Methicillin resistant Staphylococcus aureus infections following cardiac surgery: incidence, impact and identifying adverse outcome traits.

OBJECTIVE: To assess the incidence and impact of Methicillin-resistant Staphylococcus aureus (MRSA) infections on cardiac surgery outcomes and to identify adverse outcome traits. METHODS: Retrospective analysis of prospectively collected data from cardiac surgical and microbiology databases between April 2000 and March 2005. The overall and yearly incidence of positive MRSA cultures was examined along with the distribution of clinical infections and the associated mortality. Pre-operative patient characteristics were analysed between non-survivors and survivors of MRSA infections. Multivariate logistic regression was used to assess the relationship between pre-operative patient characteristics and in-hospital mortality in patients with MRSA. A comparison of post-operative outcomes between non-survivors and survivors of MRSA infections was also carried out and included in the logistic regression analysis. RESULTS: There were 319 patients with positive MRSA cultures during the study period with an overall incidence of 3.9%. Yearly incidence ranged from 2.4% to 5.2%. There were 120 carriers with pre-operative positive cultures of which 25 developed clinical surgical infections leaving 224 patients as the study group. Overall mortality in patients with MRSA during the study period was 12.9%(41/319). Mortality in the study group was 17.8% (40/224). Mortality comparison between MRSA and non-MRSA mediastinitis was 26.7%(8/30) and 17.1%(13/76), respectively (p=0.26). Mortality between MRSA and non-MRSA septicaemia was 46.9% (15/32) and 52.9% (37/70) (p=0.57). Applying the logistic EuroSCORE to the MRSA patients revealed that non-survivors had a significantly higher pre-operative risk of 10.4% compared to survivors with a pre-operative risk of 6.2% (p=0.003). Renal dysfunction and poor ejection fraction were found to be pre-operative factors associated with mortality in MRSA patients following the multivariate logistic regression analysis. Non-survivors had longer stays on intensive care, longer ventilation times, and were more likely to require support with balloon pumps and haemofiltration. MRSA septicaemia and length of ventilation were significantly associated with mortality in MRSA patients ahead of pre-operative characteristics. CONCLUSIONS: The incidence of MRSA is low, but carries a high mortality. MRSA septicaemia and mediastinitis have the highest associated mortality; however, this is not significantly different from non-MRSA infections. Patients with MRSA who die have higher pre-operative risk and have a poorer post-operative course than survivors.

Cardiac surgery take-away kit.

BACKGROUND: Trauma to the heart is usually rapidly fatal, but survival can be improved with timely and appropriate surgical management. However, certain injuries require specialist cardiothoracic surgical intervention. METHODS: Three patients with coronary artery lacerations treated by cardiac surgeons at remote hospitals are presented. The recent literature, the current treatment options available and suggestions on techniques to improve survival are reviewed. CONCLUSIONS: Laceration of the coronary arteries is difficult to manage, especially in the absence of specialty equipment. Appropriate protocols should be established to provide this service in order to optimise the management of patients with complicated trauma. A cardiac surgical take-away kit could facilitate the management of these difficult patients in a setting remote from the cardiac operating room.

Timing of intra-aortic balloon pump support and 1-year survival.

OBJECTIVE: The relationship between the timing of intra-aortic balloon pump (IABP) support and surgical outcome remains a subject of debate. Peri-operative mechanical circulatory support is commenced either prophylactically or after increasing inotropic support has proved inadequate. This study evaluates the effect timing of IABP support on the 1-year survival of patients undergoing cardiac surgery. METHODS: From April 1997 to September 2002, 7698 consecutive cardiac surgical procedures were performed. This included 5678 isolated coronary artery bypasses (CABGs), 1245 isolated valve procedures and 775 simultaneous CABG and valve procedures. IABP support was required in 237 patients (3.1%). Twenty-seven patients (0.35%) were classed as high-risk and received preoperative IABP support, 25 patients (0.32%) were haemodynamically compromised and required preoperative IABP support, 120 patients (1.56%) required intra-operative IABP support, and 65 patients (0.84%) required post-operative IABP support. Multiple variables were offered to a Cox proportional hazards model and significant predictors of 1-year survival were identified. These were used to risk adjust Kaplan-Meier survival curves. RESULTS: 1-year follow-up was complete and 450 deaths (5.8%) were recorded. The significant independent predictors of increased mortality at 1-year (P<0.05, HR=hazard ratio) were post-operative renal failure (HR=3.5), increasing EuroSCORE (HR=1.2), post-operative myocardial infarction (HR=3.7), post-operative IABP (HR=4.1) intra-operative IABP (HR=2.8), post-operative stroke (HR=2.5), increasing number of valves (HR=1.6), ejection fraction <30% (HR=1.3) and triple-vessel disease (HR=1.3). After risk-adjustment, 1-year survival for patients who required intra-operative IABP support was significantly greater than for those patients who required IABP support in the post-operative period. CONCLUSIONS: Patients who warrant IABP support in the post-operative setting have a significantly increased mortality at 1-year when compared to any other group. Therefore, earlier IABP support as part of surgical strategy may help to improve the outcome.

Impact of chronic obstructive pulmonary disease severity on surgical outcomes in patients undergoing non-emergent coronary artery bypass grafting.

OBJECTIVES: Although the association between chronic obstructive pulmonary disease (COPD) and adverse surgical outcomes has been previously demonstrated, the impact of COPD severity on postoperative mortality and morbidity remains unclear. Our objective was to analyse the prognostic implication of COPD stages as defined by the Global Initiative for Chronic Obstructive Lung Disease. METHODS: Between September 1997 and April 2010, 13,638 patients undergoing first time isolated CABG were retrospectively reviewed, of whom 2421 patients were excluded due to lack of spirometry records or restrictive pattern on spirometry. The remaining 11,217 patients were divided into three groups: group 1 (including patients with normal spirometry and patients with mild COPD (FEV1/FVC ratio<70%, FEV1≥80% predicted), group 2 (moderate COPD: FEV1/FVC ratio<70%, 50%≤FEV1<80% predicted) and group 3 (severe COPD: FEV1/FVC ratio<70%, FEV1<50% predicted). Logistic regression was used to examine the effect of COPD severity on early mortality and morbidity, after adjusting for differences in patient characteristics. RESULTS: Early mortality in the three groups was 1.4, 2.9 and 5.7% respectively (P<0.001). Similarly, a consistent trend of increasing frequency of postoperative complications with advanced COPD stage was noted. On multivariate analysis, severe COPD was found to be significantly associated with early mortality [adjusted OR, 2.31 (95% CI) (1.23-4.36)], P=0.01. CONCLUSIONS: The severity of COPD as defined by spirometry can be a prognostic marker in patients undergoing CABG. Spirometric criteria may help refining currently used operative risk scores.

Outcomes and predictors of prolonged ventilation in patients undergoing elective coronary surgery.

OBJECTIVES Despite the seriousness of prolonged mechanical ventilation (PMV) as a postoperative complication, previously proposed risk prediction models were met with limited success. The purpose of this study was to identify perioperative variables associated with PMV in elective primary coronary bypass surgery. PMV was defined as the need for intubation and mechanical ventilation for >72 h, after completion of the operation. METHODS Between April 1997 and September 2010, 10 ,977 consecutive patients were retrospectively reviewed. A series of two multivariate logistic regression analyses were carried out to identify preoperative predictors of prolonged ventilation and the impact of operative variables. RESULTS PMV occurred in 215 (1.96%) patients; 119 (55.3%) of these underwent tracheostomy. At multivariate analysis, predictors included NYHA higher than class II (odds ratio [OR], 1.77; 95% confidence intervals [CI], 1.34-2.34), renal dialysis (OR, 5.5; 95% CI, 2.08-14.65), age at operation (OR, 1.04; 95% CI, 1.02-1.06), reduced FEV(1) (OR, 0.99; 95% CI, 0.98-0.99), body mass index >35 kg/m(2) (OR, 1.73; 95% CI, 1.14-2.63). On serial logistic regression analyses, operative variables added little to the discriminatory power of the model. Kaplan-Meier survival curves showed reduced survival among PMV patients (P < 0.001) with an improved survival in the tracheostomy subgroup. CONCLUSIONS PMV after coronary bypass is associated with a reduction in early and mid-term survival. Risk modelling for PMV remains problematic even when examining a more homogenous lower risk group.

Does avoidance of cardiopulmonary bypass confer any benefits in octogenarians undergoing coronary surgery?

OBJECTIVES: There remain concerns about hospital outcomes in octogenarians being referred for coronary artery bypass grafting (CABG). Avoiding the use of cardiopulmonary bypass (CPB) may be an attractive option to improve early outcomes in this group of patients. METHODS: Between April 1997 and March 2010, 343 consecutive patients aged 80-89 years received isolated first time CABG. We used logistic regression to develop a propensity score for off-pump group membership and then performed a propensity matched analysis comparing off-pump (n=107) to on-pump (n=107) groups for early mortality and morbidity. All analysis was performed retrospectively. RESULTS: Preoperative patient characteristics were comparable in both groups, with mean age 82.0 years (80.6-83.7 years) and logistic EuroSCORE 9.9 (6.1-19.5) in the on-pump group compared to 81.6 (80.7-83.2) and 8.5 (5.3-15.7) in the off-pump group (P=0.96, P=0.23, respectively). Postoperatively, in-hospital mortality was 6.5% in the on-pump group compared to 4.7% in the off-pump group (P=0.55). Postoperative complications showed no statistically significant difference between the two groups. However, off-pump was associated with a shorter mechanical ventilation and intensive care unit (ICU) stay and less use of inotropes. CONCLUSION: In our experience, avoiding CPB was not associated with a statistically significant reduction in early mortality, myocardial infarction or stroke rates. It was only associated with a shorter postoperative ventilation and ICU stay and less use of inotropes.

Effect of risk-adjusted diabetes on mortality and morbidity after coronary artery bypass surgery.

BACKGROUND: Diabetes is commonly regarded as a risk factor for mortality and morbidity after coronary artery bypass surgery. METHODS: Between April 1997 and December 2002, 6,033 consecutive patients underwent isolated coronary artery bypass surgery. Eight hundred and fourteen (13.5%) patients had diabetes (530 oral-dependent, 284 insulin-dependent). Patients with diet-controlled diabetes were classified as nondiabetics. Deaths occurring over time were described using Kaplan-Meier techniques. To control for differences in patient characteristics, we constructed a propensity score (for diabetes) and this was included along with the comparison variable in multivariate logistic regression and Cox proportional hazards analyses. RESULTS: In-hospital mortality was significantly higher for diabetic patients in the univariate analyses; however, this association disappeared after adjusting for the propensity score. Further analyses found that insulin-dependent diabetes was associated with an increased incidence of acute renal failure (adjusted odds ratio 4.15; p = 0.002), deep sternal wound infection (adjusted odds ratio 2.96; p = 0.039), and prolonged postoperative stay (adjusted odds ratio 1.60; p = 0.017). Oral-controlled diabetes was not associated with any of these outcomes. Four hundred and ninety-eight (8.3%) deaths occurred during the study follow-up. After adjusting for patient characteristics, the adjusted hazard ratio of midterm mortality for diabetes was 1.35; p = 0.013. CONCLUSIONS: Insulin-dependent diabetes has a significant impact on in-hospital morbidity. Although diabetic patients are not at increased risk of in-hospital mortality, longevity is significantly decreased during a five-year follow-up period.