Evolution of antimicrobial prophylaxis in cardiovascular surgery.

OBJECTIVE: To examine the optimal duration of antibiotic prophylaxis in major cardiovascular surgery. MTHODSs: In the past 15 years, four prospective randomized, controlled studies, conducted by the same group of authors, compared seven prophylactic antimicrobial regimens in 2970 patients undergoing major cardiovascular surgery. In 1980/81, a 4-day cefazolin (CFZ) prophylaxis was compared with a 2-day cefuroxime (CFX) administration (n=566). In 1982/83, a 2-day CFX prophylaxis was compared with a two shot ceftriaxone (CRO) prophylaxis (n=512). In 1984/87, a 1-day CFZ prophylaxis was compared with a single shot prophylaxis of CRO (n=883). In 1994/1995, a 4 day combination of amoxicillin (AM) and netilmicin (NET) prophylaxis was compared with a single shot prophylaxis of CFX (n=1009). RESULTS: Total infection rate varied between 4.5 and 5.7%, despite different antimicrobial regimen used and their varying duration. Wound infection rate was 1.1% (range 0.4-2.5%), sepsis rate was 0.8% (range 0.4-1.6%), pneumonia rate 2% (0.7-2.9%), urinary tract infection rate 0.4% (range 0-1.4%), and central venous catheter-related infection rate was 0.4% (0-1%). The 30-day mortality rate was 1.3% (range 0.4-2%). All these differences were not statistically significant. CONCLUSIONS: A low infection rate (range 4.5-5.7%) occurred despite changes in duration of various prophylactic antibiotic regimen with cephalosporins of first, second or third generation. As a single shot prophylaxis could nowadays successfully be used in cardiovascular surgery, no postoperative antibiotics should be used, unless an intraoperative or a postoperative infection is documented or in presence of major perioperative complications.     

Scope and limitations of antimicrobial therapy of sepsis in surgery

Objective: The goal of antibiotic therapy for surgical sepsis is to kill bacteria that intermittently or continuously reach the bloodstream from the residue of an operatively treated focus. While sepsis and conditions leading to sepsis compromise the immune system, antibiotics may become a fundamental determinant of the host's defense. No data from sound prospective randomized clinical antibiotic trials dealing with sepsis are available. Therefore we tested the hypothesis that treatment recommendations can be based on pharmacodynamics comparing in vitro activity of commonly used antimicrobials with concentrations sustained in vivo to provide for full coverage for bacteria of concern. Results: The application of strict criteria for antibiotic choice to avoid selection of primary resistant strains reveals that most commonly used antibiotics render insufficient activity to eliminate pathogens that commonly cause surgical sepsis. Antibiotics that sustain in vivo concentration exceeding fourfold the MIC₁₀₀ (highest minimal inhibitory concentration for all (100%) species tested) of Escherichia coli, for example, are 400 mg ciprofloxacin IV (MIC₁₀₀ of 1224 strains = 0.06 mg/dl, in vivo concentration = 1 mg/dl for 12 h), and 1000 mg imipenem/cilastatin (MIC₁₀₀ of 3142 strains = 0.14 mg/dl, in vivo concentration = 2 mg/dl for 6 h). The third choice is one of the fourth- or, less convincingly, third-generation cephalosporins. Similar data for most pathogens causing sepsis are provided. First- and second-generation cephalosporins and penicillin β-lactamase inhibitor combinations generally do not achieve sufficient concentrations to cover the most important pathogens of sepsis. Conclusion: Sepsis is defined as a whole body's inflammatory response that is characterized by systemic signs and symptoms secondary to a focal infection. While many antibiotic trials have dealt with a focal infection, no prospective randomized antibiotic trial has dealt with sepsis per se. Antibiotic trials on focal infections generally exclude patients when their focal infection has progressed to sepsis. To circumvent the lack of controlled clinical trials we show that pharmacodynamics may provide sound foundation for antibiotic choice for sepsis. Received: 10 December 1997     

Proteomics in cardiovascular surgery

Proteomics describes, analogous to the term genomics, the study of the complete set of proteins present in a cell, organ, or organism at a given time. The genome tells us what could theoretically happen, whereas the proteome tells us what does happen. Therefore, a genomic-centered view of biologic processes is incomplete and does not describe what happens at the protein level. Proteomics is a relatively new methodology and is rapidly changing because of extensive advances in the underlying techniques. The core technologies of proteomics are 2-dimensional gel electrophoresis, liquid chromatography, and mass spectrometry. Proteomic approaches might help to close the gap between traditional pathophysiologic and more recent genomic studies, assisting our basic understanding of cardiovascular disease. The application of proteomics in cardiovascular medicine holds great promise. The analysis of tissue and plasma/serum specimens has the potential to provide unique information on the patient. Proteomics might therefore influence daily clinical practice, providing tools for diagnosis, defining the disease state, assessing of individual risk profiles, examining and/or screening of healthy relatives of patients, monitoring the course of the disease, determining the outcome, and setting up individual therapeutic strategies. Currently available clinical applications of proteomics are limited and focus mainly on cardiovascular biomarkers of chronic heart failure and myocardial ischemia. Larger clinical studies are required to test whether proteomics may have promising applications for clinical medicine. Cardiovascular surgeons should be aware of this increasingly pertinent and challenging field of science.     

Effect of uric acid lowering therapy on the prevention of acute kidney injury in cardiovascular surgery

Purpose

Serum uric acid (SUA) is a novel risk factor for acute kidney injury (AKI), which adversely affects renal blood flow autoregulation, glomerular filtration rate (GFR), and promotes inflammation and angiogenesis. This pilot study investigated the effect of lowering SUA therapy on AKI, by using traditional and non-traditional markers.

Materials and methods

In this prospective, double-blind, placebo-controlled, randomized pilot trial, 26 hyperuricemic patients undergoing cardiac surgery were randomized to receive rasburicase or placebo in the preoperative period.

Results

Subjects receiving rasburicase showed no difference in serum creatinine compared with the control group receiving placebo. Despite no difference in primary endpoint, the rasburicase group had less evidence of renal structural injury as reflected by urine neutrophil-associated lipocalin (uNGAL) concentrations, especially in subjects with higher SUA levels, more severe renal dysfunction (baseline GFR ≤ 45 mL/min/1.73 m²) or heart failure (left ventricular ejection fraction ≤45 %).

Conclusions

In this study, rasburicase showed no benefit on postoperative serum creatinine in hyperuricemic subjects undergoing cardiac surgery. However, the observation that markers of structural renal injury such as uNGAL tended to be lower in rasburicase-treated subjects suggests potential different effects of uricase treatment on hemodynamic alterations in renal function versus structural mechanisms of kidney injury.     

Rational antimicrobial therapy

Rational antimicrobial therapy depends on the identity of the causative organisms, the location of the infection, and the condition of the host. Selection of antimicrobial therapy is often started before identification of the causative organism is complete. Certain cultural and staining procedures must be instigated prior to therapy in order to isolate the causative organism. Knowledge of the host's physiologic state is necessary to minimize toxicities and/or failures of therapy. Knowledge of synergistic and antagonistic actions of some antimicrobial agents is necessary for optimal results.     

Preoperative cerebrovascular screening before cardiovascular surgery in a high risk area of cerebrovascular events in Japan

BACKGROUND: Cerebrovascular disease and cervical artery diseases are potentially treatable conditions that are associated with an increased incidence of stroke after cardiac surgery. This prospective study was designed to determine the prevalence of cerebrovascular diseases in the high risk population of cerebrovascular event including some young patients in Japan and establish the strategy for cardiac surgery of patients with cerebrovascular disease. METHODS: 100 (71 male, 29 female) of 126 consecutive patients undergoing cardiac surgery under cardiopulmonary bypass were screened for the presence of cerebrovascular disease by intra-arterial angiogram. RESULTS: In seven patients angiographic evaluation disclosed some evidence of cerebrovascular disease for 50% or greater stenosis or cerebral aneurysm. Preoperative 99mTc-Hexamethyl propylene amino oxime (99mTc-HMPAO) single emission computed tomography (SPECT) with combination of balloon arterial occlusion test provided detailed information of cerebral ischemic tolerance and reliable decision making for surgical repair of cerebrovascular disease. No deaths were recorded and a small stroke in one patient. CONCLUSIONS: We concluded that cerebrovascular screening in patients with cardiovascular disease may be requested in a high risk population of cerebrovascular events.     

New directions in antimicrobial therapy

The virulent microorganisms that we try to contain with new antimicrobial agents quickly find the gap in our defenses and exploit it. Resistance to all available antibiotics at the same time, however, rarely occurs. The authors report the most current antimicrobials used as monotherapy or in combination to successfully treat the more resistant pathogens. The higher mortality and subsequent cost to treat these infections are reviewed.     

Guideline of guidelines: thromboprophylaxis for urological surgery

Decisions regarding thromboprophylaxis in urologic surgery involve a trade‐off between decreased risk of venous thromboembolism (VTE) and increased risk of bleeding. Both patient‐ and procedure‐specific factors are critical in making an informed decision on the use of thromboprophylaxis. Our systematic review of the literature revealed that existing guidelines in urology are limited. Recommendations from national and international guidelines often conflict and are largely based on indirect as opposed to procedure‐specific evidence. These issues have likely contributed to large variation in the use of VTE prophylaxis within and between countries. The majority of existing guidelines typically suggest prolonged thromboprophylaxis for high‐risk abdominal or pelvic surgery, without clear clarification of what these procedures are, for up to 4 weeks post‐discharge. Existing guidance may result in the under‐treatment of procedures with low risk of bleeding and the over‐treatment of oncological procedures with low risk of VTE. Guidance for patients who are already anticoagulated are not specific to urological procedures but generally involve evaluating patient and surgical risks when deciding on bridging therapy. The European Association of Urology Guidelines Office has commissioned an ad hoc guideline panel that will present a formal thromboprophylaxis guideline for specific urological procedures and patient risk factors.     

Newer concepts in antimicrobial therapy

Advances in the treatment of infection have continued to increase both the length and quality of life. Unfortunately, many bacteria can readily adapt to their environment and develop a tolerance to the antimicrobial agents in widespread use. During the recent past, the consumption of cephalosporins has increased so dramatically as to parallel the initial acceptance of penicillin. Organisms that are resistant to the cephalosporins will no doubt continue to thrive, especially within the susceptible host. It is essential for the clinician to become familiar with the newest antimicrobial agents to more effectively treat modern infections.     

Training of cardiovascular surgery

Among all the other fields in medicine where safety and good quality are always expected, cardiovascular surgery is the one field where you are expected the most. Therefore cardiovascular surgeons should have an ability to deal adequately with a severe relationship between patients and surgeons. A long-term education after several years of basic surgery training is mandatory to be an authorized high quality cardiovascular surgeon. However, basic surgery is a synonym of general surgery in the present system. In order to authorize general surgeons as well, basic surgery and general surgery should be separated. To avoid the world of cardiovascular surgery becoming the aging society, a long-term training of cardiovascular surgery should begin as early as possible after efficient short-term training of basic surgery. Meanwhile high income should be guaranteed for high risk/volume work.     

Tissue adhesives in cardiovascular surgery

Tissue adhesives are increasingly being used in cardiovascular surgery as adjuncts to obtain more rapid hemostasis, as tissue reinforcing agents, as carriers for prolonged local release of antibiotics, to spatially fix long saphenous vein grafts that could otherwise possibly kink, and to promote endothelialization of prosthetic graft surfaces. The available tissue adhesives, their current indications for use, and possible future trends are discussed.     

Tissue-engineered devices in cardiovascular surgery

Manufacturing life-long functional cardiovascular (CV) implants is the ultimate goal for researchers and clinicians in the cardiothoracic field. Tissue engineering (TE) is an opportunity to create ideal prostheses that are vital, growing, adaptive, autologous and functionally optimally performing. Today, initial translation from basic science to first clinical trials has begun. The article depicts the state of the art in TE techniques for CV products and describes milestones in the ongoing development of tissue-engineered myocardial, valvular and vascular devices from an experimental and clinical point of view. Artificial CV implants still reveal remarkable limitations but promising advances regarding optimal structural design, the prevention of intimal hyperplasia and the reduction of antigenicity and thrombogenicity. Where applicable, the implantation of vascularized autografts should still be preferred. Apart from that, decellularized allogen bioprostheses currently represent most promising matrix scaffolds that can be autologously cellularized in vitro prior to or in vivo after implantation. Capable biologic alternatives have been described like the decellularized porcine small intestinal submucosa. Rising evidence suggests that in vitro endothelialization might be the minimal requirement for improved long-term results of biological tissue-engineered CV grafts.     

Informed consent in cardiovascular surgery

Informed consent is a core component of partnership between the surgeon and the patient. Cardiovascular surgery is a high risk area in medical and surgical fields. An appropriate informed consent is essential for safety management of cardiovascular surgery and good relationship between the surgeon and the patient and his/her family. Concrete explanation of surgical procedures including the risk and benefit is important to share the common understanding of disease and treatment. Before the surgical procedure, we need to explain at least the following 5 contents, (1) name and extent of the disease, (2) contents of surgical procedure, (3) risk of surgery, (4) other options of treatment, and (5) prognosis of the disease.     

Deep hypothermia in cardiovascular surgery

Recent experimental studies and clinical application of deep hypothermia for cardiovascular surgery are reviewed. At most institutions, surface hypothermia alone or in combination with limited cardiopulmonary bypass has been employed. Circulatory dynamics were well maintained following prolonged cardiac arrest at 20°C. Some degree of acidosis usually developed after the arrest period but was gradually corrected during rewarming. Total circulatory occlusion could be maintained for at least one hour at 20°C. without evidence of cerebral damage in infants. Many complex congenital cardiac anomalies, including transposition of the great arteries, total anomalous pulmonary venous return, ventricular septal defect, and tetralogy of Fallot, have been successfully corrected in the first few weeks of life. Less encouraging results have been achieved in patients with infradiaphragmatic total anomalous pulmonary venous return, complete atrioventricular canal, or pulmonary atresia.