Is the Use of BIMA in CABG Sub-Optimal? A Review of the Current Clinical and Economic Evidence Including Innovative Approaches to the Management of Mediastinitis.

Bilateral internal mammary artery (BIMA) in coronary artery bypass grafting (CABG) has traditionally been limited. This review looks at the recent outcome data on BIMA in CABG focusing on the management of risk factors for mediastinitis, one of the potential barriers for more extensive BIMA utilization. A combination of pre-, intra- and postoperative strategies are essential to reduce mediastinitis. Limited data indicate that the incidence of mediastinitis can be reduced using closed incision negative-pressure wound therapy as a part of these strategies with the possibility of offering patients best treatment options by extending BIMA to those with a higher risk of mediastinitis. Recent economic data imply that the technology may challenge the current low uptake of BIMA by reducing the short-term cost differentials between single internal mammary artery and BIMA. Given that most published randomized controlled trials and meta-analyses of observational long-term outcome data favor BIMA, if short-term complications of BIMA including mediastinitis can be controlled adequately, there may be opportunities for more extensive use of BIMA leading to improved long-term outcomes. An ongoing study looking at BIMA in high-risk patients may provide evidence to support the hypothesis that mediastinitis should not be a factor in limiting the use of BIMA in CABG.

Assessment of Prognosis in Odontogenic Descending Necrotizing Mediastinitis: A Longitudinal Retrospective Study.

Background: Descending necrotizing mediastinitis [DNM] is a serious complication of odontogenic infections, being associated with a high mortality rate. The diagnosis, classification, and management depend on computed tomography [CT] findings. Incision, drainage, and debridement represent the principal management. This study aimed to assess the prognosis in odontogenic DNM. Methods: The DNM type I was managed by transcervical mediastinal drainage, while in DNM type II, a right or left posterolateral thoracotomy was used. Data were compared among survivors and deceased to detect the risk factors affecting the prognosis. Results: This study included 63 patients. Transcervical mediastinal drainage was performed in 57 patients with Endo Type I while drainage through a right posterolateral thoracotomy was performed in the other five patients with Endo Type I and one patient with Endo Type IIA. Of patients in the study, 82.5% survived while 17.5% died because of multiple organ failure. Multiple complications and severe sepsis or septic shock as risk factors were statistically significant. Conclusion: A CT scan is the modality of choice for diagnosis and classification of DNM. Incision and drainage of the maxillofacial infection with mediastinal drainage and debridement represent the main management. Multiple complications and severe sepsis or septic shock were associated with poor prognosis.

Impact of Medicare's payment policy on mediastinitis following coronary artery bypass graft surgery in US hospitals.

BACKGROUND: The Centers for Medicare and Medicaid Services (CMS) implemented a policy in October 2008 to eliminate additional Medicare payment for mediastinitis following coronary artery bypass graft (CABG) surgery. OBJECTIVE: To evaluate the impact of this policy on mediastinitis rates, using Medicare claims and National Healthcare Safety Network (NHSN) prospective surveillance data. METHODS: We used an interrupted time series design to compare mediastinitis rates before and after the policy, adjusted for secular trends. Billing rates came from Medicare inpatient claims following 638,761 CABG procedures in 1,234 US hospitals (January 2006-September 2010). Prospective surveillance rates came from 151 NHSN hospitals in 29 states performing 94,739 CABG procedures (January 2007-September 2010). Logistic regression mixed-effects models estimated trends for mediastinitis rates. RESULTS: We found a sudden drop in coding for index admission mediastinitis at the time of policy implementation (odds ratio, 0.36 [95% confidence interval (CI), 0.23-0.57]) and a decreasing trend in coding for index admission mediastinitis in the postintervention period compared with the preintervention period (ratio of slopes, 0.83 [95% CI, 0.74-0.95]). However, we saw no impact of the policy on infection rates as measured using NHSN data. Our results were not affected by changes in patient risk over time, heterogeneity in hospital demographics, or timing of hospital participation in NHSN. CONCLUSIONS: The CMS policy of withholding additional Medicare payment for mediastinitis on the basis of claims-based evidence of infection was associated with changes in coding for infections but not with changes in actual infection rates during the first 2 years after policy implementation.

Acute kidney injury following coronary artery bypass grafting: early mortality and postoperative complications.

OBJECTIVES: To investigate the prognostic importance of acute kidney injury on early mortality, postoperative stroke, and mediastinitis in patients undergoing a first isolated coronary artery bypass grafting. DESIGN: 7594 patients undergoing coronary artery bypass grafting with information on pre- and postoperative serum-creatinine values were included. Patients were classified using the Acute Kidney Injury Network classification. Odds ratios (OR) for mortality and postoperative complications within 60 days of surgery were calculated after adjustment for confounders separately for stage 1 and for stages 2 and 3 together. RESULTS: 1047 (14%) patients developed acute kidney injury. There were 132 (1.7%) deaths, 103 (1.4%) strokes and 118 (1.6%) cases of mediastinitis during follow-up. Among patients in stage 1 the adjusted odds ratio for death was 4.36 (95% confidence interval 2.83-6.71) and for stage 2 plus 3; 21.5 (12.0-38.6) compared to patients without acute kidney injury. Corresponding OR for stroke were 2.34 (1.43-3.82) and 6.52 (2.97-14.3) and for mediastinitis 2.88 (1.84-4.50) and 4.68 (2.07-10.6), respectively. CONCLUSIONS: Acute kidney injury following coronary artery bypass grafting is related to postoperative mortality, stroke, and mediastinitis. Patients undergoing coronary artery bypass grafting should be assessed for presence of acute kidney injury postoperatively, in order to predict early prognosis.

Changes in cardiac pumping efficiency and intra-thoracic organ volume during negative pressure wound therapy of sternotomy wounds, assessment using magnetic resonance imaging.

Knowledge on the effects of negative pressure wound therapy (NPWT) on the intra-thoracic organs is limited. The present study was performed to investigate the effects of NPWT on the volume of the intra-thoracic organs, using magnetic resonance imaging (MRI), in a porcine sternotomy wound model. Six pigs underwent median sternotomy followed by NPWT at -75, -125 and -175 mmHg. Six pigs were not sternotomised. MR images covering the thorax and heart were acquired. The volumes of the thoracic cavity, lungs, wound fluid and heart were then determined. The volumes of the thoracic cavity and intra-thoracic organs increased after sternotomy and decreased upon NPWT application. The total heart volume variation, which is inversely related to cardiac pumping efficiency, was higher after sternotomy and decreased during NPWT. NPWT did not result in the evacuation of wound fluid from the bottom of the wound. NPWT largely closes and restores the thoracic cavity. Cardiac pumping efficiency returns to pre-sternotomy levels during NPWT. This may contribute to the clinical benefits of NPWT over open-chest care, including the stabilizing effects and the reduced need for mechanical ventilation.

Surgeon involvement in the care of patients deemed to have "preventable" conditions.

BACKGROUND: As of October 1, 2008, the Centers for Medicare and Medicaid Services stopped payment for 8 "preventable" conditions: retained foreign body, air embolism, blood incompatibility, catheter-associated urinary tract infection, pressure ulcer, vascular catheter-associated infection, mediastinitis, and hospital fall. Our hypothesis was that surgeons are frequently involved in the care of patients deemed to have "preventable" conditions. STUDY DESIGN: This is a retrospective cohort of patients with "preventable" conditions identified from 2004 California and New York discharge data. The proportion of patients who required a surgical procedure during the index hospital stay was then determined. RESULTS: "Preventable" conditions were identified in 286,509 (4%) of 6,618,637 total patient discharges, of which 224,073 (78.2%) were insured by Medicare or Medicaid. A surgical procedure was performed in 168,886 (59.5%) patients. In the subset that developed a "preventable" condition during the index hospital stay, 1 or more surgical procedures were performed in 100% of patients with mediastinitis; 96% of patients with retained foreign bodies; 96% of patients with air embolism; 92% of patients with vascular catheter-associated infections; 79% of patients with blood incompatibility; 70% of patients with catheter-associated urinary tract infections; and 65% of patients with pressure ulcers. The most common surgical procedures were cardiovascular, gastrointestinal, and respiratory. CONCLUSIONS: A large number of patients are coded as having "preventable" conditions, and surgeons are frequently involved in their care. Nonpayment for "preventable" conditions may lead hospitals and surgeons to avoid complex procedures, refuse care to high-risk patients, or both.

Use of steel bands in sternotomy closure: implications in high-risk cardiac surgical population.

A retrospective-prospective descriptive and comparative study of two sternal closure techniques in a population of 621 patients divided into: group A, steel band closure (n=300) and group B, conventional technique closure (n=321), was carried out between January 2005 and December 2007 in order to describe and compare the results of both techniques in high-risk patients for sternal dehiscence and mediastinitis. Differences between both groups and association with risk factors were obtained using non-parametric tests for statistical analysis. No complications or mortality related to the use of the steel sternal bands were found. A statistically significant difference was found in the frequency of sternal dehiscence between both groups (P=0.022) in favor of group A. Although the frequency of mediastinitis was higher in group B, a statistically significant difference could not be established in terms of this complication. Sternal dehiscence was found to be a risk factor for mediastinitis. This study demonstrates that the use of steel bands for median sternotomy closure is a safe, reliable and reproducible technique. The frequency of sternal dehiscence significantly decreases with this technique in high-risk patients.

[Mediastinitis following cardiac surgery. Patient insurance reports]. / Mediastinitis efter hjertekirurgi. Et patientforsikringsmateriale.

INTRODUCTION: Mediastinitis in cardiac surgery is a well-known complication associated with high morbidity, invalidity, and mortality. Since the establishment by law of patients insurance in Denmark 1992, it has been possible to get compensation in some instances. MATERIALS AND METHODS: During a period of 8 years (1996-2003) 30 cases of mediastinitis were reported to the Danish Patient Insurance Association (DPIA). The initial cardiac operations consisted of 28 coronary artery bypass graft operations (CABG), 1 CABG associated with substitution of the aortic valve, and 1 CABG with cryoablation because of atrial fibrillation. The median preoperative mortality risk (EuroSCORE) was 2 (0-6+). The treatment of mediastinitis consisted of open revision or closed rinsing-system and of vacuum assisted closure in the later part of the period. RESULTS: Eighty percent of the patients had a transposition of thoracic muscle undertaken as a compensation for the lack of sternum. The median number of universal anaesthesias was 23 (3-32). The median admission time was 73 days (21-180), hospital mortality was 6.7%. A patient may receive compensation for an injury sustained during treatment if: 1) the best specialist would have acted differently, 2) the injury was caused by defect or malfunction of equipment, 3) the injury could have been prevented by using a different similar method of treatment, or 4) the patient had suffered more than is acceptable given the severity of the disease. Seventeen claims were approved (57%), the remainders were rejected. The criteria for acceptance according to the law of patient insurance are presented. In the actual period 511 cases of deep sternal infection after cardiac surgery were reported to the Danish Patient Registry. CONCLUSION: The majority of mediastinitis cases were not reported to the DPIA. The parties involved (patients, patient advisors, general practitioners, and hospital departments) are asked to concentrate on the need of reporting these cases to the DPIA.

The cost of vacuum-assisted closure therapy in treatment of deep sternal wound infection.

OBJECTIVES: Surgical sites infections are very expensive and the total costs for coronary artery bypass grafting (CABG) surgery followed by deep sternal wound infection (DSWI) with conventional therapy are estimated to be 2.8 times that for normal, CABG surgery. Promising results have been reported with vacuum-assisted closure (VAC) therapy in patients with DSWI. This study presents the cost of VAC therapy in patients with DSWI after CABG surgery. DESIGN: Thirty-eight CABG patients with DSWI, between 2001 and 2005, were treated with VAC therapy. The cost of surgery, intensive care, ward care, laboratory tests and other costs were analyzed. RESULTS: No three-month mortality or recurrent infection was observed. The average cost of CABG procedure and treatment of DSWI was 2.5 times higher than the mean cost of CABG alone. No significant correlations were found between the preoperative EuroSCORE and the cost of DSWI therapy. CONCLUSIONS: VAC therapy for patients who underwent CABG surgery followed by DSWI seems to be cost effective, and has low mortality rate.

Regarding three cases of descending necrotizing mediastinitis: spiral CT assessment.

Descending necrotizing mediastinitis (DNM) is a rare and life-threatening complication of deep neck space infection which occurs when infection spreads from the deep spaces of the neck, propagating within the soft tissue into the mediastinal spaces. The disease has a high mortality rate due to frequent delay in diagnosis and treatment. Computed Tomography (CT) is important in determining the level of infection, showing the presence and extension of fluid collections (with or without gas bubbles) and diffuse soft-tissue infiltration of the mediastinal fat, and indicating the best surgical approach and progress of treatment. Three cases of DNM evaluated with spiral CT from June 1999 to June 2001 are presented.

Vacuum-assisted closure as a treatment modality for infections after cardiac surgery.

OBJECTIVE: Wound infections after cardiac surgery carry high morbidity and mortality. A plethora of management strategies have been used to treat such infections. We assessed the impact of vacuum-assisted closure on the management of sternal wound infections in terms of wound healing, duration of vacuum-assisted closure, and cost of treatment. METHODS: Between November 1998 and June 2001, a total of 27 mediastinal infections were managed with vacuum-assisted closure. Group A (n = 14) had vacuum-assisted closure as the final treatment modality, whereas in group B (n = 13) vacuum-assisted closure was followed by either a myocutaneous flap (n = 8) or primary (n = 5) wound closure. The choice of additional treatment modality was based on wound size. RESULTS: In group A, 4 patients died and a satisfactorily healed scar was achieved in 64% of cases. Median durations of vacuum-assisted closure and hospital stay in group A were 13.5 days (interquartile range 8.8-32.2 days) and 20 days (interquartile range 16.7-25.2 days), respectively. Mortality was 7.7% in group B, with a treatment failure rate of 15%. Median duration of vacuum-assisted closure in group B was 8 days (interquartile range 5.5-18 days), and median hospital stay was 29 days (interquartile range 25.8-38.2 days). During the year before institution of vacuum-assisted closure, poststernotomy infection (n = 13) was managed with rewiring and closed irrigation system. Treatment during this year failed in 30.7% of cases (n = 4/13), and mortality was also 30.7%. The total cost (hospitalization and treatment) per patient for vacuum-assisted closure was 16,400 dollars, compared with 20,000 dollars for the closed irrigation system treatment. CONCLUSION: Vacuum-assisted closure, used alone or before other surgical treatment strategies, is an acceptable treatment modality for infections in cardiac surgery with reasonable morbidity, mortality, and cost.

Assessment of the diagnostic capacity of planar scintigraphy and SPECT with 99mTc-HMPAO-labelled leukocytes in superficial and deep sternal infections after median sternotomy.

Sternal infection is a rare complication of median sternotomy but is associated with considerable morbidity and mortality, particularly in the case of deep sternal infection (mediastinitis). Successful treatment depends on early diagnosis and on the location (deep or superficial) of the infection. Radiological techniques have many limitations, and although 67Ga scintigraphy is effective, it delays diagnosis by 48 h. We assessed the diagnostic capacity of planar scintigraphy and single photon emission computed tomography (SPECT) with 99mTc-hexamethylpropylene amine oxime (HMPAO)-labelled leukocytes in deep sternal infections after median sternotomy. We prospectively studied 41 patients with clinical suspicion of deep sternal infection 4 and 20 h after administration of the tracer. The final diagnosis was deep sternal infection in nine patients and superficial sternal infection in 10, with infection being ruled out in 22 patients. Planar scintigraphy did not detect any of the deep sternal infections at either 4 h or 20 h. SPECT correctly identified eight of the nine deep sternal infections at 4 h and all seven at 20 h, with no false positive results. Planar scintigraphy identified 16 of the 18 superficial sternal infections at 4 h and all of them at 20 h. SPECT identified 17 of these 18 infections at 4 h and all of them at 20 h. Other infections unrelated to the sternotomy were identified in seven patients. Leukocytes labelled with 99mTc-HMPAO are a highly reliable method for the early diagnosis of sternal infections after median sternotomy. Use of SPECT allows determination of the depth of the infection and differentiation of superficial from deep sternal infections. It is also possible to detect other sites of infection, thus providing alternative diagnoses.

[Clinical manifestations and lethality of descending necrotizing mediastinitis]. / Manifestaciones clínicas y letalidad de la mediastinitis necrosante descendente.

OBJECTIVE: To describe the clinical manifestations, treatment and lethality of a series of patients with descending necrotizing mediastinitis (DNM). DESIGN: Retrospective study of a series of cases. SITE OF STUDY: The Infectious Diseases Hospital (IDH) of the Mexican Social Security Institute, Mexico City; a national reference hospital. PATIENTS AND METHODS: From January 1996 through December 1998, 18 consecutive patients with diagnostic criteria for DNM were treated in the IDH. Demographic variables, precedents, clinical manifestations, characteristics of paraclinical studies, and treatment results were recollected from the chart of each patient. We made a comparison between patients who survived and the patients who died. RESULTS: The mean age of the patients was 48.8 +/- 19.1 years; 13 (72.5%) were men. Nine (50%) had an underlying disease, being diabetes mellitus the most frequent one. In 13 (72.5%) cases an odontogenic abscess was the original infection; three (16.6%) patients had retropharyngeal abscesses. The mean time between the beginning of symptoms and admission to the hospital was 10.6 +/- 6.7 days. The most frequent symptoms were fever, dyspnea, dysphagia, and hypotension. The treatment was medical and surgical in all cases, with antibiotics, thoracotomy, drainage and debridement. The most frequent complications were septic shock, nosocomial pneumonia and ARDS. Nine patients died, the lethality rate was 50%. Patients who died had, at admission lower leukocytes and platelets counts; higher glycemia, and developed more frequently cardiovascular complications and septic shock. CONCLUSIONS: Odontogenic abscesses are the most frequent primary infections in patients with DNM. This is an infectious problem with high lethality. Septic shock is the principal cause of death.

Recycling of cardiopulmonary bypass cannulae: a risk-benefit analysis.

OBJECTIVE: To determine whether recycling of arterial and venous cannulae for cardiopulmonary bypass is associated with an increased risk of infectious complications after open heart surgery. DESIGN: A prospective, risk-benefit analysis. SETTING: A university teaching hospital. PATIENTS: Five hundred and forty patients underwent a variety of non-transplant cardiac operations, which were performed by one surgeon between October 1988 and July 1993. INTERVENTIONS: Standard techniques of open heart surgery were used. Ascending aortic and vena caval cannulae and the multiple perfusion device for administering cardioplegia down saphenous vein bypass grafts were reused an average of 10 to 15 times after sterilization with ethylene oxide after each use. MAIN OUTCOME MEASURES: The postoperative morbidity and mortality and the estimated savings achieved by recycling the cannulae. RESULTS: The operative mortality (total in hospital plus within 30 days of operation) was 2.8% (15 patients). There were no cases of endocarditis; there was only one case of superficial presternal infection and one case of mediastinitis. Gram-negative organisms were cultured from the blood of two patients and gram-positive organisms from the blood of one patient. Only one patient died of an infectious complication. The estimated cost saving during the study period was more than $50,000. CONCLUSIONS: The risk of wound and hematogenous infection after open heart surgery in which recycled cannulae are used is less than 1%. This rate is lower than that quoted in most recent reports. Reuse of heart-lung bypass cannulae may realize substantial cost savings without detriment to the patient.

Diagnosis of poststernotomy infection: comparison of three means of assessment.

Of 737 adults undergoing cardiac operations through a median sternotomy over a 2-year period (January 1988 to January 1990), sternal-substernal space infection requiring mediastinal exploration developed in 8. Six of these patients as well as 18 additional patients were evaluated for possible poststernotomy wound infection by computed tomography (4 true positive, 4 false positive, 10 true negative, 2 false negative), indium-111 leukocyte scanning (5 true positive, 0 false positive, 18 true negative, 1 false negative), and epicardial pacer wire cultures (6 true positive, 1 false positive, 12 true negative, 0 false negative). On the basis of this experience it is suggested that in addition to computed tomography, indium-111 leukocyte scanning and epicardial pacer wire cultures may be useful in the diagnosis of poststernotomy deep wound infection.

J. Maxwell Chamberlain memorial paper. Sternal wound complications after isolated coronary artery bypass grafting: early and late mortality, morbidity, and cost of care.

Of 6,504 consecutive patients who underwent isolated coronary bypass grafting in 1985 to 1987, 72 (1.1%) patients experienced sternal wound complications. Ten patients (14%) with wound complications died of multi-system failure. Only the patients with negative cultures fared well; of the bacterial culture categories, polymicrobial infection carried the worst prognosis. Effects of recurring infection were seen throughout the first year. Patients, grouped according to conduits received, experienced these wound complication rates: vein grafts only, 11/1,085 (1.0%); one internal thoracic artery, 38/4,073 (0.9%); and bilateral internal thoracic artery grafts, 23/1,346 (1.7%). There were no significant differences in wound complication rates between primary and reoperation patients or among conduit groups. By logistic regression analysis, the relative risk for patients with diabetes and bilateral internal thoracic artery grafting was 5.00 (95% confidence interval, 2.4 to 10.5). Operation time as a continuous variable increased the relative risk of wound complication 1.47 times per hour (1.3 to 1.7); obesity, 2.90 times (1.8 to 4.8); and blood units as continuous variable, 1.05 times per unit (1.01 to 1.10). Bilateral internal thoracic artery grafting in nondiabetic patients carried no greater risk of wound complication than that in patients with vein grafts only or with one internal thoracic artery graft.