Preoperative assessment of the likelihood of infection of the lower respiratory tract after cardiac surgery

Cholangiocarcinoma

Cholangiocarcinoma (CCA) is a highly lethal adenocarcinoma of the hepatobiliary system, which can be classified as intrahepatic, perihilar and distal. Each anatomic subtype has distinct genetic aberrations, clinical presentations and therapeutic approaches. In endemic regions, liver fluke infection is associated with CCA, owing to the oncogenic effect of the associated chronic biliary tract inflammation. In other regions, CCA can be associated with chronic biliary tract inflammation owing to choledocholithiasis, cholelithiasis, or primary sclerosing cholangitis, but most CCAs have no identifiable cause. Administration of the anthelmintic drug praziquantel decreases the risk of CCA from liver flukes, but reinfection is common and future vaccination strategies may be more effective. Some patients with CCA are eligible for potentially curative surgical options, such as resection or liver transplantation. Genetic studies have provided new insights into the pathogenesis of CCA, and two aberrations that drive the pathogenesis of non-fluke-associated intrahepatic CCA, fibroblast growth factor receptor 2 fusions and isocitrate dehydrogenase gain-of-function mutations, can be therapeutically targeted. CCA is a highly desmoplastic cancer and targeting the tumour immune microenvironment might be a promising therapeutic approach. CCA remains a highly lethal disease and further scientific and clinical insights are needed to improve patient outcomes.

Normal Reference Interval of WBC Count After On - Pump Coronary Artery Bypass Graft; When Values Could Be Misleading

Background

Applying the cardiopulmonary pump produces inflammatory responses and induces leukocytosis. White Blood Cell (WBC) count has a diagnostic value for detecting different infections. In this study, we want to redefine the normal value reference intervals of WBC count in Coronary Artery Bypass Graft (CABG) patients, to prevent misdiagnose leukocytosis as a sign of infection.

Methods

In an observational study, 140 patients who underwent on - pump CABG were enrolled to find out normal values of the reference interval. WBC counts were evaluated for all of them one day before the operation, first 30 minutes of ICU entrance, after 24 hours, and 48 hours after operation. Normal values of reference intervals were calculated for each measurement by two different statistical methods.

Results

There were 102 men and 38 women with age average of 61 years. There was no significant difference between genders’ WBC counts before operation (P = 0.151), ICU entrance (P = 0.391), 24 hours after surgery (P = 0.698), and 48 hours after surgery (P = 0.523). The mean values of WBC after surgery were higher than the normal range of reference interval and had an increasing trend in the first 48 hours after surgery. The WBC values were significantly different between pre and post operation (before operation and ICU admission (P = 0.001), ICU admission and 24 hours later (P = 0.001), 24 hours after surgery, and 48 hours after surgery (P = 0.001)). All post - operative reference values were significantly higher than the range for the general population.

Conclusions

There is a significant increase in WBC count after on - pump CABG. The normal range of WBC should be revised and adjusted to prevent misinterpretation as a sign of infection.

Variable Definitions: Implications for the Prediction of Pulmonary Complications after Adult Cardiac Surgery

AIM

The aim of this paper was to review the implications that variable definitions have for the prediction of post-operative pulmonary complications after cardiac surgery.

METHOD

A review of the literature from 1980 to 2002. Selected studies demonstrated an original attempt to examine multivariate associations between pre, intra or post-operative antecedents and pulmonary outcomes in patients undergoing coronary artery bypass grafting (CABG). Reports that described the validation of established clinical prediction rules, testing interventions or research conducted in non-human cohorts were excluded from this review.

RESULTS

Consistently, variable factor and outcome definitions are combined for the development of multivariate prediction models that subsequently have limited clinical value. Despite being prevalent there are very few attempts to examine post-operative pulmonary complications (PPC) as endpoints in isolation. The trajectory of pulmonary dysfunction that precedes complications in the post-operative context is not clear. As such there is little knowledge of post-operative antecedents to PPC that are invariably excluded from model development.

CONCLUSION

Multivariate clinical prediction rules that incorporate antecedent patient and process factors from the continuum of cardiovascular care for specific pulmonary outcomes are recommended. Models such as these would be useful for practice, policy and quality improvement.

Role of microdialysis in pharmacokinetics and pharmacodynamics: current status and future directions

Diagnostic and therapeutic decisions in medical practice are still generally based on blood concentrations of drugs and/or biomolecules despite the knowledge that biochemical events and pharmacological effects usually take place in tissue rather than in the bloodstream. Microdialysis is a semi-invasive technique that is able to measure concentrations of the free, active drug or endogenous compounds in almost all human tissues and organs. It is currently being used to monitor brain metabolic processes and quantify tissue biomarkers, and determine transdermal drug distribution and tissue pharmacokinetics, confirming its importance as a widely used sampling technique in clinical drug monitoring and drug development as well as therapy and disease follow-up, contributing to rationalizing drug dosing regimens and influencing the clinical decision-making process.

Role of microdialysis in pharmacokinetics and pharmacodynamics: current status and future directions

Diagnostic and therapeutic decisions in medical practice are still generally based on blood concentrations of drugs and/or biomolecules despite the knowledge that biochemical events and pharmacological effects usually take place in tissue rather than in the bloodstream. Microdialysis is a semi-invasive technique that is able to measure concentrations of the free, active drug or endogenous compounds in almost all human tissues and organs. It is currently being used to monitor brain metabolic processes and quantify tissue biomarkers, and determine transdermal drug distribution and tissue pharmacokinetics, confirming its importance as a widely used sampling technique in clinical drug monitoring and drug development as well as therapy and disease follow-up, contributing to rationalizing drug dosing regimens and influencing the clinical decision-making process.

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.

In vivo measurement of levofloxacin penetration into lung tissue after cardiac surgery

Nosocomial pneumonia is a severe complication after cardiac surgery (CS). Levofloxacin, a fluoroquinolone, qualifies for the therapy of postoperative pneumonia. However, penetration properties of levofloxacin into the lung tissue could be substantially affected by CS: atelectasis, low cardiac output after CS, high volume loads, and inflammatory capillary leak potentially influence drug distribution. The aim of our study was to gain information on interstitial antibiotic concentrations in lung tissue in patients undergoing coronary artery bypass grafting with cardiopulmonary bypass. Therefore, six patients undergoing elective CS participated in this prospective study. A dose of 500 mg of levofloxacin was administered intravenously in addition to standard antibiotic prophylaxis immediately after the end of surgery. Time versus concentration profiles of levofloxacin in the interstitial lung tissue and plasma were determined. A microdialysis technique was used for lung interstitial concentration measurements. The microdialysis procedure was well tolerated in all patients and no adverse events were observed. The median area under the concentration curve (AUC) of levofloxacin in interstitial lung fluid was 18.6 microg.h/ml (range, 10.1 to 33.6). The median AUC for tissue (AUC(tissue)) of unbound levofloxacin/AUC(total) in plasma was 0.6 (range, 0.4 to 0.9). The median unbound AUC(tissue)/MIC was 2.4 (range, 1.3 to 4.2) for Pseudomonas aeruginosa. Our study demonstrated the feasibility and safety of microdialysis in human lung tissue in vivo after CS. The unbound AUC/MIC ratio revealed that levofloxacin used in the described manner was borderline sufficient for the treatment of nosocomial pneumonia caused by Klebsiella pneumoniae and insufficient for the treatment of pneumonia caused by Pseudomonas aeruginosa, because the breakpoint of 30 to 40 for AUC/MIC could not be reached by the conventionally used dosage schema in our post-CS setting. Penetration was lower than in previous reports.

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.

Postoperative Pulmonary Dysfunction in Adults After Cardiac Surgery With Cardiopulmonary Bypass: Clinical Significance and Implications for Practice

Postoperative pulmonary complications are the most frequent and significant contributor to morbidity, mortality, and costs associated with hospitalization. Interestingly, despite the prevalence of these complications in cardiac surgical patients, recognition, diagnosis, and management of this problem vary widely. In addition, little information is available on the continuum between routine postoperative pulmonary dysfunction and postoperative pulmonary complications. The course of events from pulmonary dysfunction associated with surgery to discharge from the hospital in cardiac patients is largely unexplored. In the absence of evidence-based practice guidelines for the care of cardiac surgical patients with postoperative pulmonary dysfunction, an understanding of the pathophysiological basis of the development of postoperative pulmonary complications is fundamental to enable clinicians to assess the value of current management interventions. Previous research on postoperative pulmonary dysfunction in adults undergoing cardiac surgery is reviewed, with an emphasis on the pathogenesis of this problem, implications for clinical nursing practice, and possibilities for future research.

Surveillance for hospital-acquired infections on surgical wards in a Dutch university hospital

OBJECTIVES

To determine incidence rates of hospital-acquired infections and to develop preventive measures to reduce the risk of hospital-acquired infections.

METHODS

Prospective surveillance for hospital-acquired infections was performed during a 5-year period in the wards housing general and vascular, thoracic, orthopedic, and general gynecologic and gynecologic-oncologic surgery of the University Medical Center Utrecht, the Netherlands. Data were collected from patients with and without infections, using criteria of the Centers for Disease Control and Prevention.

RESULTS

The infection control team recorded 648 hospital-acquired infections affecting 550 (14%) of 3,845 patients. The incidence density was 17.8 per 1,000 patient-days. Patients with hospital-acquired infections were hospitalized for 19.8 days versus 7.7 days for patients without hospital-acquired infections. Prolongation of stay among patients with hospital-acquired infections may have resulted in 664 fewer admissions due to unavailable beds. Different specialties were associated with different infection rates at different sites, requiring a tailor-made approach. Interventions were recommended for respiratory tract infections in the thoracic surgery ward and for surgical-site infections in the orthopedic and gynecologic surgery wards.

CONCLUSIONS

Surveillance in four surgical wards showed that each had its own prominent infection, risk factors, and indications for specific recommendations. Because prospective surveillance requires extensive resources, we considered a modified approach based on a half-yearly point-prevalence survey of hospital-acquired infections in all wards of our hospital. Such surveillance can be extended with procedure-specific prospective surveillance when indicated.

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.

Pneumonia after cardiac surgery is predictable by tracheal aspirates but cannot be prevented by prolonged antibiotic prophylaxis

BACKGROUND

The purpose of this study was to assess the value of tracheal aspirate as a predictor of pneumonia after coronary artery bypass grafting and to evaluate the efficacy of prolonged perioperative antibiotic prophylaxis.

METHODS

Tracheal aspirates of 500 patients undergoing coronary artery bypass grafting were taken immediately after intubation and analyzed for microorganisms by Gram stain and semiquantitative microbiologic cultures. All patients received 2 g ceftriaxone as a single-dose perioperative antibiotic prophylaxis before operation. Results of Gram stains were available before the patients were transferred to the intensive care unit. After the results were known, both groups of patients (positive Gram stain, group 1; negative Gram stain, group 2) were randomly assigned to either conventional antibiotic prophylaxis (A), consisting of ceftriaxone 2 g on postoperative day 1, or prolonged antibiotic prophylaxis (B), with ticarcillin + clavulanic acid 3 x 5.2 g during 72 hours.

RESULTS

From 500 patients, 91 had a positive Gram stain whereas 409 had a negative one. The incidence of pneumonia was significantly higher in patients with preoperative positive tracheal aspirates (15.3%) than in patients with a negative one (3.6%; p < 0.01). However, prolonged prophylaxis did not reduce the rate of postoperative pneumonia, which was as high as 13% in untreated positive patients versus 17% in treated positive patients, and 2% in untreated negative patients versus 4% in treated patients. In patients who had pneumonia, there was a high correlation between the microorganisms found in preoperative aspirates and those observed when aspirates were repeated (100% correlation in patients with conventional antibiotic prophylaxis and 87% in those with prolonged prophylaxis).

CONCLUSIONS

Early postoperative pneumonia (<7 days) is most likely caused by microorganisms that colonize the respiratory tract before operation. The risk of pulmonary infection after coronary artery bypass grafting can be predicted from the preoperative tracheal aspirates. Prolonged perioperative antibiotic prophylaxis has no efficacy in reducing the incidence of pulmonary infections.

Evaluation and management of patients with pulmonary disease before thoracic and cardiovascular surgery

The risks of respiratory complications after thoracic and cardiovascular surgeries are particularly high for patients with chronic pulmonary disease and are associated with prolonged hospital stays and increased mortality. The primary goals of preoperative management are to identify risk factors and institute interventions likely to reduce subsequent postoperative pulmonary complications. Smoking, symptomatic obstructive lung disease, respiratory infection, obesity, and malnutrition are all potentially modifiable risk factors. Chest physiotherapy is indicated in all patients regardless of risk factor profile. Providing a thoughtfully designed, multifaceted course of preoperative care can result in a clinically significant reduction in postoperative morbidity and mortality, particularly if instituted well in advance of surgery.

Nosocomial pneumonia in patients undergoing heart surgery

OBJECTIVE

To determine the risk factors related to the presence of postsurgical nosocomial pneumonia (NP) in patients who had undergone cardiac surgery.

DESIGN

A case-control study.

SETTING

Postcardiac surgical intensive care unit at a university center.

PATIENTS

A total of 45 patients with NP and 90 control patients collected during a 4-yr period.

INTERVENTIONS

Pre-, intra-, and postoperative factors were collected and compared between two groups of patients (cases vs. controls) to determine their influence on the development of NP. The diagnosis of NP was always microbiologically confirmed as pulmonary specimen brush culture of > or =10(3) colony-forming units/mL or positive blood culture/pleural fluid culture by the growth of identical microorganisms isolated at the lung. For each patient diagnosed with NP, we selected control cases at a ratio of 1:2.

MEASUREMENTS AND MAIN RESULTS

The incidence of NP was 6.5%. Multivariate analysis found a probable association of the following variables with a greater risk for the development of NP: reintubation (adjusted odds ratio [AOR], 62.5; 95% confidence interval [CI], 8.1-480; p = .01); nasogastric tube (AOR, 19.7; 95% CI, 3.5-109; p = .01), transfusion of > or =4 units of blood derivatives (AOR, 12.8; 95% CI, 2-82; p = .01) and empirical treatment with broad-spectrum antibiotics (AOR, 6.6; 95% CI, 1.2-36.8; p = .02). Culture results showed 13.3% of the NP to be of polymicrobial origin, whereas 77.3% of the microorganisms isolated were Gram-negative bacteria. The mortality (51 vs. 6.7%, p < .01) and the length of stay in the intensive care unit (25+/-14.8 days vs. 5+/-5 days, p < .01) were both greater in patients with NP.

CONCLUSIONS

We conclude that the surgical risk factors, except the transfusion of blood derivatives, have little effect on the development of NP. Reintubation, nasogastric tubing, previous therapy with broad-spectrum antibiotics, and blood transfusion are factors most likely associated with NP acquisition.

Smoking is not a predictor of mortality and morbidity following coronary artery bypass grafting

BACKGROUND

The objective of this study was to determine the significant differences in preoperative and operative characteristics, and postoperative outcomes in patients having coronary artery bypass grafting (CABG) who are smokers and in those who are not smokers.

METHODS

Data were collected prospectively in all (2916) patients having their first CABG. The patients were cared for in a regional medical center by private physicians. No operations were denied because of smoking status. Smokers differed from nonsmokers in several characteristics.

RESULTS

Analysis of morbidity and mortality showed no instance in which smokers fared worse than nonsmokers. Stepwise logistic regression analysis showed that smoking was not predictive of mortality. Smoking was not predictive of morbidity except that it was predictive of less probability of need for intra-aortic balloon pump (7.5% in nonsmokers and 4.7% in smokers). We then created groups of smokers and nonsmokers that were individually matched for age and sex. Analysis of the matched groups of smokers and nonsmokers showed that there was no significant difference in the incidence or magnitude of preoperative and operative factors except that recent myocardial infarction was more common in smokers. Nonsmokers had greater weight, body mass index (obesity), and ejection fraction. There was no difference in smokers and nonsmokers in mortality or morbidity at the 99% confidence level.

CONCLUSION

We conclude that there is no need to delay CABG for the patients who are smokers.

Preoperative pulmonary evaluation. Identifying patients at increased risk for complications

During surgical procedures, multiple physiologic changes affect the pulmonary system and its defense mechanisms. The presence of basic risk factors (eg, smoking, chronic obstructive pulmonary disease, severe obesity) can affect whether these physiologic changes result in pulmonary complications or even death. Therefore, the presence of risk factors should be ascertained in all patients before abdominal or thoracic surgery. The degree of risk can be further determined preoperatively by additional evaluation, such as pulmonary function testing, newer assessment of cardiorespiratory status, history taking, and physical examination. The presence of risk factors and the type of operation to be performed should guide decisions about whether to perform a procedure or to use prophylactic measures before and after surgery. New operative techniques may allow some procedures that were prohibited in the past to be performed in high-risk patients.

Perioperative microbiologic monitoring of tracheal aspirates as a predictor of pulmonary complications after cardiac operations

The value of preoperative and early postoperative microbiologic testing of tracheal aspirates as a prognostic indicator of the development of pneumonia was evaluated in a prospective study of 213 cardiac surgical patients. Tracheal aspirates were obtained immediately after intubation and after the patient's arrival at the intensive care unit. Diagnosis of pneumonia was accepted if at least three of the following criteria were fulfilled: leukocytosis > 15,000 cells/mm3, body temperature >38.5 degrees C, positive results of auscultation, positive results of radiography (new infiltrates that seemed to be consistent with pneumonia), and increased core-reactive protein for more than 2 days after operation. Potentially pathogenic microorganisms were found in 54 (25.4%) of the preoperative tracheal aspirates and in 27 (12.7%) of the early postoperative tracheal aspirates. Positive microbiologic findings correlated with pneumonia in the postoperative course in 24.1% (p < 0.001) if the preoperative culture results were positive, in 48.2% (p < 0.001) if the postoperative culture results were positive, and in 44.0% (p < 0.001) if both were positive. The risk of pneumonia was increased in male patients (p < 0.05) and in patients with chronic obstructive pulmonary disease (p < 0.05). Demographic variables, smoking, acute pulmonary symptoms, temperature, leukocyte count at the day of the operation, and data on the operation and the extracorporeal circulation were not significantly related to pneumonia in the early postoperative course. The risk of development of postoperative pneumonia is significantly higher among patients with colonization of the lower respiratory tract. Positive culture results in routine microbiologic monitoring of tracheal aspirates are predictive of pulmonary complications after cardiac operations.

["Single-shot" antibiotic prophylaxis in thoracic surgery; reduction of the postoperative infection rate]

A prospective, controlled and randomised trial was started to detect the effectivity of a "single-shot" antibiotic prophylaxis in thoracic surgery using cefuroxime. Therefore 200 unselected patients, consecutively scheduled for major thoracic surgery except endoscopic procedures or mediastinoscopy were enrolled in this study and randomized into either the control group (no antibiotics perioperatively; n = 100) or the prophylaxis group (one dose of 1.5 g cefuroxime i.v. at induction of anaesthesia; n = 100). Clinical signs correlated with infection, radiological findings and the results of repeated microbiological examinations were recorded and a comparative statistical analysis was done. Compared to controls the prophylaxis group had fewer (not significant) infections of the wound, the pleural cavity and the urinary tract and fewer patients of this group showed "pronounced infiltration" in daily taken chest roentgenograms (significant), clinical signs for pneumonia and pathologic sputum findings, or new bacterial colonisation of sputum specimens on the first postoperative day, whereas bacteria, isolated from tracheal aspirates, immediately taken after intubation disappeared more often. Specimens of pleural fluid taken postoperatively were less often positive for bacteria. Fewer patients were treated with antibiotics in the postoperative course and the courses were shorter in the prophylaxis group compared to controls. Considering the risk factor "positive microbiological culture" in preoperative tracheal aspirates, patients of the prophylaxis group showed much more seldom new radiological "infiltration" (statistically highly significant) and, in addition, had lower white blood cell counts (significant) and lower mean maximal body temperatures. The results of our trial confirm the preventive effect of "single-shot" antibiotic prophylaxis in thoracic surgery against infections.