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Biomedical subjects

A Bach

Publications and source records attributed to A Bach.

At least 109 records · Page 6Linked to original sources
PubMed1995

A definition of catheter-related infection.

There is controversy about the definitions of catheter-related infection. The term "infection" implies a physiological reaction by the patient to a pathogenic microorganism. However, the organism has no pathognomonic infectious reaction to a colonised catheter, with the exception of a local exit-site infection. Therefore, suggestions have been made that the definition of catheter-related infection should be based solely on the degree of bacterial colonisation, i.e. the number of colony forming units recovered from the catheter. Although this method does not define catheter-related infections in the strict sense, the approach may be useful for comparing various studies carried out on this topic. However, various methods are used to analyse intraluminal and/or extraluminal colonisation, and comparison of data across studies is difficult. Ideally studies addressing this issue should use a combination of different methods to analyse catheter colonisation. On the basis of microbiological semi-quantitative or quantitative analysis of bacterial colonisation, an attempt should be made to correlate the clinical symptoms of infection to these culture results in order to define useful cutoff values.

Bacterial Infections↗
PubMed1995

Review of animal studies on antimicrobial catheters to prevent catheter-related infections.

Various experimental models have been developed to investigate the pathogenesis of intravascular catheter-related infections. Catheters are implanted either subcutaneously or intravenously, and the test animals are inoculated via either the subcutaneous tissue near the catheter exit site or the bloodstream. Catheters containing antimicrobial agents were investigated in various test models and their efficacy in inhibiting bacterial colonisation and reducing catheter-related infections was demonstrated.

Animals↗
PubMed1995

Clinical studies on the use of antibiotic- and antiseptic-bonded catheters to prevent catheter-related infection.

Central venous catheter-related infections are common despite adherence to hygienic guidelines for insertion and maintenance of these devices. It has been suggested that coating of intravascular catheters with antimicrobial agents, either antibiotics or antiseptics, could reduce the incidence of catheter-related infections. Recent studies have demonstrated the efficacy of antibiotic-coated and antiseptic-impregnated catheters in reducing bacterial colonisation and infection. Preliminary results of pilot studies indicate that silver impregnation of intravascular catheters may be effective. At present, these antimicrobial-bonded catheters seem to be an important addition to the choice of preventive strategies, but their definitive role and possible disadvantages such as induction of resistance still have to be clearly delineated.

Anti-Infective Agents↗
PubMed1995

Ketamine attenuates endotoxin-induced leukocyte adherence in rat mesenteric venules.

OBJECTIVES: To determine the influence of ketamine on endotoxin-induced leukocyte adherence and venular microhemodynamics. DESIGN: Randomized, controlled trial. SETTING: Experimental laboratory. SUBJECTS: Thirty male Wistar rats. INTERVENTIONS: The rats were pretreated with ketamine (10 mg/kg iv) or 0.9% saline, and both groups were given endotoxin (Escherichia coli lipopolysaccharide; 5 mg/kg iv). The control group received two doses of 0.9% saline. MEASUREMENTS AND MAIN RESULTS: The rates of leukocyte adherence and changes in microhemodynamics were monitored in rat mesenteric venules, using in vivo video microscopy. The number of adherent leukocytes was determined on-line in 10-min intervals from 60 mins before until 2 hrs after endotoxin administration. Venular diameters, red blood cell velocity, volumetric blood flow, and the venular wall shear rate were monitored before and at 10, 30, and 60 mins after endotoxin exposure. A 6.3-fold increase in the number of adherent leukocytes was observed 10 mins after administration of endotoxin when compared with control animals (5.87 +/- 0.69 vs. 0.93 +/- 0.21 adherent cells/100 microns; p < .001). This increase remained unchanged for 120 mins. In ketamine-pretreated rats, a 2.6-fold increase in leukocyte adherence occurred during the first 20 mins after endotoxin exposure (2.40 +/- 0.46 vs. 0.93 +/- 0.21 adherent cells/100 microns; p < .01). However, no difference in the number of adherent leukocytes between ketamine-pretreated and control animals was found after this 20-min period. In animals of the control group, no increase in leukocyte adherence occurred during the entire observation time. Diameters of mesenteric venules did not change after endotoxin exposure in any of the groups. Red blood cell velocity and venular blood flow in the endotoxin-treated groups decreased 10 mins after the injection of endotoxin when compared with controls, but these values did not show any difference when they were compared between ketamine and saline-pretreated animals. Similarly, venular wall shear rate in the endotoxin-treated groups decreased 10 and 30 mins after injection of endotoxin. However, no significant difference occurred between ketamine and saline-pretreated animals. CONCLUSIONS: Pretreatment with ketamine attenuates endotoxin-induced leukocyte adherence by a shear rate-independent mechanism, suggesting reduced expression of adhesion molecules. These results indicate that ketamine exerts an anti-inflammatory effect, which might be beneficial in septic patients.

Animals↗
PubMed1995

Gastric tonometry: effect of sucralfate on calculated intramural pH.

Tonometric measurement of gastric intramural pH (pHi) is a noninvasive method to assess adequacy of splanchnic perfusion. Calculation of pHi may be influenced by various factors. This prospective study was designed to determine if stress ulcer prophylaxis with sucralfate interferes with pHi measurement. Twenty-five adult patients admitted to the intensive care unit (ICU) after open heart surgery were studied. Nasogastric tonometers were placed. Patients received sucralfate 1 g via the nasogastric tube 8 hours after termination of surgery, thereafter every 6 hrs. Gastric luminal pH and intramural pH were determined immediately prior and 1 hour after the first sucralfate administration. Gastric intramural pH was calculated from the arterial HCO3- concentration and the tonometrically determined intraluminal PCO2 value using the Henderson-Hasselbalch equation. Intraluminal PCO2(ss) was measured to 6.86 +/- 0.75 kPa prior to sucralfate administration as compared to 6.96 +/- 0.68 kPa 1 hour after 1 g sucralfate (P = 0.92). Intramural pH, as calculated by tonometry, was 7.31 +/- 0.05 vs 7.31 +/- 0.05, and was thus not influenced by sucralfate administration (P = 0.97). Mean gastric intraluminal juice pH was 4.2 +/- 1.3 compared to 4.2 +/- 1.2 (P = 0.59). These data suggest that sucralfate does not interfere with tonometrically determined intraluminal PCO2 measurement and calculation of gastric intramural pH.

Aged↗
PubMed1995

Dose-response, time-course of action and recovery of rocuronium bromide in children during halothane anaesthesia.

Two groups of children, aged 1-4 years (n = 28) and 5-10 years (n = 28), respectively, received at random one of four doses of rocuronium (0.12, 0.17, 0.22 or 0.27 mg kg-1). When maximum block was obtained, further rocuronium to a total dose of 0.5 mg kg-1 was given. At a spontaneous T1 recovery of 25% the block was reversed with atropine and neostigmine in half the patients. The remainder were allowed to recover spontaneously. There was no difference in potency in the two age groups. An ED50 of 0.2 mg kg-1 was estimated. The estimates of ED50 were model-dependent of approximately 0.32 mg kg-1. The maximum block was found significantly higher in the younger age group (99.0 +/- 1.5% (mean +/- SD)) as compared to the older group (97.5 +/- 2.3%), and the clinical duration was also longer (16.6 +/- 5.3 min vs. 13.3 +/- 3.8 min), respectively. There was no significant difference between the two age groups in duration90 (26.9 +/- 6.5 min, 22.5 +/- 6.7 min, respectively) and duration0.7 (27.6 +/- 6.0 min, 24.9 +/- 7.9 min, respectively). Recovery time25-75, recovery time25-90, but not recovery time25-0.7 were found significantly longer in the 1-4 year group as compared to the times in older children. Neostigmine administration reduced recovery time by approximately half to two-thirds. MAP was not influenced by rocuronium. Following the injection of rocuronium in the younger age group there was a 15% increase in heart rate compared to a 10% increase in the age group 5-10 years.

Androstanols↗
PubMed1994

Control of kinetic properties of AMPA receptor channels by nuclear RNA editing.

AMPA (alpha-amino-3-hydroxy-5-methyl-4-isoxazolepropionic acid) receptor channels mediate the fast component of excitatory postsynaptic currents in the central nervous system. Site-selective nuclear RNA editing controls the calcium permeability of these channels, and RNA editing at a second site is shown here to affect the kinetic aspects of these channels in rat brain. In three of the four AMPA receptor subunits (GluR-B, -C, and -D), intronic elements determine a codon switch (AGA, arginine, to GGA, glycine) in the primary transcripts in a position termed the R/G site, which immediately precedes the alternatively spliced modules "flip" and "flop." The extent of editing at this site progresses with brain development in a manner specific for subunit and splice form, and edited channels possess faster recovery rates from desensitization.

Alternative Splicing↗
PubMed1994

Bolus injection of thrombolytic agents during cardiopulmonary resuscitation for massive pulmonary embolism.

Thrombolytic therapy has proved to be efficacious in the treatment of massive and fulminant pulmonary embolism (PE), but thrombolysis has been considered as contraindicated during cardiopulmonary resuscitation (CPR). This review on the administration of thrombolytic agents in patients who have suffered massive PE necessitating CPR summarises 14 anecdotal reports and three case series involving 34 patients. The case series revealed an overall initial survival rate of 55-100% following bolus administration of thrombolytic agents. In general, bleeding complications were managed conservatively. The establishment of the diagnosis may be feasible using echocardiography or bedside angiography during CPR. However, therapeutic measures should be taken without delay; the patient's history and the clinical picture may thus be the only diagnostic criteria. Even where myocardial infarction is misinterpreted as PE during CPR, bolus injection of a thrombolytic agent can be an appropriate therapeutic option. An alternative may be mechanical catheter fragmentation of the thrombus with subsequent local thrombolysis. Surgery may be restricted to hospitals with ready access to extracorporeal circulation. We conclude that early administration of thrombolytic agents during PE necessitating CPR may help to reduce mortality. We favour the administration of urokinase (2- to 3,000,000-U bolus) or rt-PA.

Adult↗
PubMed1994

Prevention of bacterial colonization of intravenous catheters by antiseptic impregnation of polyurethane polymers.

The use of intravascular catheters is associated with infectious complications. Using plastic materials with antibacterial activity may reduce catheter-related bacterial colonization. A novel intravascular catheter impregnated with the antiseptics silver-sulphadiazine and chlorhexidine was tested in an in-vivo model using implantation of catheters into the internal jugular veins of rats. The rate and magnitude of bacterial colonization in groups with implantation of silver-sulphadiazine and chlorhexidine bonded (SSC) and control (C) catheters were assessed 3 and 7 days after intravenous implantation, and local challenge at the exit site by 10(7) cfu Staphylococcus epidermidis ATCC 35984. Significant reductions in the culture positivity of catheters were observed in the test compared with control groups. After 3 and 7 days, the magnitude of bacterial colonization of implanted catheter segments was significantly lower compared with control catheters (P < 0.01). These findings indicate that antiseptic-bonded catheters substantially reduce the incidence and magnitude of catheter-related bacterial colonization, and may subsequently reduce catheter-related infection.

Animals↗
PubMed1994

Long-term sedation with propofol and green discolouration of the liver.

Propofol has been reported to cause discolouration of urine and hair. A case of green discolouration of the liver is reported in a 56-year-old man after long-term sedation with propofol in the intensive care unit. After discontinuation of propofol the discolouration of the liver disappeared. This phenomenon is due to metabolism of propofol which may lead to a phenolic green chromophore which is conjugated in the liver and excreted in the urine.

Chemical and Drug Induced Liver Injury↗
PubMed1994

Porphyrinogenic effects of atracurium, vecuronium, and pancuronium in a primed rat model.

Steroidal muscle relaxants might theoretically be contraindicated in acute hepatic porphyrias. Atracurium, on the other hand, has been proposed as the muscle relaxant of choice because of its extrahepatic degradation. To further investigate this problem, equipotent doses of atracurium, vecuronium, and pancuronium were determined in male Sprague Dawley rats, using evoked electromyography. After this pilot study, 64 rats were anesthetized, mechanically ventilated, and randomly allocated to eight groups. Animals in groups 1 through 4 received an intraperitoneal injection of arachis-oil 20 h before the experiments. For groups 5 through 8, an experimental porphyria was induced by use of the chemical substance 3,5-dicarbethoxy-1,4-dihydrocollidine (DDC), which was dissolved in arachis-oil and given 20 h prior to the beginning of the study. Rats of groups 1 and 5 served as controls; they received saline and were not given muscle relaxants throughout the experiment. For groups 2 and 6, atracurium was administered at a dosage of 4 mg/kg of body weight, followed by a continuous infusion of 15 mg/kg/h. Animals of groups 3 and 7 received vecuronium at a dosage of 1.5 mg/kg, followed by 7.5 mg/kg/h. For groups 4 and 8, pancuronium was given (0.75 mg/kg and 2.5 mg/kg/h, respectively). At the end of the 3-h study period, the liver was perfused and excised, and urine was obtained. Activity of the hepatic enzyme delta-aminolevulinic acid synthase (ALAS) and urinary concentrations of delta-aminolevulinic acid (ALA) and porphobilinogen (PBG) were determined.(ABSTRACT TRUNCATED AT 250 WORDS)

5-Aminolevulinate Synthetase↗
PubMed1994

[Prevention of infections caused by intravascular catheters--a review of the literature].

OBJECTIVE: The literature on catheter-related infections was reviewed to discuss appropriate strategies for the prevention of infections related to intravenous catheters. DATA SOURCES AND SELECTION CRITERIA: The data bases Medline, Biosis and Embase (publication years 1988 to June 1993) were used to retrieve all articles with the key words catheter and infection. Papers covering infections related to intravenous catheters were included. Furthermore, landmark articles from previous years were selected. Only a selected number of articles was listed in the References. RESULTS: Most authors stress the importance of strict aseptic precautions in the management of intravenous lines and the need for dedicated, specialized care of intravascular devices. Quantitative culture of catheter segments and molecular subtyping of microorganisms provide new insights into the pathogenesis and diagnosis of catheter-related infections and enable the evaluation of preventive measures. Technological advances in manufacturing catheter polymers with anti-infective properties will facilitate a reduction in the incidence of catheter-related infections to a greater extent than with any other methods used to date. CONCLUSION: Prevention of catheter-related infections is based on the care of these devices according to strict hygienic standards. In the near future, modification of plastic polymers with anti-infective properties will allow for a further reduction in these infections.

Asepsis↗