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

Chest Reexploration in the Intensive Care Unit After Cardiac Surgery: A Safe Alternative to Returning to the Operating Theater

BACKGROUND

The aim of this study was to determine the outcome of patients who had chest reexploration in the intensive care unit (ICU) for bleeding or cardiovascular instability after heart surgery.

METHODS

This was a retrospective analysis of medical records of patients who had a chest reexploration in the ICU for bleeding or possible cardiac tamponade over a 9-year period (1991 to 2000), at the Cardiothoracic Centre of Manchester Royal Infirmary, England.

RESULTS

Between 1991 and 2000, 240 patients (3.4% of the total heart operations) who fitted the above criteria were identified. Two hundred and seven (86%) were reexplored for bleeding, 22 (9%) for possible tamponade, and 11 (5%) for both. Ninety-five percent were reexplored within 24 hours (median, 5 to 6 hours). Two hundred and twenty-six patients were found to have bleeding on reexploration. Of these, 125 (55%) were found to have focal bleeding, 74 (33%) diffuse bleeding, and 11 (5%) both. Two hundred and twelve (88%) had their chest closed, 25 (12%) packed, and 13 (10%) had further chest openings while in ICU. Sixteen (6.7%) of the patients died. Seven (2.9%) had sternal wound infection. For the survivors, ICU stay ranged from 1 to 60 days (median, 1) and their hospital stay ranged from 2 to 90 days (median, 8).

CONCLUSIONS

Chest reexploration in ICU for bleeding or tamponade after heart surgery can be a safe alternative to return to the operating theater.

Sternal wound complications in bilateral internal thoracic artery grafting: a comparison of the off-pump technique and conventional cardiopulmonary bypass

BACKGROUND

Sternal wound complication is a major concern in bilateral internal thoracic artery grafting. The purpose of this study was to assess whether avoiding cardiopulmonary bypass has beneficial effects with fewer wound complications in patients receiving bilateral internal thoracic artery grafting.

METHODS

Retrospective review was performed using prospectively gathered data of 69 patients who had undergone elective coronary artery bypass grafting and received conventional pedicled bilateral internal thoracic artery grafting from December 2002 through April 2004 by the same surgical team. The patients were divided into 2 groups: those who underwent coronary artery bypass grafting without cardiopulmonary bypass (off-pump group, n = 41), and those who underwent coronary artery bypass grafting with cardiopulmonary bypass (CPB group, n = 28). Chart review and 3-month follow-up were obtained for all patients. These 2 groups were compared for sternal wound complications and preoperative, intraoperative, and postoperative variables.

RESULTS

Deep sternal wound infection (SWI) was seen in 1 patient (2.4%), superficial SWI in 2 patients (4.8%), and sternal dehiscence in 1 patient (2.4%) in the off-pump group. Deep SWI was seen in no patients, superficial SWI in 2 patients (7.1%) and sternal dehiscence in 2 patients (7.1%) in the CPB group. No statistically significant difference in the frequency of occurrence of sternal complications was detected between the 2 study groups.

CONCLUSIONS

The results suggest that the avoidance of CPB has no beneficial effect on the number of sternal wound complications in patients receiving bilateral internal thoracic artery grafting. However, further prospective, randomized studies on large patient groups are required to assess this finding.

Treatment of deep sternal wound infections post-open heart surgery by application of activated macrophage suspension

Postoperative sternal wound infection remains a significant complication and generally causes considerable morbidity and mortality. Macrophages play a major role in the process of wound healing. In order to evaluate the efficacy of local injection of activated macrophage suspensions into open infected sternal wound space, a retrospective case-control study was conducted. Sixty-six patients with deep sternal wound infection treated by activated macrophages (group 1) and 64 patients with deep sternal wound infection treated by sternal reconstruction surgery with various regional flaps (group 2), were matched for gender, age, and risk index. In up to 54 months of follow-up of group 1, 60 patients (91%) achieved complete wound closure. Two (3%) late deaths occurred unrelated to the procedure. Mortality rate in group 2 was 29.7% (19/64). Duration of hospitalization was 22.6 days in group 1 vs. 56.2 days in group 2. Patients with deep sternal wound infection following open heart surgery that were treated by activated macrophages had significantly less mortality as well as significant reduction of hospitalization in comparison to the surgically treated group. These results illustrate the advantages of using a biologically based activated macrophage treatment.

Nosocomial pneumonia in elderly patients following cardiac surgery

OBJECTIVE

To identify modifiable risk factors of nosocomial pneumonia (NP) in elderly patients post-cardiac surgery.

DESIGN

A case-control study.

SETTING

Post-operative intensive care unit of a tertiary-level university affiliated hospital.

SUBJECTS

Seventy three case-control pairs. Case patients referred to elderly patients who developed pneumonia post-cardiac surgery. Controls subjects were matched for age, gender, type of surgery, forced expiratory volume in 1s (FEV(1)), and ejection fraction.

MEASUREMENTS

Baseline sociodemograpahic information, Charlson Comorbidity Index score, intra- and post-operative data were collected. When suspected, the presence of NP was confirmed by quantitative culture of protected bronchoalveolar lavage fluid 10(3) colony forming unit/ml or positive blood/pleural fluid culture identical to that recovered from respiratory samples.

RESULTS

The incidence of NP in elderly post-heart surgery was 8.3%. The mean duration after heart surgery to the occurrence of pneumonia was 7.2+/-4.9 days. Four variables were found to be significantly related to the development of NP by multivariate analysis: Charlson Index >2 (adjusted odds ratio [AOR] 4.7; 95% confidence interval [CI], 1.9-11.4; P<0.001), reintubation (AOR 6.2; 95% CI, 1.1-36.1; P=0.04), transfusion 4 units of PRBC (AOR 2.8; 95% CI, 1.2-6.3; P=0.01), and the mean equivalent daily dose of morphine (AOR 4.6; 95% CI, 1.4-14.6; P=0.01).

CONCLUSIONS

Although there are limited effective measures to lessen the burden of comorbidities, avoiding reintubation, finding a substitute to allogenic blood transfusion, and improved assessment of pain management could reduce the rate of NP in the post-operative period of cardiac surgery in the elderly population.

Surgical-site infection after cardiac surgery: incidence, microbiology, and risk factors

OBJECTIVE

To identify risk factors associated with surgical-site infection according to the depth of infection, the cardiac procedure, and the National Nosocomial Infections Surveillance System risk index.

DESIGN

Prospective survey conducted during a 12-month period.

SETTING

A 48-bed cardiac surgical department in a teaching hospital.

PATIENTS

Patients admitted for cardiac surgery between February 2002 and January 2003.

RESULTS

Surgical-site infections were diagnosed in 3% of the patients (38 of 1,268). Of the 38 surgical-site infections, 20 were superficial incisional infections and 18 were mediastinitis for incidence rates of 1.6% and 1.4%, respectively. Cultures were positive in 28 cases and the most commonly isolated pathogen was Staphylococcus. A National Nosocomial Infections Surveillance System risk index score of 2 or greater was associated with a risk of surgical-site infection (relative risk, 2.4; P < .004). Heart transplantation, mechanical circulatory assistance, coronary artery bypass graft with the use of internal mammary artery, and reoperation for cardiac tamponade or pericard effusion were independent risk factors associated with surgical-site infection.

CONCLUSIONS

Data surveillance using incidence rates stratified by cardiac procedure and type of infection is relevant to improving infection control efforts. Risk factors in patients who developed superficial infection were different from those in patients who developed mediastinitis. Coronary artery bypass graft using internal mammary artery was associated with a high risk of surgical-site infection, and independent factors such as reoperation for cardiac tamponade or pericard effusion increased the risk of infection.

Numerical Simulation Techniques to Study the Structural Response of the Human Chest Following Median Sternotomy

BACKGROUND

The optimal closure technique of median sternotomy remains controversial. The objective of this study was to analyze the structural response of the separated sternum using computer-based numerical discretization techniques, such as finite element methods.

METHODS

Thoracic computer tomographic scans (2.5-mm slices) were segmented, analyzed by image processing techniques, and transferred into a three-dimensional finite element model. In a first approach a linear elastic material model was used; neglecting nonlinear and damage effects of the bones. The influence of muscles and tendons was disregarded. Nonlinear contact conditions were applied between the two sternal parts and between fixation wires and sternum. The structural response of this model was investigated under normal breathing and asymmetric leaning on one side of the chest. Displacement and stress response of the segmented sternum were compared regarding two different closure techniques (single loop, figure-of-eight).

RESULTS

The obtained results revealed that for the normal breathing load case the single loop technique is capable of clamping the sternum sufficiently, assuming that the wires are prestressed. For asymmetric loading conditions, such as leaning on one side of the chest, the figure-of-eight loop can substantially reduce the relative longitudinal displacement between the two parts compared with the single loop.

CONCLUSIONS

The application of numerical simulation techniques using complex computer models enabled the determination of structural behavior of the chest regarding the influence of different closure techniques. They allowed easy and fast modifications and therefore, in contrast to a real physical model, in-depth parameter studies.

The Women's Recovery from Sternotomy (WREST) study: design of a randomized trial of a novel undergarment for early use after sternotomy

BACKGROUND

Clinicians who work with women poststernotomy often suggest that they wear a supportive brassiere to ameliorate pain, discomfort, and potential wound complications. There is no empirical evidence that supports this practice.

METHODS

Despite methodological challenges, a clinical trial is currently underway to investigate the efficacy of early use of a novel undergarment after sternotomy. Women (N = 430) having first time sternotomy in 9 Canadian centers will be randomized to receive either the usual care of the institution or early use of a novel undergarment. Follow-up is planned over 12 postoperative weeks. Coprimary outcomes are pain, discomfort, and return to function. Wound healing is a secondary outcome. An economic evaluation substudy is also underway.

CONCLUSIONS

The WREST Study is a unique ongoing trial examining the efficacy of a novel undergarment in reducing women's pain and enhancing their comfort and return to function. The findings of the trial and its economic substudy will enable health care providers to make rational evidence-based clinical decisions regarding women's early care after sternotomy.

Management of Intractable Sternal Wound Infections with Topical Negative Pressure Dressing

BACKGROUND

Sternal osteomyelitis after cardiac surgery is a life-threatening complication. The potential spread of infection into the mediastinum, involving the prosthetic valve, grafts, and suture lines, makes this an extremely serious complication confronting both cardiac and plastic surgeons.

AIM

Topical negative pressure (TNP) dressing has been proven to be effective for wound healing. We want to take advantages of this equipment to improve the results of intractable sternal wound infection. The results are discussed.

METHODS

From December 1996 to July 2002, 25 patients with sternal wound infections were treated at Kaohsiung Medical University Hospital. Nine patients suffering intractable sternal osteomyelitis were managed with debridement and TNP dressings. These patients received 1-3 debridements (an average of 2.2 debridements), and the average TNP dressing treatment period was 20.2 days (ranging from 3 to 43 days). After management, the infections were controlled and healthy vascularized wounds were achieved. Then, flap reconstruction could be performed for complete wound closure. Seven of the nine patients survived, and there was no recurrence of sternal osteomyelitis during follow-up period (ranging from 5 to 70 months).

CONCLUSION

The advantages of applying TNP dressings in cases of intractable sternal wound infections include (1) protecting the underlying mediasternal structure from infection, (2) permitting delayed sternal closure to avoid cardiac compression induced compromised cardiopulmonary function, (3) possibility of repeated wound inspection and bedside debridement, (4) cost-effectiveness of wound care, and (5) providing an option to promote sternal wound secondary healing for patients in poor physical condition.

The effect of bilateral internal thoracic artery harvesting on superficial and deep sternal infection: The role of skeletonization

OBJECTIVE

To determine the relative risk of sternal dehiscence in patients undergoing bilateral internal thoracic artery harvesting and to assess whether and to what extent the technique of artery skeletonization might reduce this risk.

METHODS

Prospectively collected data on patients undergoing coronary artery bypass operations with at least a single internal thoracic artery were reviewed. The last 450 patients receiving bilateral internal thoracic artery grafts were compared with 450 patients who received a single internal thoracic artery during the same period. The left internal thoracic artery was always harvested in a pedicled fashion. Among patients receiving a bilateral internal thoracic artery, both arteries were harvested in a pedicled fashion in 300 cases, whereas both internal thoracic arteries were skeletonized in the remaining 150 cases.

RESULTS

Compared with a single internal thoracic artery, harvesting both internal thoracic arteries either in a skeletonized or in a pedicled fashion increased the chance of deep (1.1% vs 3.3% vs 4.7%; P = .01) or superficial (4.8% vs 7.8% vs 12%; P = .002) sternal infection. However, the technique of artery harvesting (odds ratio, 4.1; 95% confidence interval, 1.4-12.1); the presence of peripheral arteriopathy (odds ratio, 3.1; 95% confidence interval, 1.2-8.5), and resternotomy for bleeding (odds ratio, 8.2; 95% confidence interval, 2.0-33.6) were the only independent predictors for deep sternal infection, whereas the technique of artery harvesting (odds ratio, 3.0; 95% confidence interval, 1.6-5.4), female sex (odds ratio, 2.2; 95% confidence interval, 1.2-4.2), and diabetes (odds ratio, 1.7; 95% confidence interval, 1.0-2.9) were the only independent predictors of superficial sternal infection. In diabetic patients, there was no difference in the incidence of deep sternal infection among patients receiving a single internal thoracic artery or double skeletonized internal thoracic arteries ( P = .4).

CONCLUSIONS

Bilateral internal thoracic artery harvesting carries a higher risk of sternal infection than harvesting a single internal thoracic artery. Skeletonization of both internal thoracic arteries significantly decreases this risk. A strategy of bilateral thoracic artery grafting can also be offered to patients at high risk for wound infection.

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

OBJECTIVE

The purpose of the study is to describe an intensive care unit's experience in the treatment of poststernotomy mediastinitis and to identify factors associated with intensive care unit death.

METHODS

Over a 10-year period, 316 consecutive patients with mediastinitis occurring less than 30 days after sternotomy were treated in a single unit. First-line therapy was closed-drainage aspiration with Redon catheters. Variables recorded, including patient demographics, underlying disease classification, clinical and biologic data available at intensive care unit admission and day 3, and their association with intensive care unit mortality, were subjected to multivariate analyses.

RESULTS

Intensive care unit mortality (20.3%) was significantly associated with 5 variables available at admission: age greater than 70 years (odds ratio, 2.70), operation other than coronary artery bypass grafting alone (odds ratio, 2.59), McCabe class 2/3 (odds ratio, 2.47), APACHE II score (odds ratio, 1.12 per point), and organ failure (odds ratio, 2.07). After introducing day 3 variables into the logistic regression model, independent risk factors for intensive care unit death were as follows: age greater than 70 years, operations other than coronary artery bypass grafting alone, McCabe class 2/3, APACHE II score, mechanical ventilation still required on day 3, and persistently positive bacteremia. For patients receiving mechanical ventilation for less than 3 days, mortality was very low (2.4%). In contrast, for patients receiving mechanical ventilation for 3 days or longer, mortality reached 52.8% and was associated with non-coronary artery bypass grafting cardiac surgery, persistently positive bacteremia, and underlying disease.

CONCLUSIONS

In patients requiring intensive care for acute poststernotomy mediastinitis, age, type of cardiac surgery, underlying disease, and severity of illness at the time of intensive care unit admission were associated with intensive care unit death. Two additional factors (mechanical ventilation dependence and persistently positive bacteremia) were identified when the analyses were repeated with inclusion of day 3 patient characteristics.

Cost-effectiveness of recombinant human erythropoietin for reducing red blood cells transfusions in critically ill patients

OBJECTIVE

To examine the cost-effectiveness of using recombinant human erythropoietin (rHuEPO) to reduce red blood cells (RBC) transfusions in intensive care unit (ICU) patients.

METHODS

Decision analysis examining costs and effectiveness of using rHuEPO versus not using rHuEPO in a simulated adult medical/surgical/trauma (mixed) ICU. Two independent cost-effectiveness models were created based on the results of two multicenter studies that investigated the use of rHuEPO. Base case assumptions and estimates of effectiveness were obtained from these two studies. Mean cumulative doses of rHuEPO were 190,900 units and 102,400 units for studies 1 and 2, respectively. The models accounted for the deferral rate for allogeneic RBC transfusions, rHuEPO efficacy (the reduction in allogeneic RBC use), and adverse effects of rHuEPO and allogeneic RBC transfusions. Model estimates were obtained from published sources. Costs were expressed in 2002 US dollar (dollars) and effectiveness was measured using discounted quality-adjusted life-years (QALYs). A 3% discount rate was used. Probabilistic sensitivity analysis was conducted using second-order Monte Carlo simulation.

RESULTS

Incremental costs of using rHuEPO to reduce RBC transfusions amounted to 1918 dollars and 1439 dollars; incremental effectiveness values were 0.0563 QALYs and 0.0305 QALYs; and the cost-effectiveness ratios were 34,088 dollars and 47,149 dollars per QALY for studies 1 and 2, respectively. The model was most sensitive to the attributable risk of nosocomial bacterial infections per RBC unit. rHuEPO was cost-effective in 52.0% of the Monte Carlo simulations for a willingness to pay of 50,000 dollars/QALY.

CONCLUSION

rHuEPO appears to be cost-effective for reducing RBC transfusions in heterogeneous ICU populations, assuming RBC transfusions increase the risk of nosocomial bacterial infections.

Anemia, allogenic blood transfusion, and immunomodulation in the critically ill

Anemia and allogenic RBC transfusions are exceedingly common among critically ill patients. Multiple pathologic mechanisms contribute to the genesis of anemia in these patients. Emerging risks associated with allogenic RBC transfusions including the transmission of newer infectious agents and immune modulation predisposing the patient to infections requires reevaluation of current transfusion strategies. Recent data have suggested that a restrictive transfusion practice is associated with reduced morbidity and mortality during critical illness, with the possible exception of acute coronary syndromes. In this article, we review the immune-modulatory role of allogenic RBC transfusions in critically ill patients.

Prophylaxis of sternal wound infections with gentamicin-collagen implant: randomized controlled study in cardiac surgery

Postoperative infections may lead to prolonged hospital stay and increased morbidity, mortality and hospital costs, especially in heart surgery. Finding new means to prevent infections would benefit both the patient and society. The aim of this study was to assess if locally administered gentamicin prevents sternal wound infections in coronary artery bypass (CABG) surgery. We randomized 542 consecutive CABG patients to two groups: those who received gentamicin-collagen implant under their sternum before closure (N=272) and controls (N=270). The subjects received routine intravenous antimicrobial prophylaxis (85% cefuroxime, 14% cefuroxime and vancomycin), and were followed-up for three months. The sternal wound infection rate was 4.0% (11/272) in the gentamicin group and 5.9% (16/270) in the control group. The mediastinitis rates were 1.1 and 1.9%, respectively. This treatment was safe and easy to administer, and no side-effects occurred. No statistically significant difference was demonstrated between infection rates in the two groups. This is the first study on the use of gentamicin-collagen sponge as prophylaxis in cardiac surgery. Our data show that infection was reduced slightly in the gentamicin-collagen group compared with the control group, but the study population was too small to draw conclusions. Further evaluation is needed, and the results may warrant another larger, better-powered study.

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.

A New Technical Approach for Sternal Closure with Suture Anchors (Dogan Technique)

OBJECTIVES

Various methods for sternal approximation have been described previously. Some patients undergoing these procedures are at risk for sternal dehiscence and mediastinitis. We used a different method, with a suture anchor system, for median sternotomy closure as an alternate technique in patients with a high risk of postoperative sternal dehiscence and sternal nonunion.

MATERIAL AND METHOD

Suture anchor systems have been developed principally for the fixation of tendons or ligaments to the bone. We first used the suture anchor system for median sternotomy closure, although it has been frequently used in various orthopedic surgical procedures. In this report, we describe the use, after fresh cadaveric tests, of an alternative technique in a patient undergoing coronary artery bypass grafting.

RESULTS

There were no complications due to the suture anchor device, and successful application was performed for sternotomy fixation after surgical procedure in a patient. The standard techniques have several disadvantages, such as osteomyelitis, chondritis, cutting into the sternum and sternal dehiscence, prolonged hospitalization, and increased mortality and morbidity due to the listed complications, but these devices may protect the wire from cutting into the sternal bone.

CONCLUSION

We propose suture anchors for reapproximation of the sternum to decrease the complications related to surgical steel wires. We therefore consider this technique to be easy, safe, and effective in patients with diabetes mellitus or severe osteoporosis considered to have risk for sternal dehiscence postoperatively. Another advantage of this suture system is that the titanium wire makes it more magnetic resonance compatible than systems using surgical steel wire.

Coagulation disorders of cardiopulmonary bypass: a review

BACKGROUND

Postoperative bleeding is one of the most common complications of cardiac surgery.

DISCUSSION

Extensive surgical trauma, prolonged blood contact with the artificial surface of the cardiopulmonary bypass (CPB) circuit, high doses of heparin, and hypothermia are all possible triggers of a coagulopathy leading to excessive bleeding. Platelet activation and dysfunction also occur and are caused mainly by heparin, hypothermia, and inadequate protamine administration. Heparin and protamine administration based on heparin concentrations as opposed to fixed doses may reduce coagulopathy and postoperative blood loss.

CONCLUSIONS

A better comprehension of the multifactorial mechanisms of activation of coagulation, inflammation, and fibrinolytic pathways during CPB may enable a more effective use of the technical and pharmaceutical options which are currently available.

Phlebotomy in the intensive care unit: strategies for blood conservation

The quality and economy of critical care could both be improved if blood losses due to phlebotomy and sampling from indwelling catheters for unnecessary diagnostic testing were curtailed. Practice guidelines can help to break bad diagnostic 'habits', such as fever work-ups that require substantial blood to be drawn yet typically yield little useful information. Invasive hemodynamic monitoring is associated with morbidity due to blood loss as well as infection, and newer noninvasive technologies should be encouraged. Several devices allow blood that would otherwise be wasted during sampling to be returned to the patient aseptically. Point-of-care testing uses microliter quantities of blood, has acceptable precision, and can provide valuable diagnostic information while being minimally invasive.

Use of exogenous erythropoietin in critically ill patients

OBJECTIVE

Review the literature regarding the use of recombinant human erythropoietin (rHuEPO) to prevent red blood cell (RBC) transfusion in critically ill patients.

DATA SOURCES

A computerized search of MEDLINE and EMBASE from 1966 through June 2003 was conducted using the terms erythropoietin, anemia, hemoglobin, critical care, intensive care, surgery, trauma, burn, and transfusion. References of selected articles were reviewed. A manual search of critical care, surgery, trauma, burn, hematology, and pharmacy journals was conducted to identify relevant abstracts.

RESULTS

Six randomized studies have evaluated exogenous administration of erythropoietin to prevent RBC transfusions in critically ill patients. Studies vary with respect to rHuEPO dosage regimens, dose of concurrently administered iron, patient characteristics, and transfusion thresholds. Administration of rHuEPO rapidly produces erythropoiesis to reduce the need for RBC transfusions. The largest study conducted to date used weekly rHuEPO administration and found a modest decrease in transfusion requirements although the time to first transfusion was delayed. Reduced intensive care unit (ICU) length of stay (LOS) was shown in only one study of surgical/trauma patients. Reduced LOS after ICU discharge was found in another study of severely ill patients (APACHE II score >22). Other clinical outcomes were not altered by rHuEPO use. No adverse events were associated with rHuEPO use although studies were not designed to evaluate safety.

CONCLUSIONS

rHuEPO reduces the need for transfusions. A cost-effectiveness analysis of rHuEPO for this indication is needed. Defining an optimal dosage regimen, identifying patients most likely to respond to rHuEPO, and determining risk factors for ICU associated anaemia would provide information for appropriate rHuEPO utilization.

Deep sternal wound infection caused by group g streptococcus after open-heart surgery

We report the first case of deep sternal wound infection caused by group G Streptococcus after open-heart surgery. The patient's clinical presentation was nonspecific and his diagnosis was delayed. Surgical debridement and a 4-week course of intravenous antibiotics consisting of sequential penicillin plus gentamicin/ceftriaxone led to recovery. Group G Streptococcus should be suspected as an important postoperative pathogen.

The effect of universal leukoreduction on postoperative infections and length of hospital stay in elective orthopedic and cardiac surgery

BACKGROUND

A before and after study was undertaken to investigate the effect of universal leukoreduction (ULR) in the UK on postoperative length of hospital stay (LOS) and infections.

STUDY DESIGN AND METHODS

Consecutive patients undergoing elective coronary artery bypass grafting or total hip and/or knee replacement in 11 hospitals received non-WBC-reduced RBCs before implementation of ULR (T1, n=997) or WBC-reduced RBCs after implementation of ULR (T2, n=1098).

RESULTS

Patients in T1 and T2 were comparable except patients in T2 received on average more units of RBCs but had lower discharge Hct levels. Postoperative LOS (T1, 10 +/- 8.9 days; T2, 9.6 +/- 6.9 days) and the proportion of patients with suspected and proven postoperative infections (T1, 21.0%; T2, 20.0%) were unchanged before and after ULR (LOS, hazard ratio 1.01, 95% CI 0.92-1.10; infections, OR 0.83, 95% CI 0.77-1.02). Subgroup analysis showed no significant interaction between storage age or dose of blood on responsiveness of primary outcomes to ULR. Secondary outcomes were unchanged overall. Analysis by surgical procedure gave conflicting results with both increased mortality (p=0.031) and an increased proportion of cardiac patients with proven infections (p=0.004), whereas the proportion of orthopedic patients with proven infections was reduced (p=0.002) after ULR.

CONCLUSION

Implementation of ULR had no major impact on postoperative infection or LOS in patients undergoing elective surgical procedures who received transfusion(s). Smaller effects, either detrimental or beneficial of ULR, cannot be excluded.

A modified parasternal wire technique for prevention and treatment of sternal dehiscence

BACKGROUND

Sternal dehiscence with or without mediastinitis is a devastating complication of median sternotomy. Various techniques of sternotomy closure including 'figure of eight' wire sutures, nylon bands, and custom-made titanium-H plates have been described. We have devised and tested a new method of sternal closure to prevent sternal wound complications in patients at high risk of sternal dehiscence.

METHODS

1336 patients underwent sternotomy for various cardiac operations from January 1996 to January 2002. Patients were divided into two groups. Group I consisted of 560 patients who did not have any high risk factors for sternal dehiscence and received a standard six wire closure. Group II comprised of patients at high risk of sternal dehiscence and were divided randomly into subgroup II A (n = 390), which included patients who had conventional sternal closure. While in subgroup II B (n = 386) patients had a modified parasternal wire closure according to the finalized protocol.

RESULTS

Sternal instability was noticed in 1/560 and none had sternal dehiscence in group I, but 16/390 patients had sternal instability and 3/390 had sternal dehiscence in subgroup II A, whereas only one patient in high risk subgroup II B developed sternal dehiscence with mediastinitis and required a pectoral flap advancement for sternal closure.

CONCLUSIONS

Use of modified parasternal wire closure in patients with a high risk of sternal dehiscence is a safe, effective, technically easily reproducible, as well as economical, method of preventing and treating sternal dehiscence.

Prevention and management of deep sternal wound infection

Deep sternal wound infection (DSWI) is an uncommon but serious complication of median sternotomy in cardiac surgery, associated with significant mortality and morbidity. We performed a retrospective review of 30,102 consecutive cardiac surgical patients operated on at our institution from 1990 to 2003 and found an incidence of DSWI of 0.77%. The in-hospital mortality rate was 6.9% for DSWI patients versus 2.8% for patients without DSWI (P = 0.0002). Multivariable predictors for development of DSWI were old age, diabetes, previous stroke or TIA, and congestive heart failure. The use of bilateral internal thoracic artery (BITA) grafts increased the risk of DSWI in patients undergoing coronary artery bypass surgery, particularly in those with congestive heart failure alone or with diabetes. Skeletonization of BITA grafts resulted in a lower risk of DSWI, comparable to nondiabetic patients (1.3% versus 1.6%, P = 0.8). Patients with DSWI were treated with either sternal debridement and primary closure or sternectomy with myocutaneous flap reconstruction, resulting in a 6-month freedom from adverse event rate of 76% in both groups.

Risk factors for mediastinitis after cardiac surgery

BACKGROUND

Postoperative mediastinitis is one of the most feared complications in patients who undergo cardiac surgery because in addition to a high mortality rate (10% to 47%), there are increases in the length of hospital stay and in hospital costs. The purpose of the present study is to assess the risk factors for mediastinitis after cardiac surgery, the mediastinitis rate, and the mortality rate in our institution.

METHODS

To determine the risk factors, a matched case-control study was carried out, with 39 cases and 78 controls, among the patients who underwent cardiac surgery at the Dante Pazzanese Cardiology Institute, São Paulo, Brazil.

RESULTS

In the period of the study, 9,136 cardiac surgeries were performed and the mediastinitis rate was 0.5%. In the multivariate analysis, the independent risk factors found were obesity (odds ratio, 6.49; 95% confidence interval, 2.24 to 18.78), smoking (odds ratio, 3.27; 95% confidence interval, 1.04 to 10.20), intensive care unit stay more than 2 days (odds ratio, 4.50; 95% confidence interval, 1.57 to 12.90), and infection at another site (odds ratio, 8.86; 95% confidence interval, 1.86 to 42.27). The mortality rate was 23% among the patients with mediastinitis.

CONCLUSIONS

We observed two independent risk factors related to patients' antecedents (obesity and smoking) and two risk factors related to problems in the postoperative period (length of intensive care unit stay and infection at another site). Efforts should be concentrated so that patients lose weight and stop smoking before elective surgeries. There should also be a prevention program against hospital infection directed to, and intensified for, at-risk patients.

Bacterial mediastinitis after heart transplantation: clinical presentation, risk factors and treatment

BACKGROUND

The incidence of mediastinitis after heart transplantation has been reported to be between 2.5% and 7.5%. Most previous reports from the transplant literature have assessed patients who had not received induction therapy.

METHODS

From December 1996 to January 2002, a total of 230 heart transplants were performed using induction therapy with rabbit anti-thymocyte globulin at La Pitié Salpêtrière Hospital (Paris, France). Mediastinitis developed in 15 patients (6.5%). A case-control study was performed to characterize the clinical presentation, microbiology, risk factors and therapy of mediastinitis after heart transplantation.

RESULTS

Only 4 patients (26%) had a temperature of >38 degrees C and 6 patients (40%) had a white blood cell count of >10,000 cells/mm(3). Septicemia (46%) and positive temporary epicardial pacing wires culture (60%) were frequently observed. Staphylococcus aureus (5 of 15), Staphylococcus epidermidis (5 of 15) and gram-negative bacteria (5 of 15) were the causative organisms cultured intra-operatively. Mean duration of mechanical ventilation (2.4 vs 1.6 days; p < 0.03) and use of ventricular assistance (20% vs 0%; p < 0.04) were different between cases and controls. The mortality rate at hospital discharge was 6.7% (1 of 15).

CONCLUSIONS

In the context of immunosuppression after heart transplantation, a high degree of suspicion is necessary to make the diagnosis of mediastinitis. Positive blood and temporary epicardial pacing wires cultures can be helpful in suggesting the presence of mediastinitis. Using vancomycin and an aminoglycoside as prophylaxis has to be considered because of the high prevalence of methilcilin-resistant S epidermidis and gram-negative bacteria. Conservative therapy (sternal debridement without muscle flap closure, and closed-chest drainage) showed excellent results in this series.

Superficial wound dehiscence after median sternotomy: surgical treatment versus secondary wound healing

BACKGROUND

Superficial wound dehiscence after midline sternotomy is considered a minor complication in cardiac surgery, although it is quite frequent and requires prolonged medical treatment. It can be managed conventionally by topical treatment, with delayed secondary healing, or by surgical treatment and primary skin closure. We report the outcome of 96 patients who underwent conventional treatment, compared with a second group of 42 patients who underwent surgical treatment and direct closure.

METHODS

From October 1999 to December 2002, 2400 consecutive patients underwent median sternotomy: 207 patients had sternal wound complications: 3 patients (0.125%) had mediastinitis, 66 patients (2.75%) had aseptic deep sternal wound dehiscence, and 138 patients (5.75%) had superficial wound dehiscence. The latter are the object of the present study; patients entered a protocol of skin wound care on an outpatient basis. The first 96 consecutive patients (group 1) required medications three times a week until complete healing. The last 42 patients (group 2) were treated by extensive surgical debridement of skin and subcutaneous tissue, direct closure of the superficial layers, and suture removal after 15 days.

RESULTS

The two groups were comparable as to age, sex, and preoperative risk factors. The incidence of contaminated wounds was similar in the two groups (32 of 96 in group 1 and 11 of 42 in group 2; p = NS). The length of treatment was 29.7 days (range 2 to 144 days) for group 1 and 12.2 days (range 2 to 37 days) for group 2 (p < 0.0001). The mean number of medical treatments was 9.4 per patient in group 1 and 3.7 per patient in group 2 (p < 0.0001).

CONCLUSIONS

Surgical debridement and primary closure of superficial surgical wound dehiscence after median sternotomy is a safe and valid treatment. Wound infection is not a contraindication to surgical treatment. Primary closure may contribute to reduce the risk for later infection. It also definitely contributes to decreasing healing time and strongly lessens patients' discomfort, diminishing hospital costs and hospital staff workload.

Laparoscopic omental flap for the treatment of major sternal wound infection after cardiac surgery

BACKGROUND

The ideal reconstructive procedure after sternal debridement is still a matter of debate. The omentum might be theoretically preferable for its favorable properties, but it is seldom used because it entails the added trauma of a laparotomy.

METHODS

Three female patients with severe osteomyelitis after myocardial revascularization underwent sternal debridement and filling of the defect with a laparoscopically prepared omental flap. Sternal wound closure was achieved as a single-stage procedure in 2 patients. The third patient had a poststernotomy septicemia and required a 2-stage procedure. The abdominal procedures were conducted through 3 operating 5-mm ports. Omental flaps were developed by complete separation from the transverse colon and lengthening by division of some anastomosing arteries between gastroepiploic vessels and Barkow's arcade. Thoracic transposition of the omentum was achieved through a 5-cm diaphragmatic incision. The flaps were able to reach the base of the neck and fill the sternal defect in all patients.

RESULTS

A smooth postoperative course was observed. Oral intake was started from day 2; sole oral nutrition was maintained from day 3 or 4. Optimal wound healing was observed with minimal or absent local discomfort. Minor transient paradoxical movements of the anterior chest wall disappeared within 1 month. Postoperative hospital stay was 9, 14, and 14 days, respectively.

CONCLUSIONS

Laparoscopic omentoplasty, compared with the open procedure, entails several advantages for the treatment of sternal osteomyelitis. The introduction of minimally invasive techniques may widen the indications for the use of the omentum in the treatment of major sternal wound infections.

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.

Improvement of sternal closure stability with reinforced steel wires

BACKGROUND

Sternal dehiscence occurs when steel wires pull through sternal bone. This study tests the hypothesis that closure stability can be improved by jacketing sternal wires with stainless steel coils, which distribute the force exerted on the bone over a larger area.

METHODS

Midline sternotomies were performed in 6 human cadavers (4 male). Two sternal closure techniques were tested: (1) approximation with six interrupted wires, and (2) the same closure technique reinforced with 3.0-mm-diameter stainless steel coils that jacket wires at the lateral and posterior aspects of the sternum. Intrathoracic pressure was increased with an inflatable rubber bladder placed beneath the anterior chest wall, and sternal separation was measured by means of sonomicrometry crystals. In each trial, intrathoracic pressure was increased until 2.0 mm of motion was detected. Differences in displacement pressures between groups were examined at 0.25-mm intervals using the paired Student's t test.

RESULTS

The use of coil-reinforced closures produced significant improvement in sternal stability at all eight displacement levels examined (p < 0.03). Mean pressure required to cause displacement increased 140% (15.5 to 37.3 mm Hg) at 0.25 mm of separation, 103% (34.3 to 69.8 mm Hg) at 1.0 mm of separation, and 122% (46.8 to 103.8 mm Hg) at 2.0 mm of separation.

CONCLUSIONS

Reinforcement of sternal wires with stainless steel coils substantially improves stability of sternotomy closure in a human cadaver model.

Risk factors for leg harvest surgical site infections after coronary artery bypass graft surgery

OBJECTIVE

Harvest site infections are more common than chest surgical infections after coronary artery bypass surgery, yet few studies detail risk factors for these infections. We sought to determine independent risk factors for leg surgical site infections using our institutional Society of Thoracic Surgeons database.

METHODS

We retrospectively analyzed data collected from 1980 coronary artery bypass patients undergoing surgery at our institution from January 1, 1996, through June 30, 1999, using The Society of Thoracic Surgeons database. Independent risk factors for leg harvest site infection were identified by multivariate logistic regression.

RESULTS

Seventy-six patients (4.5%) were coded as having had a leg harvest site infection, of which 67 were confirmed by infection control. The length of hospital stay after surgery was significantly longer in patients with leg harvest site infection (mean 10.1 days) compared with that of patients without infection (mean 7.1 days, P <.001), and infected patients were more likely to be readmitted to the hospital within 30 days of surgery. Independent risk factors for leg harvest site infection included previous cerebrovascular accident (odds ratio, 2.9), postoperative transfusion of 5 units or more of red blood cells (odds ratio, 2.8), obesity (odds ratio, 2.5), age 75 years or older (odds ratio, 1.9), and female gender (odds ratio, 1.8).

CONCLUSIONS

Consistent with previous studies, female gender and obesity were identified as independent risk factors for leg harvest site infection, while previous cerebrovascular accident, postoperative transfusion, and older age are newly described risk factors. The Society of Thoracic Surgeons database is a useful tool for identification of predictors of leg harvest site infections.

Monitoring blood transfusion in patients undergoing coronary artery bypass grafting: an audit methodology

BACKGROUND AND OBJECTIVES

The purpose of this work was to describe the methodology used to build a transfusion database that allows continuous audit of transfusion practices in coronary artery bypass surgery.

MATERIALS AND METHODS

The transfusion database requires electronic data available from two sources: the hospital's patient administration system; and the local blood transfusion service.

RESULTS

We demonstrated a reduction in the percentage of patients receiving red blood cell transfusion: from 47.4% in 1997/1998 to 31.6% in 2001/2002 (P<0.001). Reductions have also been shown in the percentage of patients receiving fresh-frozen plasma and platelet units.

CONCLUSIONS

The data sourcing the transfusion database should be available to all hospitals through their patient administration systems and local blood transfusion service. Its use can help to reduce transfusion rates significantly.

Reinforced sternal closure: the bilateral straight longitudinal wire technique

Sternal dehiscence and mediastinitis are among the most severe complications of median sternotomy. A simplified technique of reinforced closure is described. A straight wire is inserted longitudinally on each side of the sternum, placed within the transverse wires when the latter are approximated. Using this technique in 112 patients with a precarious sternum, no cases of sternal dehiscence or mediastinitis have been seen.

A risk index for sternal surgical wound infection after cardiovascular surgery

OBJECTIVES

To identify factors that increase the risk of sternal surgical wound infection after cardiovascular surgery and to develop a bedside clinical risk index using these factors.

DESIGN

A risk index was developed using clinical data collected from a cohort of 11,508 cardiac surgery patients and validated using three independent subsets of the data. With two of these subsets, we derived a logistic regression equation and then modified the scoring algorithm to simplify the calculation of patient risk scores by clinicians. The final subset was used to validate the index. The area under the receiver operating characteristic (aROC) curve was the primary measure of goodness of fit.

SETTING

Toronto General Hospital, a teaching hospital and the largest center for cardiac surgery in Ontario, Canada.

PATIENTS

Cardiac surgery patients receiving cardiopulmonary bypass between April 1, 1990, and December 31, 1995, who survived at least 6 days after surgery.

RESULTS

Variables that were used to construct the risk index included reoperation due to complication (odds ratio, 4.3; range, 1.9 to 8.5), diabetes (odds ratio, 2.4; range, 1.5 to 3.7), more than 3 days in the intensive care unit (odds ratio, 5.4; range, 3.2 to 8.7), and use of the internal mammary artery for revascularization (odds ratio, 3.2; range, 1.7 to 5.8). Validation showed that the index had an aROC curve of 0.64.

CONCLUSIONS

The risk index described in this article allows clinicians to quickly stratify patients into four risk groups associated with an increasing risk of sternal surgical wound infection. It may be used perioperatively or as part of a wound infection surveillance system.

Nosocomial infections occurring during receipt of circulatory support with the paracorporeal ventricular assist system

This retrospective study sought to report the spectrum of infections in a homogenous group of 39 patients who underwent implantation of the Thoratec paracorporeal ventricular assist device system (Thoratec Laboratories) in an emergency setting. Thirty-one of the 39 patients developed a total of 99 nosocomial infections (attack rate, 79.5%; incidence, 4.9 per 100 support-days). The lungs were the most frequently involved site (31.3%), and coagulase-negative Staphylococcus species were the pathogens most frequently isolated (16.2%). Infected patients required more transfusions and chest surgical revisions, as well as a longer duration of mechanical ventilation and a longer stay in the intensive care unit, compared with uninfected patients. Cox regression analysis revealed that chest surgical revision was the only independent risk factor for infection at any site (odds ratio, 2.6; 95% confidence interval, 1.2-5.7). There was no significant effect of infection on heart transplantation rate and overall survival.

Candida albicans sternal wound infections: a chronic and recurrent complication of median sternotomy

Eleven patients developed deep sternal wound infections due to Candida albicans after undergoing coronary artery bypass grafting (CABG) and were assessed. Six had sternal osteomyelitis, 1 had osteomyelitis and mediastinitis, and 4 had deep wound infections that probably involved bone. Seven patients experienced onset of infection within 28 days of CABG, but 4 experienced onset 48-150 days after CABG. Infections were characterized by a chronic, indolent course requiring prolonged treatment with an antifungal agent. Delay in initiating antifungal therapy was common. All patients were treated with fluconazole, and 1 also received amphotericin B. Six patients underwent incision and drainage, with or without wire removal, and 3 underwent sternectomy with placement of a muscle flap. Of 10 patients for whom follow-up data were available, 7 were cured after initial therapy (median duration of treatment, 6 months), and 3 experienced a relapse and required a second course of fluconazole.

Association of sternal wound infection with parasternal muscle sutures

BACKGROUND

Sternal wound infection complicating open-heart surgery is a potentially devastating complication that has been associated with a number of risk factors. We recently consulted on three consecutive patients with this complication who had heavy nonabsorbable parasternal sutures placed in muscle tissue adjacent to the sternum. The aim of this report is to document our findings and caution that this technique to control bleeding from the parasternal intercostal muscles my increase risk of infection.

METHODS

The pathology, surgical findings, and microbiology of these three cases are analyzed for similarity and possible cause of infection.

RESULTS

By surgical observation and culture reports, each infection appeared to have originated at the site of nonabsorbable suture in devascularized parasternal muscle tissue. Sinus tracts could be probed to a similar site in each patient.

CONCLUSION

Placement of sutures in the parasternal muscles where the sternal wires wrap around the bone leads to compression and necrosis of muscle tissue. We caution that this technique to control bleeding may cause a nidus of infection and increase the risk of deep sternal wound infection.

Impact of allogenic packed red blood cell transfusion on nosocomial infection rates in the critically ill patient

OBJECTIVE

To determine whether critically ill patients who receive allogenic packed red blood cell transfusions are at increased risk of developing nosocomial infections during hospitalization.

DESIGN

Retrospective database study utilizing Project IMPACT.

SETTING

A 40-bed medical-surgical-trauma intensive care unit in an 825-bed tertiary referral teaching hospital.

PATIENTS

One thousand seven hundred and seventeen patients admitted to the medical-surgical-trauma intensive care unit.

MEASUREMENTS AND MAIN RESULTS

Data were collected by using the Project IMPACT database. Nosocomial infection rates were compared among three groups: the entire cohort, the transfusion group, and the nontransfusion group. We determined the nosocomial infection rates in these groups while adjusting for probability of survival by using Mortality Prediction Model (MPM-0) scores, age, gender, and number of units of packed red blood cells transfused. The average number of units transfused per patient was 4.0. The nosocomial infection rate for the entire cohort was 5.94%. The nosocomial infection rates for the transfusion group (n = 416) and the nontransfusion group (n = 1301) were 15.38% and 2.92%, respectively (p <.005 chi-square). Transfusion of packed red blood cells was related to the occurrence of nosocomial infection, and there was a dose-response pattern (the more units of packed red blood cells transfused, the greater the chance of nosocomial infection; p< 0.0001 chi-square). The transfusion group was six times more likely to develop nosocomial infection compared with the nontransfusion group. In addition, for each unit of packed red blood cells transfused, the odds of developing nosocomial infection were increased by a factor of 1.5. A subgroup analysis of nosocomial infection rates adjusted for probability of survival by using MPM-0 scores showed nosocomial infection to occur at consistently higher rates in transfused patients vs. nontransfused patients. A second subgroup analysis adjusted for patient age showed a statistically significant increase in rates of nosocomial infection for transfused patients regardless of age.

CONCLUSIONS

Transfusion of packed red blood cells is associated with nosocomial infection. This association continues to exist when adjusted for probability of survival and age. In addition, mortality rates and length of intensive care unit and hospital stay are significantly increased in transfused patients.

Liberation From Mechanical Ventilation Following Heart Surgery

The definition of ventilator dependency following heart surgery has evolved from a requirement for mechanical ventilation for more than 48 hours to less than 24 hours. Minimization of risk factors assessed in the preoperative period and improved surical and anesthetic techniques lead to improved and shortned postoperative courses and decreased hospital lengths of stay. The management of ventilator dependency following heart surgery should be approached from the perspective of pre-intensive care unit, intensive care unit, and post-intensive care unit Issues. A thorough understanding of risk factors for adverse postoperative morbidity and mortality leads to foused intraoperative and postoperative management aimed at improved quality of life following surgery. Minimizing preoprative risks and matching the postoperative state with criteria for the ideal candidate for early extubation improves outcome and minimizes requirements for mechanical ventilation in the postoperative period. In the event of prolonged requirements for mechanical ventilation, correcting impediments to weanng from mechanical ventilation provides the best circumtances to facilitate the process of rehabilitation and liberaion from mechanical ventilation.

Mediastinitis after cardiac surgery: improvement of bacteriological diagnosis by use of multiple tissue samples and strain typing

The diagnosis of postsurgical mediastinitis (PSM) among patients with sternal wound complication (SWC) after cardiac surgery is sometimes difficult, as fever, elevated C-reactive protein levels, and chest pain can be caused by a general inflammatory reaction to the operative trauma and/or sternal dehiscence without infection. The definitions of PSM usually used emphasize clinical signs and symptoms easily observed by the surgeon. The aim of the study was to investigate whether the use of standardized multiple tissue sampling, optimal culturing methods, and strain typing, together with a microbiological criterion for infection, could identify more infected patients than clinical assessment alone. Patients reexplored due to SWC after cardiac artery bypass grafting (CABG) or heart valve replacement (HVR) with or without CABG performed at the Department for Cardio-Thoracic Surgery at the Uppsala University Hospital between 10 March 1998 and 9 September 2000 were investigated prospectively. Tissue samples were taken from the sternum or adjacent mediastinal tissue, preferably before the administration of antibiotics. Culturing was performed both directly (on agar plates) and using enrichment broth. Species identification was performed by standard methods, and strain typing was performed by pulsed-field gel electrophoresis. A total of 41 cases with at least five tissue samples each were included in the study group. Of these patients, 32 were infected according to the microbiological criterion (i.e., the same strain was found in >/=50% of the samples). Staphylococcus epidermidis was the primary pathogen in 38% of the cases (12/32), S. aureus was the primary pathogen in 31% (10/32), P. acnes was the primary pathogen in 25% (8/32), and S. simulans and S. haemolyticus were the primary pathogens in 3% (1/32) each. All cases of S. aureus infection and 86% (12/14) of coagulase-negative staphylococcus (CoNS) infections were identified from primary cultures. All cases fulfilling the microbiological criterion for S. aureus infection were clinically diagnosed as cases of infection, but among the 14 cases fulfilling the criterion for microbiological diagnosis of CoNS infection, only 10 appeared to qualify clinically as cases of infection. Among the patients with sternal dehiscence in whom a microbiological diagnosis was established, 67% (12/18) had a CoNS infection, compared to 14% (2/14) of those without sternal dehiscence. The difference was statistically significant. PSM caused by S. aureus is readily identified by the surgeon, whereas 30% of cases with CoNS infections may be misinterpreted as noninfected. Multiple sampling before administration of antibiotics, primary culturing on agar plates, species identification, strain typing, and susceptibility testing should be used to ensure a fast and microbiologically correct diagnosis which identifies the primary pathogen and infected patients among those with minor infective symptoms. The role of P. acnes as a possible cause of PSM needs further investigation. PSM caused by CoNS is significantly related to sternal dehiscence.

[Fulminant mediastinitis from Streptococcus pneumoniae following cardiac surgery]

A 62-year-old patient was scheduled for coronary artery bypass surgery because of tritroncular coronary artery disease. The early postoperative period was uncomplicated until the 10th postoperative day when purulent fluid appeared from the sternal wound. Cultures of blood, wound and mediastinal tissues yielded Streptococcus pneumoniae with decreased susceptibility to penicillin G. Despite prompt surgical debridement and appropriate antibiotics, a septic shock with multiorgan failure occurred and the patient died on the 19th postoperative day. Although Streptococcus pneumoniae is uncommonly implicated in postoperative mediatinitis, it frequently leads to multiple organ failure and death.

An outbreak of mediastinitis among heart transplant recipients apparently related to a change in the united network for organ sharing guidelines

OBJECTIVE

To describe an outbreak of mediastinitis in heart transplant recipients.

DESIGN

Retrospective and contemporaneous cohort

SETTING

Urban tertiary-care university hospital with a large cardiac transplantation program.

PATIENTS

Heart transplant recipients.

INTERVENTIONS

Modifications of donor harvest technique; procedures aimed at decreasing skin and mucosal bacterial colonization; strict aseptic technique in the intensive care unit; and aggressive policing of established infection control practices.

RESULTS

In April 1999, mediastinitis rates among heart transplant recipients increased abruptly from a baseline of 6 cases per 100 procedures to sequential quarterly rates of 22, 31, and 50 cases per 100 procedures, whereas infection rates in other cardiac operations were unchanged. Bacteria causing these infections were multidrug-resistant "nosocomial" organisms. The epidemic occurred 2 months after a change in the United Network for Organ Sharing organ allocation algorithm. This change resulted in an increase in the duration of preoperative hospitalization from a median of 52 to 79 days (P = .008) and may have promoted prolonged hospitalization of patients with high illness severity. Aggressive multidisciplinary interventions were temporally associated with a return to preoperative mediastinitis rates without changing length of hospitalization prior to transplantation.

CONCLUSIONS

Changes in organ allocation for transplant that prolong waiting time in the hospital and alter illness acuity may lead to increased rates of postoperative infection. Measures to limit bacterial colonization may be a helpful countervailing strategy.

Primary closure of median sternotomy: techniques and principles

Understanding the biomechanics of midline sternotomy repair is important to successful surgical outcome. High-risk patients, particularly those with immunosuppression, diabetes, and osteoporosis, should be identified. Details of technique should be monitored, and closure should incorporate lateral support of the sternum in patients at risk. Sternal dehiscence can occur under physiologic loads. Closure techniques and materials should insure stable repair, with avoidance of material migration through the bone.

Suppurative mediastinitis after open-heart surgery: a comparison between cases caused by Gram-negative rods and by Gram-positive cocci

OBJECTIVE: To compare clinical characteristics and risk factors of suppurative postsurgical mediastinitis according to its etiology. METHODS: Suppurative postsurgical mediastinitis developed in 45 (2.5%) of 1779 patients who underwent open-heart surgery at the Hospital Virgen del Rocío in Seville, Spain, from 1986 to 1996. Microbiological diagnosis was available in 42 patients. RESULTS: Gram-negative rods were isolated in 19 cases and Gram-positive cocci in 23 cases. Seventeen isolates (38%) were sensitive to the antimicrobial agent used perioperatively. Patients with Gram-negative rod infection had a longer duration of bypass (127plus minus36 min versus 96plus minus34 min, p<0.01), and a worse postoperative condition. Longer mechanical ventilation (4plus minus7 days versus 1plus minus2 days, p<0.05) and concomitant infection in a remote site (pulmonary and/or urinary infection) were more frequently observed in this group than in patients with Gram-positive infections (58% versus 22%, p<0.05). Twenty patients (51%) were bacteremic. The mortality rate was 20% (five of 45). CONCLUSIONS: Preventable postoperative remote-site infection may lead to mediastinitis, especially if Gram-negative rods are involved.

Superficial and deep sternal wound complications: incidence, risk factors and mortality

OBJECTIVES

Sternal wound complications often have a late onset and are detected after patients are discharged from the hospital. In an effort to catch all sternal wound complications, different postdischarge surveillance methods have to be used. Together with this long-term follow-up an analysis of risk factors may help to identify patients at risk and can lead to more effective preventive and control measures.

METHODS

This retrospective study of 3008 adult patients who underwent consecutive cardiac surgery from January 1996 through September 1999 at Linköping University Hospital, Sweden, evaluated 42 potential risk factors by univariate analysis followed by backward stepwise multivariate logistic regression analysis.

RESULTS

Two-thirds of the 291 (9.7%) sternal wound complications that occurred were identified after discharge. Of the 291 patients, 47 (1.6%) had deep sternal infections, 50 (1.7%) had postoperative mediastinitis, and 194 (6.4%) had superficial sternal wound complications. Twenty-three variables were selected by univariate analysis (P<0.15) and included in a multivariate analysis where eight variables emerged as significant (P<0.05). Preoperative risk factors for deep sternal infections/mediastinitis were obesity, insulin-dependent diabetes, smoking, peripheral vascular disease, and high New York Heart Association score. An intraoperative risk factor was bilateral use of internal mammary arteries, and a postoperative risk factor was prolonged ventilator support. Risk factors for superficial sternal wound complications were obesity, and an age of <75 years. The 30 day mortality was 2.7% for patients without sternal wound complications and 2/291 (0.7%) for all patients with sternal wound complications, 0.5% for superficial sternal wound complications, and 1.0% for deep sternal infections/mediastinitis. The 1 year mortality rate was 4.8% for patients without sternal wound complications and 11/291 (3.8%) for patients with sternal wound complications, 2.1% for superficial sternal wound complications, and 7.2% for deep sternal infections/mediastinitis.

CONCLUSIONS

The risk factors found in this study have been detected and reported in previous studies. The predictive ability was stronger though for deep sternal infections/mediastinitis (those needing surgical revisions) than for superficial sternal wound complications. Earlier recognition of sternal wound complications and aggressive treatment have probably contributed to the relatively low mortality rate seen in this study.

A rational approach to wound difficulties after sternotomy: the problem

One hundred fifty-one patients with mediastinitis after median sternotomy were treated by a single surgeon over a 6-year period. The infections were analyzed in regard to the depth of infection, time of presentation, and the mediastinal defect. Preoperative evaluations included computed tomographic (CT) scans, testing for sternal stability, and the level of contamination. Intraoperative evaluations included bone, inflammatory tissues, Gram stain, and cultures. Treatment options included rewire procedures (20 patients), immediate reconstruction (63 patients), or delayed reconstructions (88 patients). The issues of exposed prosthetic material, right ventricular laceration, long-term intravenous antibiotics, Candida infections, and reexploration of the healed mediastinum after flap reconstruction are discussed. The overall approach to postoperative healing difficulties after sternotomy is examined.

Cardiac reoperation in the intensive care unit

BACKGROUND

At our institution, cardiac reoperations are routinely performed in the cardiac intensive care unit, as opposed to taking these patients back to the operating room. Our hypothesis was that reoperation in a cardiac intensive care unit does not increase sternal infection rate.

METHODS

A retrospective analysis was performed on 6,908 adult patients undergoing cardiac operation over a 9-year period. Excluding those in cardiac arrest, 340 (4.9%) patients underwent reoperation in the cardiac intensive care unit, of which 289 survived (85%).

RESULTS

Of the 289 patients who survived reoperation in the intensive care unit, 6 developed wound infections that required operative debridement (2.1%), which was not significantly different from those patients not requiring reoperation (1.9%, 121 of 6,497, p = 0.70). Hospital charges for a 2-hour reoperation in the intensive care unit and operating room are approximately $1,972/patient and $5,832/patient, respectively.

CONCLUSIONS

Reoperation in the intensive care unit does not increase wound infection rate compared to those without reoperation. Decreased charges, avoiding transport of potentially unstable patients, quicker time to intervention, and convenience are advantages of reoperation in an intensive care unit.

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 morbidity and mortality following post-cardiotomy deep sternal wound infection.

METHODS

Between 1979 and 2000, 14620 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 debridement, 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 morbidity and mortality of deep sternal wound infection.

Prevalence and characteristics of post coronary artery bypass graft surgery pain (PCP)

Coronary artery bypass grafting (CABG) is one of the most common surgical procedures performed worldwide. However, its frequent complication, the post-CABG pain (PCP) syndrome, remains poorly documented. This retrospective cohort study was aimed to investigate the prevalence and characteristics of this syndrome. Five hundred and four of 540 subjects, who underwent CABG surgery at our institution between January 1995 and December 1996 and who could be identified, were mailed questionnaires regarding the presence and characteristics of chest wall pain. Eighty of 217 patients, who were defined as having PCP based on these questionnaires, were evaluated in detail. Main outcome measures included a preliminary pain questionnaire, pain localization on a body scheme, a five-point verbal scale and the Visual Analogue Scale (VAS) for measuring pain intensity. Pain qualities, disability and depression were measured by the McGill Pain Questionnaire (MPQ), the Pain Disability Index (PDI), and the Beck Depression Inventory (BDI), respectively. Medical and neurological examinations were also conducted, as well as quantitative thermal testing (QTT) of the chest wall. The preliminary pain questionnaires indicated that 219 of the 387 respondents (56%) reported chest wall pain, which was categorized as PCP. One hundred and forty-two (65%) of the patients with PCP reported pain of at least moderate severity, and 151 (72%) reported that the pain interfered with their daily activities. Eighty PCP patients were available for a detailed evaluation. Left-sided chest wall pain was noted by 53 subjects, midline scar pain by 47, and right-sided pain by nine subjects. Pain intensity (VAS) was 35 +/- 22 (mean +/- SD), MPQ score was 4.9 +/- 3.7, PDI score was 2.0 +/- 0.7, and BDI score was 9.3 +/- 7.3. The neurological examination and the QTT indicated three subcategories of PCP: (1) left-sided chest wall pain often associated with hypoesthesia, mechanical allodynia, and elevated thermal thresholds; (2) midline scar pain accompanied primarily by mechanical allodynia; (3) right-sided, relatively infrequent pain. While the first two subcategories seem to have a neurogenic etiology, this later subcategory of pain is of a mal-defined etiology. This study indicates that PCP is a group of pain syndromes with a high prevalence, and with a negative effect on mood and performance of daily activities. The risk of developing PCP and its potential consequences should therefore be discussed with every patient prior to CABG surgery. These results will need to be confirmed in larger, multi-center studies.

Transfusion of Blood Components and Postoperative Infection in Patients Undergoing Cardiac Surgery

OBJECTIVE

To investigate the influence of blood derivatives on the acquisition of severe postoperative infection (SPI) in patients undergoing heart surgery.

SETTING

The postoperative ICUs of a tertiary-level university hospital.

DESIGN

A cohort study.

METHODS

During a 4-year period, 738 patients, classified as patients with SPIs and patients without SPIs (non-SPI patients), were included in the study. We studied the influence of 36 variables on the development of SPI in general and individually for pneumonia, mediastinitis, and/or septicemia. The influence of the blood derivatives on infections was assessed for RBC concentrates, RBC and plasma, and RBC and platelets.

RESULTS

Seventy patients (9.4%) were classified as having SPIs, and 668 (90.6%) were classified as not having SPIs. After multivariate analysis, the variables associated with SPI (incidence, 9.4%) were reintubation, sternal dehiscence, mechanical ventilation (MV) for > or = 48 h, reintervention, neurologic dysfunction, transfusion of > or = 4 U RBCs, and systemic arterial hypotension. The variables associated with nosocomial pneumonia (incidence, 5.9%) were reintubation, MV for > or = 48 h, neurologic dysfunction, transfusion of > or = 4 U blood components, and arterial hypotension. The variables associated with mediastinitis (incidence, 2.3%) were reintervention and sternal dehiscence, and those associated with sepsis (incidence, 1.6%) were reintubation, time of bypass > or = 110 min, and MV for > or = 48 h. The mortality rate (patients with SPI, 52.8%; non-SPI patients, 8.2%; p < 0.001) and mean (+/- SD) length of stay in the ICU (patients with SPI, 15.8 +/- 12.9 days; non-SPI patients, 4.5 +/- 4.4 days; p < 0.001) were greater for the infected patients. The transfused patients also had a greater mortality rate (13.3% vs 8.9%, respectively; p < 0.001) and a longer mean stay in the ICU (6.1 +/- 7.2 days vs 3.7 +/- 2.8 days, respectively; p < 0.01) than those not transfused.

CONCLUSION

The administration of blood derivatives, mainly RBCs, was associated in a dose-dependent manner with the development of SPIs, primarily nosocomial pneumonia.