Infections following major heart surgery in European intensive care units: there is room for improvement (ESGNI 007 Study)

Infectious complications following major heart surgery from the day of the surgery to hospital discharge

BACKGROUND

At some point in their lives, many people will require major heart surgery (MHS). Patients are generally older adults with various risk factors for infection. However, the incidence of infection after MHS is poorly known, as reported infection data are frequently biased due to different factors like the surgical procedure, postoperative timing, and infectious syndromes or etiologic agents, among others. In addition, most patient data are retrospectively obtained.

PURPOSE AND METHODS

Data were prospectively collected regarding the incidence of all nosocomial infections produced from the time of surgery to hospital discharge in a cohort of 800 adults consecutively undergoing a MHS procedure.

RESULTS

During postoperative hospitalization, 124 of the 800 participants developed one or more infections (15.5%): during their ICU stay in 68 patients (54.8%), during their stay on the general ward post ICU in 50 (40.3%), and during their stay in both wards in 6 (4.8%). The most common infections were pneumonia (related or not to mechanical ventilation), surgical site and bloodstream. As etiological agents, 193 pathogens were isolated: mostly Gram-negative bacilli (54.4%), followed by Gram-positive bacteria (30%), viruses (4.6%) and fungi (1.5%). In our cohort, all-cause mortality was recorded in 33 participants (4.1%) and 9 infection-related deaths (1.1%) were produced. Among subjects who developed infections, overall mortality was 13.7% and in those who did not, this was only 2.3%.

CONCLUSION

Infection following MHS remains frequent and severe. Our data suggest that hospital-acquired infection studies should consider episodes of infection in all populations during their entire hospital stay and not only those related to specific clinical syndromes or acquired while the patient is in intensive care.

Effects of perioperative transcutaneous electrical acupoint stimulation on monocytic HLA-DR expression in patients undergoing coronary artery bypass grafting with cardiopulmonary bypass: study protocol for a double-blind randomized controlled trial

BACKGROUND

Cardiac surgery involving cardiopulmonary bypass (CPB) is known to be associated with a transient postoperative immunosuppression. When severe and persistent, this immune dysfunction predisposes patients to infectious complications, which contributes to a prolonged stay in the intensive care unit (ICU), and even mortality. Effective prevention and treatment methods are still lacking. Recent studies revealed that acupuncture-related techniques, such as electroacupuncture and transcutaneous electrical acupoint stimulation (TEAS), are able to produce effective cardioprotection and immunomodulation in adult and pediatric patients undergoing cardiac surgery with CPB, which leads to enhanced recovery. However, whether perioperative application of TEAS, a non-invasive technique, is able to improve immunosuppression of the patients with post-cardiosurgical conditions is unknown. Thus, as a preliminary study, the main objective is to evaluate the effects of TEAS on the postoperative expression of monocytic human leukocyte antigen (-D related) (mHLA-DR), a standardized "global" biomarker of injury or sepsis-associated immunosuppression, in patients receiving on-pump coronary artery bypass grafting (CABG).

METHODS

This study is a single-center clinical trial. The 88 patients scheduled to receive CABG under CPB will be randomized into two groups: the group receiving TEAS, and the group receiving transcutaneous acupoint pseudo-electric stimulation (Sham TEAS). Expression of mHLA-DR serves as a primary endpoint, and other laboratory parameters (e.g., interleukin [IL]-6, IL-10) and clinical outcomes (e.g., postoperative infectious complications, ICU stay time, and mortality) as the secondary endpoints. In addition, immune indicators, such as high mobility group box 1 protein and regulatory T cells will also be measured.

DISCUSSION

The current study is a preliminary monocentric clinical trial with a non-clinical primary endpoint, expression of mHLA-DR, aiming at determining whether perioperative application of TEAS has a potential to reverse CABG-associated immunosuppression. Although the immediate clinical impact of this study is limited, its results would inform further large-sample clinical trials using relevant patient-centered clinical outcomes as primary endpoints.

TRIAL REGISTRATION

ClinicalTrials.gov, NCT02933996. Registered on 13 October 2016.

Med-Score 24: A multivariable prediction model for poststernotomy mediastinitis 24 hours after admission to the intensive care unit

OBJECTIVES

Mediastinitis is a serious complication of heart surgery. In this study, we developed a bedside risk score for poststernotomy mediastinitis.

METHODS

Data were prospectively collected from 4625 patients admitted to our intensive care unit after heart surgery (January 2005-June 2011). Mediastinitis was defined according to Centers for Disease Control and Prevention criteria. A logistic model was constructed in a randomly selected subgroup of 2618 patients and validated in a second cohort of 1352, as well as in a prospective cohort of 2615 (June 2011-December 2015). Model discriminatory power was assessed according to the area under the receiver operating characteristic curve (AUROC). The β coefficients of the model were used to define 3 levels of mediastinitis risk as a score designated Med-Score 24. Its performance to predict mediastinitis was compared with that of the logistic EuroSCORE and Society of Thoracic Surgeons score.

RESULTS

Ninety-four (2.36%) patients developed mediastinitis. The risk factors identified as predictive of mediastinitis (AUROC 0.80) were 4 preoperative variables (age >70 years, chronic obstructive lung disease, obesity, and antiplatelet therapy) and 3 perioperative variables (prolonged ischemia, emergency reoperation, and prolonged intubation). AUROCs for the Society of Thoracic Surgeons score and logistic EuroSCORE were 0.63 and 0.55, respectively, both differing significantly from the area calculated for Med-Score 24 (P < .001).

CONCLUSIONS

The score developed showed excellent predictive power 24 hours after admission to the intensive care unit for mediastinitis risk. This simple tool helps stratify patients according to this risk, thus identifying high-risk patients for preventive measures. In our patient cohort, Med-Score 24 performed better than other scores used for this purpose.

Bloodstream infections following different types of surgery in a Finnish tertiary care hospital, 2009-2014

The risk and outcome of bloodstream infections (BSIs) were evaluated following surgery. BSIs were identified in Helsinki University Hospital during 2009-2014 as part of the national surveillance. Of 711 BSIs identified, 51% were secondary and 49% primary. The rate was highest after cardiovascular surgery (8.7 per 1000 procedures) and lowest after gynaecologic (1.0 per 1000). Surgical site infection was the most frequent source of secondary BSIs (34%) and 45% of primary BSIs were central-line-associated. The 28-day case fatality ranged from zero in gynaecology/obstetrics to 21% in cardiovascular surgery. Besides BSIs related to surgical site infections, half of BSIs were primary, providing additional foci for prevention.

Emergence of Carbapenem-Resistant Klebsiella pneumoniae: Progressive Spread and Four-Year Period of Observation in a Cardiac Surgery Division

Frequent use of carbapenems has contributed to the increase to K. pneumoniae strains resistant to this class of antibiotics (CRKP), causing a problem in the clinical treatment of patients. This investigation reports the epidemiology, genetic diversity, and clinical implication of the resistance to drugs mediated by CRKP in our hospital. A total of 280 K. pneumoniae strains were collected; in particular 98/280 (35%) were CRKP. Sequencing analysis of CRKP isolated strains showed that 9/98 of MBL-producing strains carried the bla VIM-1 gene and 89/98 of the isolates were positive for bla KPC-2. Antimicrobial susceptibility tests revealed a complete resistance to third-generation cephalosporins and a moderate resistance to tigecycline, gentamicin, and fluoroquinolones with percentages of resistance of 61%, 64%, and 98%, respectively. A resistance of 31% was shown towards trimethoprim-sulfamethoxazole. Colistin was the most active agent against CRKP with 99% of susceptibility. Clonality was evaluated by PFGE and MLST: MLST showed the same clonal type, ST258, while PFGE analysis indicated the presence of a major clone, namely, pulsotype A. This finding indicates that the prevalent resistant isolates were genetically related, suggesting that the spread of these genes could be due to clonal dissemination as well as to genetic exchange between different clones.

Independent risk factors for ventilator-associated pneumonia after cardiac surgery

OBJECTIVE

To investigate the related factors and pathogens of ventilator-associated pneumonia (VAP) after heart surgery so as to provide evidences for clinical prevention and therapy.

METHODS

In total 1,688 cases were collected from January 2004 to January 2011. Overall 105 patients developed VAP. Retrospectively analyzed these patients after heart surgery to determine the clinical data, pathogens and treatment measures.

RESULTS

The frequency of ventilator-associated pneumonia was 6.2% (105/1 688), and mortality was 25.7% (27/105), 198 pathogen strains were isolated by bacterial culture, in which Gram negative bacteria accounted for 69.2% (137/198), Gram positive bacteria 27.8% (55/198), and fungi 3.0% (6/198). The independent risk factors for VAP after cardiac surgery were: age >70 (p < .01), emergent surgery (p < .01), perioperative blood transfusions (p < 0.01), reintubation (p < .01) and days of mechanical ventilation (MV) (p < .01). Median length of stay in the ICU for patients who developed VAP or not was, respectively, (24.7 ± 4.5) days versus (3.2 ± 1.5) days (p < .05), and mortality was, respectively, 25.7% versus 2.9% in both populations (p < .05).

CONCLUSION

Age >70, emergent surgery, perioperative blood transfusions, reintubation and days of MV are the risk factors for VAP in patients following cardiac surgery. P. aeruginosa, P. klebsiella, S. aureus, and Acinetobacter baumannii were the main pathogens of VAP. According to the cause of VAP, active prevention and treatment measures should be developed and applied to shorten the time of MV and improve chances of survival.

Methicillin-resistant Staphylococcus aureus infection: an independent risk factor for mortality in patients with poststernotomy mediastinitis

OBJECTIVE

The mortality rate of patients with poststernotomy mediastinitis remains very high. The aim of this study was to identify the risk factors associated with mortality in these patients.

SUBJECTS AND METHODS

Surveillance of sternal surgical-site infections including mediastinitis was carried out for adult patients undergoing a sternotomy between 2004 and 2012. Criteria from the US Centers for Disease Control and Prevention were used to make the diagnosis. All data on patients with a diagnosis of mediastinitis who were included in the study and on mortality risk factors were obtained from the hospital database and then analyzed using SPPS 16.0 for Windows.

RESULTS

Of the 19,767 patients undergoing open heart surgery, 117 (0.39%) had poststernotomy mediastinitis; 32% of these 117 died. The independent risk factors for mortality were methicillin-resistant Staphylococcus aureus (MRSA) [odds ratio (OR) 12.11 and 95% confidence interval (CI) 3.15-46.47], intensive-care unit stays >48 h after the first operation (OR 11.21 and 95% CI 3.24-38.84) and surgery that included valve replacement (OR 6.2 and 95% CI 1.44-27.13). The mortality rate decreased significantly, dropping from 38% (34/89) between 2004 and 2008 to 14% (4/28) between 2009 and 2012 (p = 0.018).

CONCLUSION

In this study, elimination of MRSA from the hospital setting decreased the rate of mortality in patients with poststernotomy mediastinitis.

Dysfunction of alveolar macrophages after cardiac surgery and postoperative pneumonia?--An observational study

Introduction

Patients undergoing cardiac surgery have an increased risk of postoperative pneumonia. Pulmonary immune dysfunction might be a contributing factor. We therefore determined changes of the surface molecules on alveolar macrophages (AMs). To characterize modulation in patients with pneumonia we correlated these changes to the development of postoperative pneumonia.

Methods

After ethical approval and written informed consent, 33 patients undergoing elective coronary bypass grafting surgery were included in this observational study. Peripheral blood cells and alveolar lavage fluid were collected directly after induction of anesthesia and two hours after separation from cardiopulmonary bypass (CPB). Human leukocyte antigen-DR (HLA-DR) and toll-like receptors (TLR) 2/4 expression on monocytes and AM were assessed by flow cytometry. A total of three patients developed postoperative pneumonia determined according to the criteria of the Center of Disease Control. Statistical analysis was performed with the Mann–Whitney-U test and Wilcoxon test.

Results

We found significant changes of phenotypic and functional immune markers on AMs after cardiac surgery. HLA-DR expression on peripheral blood monocytes and AMs was significantly reduced compared to baseline in all patients (each approximately 30%). After surgery patients who developed postoperative pneumonia revealed a trend of stronger reduction of HLA-DR expression (83.7% versus 27.1%) and TLR4 expression on AMs (46.1% versus 9.9%) compared to patients without pneumonia. Already before surgery, the baseline of TLR2 expression on AM was significantly lower (27.7%) in patients who developed postoperative pneumonia.

Conclusions

As far as we know this is the first study that shows an early impairment of lung cellular immune response after cardiac surgery. These findings can help to understand the role of cell-mediated immunosuppression and its association to the development of postoperative pneumonia.

Pre-emptive broad-spectrum treatment for ventilator-associated pneumonia in high-risk patients

PURPOSE

Patients requiring mechanical ventilation (MV) for >48 h after major heart surgery (MHS) are at a high risk of acquiring ventilator-associated pneumonia (VAP) and tracheobronchitis (VAT). Most non-pharmacological interventions to prevent VAP in such patients are usually already implemented. The objective of this study was to evaluate the efficacy in preventing lower respiratory infections of antibiotics active against multidrug-resistant pathogens in this very high-risk population.

METHODS

We performed a prospective randomized open-label study of MHS patients requiring MV for >48 h. Patients were randomly allocated to one of two groups: the intervention group, which received a 3-day course of linezolid and meropenem, and the control group, which received the standard of care. The main outcome was the development of VAP or VAT.

RESULTS

Overall, of the 78 patients included in the study, 40 were in the intervention group and 38 in the control group. Both groups were comparable. Data for the intervention and control groups respectively were as follows: VAP + VAT/1,000 days was 31.79 vs 64.78 (p = 0.03), median length of MV before the first episode of VAP or VAT 9 vs 4.5 days (p = 0.02). No significant differences were observed in median length of stay in the intensive care unit, median length of hospital stay, antibiotic use, Clostridium difficile infection, and overall mortality rate. We detected linezolid-resistant coagulase-negative and coagulase-positive staphylococci in the MHS intensive care unit after the study period.

CONCLUSIONS

A pre-emptive approach with broad-spectrum antibiotics may be effective in reducing the incidence and delaying the onset of VAP + VAT after MHS. The ecological consequences have to be carefully evaluated in future trials.

Invasive device-related infections after heart surgery

OBJECTIVE

To analyze postoperative infections in critically ill patients undergoing heart surgery.

SETTING

Intensive care units (ICUs).

DESIGN

An observational, prospective, multicenter study was carried out.

PATIENTS

Patients in the postoperative period of heart surgery admitted to the ICU and included in the ENVIN-HELICS registry between 2005 and 2011.

MAIN OUTCOME VARIABLES

Mechanical ventilation associated pneumonia (MVP), urinary catheter-related infection (UCI), primary bacteremia (PB), PB related to vascular catheters (PB-VC) and secondary bacteremia.

RESULTS

Of a total of 97,692 patients included in the study, 9089 (9.3%) had undergone heart surgery. In 440 patients (4.8%), one or more infections were recorded. Infection rates were 9.94 episodes of MVP per 1000 days of mechanical ventilation, 3.4 episodes of UCI per 1000 days of urinary catheterization, 3.10 episodes of BP-VC per 1000 days of central venous catheter, and 1.84 episodes of secondary bacteremia per 1000 days of ICU stay. Statistically significant risk factors for infection were ICU stay (odds ratio [OR] 1.18, 95%CI 1.16-1.20), APACHE II upon admission to the ICU (OR 1.05, 95%CI 1.03-1.07), emergency surgery (OR 1.67, 95%CI 1.13-2.47), previous antibiotic treatment (OR 1.38, 95%CI 1.04-1.83), and previous colonization by Pseudomonas aeruginosa (OR 18.25, 95%CI 3.74-89.06) or extended spectrum beta-lactamase producing enterobacteria (OR 16.97, 95%CI 5.4-53.2). The overall ICU mortality rate was 4.1% (32.2% in patients who developed one or more infections and 2.9% in uninfected patients) (P < .001).

CONCLUSIONS

Of the patients included in the ENVIN-HELICS registry, 9.3% were postoperative heart surgery patients. The overall mortality was low but increased significantly in patients who developed one or more infection episodes.

[Daptomycin for the treatment of gram-positive infections after cardiac surgery]

BACKGROUND AND METHOD

Surgical infection remains a main cause of death after heart surgery, despite advances in pharmacological therapy. Daptomycin is a cyclic lipopeptide antibiotic, useful in gram-positive organisms resistant to standard treatment, including vancomycin. The aim of this study was to describe the use of daptomycin regarding efficacy, efficiency and safety in patients with gram-positive infections after heart surgery using a retrospective analysis on 49 adult patients.

CONCLUSION

Daptomycin shows excellent in vitro and in vivo activity against gram-positive organisms, such as Enterococcus faecalis, Enterococcus faecium, Staphylococcus aureus, especially MRSA. Daptomycin is also effective against increasing vancomycin-resistant or vancomycin-intermediate S. aureus.

[Urinary tract colonization and infection in critically ill patients]

Urinary tract infections (UTIs) account for 20-50% of all hospital-acquired infections occurring in the intensive care unit (ICU). In some reports UTI was found to be more frequent than hospital-acquired pneumonia and intravascular device bacteremia, with a greater incidence in developing countries. The risk factors associated with the appearance of UTI include the severity of illness at the time of admission to the ICU, female status, prolonged urinary catheterization or a longer ICU stay and poor urinary catheter management - mainly disconnection of the closed system. about the present study offers data on the epidemiology of UTI in the ICU, the identified risk factors, etiology, diagnosis, impact upon morbidity and mortality, and the measures to prevent its appearance.

Surgical wound complications after heart transplantation

Surgical wound complications are more frequent in patients undergoing heart transplantation than in other heart surgery patients. This is probably attributed to the presence of additional risk factors in these patients, such as immunosuppression, mechanical support through assist devices and generally poor health. Analyses of wound infections in heart transplantation are based on smaller patient population than those for general heart surgery, and the reported incidences vary largely. The identification of specific risk factors in heart transplant recipients to date is mainly based on retrospective case-control studies in small patient cohorts, the results are controversial, and the comparability of data is limited because of the lack of application of consistent definitions. The impact of immunosuppression and especially immunosuppression with mammalian target of rapamycin (mTOR) inhibitors on the development of surgical wound complications has been widely discussed following reports of increased occurrence with sirolimus. However, nonheart-transplant specific risk factors should also be considered to develop risk profiles and treatment algorithms for individual patients. Data on surgical wound complications in general heart surgery patients and in heart transplant recipients are compared, the impact of modern immunosuppression reviewed, and areas for further investigation discussed.

Infective endocarditis of the Dacron patch-a report of 13 cases at autopsy

AIMS

One of the complications of using a synthetic material as a patch in correction of left-to-right shunts is the development of infection. This is an autopsy report of 13 patients who developed infective endocarditis of the Dacron patch as a postoperative complication.

METHODS

We retrospectively reviewed the autopsy records of patients with infective endocarditis over a 15-year period (1994-2008) and selected cases with Dacron-patch infective endocarditis. The patch infective endocarditis was classified into early-onset and late-onset infective endocarditis.

RESULTS

Patch infective endocarditis was seen in 13 patients affecting the patches covering an atrial septal defect and 12 ventricular septal defects. There were nine males and four females, with a mean age of 13.1 years. The episodes occurred 2 to 118 days (mean of 30) after operation, with early-onset infective endocarditis in 10 and late-onset infective endocarditis in three patients. Postoperative wound infection had been present in eight. The organisms isolated or demonstrated on microscopy included Staphylococcus aureus (5), gram-positive cocci (4), Pseudomonas (2), Aspergillus species (1), and Candida species (1). Death was related to embolization and/or accompanying septicemia.

CONCLUSIONS

Correction of simple or complex congenital cardiac defects offers new substrates for organisms to colonize resulting in infective endocarditis, which are often difficult to treat.

Ventilator-associated pneumonia in patients undergoing major heart surgery: an incidence study in Europe

Introduction

Patients undergoing major heart surgery (MHS) represent a special subpopulation at risk for nosocomial infections. Postoperative infection is the main non-cardiac complication after MHS and has been clearly related to increased morbidity, use of hospital resources and mortality. Our aim was to determine the incidence, aetiology, risk factors and outcome of ventilator-associated pneumonia (VAP) in patients who have undergone MHS in Europe.

Methods

Our study was a prospective study of patients undergoing MHS in Europe who developed suspicion of VAP. During a one-month period, participating units submitted a protocol of all patients admitted to their units who had undergone MHS.

Results

Overall, 25 hospitals in eight different European countries participated in the study. The number of patients intervened for MHS was 986. Fifteen patients were excluded because of protocol violations. One or more nosocomial infections were detected in 43 (4.4%) patients. VAP was the most frequent nosocomial infection (2.1%; 13.9 episodes per 1000 days of mechanical ventilation). The microorganisms responsible for VAP in this study were: Enterobacteriaceae (45%), Pseudomonas aeruginosa (20%), methicillin-resistant Staphylococcus aureus (10%) and a range of other microorganisms. We identified the following significant independent risk factors for VAP: ascending aorta surgery (odds ratio (OR) = 6.22; 95% confidence interval (CI) = 1.69 to 22.89), number of blood units transfused (OR = 1.08 per unit transfused; 95% CI = 1.04 to 1.13) and need for re-intervention (OR = 6.65; 95% CI = 2.10 to 21.01). The median length of stay in the intensive care unit was significantly longer (P < 0.001) in patients with VAP than in patients without VAP (23 days versus 2 days). Death was significantly more frequent (P < 0.001) in patients with VAP (35% versus 2.3%).

Conclusions

Patients undergoing aortic surgery and those with complicated post-intervention courses, requiring multiple transfusions or re-intervention, constitute a high-risk group probably requiring more active preventive measures.