Biomedical subjects
Publications and source records attributed to A Bach.
Ondansetron is a new selective serotonin-3-receptor antagonist which has proved to be effective in chemotherapy-induced nausea and vomiting. Initial studies evaluating the efficacy and safety of this substance for the treatment and prevention of postoperative nausea and vomiting yielded promising results. However, ondansetron's exact role in the perioperative setting still remains to be determined.
OBJECTIVE: The aim of our review is to summarize risks and benefits using 0.2-micron in-line filters in intravenous infusion therapy. DATA SOURCES: Own data and the accessible medical literature according to current electronic information sources were exploited. RESULTS: Problems associated with intravenous infusion therapy include contamination of fluids with bacteria, endotoxins, and foreign particles. These factors may be important in the pathogenesis of sepsis, adult respiratory distress syndrome, and multiorgan failure. Elimination of bacteria, endotoxins, and particles can be achieved by 0.2-micron in-line filters. A significant reduction in the rate of phlebitis due to peripheral venous catheters has been demonstrated. However, a reduction in the rate of sepsis by the elimination of bacteria and endotoxins or the prevention of adult respiratory distress syndrome and multiorgan failure by retention of foreign material by these filters has not yet been conclusively proved. The longer intervals between changing of the whole infusion systems with the use of these filters (from 24 h without filter to 96 h with filter) result in cost-effectiveness, waste reduction, and reduction in nursing time. Due to adherence to the filter, small doses of drugs (i.e., < 5 micrograms/ml or < 5 mg/24 h) should not be given through filters. The size of the filter pores (0.2 micron) does not allow for the application of blood products or emulsions. Retention of foreign material results in increasing resistance, so that measurements of central venous pressure may be affected. Filters are constructed so that a potential increase in pressure and a following break would not result in a leakage. CONCLUSION: 0.2-micron in-line filters are useful for the elimination of the bacterial and endotoxic load to the patient and for the removal of foreign material. Thus, they represent a useful and cost-effective adjunct, but not a prerequisite in modern intravenous therapy.
Contamination of parenterally applied fluids by bacterial and particulate material may contribute to the development of sepsis, multiple organ failure, and adult respiratory distress syndrome. 0.2 microns in-line filters are effective in reducing bacteria and foreign matter in the infused fluids. The rate of thrombophlebitis was demonstrated to be significantly reduced by in-line filtration. However, to date there is no definite evidence from clinical studies that these filters are effective in reducing overall morbidity and mortality. Furthermore the use of in-line filters reduces waste material and required nursing time, because the infusion systems have to be replaced every 96 hours as opposed to 24 hours without filters. In conclusion, use of 0.2 microns in-line filters in infusion therapy is cost effective and may enhance patients' safety.
Eighty-eight superficial finger-tip lesions were randomized after thorough cleaning to either silver sulphadiazine treatment of Fucidin fusidic acid gauze. In the silver sulphadiazine group the wounds were covered with a non-sterile PVC gloce and redressed at least every third day; in the other group Fucidin gauze was applied and a tubigauze dressing was left in situ for ten days, after which a new dressing was applied. All patients were treated until healed and followed for at least six months after injury. Patients in the silver sulphadiazine group required shorter time for healing and shorter sick leave. The treatment is recommended because of the easy procedure and the good results.
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A novel catheter pretreated with the antiseptics chlorhexidine and silver-sulfadiazine, designed to reduce catheter-related colonization and infection, was tested in both in vitro and in vivo studies. In vitro experiments demonstrated the long-lasting antibacterial properties of this catheter. For the in vivo study a total of 40 rats divided into different experimental groups were used. Colonization rates of both antiseptic bonded (AS) and control (C) catheters were assessed either three (-3) or seven (-7) days after implantation and local challenge using live Staphylococcus epidermidis ATCC 35984 with 10(7) colony-forming units (cfu) per inoculum. At the time of removal, catheters, organ specimens, and blood samples were taken for cultivation. Significant reductions in the magnitude of colonization of the antiseptic catheters by the test organism were observed in all groups. The average number of cfu colonizing control segments exceeded those found on the treated catheter segments by log 3 (C3/AS3) and log 5 (C7/AS7), respectively (C3: 1.2 x 10(6) +/- 4.1 x 10(5) cfu/segment and AS3: 1.8 x 10(3) +/- 6.6 x 10(2); C7: 2.7 x 10(5) +/- 8.6 x 10(4) and AS7: 1.1 +/- 0.7; mean +/- standard error of the mean, all differences between matching groups statistically significant, Wilcoxon rank sum test, P < 0.0001). These data suggest that antiseptic catheters may substantially decrease the magnitude of catheter-related microbial colonization and subsequent catheter-related infections and may offer a more effective alternative to current methods.
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Despite improvements in infection control measures, catheter-related infections represent a challenging problem in modern medicine. The difficulties in correctly diagnosing catheter-related infections and the necessity to remove the device in case of suspected infection require preventive measures in the first place. Most authors stress the importance of strict aseptic catheter management. Nevertheless, there may still be a high incidence of catheter-related infections. Moreover, this problem is potentiated by the increasing use of intravascular devices. The current infection rates may be reduced by instituting novel preventive measures, e.g., decontamination of carriers using the anti-staphylococcal agent mupirocin. Another approach aims at inhibiting the adhesion of bacteria to intravascular catheters by modifying these catheters with antimicrobial agents. Newer studies show that impregnation of catheters with the antiseptic substances silver-sulphadiazine and chlorhexidine is effective in reducing bacterial colonisation of the catheters. A pilot study on intensive-care patients demonstrated a significant reduction in catheter-related infections and bacteraemia by impregnated catheters. This novel approach may reduce the incidence of catheter-related infections below the level which could be achieved by employing all current preventive measures.
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The muscle relaxant atracurium is known to undergo extrahepatic degradation via Hofmann elimination and ester hydrolysis. The purpose of the present study was to evaluate the effects of atracurium on hepatic P450-dependent enzyme activities. Thirty-two male Sprague-Dawley rats were anaesthetized, mechanically ventilated, and randomly allocated to one of four study groups: group 1 received saline, group 2 atracurium, group 3 vecuronium, and group 4 pancuronium intravenously for a period of 3 hr. Equipotent doses of the muscle relaxants were applied; the doses had been obtained in a pilot study using evoked electromyography. At the end of the study period, the livers were removed and analyzed. All three muscle relaxants may lead to inhibition of hepatic drug metabolism. Atracurium influences hepatic P450, although it is predominantly degraded in extrahepatic tissues. Further studies are needed to evaluate the contribution of the major metabolite laudanosine to this inhibitory action.
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The clinical syndrome sepsis has been redefined recently, and the SIRS (systemic inflammatory response syndrome) concept has been developed. In the initial phase of sepsis, different mediator systems are activated finally resulting in a generalized endothelial inflammatory reaction. This reaction may lead to a vicious circle with subsequent multiple organ failure. Standard therapeutic regimen include the surgical removal of the source of sepsis, antimicrobial therapy, optimizing oxygenation, volume resuscitation, and treatment with catecholamines. Recently, new treatment modalities have become available. Replacement of antithrombin III, continuous venovenous hemofiltration, application of high doses of immunoglobulins and of low doses of hydrocortisone have been used. A monoclonal antibody against endotoxin (Centoxin) was taken from the German market in January 1993. Experimental aspects of treatment include the administration of C1 esterase inhibitor, pharmacological inhibition of nitric oxide (NO), plasmapheresis, the application of non-steroidal anti-inflammatory agents and of high-dose naloxone as well as manipulation of cytokines.
Pulmonary embolism must often be considered as a differential diagnosis, especially in the perioperative period. Only prompt therapeutic measures can reduce the high early mortality in the acute phase of this condition. Diagnostic and therapeutic measures are dependent on the severity of the symptoms. If pulmonary embolism is suspected, heparin is administered. In the case of cardiovascular deterioration, other measures have to be taken. Following confirmation of the diagnosis of pulmonary embolism, several thrombolytic regimens are applicable. Low-dose urokinase (bolus 250,000 U followed by 60,000-80,000 U/h) is associated with a relatively low incidence of bleeding complications. A more rapid reduction of the right ventricular afterload will be achieved via short-term thrombolysis. Newer findings suggest that bolus thrombolysis with 3 million U urokinase is as effective as 100 mg tissue plasminogen activator (rt-PA) administered over a 2-h period. When the patient is found to be in a state of shock, confirmation of the diagnosis has to be delayed. Recommendations include the bolus application of 1.5-3 million U urokinase when right ventricular decompensation is prominent or during cardiopulmonary resuscitation. In case of existing contraindications or postoperatively, low-dose urokinase treatment (bolus 250,000 U followed by 40,000-60,000 U/h, rarely up to 2,200 U/kg per hour) may be initiated when the situation is urgent and there are no treatment alternatives. Bolus application of 1-2 million U urokinase should be considered depending on the severity of the symptoms and the underlying disease. In some hospitals, alternative treatment modalities include catheter-assisted procedures with subsequent local thrombolysis and surgical embolectomy. Pathophysiological aspects as well as therapeutic options in the intensive care unit are discussed in depth. In addition to adequate oxygenation, right ventricular coronary perfusion and contractility may be maintained using various catecholamine infusions. The importance of phosphodiesterase inhibitors, mediator antagonists such as acetylsalicylic acid or ketanserin, and dilators of the pulmonary vascular bed are discussed.
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The purpose of this study was to determine if a guidewire change from a pulmonary artery catheter (PAC) to a central venous catheter (CVC) poses a significant infection risk. A total of 128 consecutive cardiac surgical patients with PACs inserted in the operating room were entered into this study. Postoperatively, patients were randomly allocated to receive a double-lumen CVC, either at the initial introducer insertion site over a guidewire, or at a new site with de novo catheterization. The tips of all introducers, PACs, and CVCs were cut off, cultured, and semi-quantitatively analyzed. The results show that insertion of CVCs over a guidewire within 48 hours after initial venapuncture is no more likely to be associated with catheter colonization than is de novo percutaneous insertion at a different site. From 48 hours up to 72 hours following initial insertion of the PAC, an incidence of catheter-related infection of 35.3% was observed in the guidewire group, as opposed to 12.5% in the de novo group. It is recommended that the use of a guidewire technique for catheter replacement (PAC to CVC) is a safe alternative to de novo insertion of a CVC within 48 hours after initial insertion of the PAC. In order to minimize the potential risk of catheter-related infection and bacteremia in cardiac surgical patients, de novo catheterization beyond 48 hours after initial venapuncture is suggested.
A total of 68 postoperative patients whose lungs were ventilated for more than 4 days were studied prospectively during a one-year study period to investigate the effect of the mode of intubation on the paranasal sinuses. After an initial X ray of the skull showing no pathological findings, patients were assigned randomly to one of the study groups; the lungs of patients in group A were ventilated via an orotracheal tube (n = 32), and patients in group B via a nasotracheal tube (n = 36). X ray examinations of the sinuses were performed at regular intervals. Diagnosis of sinusitis was confirmed by transantral needle puncture and culture of fluids obtained. Antibiotic regimens were altered according to laboratory testing. Two patients in group A developed signs of sinusitis in comparison to 15 patients in group B (p less than 0.01). However, there were significantly more airway complications in the orotracheal group, particularly during the period of weaning from ventilation. We conclude that orotracheal intubation should be preferred as the routine route of intubation.
During the perioperative period cardiac surgical patients are often monitored by pulmonary artery (PA) catheters. This catheter, which is floated through the right heart into the pulmonary artery, enables the intensivist to measure and calculate indices of myocardial performance. After a variable period of time this invasive monitoring can often be abandoned following cardiovascular stabilization in these patients, but patients usually still require a central venous (CV) access for diagnostic and therapeutic purposes. To place this CV catheter either a de novo puncture at a new site or a guide-wire change at the existing exit site through the PA catheter in place can be performed. Each de novo puncture is associated with a risk of traumatising internal vessels or organs. In contrast, guide-wire change avoids this risk but inherits a potential risk of transferring bacteria by manipulation of contaminated lines. Our study included 159 consecutive cardiac surgical patients in whom PA monitoring was established preoperatively and terminated within a period of up to 72 hours postoperatively. At random the PA catheter was replaced by a CV line either by de novo puncture or by guide-wire change. All CV lines were left in place for 7 days according to standard practice in our intensive care unit (ICU). After removal of CV catheters all catheter tips were cultured semiquantitatively by rollplate technique according to Maki (26) and subsequent immersion broth culture. A positive culture was defined as growth of one up to 15 colonies on the agar-plate or any microbial growth in the broth. A significant colonization was assumed in catheters yielding more than 15 colony forming units (cfu) on the blood agar plate (26). Our results show a significant risk of colonization and catheter-related infection associated with the guide-wire technique as opposed to the de novo puncture. The figures for relevant colonization were 33.3% in the guide-wire group as opposed to 10.5% in the de novo group. However, this difference was noted only in the subgroup in which replacement of PA catheters by CV catheters was performed beyond 48 h after initial insertion of PA catheters. Within the time intervals of 24 and 25 to 48 h, respectively, we could not detect any significant difference between groups.