Article

[Impact of obesity on surgical outcomes following coronary artery bypass graft surgery].

Hjarta- og, lungnaskurðdeild, Landspítala.
Laeknabladid (Impact Factor: 0.21). 04/2011; 97(4):223-8.
Source: PubMed

ABSTRACT Obesity has been related to increased postoperative morbidity and mortality following open-heart surgery. However, recent studies have shown no association or even a more favourable outcome in obese patients. This relationship was investigated in a well-defined cohort of patients that underwent myocardial revascularisation in Iceland.
A retrospective study including all patients that underwent isolated myocardial revascularisation in Iceland from 2002 to 2006. Altogether 720 patients were divided into two groups, an obese group, with BMI >30 kg/m2 (n=207, 29%), and a non-obese group with BMI ≤30 kg/m2 (n=513, 71%). Patient demographics, complications, operative mortality and long term survival of both groups were compared.
Demographics were comparable between the groups. Obese patients were 2.4 years younger, more likely to use statins (83,3% vs. 71,2%, had a significantly lower EuroSCORE (4.3 vs. 5.0) but a slightly longer operation time. Pleural fluid was less often drained in obese patients (8.2 vs. 15.0%) but rates for other complications were similar in both groups, as was operative mortality ≤30 days (2.0% vs. 3.7%), 1 and 5 year survival. In a multivariate analysis obesity was not an independent risk factor for minor or major complications, operative mortality or long term survival.
The rate of complications and operative mortality after myocardial revascularisation is not significantly higher in obese patients and the same applies to long term survival. This is true even after correcting for confounding factors in a multivariate analysis.

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    ABSTRACT: Infections of the sternal wound are among the most serious complications after open heart surgery. These infections result in increased morbidity for patients, can sometimes be fatal, and are associated with increased costs. Deep sternal wound infections (DSWIs) are the most common and serious of these infections. Late infections, which can result in formation of sternocutaneous fistulas (SCFs), are encountered less often, although they often represent a complex surgical problem involving several hospital admissions, prolonged antibiotic treatment, and repeated wound debridements. For the last two decades, more efficient treatments have been developed for these infections, which has lowered mortality—especially after the introduction of negative-pressure wound therapy (NPWT). In NPWT, polyurethane foam is placed in a debrided wound covered with a sterile wound drape, and a tube for transmission of negative pressure to facilitate wound healing is attached, increasing the likelihood of successful closure. The aims of the work presented in this thesis, which consists of four peer reviewed papers (I–IV), were twofold. First, to analyze the incidence, risk factors, microbiology, and outcome of DSWI in Iceland, concentrating on the outcome of NPWT. Second, to study the same outcome parameters for SCF in two well-defined cohorts of patients, one in Sweden and the other in Iceland. Clinical information was gathered from hospital charts and was registered electronically. When possible risk factors for both DSWI and SCF were evaluated, multivariate analysis was used with a case-control design and survival was analyzed using either direct comparison or the Kaplan-Meier method. In Paper I, a population-based study of DSWI in Iceland is described, involving a total of 41 patients diagnosed between 1997 and 2004, or 2.5% of all patients who underwent open heart surgery during the period. The most common pathogens were Staphylococcus aureus and coagulase-negative staphylococci (CoNS) in 41% and 37% of cases, respectively. The strongest independent risk factors were: peripheral arterial disease (odds ratio (OR) = 6.4), re-operation due to bleeding (OR = 4.5), cerebrovascular accident (OR = 4.3), obesity (OR = 3.0), low left ventricular ejection fraction (OR = 2.9), and history of smoking (OR = 2.9). The in-hospital mortality during this study period was 10% among DSWI cases, as compared to 4% in controls (p = 0.17). The one-year mortality was significantly higher in DSWI cases: 17% vs. 6% (p = 0.02). Patients with DSWI stayed an average of 33 days longer in hospital for treatment. In Paper II, 23 patients with DSWI were treated with open and/or closed irrigation between January 2000 and August 2005 (conventional treatment, the CvT group) and 20 patients were treated after this time with NPWT as a first-line therapy (the NPWT group). In all cases, the sternum could be closed with delayed primary closure except for one patient in each group. The median length of both inhospital and intensive care stay was similar in the 2 groups: 43 and 4 days, respectively. Eight patients (35%) in the CvT group required surgical revision for re-infections, including debridement and rewiring, as compared to one patient (5%) in the NPWT group (p = 0.02). Furthermore, 6 patients in the CvT group developed late chronic infections of the sternum requiring surgical revision, as compared to one in the NPWT group (p = 0.10). The 30-day mortality was not significantly different between groups (4% vs. 0%, p = 1.0), and the same was true for 1-year mortality (17% vs. 0%, p = 0.07). In Papers III and IV, the crude rate of surgically treated SCF was found to be 0.26% and 0.25% in Skåne and Iceland, respectively. The case-control study from Sweden identified a number of independent risk factors for development of SCF: previously treated sternal wound infection—superficial or deep (OR = 15.7), pre- or postoperative renal failure (OR = 12.5), history of smoking (OR = 4.7), and the use of bone wax (OR = 4.2). The most common pathogens were CoNS and S. aureus, which were the only bacteria identified in 63% and 19% of cases, respectively. In addition to antibiotic treatment, NPWT was used in 20 cases of extensive SCFs in Sweden, while CvT was performed in 12 cases; in Iceland, all cases were treated with CvT. In Sweden, the average length of stay for SCF treatment was 29 days and in-hospital mortality was 6%. Furthermore, a significantly worse five-year survival was found in the SCF patients than in the controls (hazard ratio = 5.4). In-hospital stay ranged from 0 to 50 days (average 19 days) in Iceland with no in-hospital deaths. Five years postoperatively, 58% of SCF patients were alive as compared to 85% of the control group (p = 0.003). The number of surgical intervention attempts ranged from one to more than 10. Both DSWI and SCF are associated with increased mortality and increased length of stay, and they often require repeated surgical interventions. The incidence of DSWI in Iceland is comparable to that in contemporary studies, with similar risk factors and significantly reduced survival one year after the infection. The use of NPWT is associated with a reduced need for surgical re-intervention. However, there was no statistically significant difference between groups regarding length of stay, rate of late chronic sternal infections, or mortality. The results indicate that NPWT should be considered as a firstline treatment for most DSWIs. Although SCF is relatively rare, it is a devastating diagnosis with significant morbidity and mortality. Previous sternal wound infections, renal failure, smoking, and use of bone wax are independent risk factors for formation of SCF; however, in most patients SCF is not associated with a previous diagnosis of sternal wound infection. The optimal treatment for SCF has not been established, although efficient treatment options exist.
    04/2013, Degree: PhD, Supervisor: Tomas Gudbjartsson