion data were retrospectively collected for all trauma patients treated in our Surgical Intensive Care Unit between July 2002 and December 2003. AMP was implemented in a step-wise fashion during a 6-month period (January to June 2003). Data were compared for the 6-month period before (Group I, July to December 2002) and after (Group II, July to December 2003) complete AMP implementation. Blood transfusion volumes were compared using negative binomial regression. Clinical outcomes (length of stay [LOS], death, myocardial infarction [MI], and ventilator-associated pneumonia [VAP]) were compared using risk ratios. Age, sex, and injury severity score (ISS) were examined as potential confounders.

RESULTS

In all, 514 trauma patients were treated during the study period (n = 270 in Group I and n = 244 in Group II). Group I and Group II were similar in age (mean: 43.6 versus 42.9) and ISS (mean: 18.3 versus 17.0). Mean PRBCs per patient transfused decreased from 23.1 units to 17.1 units (p = 0.057), reflecting a 22.5% reduction adjusted for confounders (p = 0.097). Outcome data revealed no differences in LOS (mean: 6.4 versus 5.9, p = 0.920), risk of death (4.1% versus 6.1%, p = 0.158), or MI (0.7% versus 0.8%, p = 0.974), but a significant reduction in the incidence of VAP (8.1% versus 0.8%, p = 0.002). Total PRBC cost decreased during the study period from 503,000 dollars to 397,000 dollars.

CONCLUSIONS

An anemia management program appears to be safe when applied in the acute ICU phase of trauma care. Implementation of AMP in the ICU reduced the volume of PRBCs transfused with significant cost savings. No significant differences in length of stay, mortality rate, or MI rate were seen. The significant decrease in the rate of VAP requires further elucidation. Further long-term and larger studies are indicated.

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.

Laparoscopic Harvest of an Omental Flap to Reconstruct an Infected Sternotomy Wound

Sternotomy dehiscence is associated with a high mortality rate. In most cases this complication may be treated by simple debridement and antibiotic therapy, but sometimes it is necessary to fill the sternal defect with viable tissue. The greater omentum seems to be the ideal tissue to be transposed because of its malleability, good vascularization, and high lymphatic tissue content. The transposition of the greater omentum usually requires a midline laparotomy for the preparation of the flap, with significant laparotomy-related morbidity. Laparoscopic access may represent an effective alternative for preparing and transposing the omental flap. The key points of the laparoscopic technique are (1) the coloepiploic detachment, (2) the section of the anastomotic arterial branches between the Barkow's arcade and the gastroepiploic arcade, (3) the mobilization of the greater omentum pedicled on the right gastroepiploic artery, and (4) its transposition into the mediastinum, taking care to avoid twisting the gastric greater curvature and the flap itself.