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Biomedical subjects

T Koch

Publications and source records attributed to T Koch.

At least 19 recordsLinked to original sources
PubMed2006

Adenosine A1 and A2 receptor agonists reduce endotoxin-induced cellular energy depletion and oedema formation in the lung.

BACKGROUND AND OBJECTIVE: Tissue depletion of adenosine during endotoxaemia has previously been described in the lung. Therapeutic approaches to prevent adenosine depletion and the role of A1 and A2 receptor agonists, however, have not been investigated until now. METHODS: In isolated and ventilated rabbit lungs, it was tested whether pretreatment with adenosine A1 agonist 2-chloro-N6-cyclopentyladenosine (CCPA; 10(-7) mol, n = 6) or A2 receptor agonist 5'-(N-cyclopropyl)-carboxyamido adenosine (CPCA; 10(-7) mol, n = 6) prior to injection of lipopolysaccharide (LPS) (500 pg mL-1) influenced pulmonary artery pressure (PAP), pulmonary energy content and oedema formation as compared with controls, solely infused with LPS (n = 6). Release rates of adenosine and uric acid were determined by high-performance liquid chromatography. Pulmonary tissue concentrations of high-energy phosphates were measured and the adenine nucleotide pool, adenosine 5'-triphosphate (ATP)/adenosine 5'-diphosphate (ADP) ratio and adenylate energy charge of the pulmonary tissue were calculated. RESULTS: Administration of LPS induced increases in PAP within 2 h up to 20.8 +/- 2.9 mmHg (P < 0.01). While pretreatment with the A1 agonist merely decelerated pressure increase (13.8 +/- 1.1 mmHg, P < 0.05), the A2 agonist completely suppressed the pulmonary pressure reaction (9.6 +/- 1.0 mmHg, P < 0.01). Emergence of lung oedema after exclusive injection of LPS up to 12.0 +/- 2.9 g was absent after A1 (0.6 +/- 0.5 g) and A2 (-0.3 +/- 0.2 g) agonists. These observations were paralleled by increased adenosine release rates compared with LPS controls (P < 0.05). Moreover, tissue concentrations of ADP, ATP, guanosine 5'-diphosphate, guanosine 5'-triphosphate, nicotinamide-adenine-dinucleotide and creatine phosphate were significantly reduced after LPS. Consequently, the calculated tissue adenine nucleotide pool and the adenylate energy charge increased after adenosine receptor stimulation (P = 0.001). CONCLUSIONS: Adenosine A1- and A2-receptor agonists reduced LPS-induced vasoconstriction and oedema formation by maintenance of tissue energy content. Thus, adenosine receptor stimulation, in particular of the A2 receptor, might be beneficial during acute lung injury.

Adenosine↗
PubMed2006

Increased limbic phosphorylated extracellular-regulated kinase 1 and 2 expression after chronic stress is reduced by cyclic 17beta-estradiol administration.

Chronic stress induced neuronal changes that may have consequences for subsequent stress responses. For example, chronic stress in rats rearranges dendritic branching patterns and disturbs the phosphorylation of extracellular-regulated kinase 1 and 2 (ERK) 1/2 throughout the limbic system. Stress-induced psychopathology occurs more often in women, however, most of studies have been done in male rats. Therefore, we studied the effect of stress in female rats. Other studies show that estradiol can modulate neuronal plasticity and might protect against stress-induced aberrations. To investigate the role of estradiol in stress responses we manipulated the hormone levels. Ovariectomized rats were cyclically treated with vehicle or with 17beta-estradiol-benzoate (1x in 4 days, 10 microg/250 g, s.c.) and subjected to either acute (3 days) or chronic (22 days) stress. In ovariectomized rats, the number of c-Fos positive cells in the infralimbic and prelimbic cortex of the prefrontal cortex and in the medial and basolateral amygdala was increased after acute stress. Moreover, acute stress reduced the number of phosphorylated ERK1/2 positive neurons in the prefrontal cortex of ovariectomized rats. Chronic stress, on the other hand, abolished normal patterns of c-Fos immunoreactivity in the prefrontal cortex and amygdala and increased the prefrontocortical phosphorylation of ERK1/2 in ovariectomized rats. Cyclic estradiol treatment preserved the neuronal reactivity in the infralimbic cortex after chronic stress and prevented sustained accumulation of phosphorylated ERK1/2. Therefore, cyclic estradiol administration apparently preserves the integrity of signal transduction cascades in limbic structures, which may protect against the harmful consequences of recurrent stress.

Amygdala↗
PubMed2006

Risk factors for prilocaine-induced methaemoglobinaemia following peripheral regional anaesthesia.

BACKGROUND: The local anaesthetic prilocaine has a low systemic toxicity mainly because of a high absorption in the lung and a large volume of distribution and thus is associated with a lower risk of neurological or cardiac side-effects. However, the major disadvantage is the formation of methaemoglobin by its metabolite o-toluidine. This prospective observational study was performed to identify factors that are associated with increased prilocaine-induced methaemoglobinaemia. PATIENTS AND METHODS: One Hundred and sixty two patients undergoing major knee surgery under general anaesthesia combined with peripheral nerve blocks (femoral nerve block, combined femoral/sciatic nerve block or lumbar plexus block) received a single bolus injection of 300 or 400 mg prilocaine about 30 min before surgery via a catheter. The proper placement was verified using nerve stimulation via a stimulating catheter. Three hours after prilocaine injection, venous blood samples were drawn and methaemoglobin levels were measured by standard photometric technique. Data was subjected to a stepwise multiple regression analysis. RESULTS: The mean methaemoglobin for all patients was 2.7% (range: 0.9-15.4%). A higher dose of prilocaine and younger age were the most important predictive factors for higher methaemoglobin formation. Female sex and to a lesser extent the use of high-concentration/low-volume prilocaine also increased methaemoglobin levels. These four factors of the model explain 36% of the total variance. Other investigated factors, including the patient's height, weight, body mass index, the site of catheter insertion, the anaesthetist's judgement concerning the difficulty of catheter placement, duration of catheter placement or an inadvertent puncture of a venous or arterial vessel, had no significant impact on the concentration of methaemoglobin. CONCLUSION: The use of prilocaine for regional block is safe, since the older patients who might be more susceptible to suffer from clinical symptoms of methaemoglobinaemia usually form less methaemoglobin. However, since prediction of high methaemoglobin levels is difficult, anaesthesiologists performing regional blocks in patients who might be jeopardized by a decreased oxygen transport capacity should avoid high doses of prilocaine.

Adolescent↗
PubMed2006

Impact of the 1998 Gobi dust event on hospital admissions in the Lower Fraser Valley, British Columbia.

The adverse public health impacts of anthropogenically derived particulate matter have been well documented, with measurable increases in both morbidity and mortality rates associated with high particulate matter pollution events. Most current research has focussed on the health impacts of anthropogenically derived particulate matter, and there is a distinct scarcity of literature that examines the role of naturally derived particulate matter and adverse health impacts in the urban context. This study of a Gobi desert dust event in the Greater Vancouver region of British Columbia, Canada, in spring of 1998 provided a unique opportunity to identify the adverse health effects related to naturally derived particulate matter in a large urban setting. Respiratory and cardiac hospitalizations were examined for a three-year period (January 1997 to December 1999), with the Gobi dust event occurring in late April 1998. A meteorological analogue was identified for spring 1997 in order to identify the public health impacts associated with anthropogenically derived particulate matter and those impacts associated with the presence of the Gobi desert dust. Results indicate that this Gobi dust event was not associated with an excess of hospitalizations in the Greater Vancouver region. Peak particulate matter concentrations of Gobi desert dust in the airshed were only associated with an additional one or two hospitalizations per 100,000 population for respiratory and cardiac illnesses, and these increases were not distinguishable from the 'normal' variability in hospitalization rates. Despite high particulate matter concentrations, fine particle size, presence of heavy metals in the dust and extended exposure periods, it appears that the Gobi desert dust event was not associated with significant risk to public health in Greater Vancouver, British Columbia. Therefore it is concluded that naturally derived particulate matter is more benign than particulate matter of anthropogenic origin, and thus poses a low risk to health for the general public.

Air Pollutants↗
PubMed2006

[Anonymous critical incident reporting system in anaesthesiology. Results after 18 months].

Two years ago we implemented a reporting system for critical incidents in the Department of Anaesthesiology and Intensive Care of the University Hospital Dresden. During the first 18 months 162 anonymous reports were registered. The most common errors involved airway and ventilation management, followed by errors in fluid and cardio-vascular management. The main causes were distraction, lack of experience, specific training and communication deficits. The confidence in the anonymity of the reporting system was very high. Following the analysis of the reports, several modifications were initiated, e.g. specific training programs or definition of standards. Over time, a change in the relative distribution of reported errors was observed. The article discusses the different kinds of errors and possible countermeasures. It also strengthens several aspects which are important to consider during the initial phase of a local critical incident reporting system.

Anesthesia↗
PubMed2006

[Long QT syndrome and anaesthesia].

The long QT syndrome (LQTS) is a rare, congenital or acquired disease, which may lead to fatal cardiac arrhythmias (torsade de pointes, TdP). In all LQTS subtypes, TdPs are caused by disturbances in cardiac ion channels. Diagnosis is made using clinical, anamnestic and electrocardiographic data. Triggers of TdPs are numerous and should be avoided perioperatively. Sufficient sedation and preoperative correction of electrolyte imbalances are essential. Volatile anaesthetics and antagonists of muscle relaxants should be avoided and high doses of local anaesthetics are not recommended to date. Propofol is safe for anaesthesia induction and maintenance. The acute therapy of TdPs with cardiovascular depression should be performed in accordance with the guidelines for advanced cardiac life support and includes cardioversion/defibrillation and magnesium. Torsades de pointes may be associated with bradycardia or tachycardia resulting in specific therapeutic and prophylactic measures.

Action Potentials↗
PubMed2006

Successful resuscitation of a patient with ropivacaine-induced asystole after axillary plexus block using lipid infusion.

Ropivacaine 1% 40 ml was mistakenly injected as part of an axillary plexus block in an 84-year-old woman. After 15 min the patient complained of dizziness and drowsiness and developed a generalised tonic-clonic seizure followed by an asystolic cardiac arrest. After 10 min of unsuccessful cardiopulmonary resuscitation, a bolus of 100 ml of Intralipid 20% (2 ml.kg(-1)) was administered followed by a continuous infusion of 10 ml.min(-1). After a total dose of 200 ml of Intralipid 20% had been given spontaneous electrical activity and cardiac output was restored. The patient recovered completely. We believe the cardiovascular collapse was secondary to ropivacaine absorption following the accidental overdose. This case shows that lipid infusion may have a beneficial role in cases of local anaesthetic toxicity when conventional resuscitation has been unsuccessful.

Aged, 80 and over↗
PubMed2006

Anti-emetic prophylaxis with oral tropisetron and/or dexamethasone.

BACKGROUND: The corticosteroid dexamethasone and the serotonine3 -antagonist tropisetron are both effective drugs for the prophylaxis of post-operative nausea and vomiting (PONV) when given intravenously. The aim of this trial was to evaluate the oral use of both drugs as part of a routine oral premedication and to compare their single and combined effectiveness. MATERIALS AND METHODS: In this randomized, placebo-controlled, double-blind study, 320 inpatients with a moderate-high risk of PONV (> or = 40% according to two validated risk scores) received an oral premedication 1-2 h pre-operatively with placebo, a fixed dose of tropisetron 5 mg, dexamethasone 8 mg, or a combination of both drugs. A standardized general anaesthesia was performed, including benzodiazepine premedication, propofol, rocuronium, desflurane in air/O2, fentanyl or sufentanil followed by a continuous infusion of remifentanil. Post-operative analgesia and anti-emetic rescue medication were standardized. The main outcome measures were the severity of PONV within the first 24 h (rated by a standardized scoring algorithm). The incidence of PONV was used as the secondary outcome. RESULTS: Data from 310 patients were analyzed. The mean severity score in the placebo-, tropisetron-, dexamethasone- and the combined-groups was 1.37, 0.8, 0.8 and 0.38, respectively. The incidence of PONV of any severity was 59.2%, 37.5%, 40% and 22.8%, respectively. The reduction of the incidence and the severity of PONV were statistically significant with all three interventions. Results from additional analyses suggested that both drugs were equally effective and that there was a simple additive effect of tropisetron and dexamethasone compared with placebo. CONCLUSION: Oral tropisetron and dexamethasone were both equally effective in reducing the severity and incidence of post-operative nausea and vomiting. The latter could be reduced by approximately 35% in a population of moderate-high risk for PONV. Both drugs had an additive effect. However, even in the combination group there still remained an unacceptably high incidence of PONV of more than 20%. This highlighted the need for a multimodal anti-emetic approach in high-risk patients and the importance of treatment of PONV.

Administration, Oral↗
PubMed2005

In situ SAXS study on cationic and non-ionic surfactant liquid crystals using synchrotron radiation.

In situ synchrotron small-angle X-ray scattering was used to investigate various surfactant/water systems with hexagonal and lamellar structures regarding their structural behaviour upon heating and cooling. Measurements of the non-ionic surfactant Triton X-45 (polyethylene glycol 4-tert-octylphenyl ether) at different surfactant concentrations show an alignment of the lamellar liquid-crystalline structure close to the wall of the glass capillaries and also a decrease in d-spacing following subsequent heating/cooling cycles. Additionally, samples were subjected to a weak magnetic field (0.3-0.7 T) during heating and cooling, but no influence of the magnetic field was observed.

Journal Article↗
PubMed2005

Observation of dipole-dipole interaction in a degenerate quantum gas.

We have investigated the expansion of a Bose-Einstein condensate of strongly magnetic chromium atoms. The long-range and anisotropic magnetic dipole-dipole interaction leads to an anisotropic deformation of the expanding chromium condensate which depends on the orientation of the atomic dipole moments. Our measurements are consistent with the theory of dipolar quantum gases and show that a chromium condensate is an excellent model system to study dipolar interactions in such gases.

Journal Article↗
PubMed2005

Teaching antiarrhythmic therapy and ECG in simulator-based interdisciplinary undergraduate medical education.

BACKGROUND: Third-year students in the Dresden Medical School Programme undergo a 6 week course 'Basics of Drug Therapy' in a problem-based learning curriculum. As part of this course a practical seminar about antiarrhythmic drugs and ECG was set up. This study was conducted to evaluate the use of a simulator in this course. METHODS: A total of 234 students were randomly allocated to receive instructions with (Group S) or without (Group C [control]) the use of a simulator. After a lecture on antiarrhythmic drugs, arrhythmias were presented to Group S using an advanced life support (ALS) manikin. The students were asked to administer a drug or to defibrillate, and the outcome was shown on the monitor. The students in Group C were presented with ECG charts without a simulator. The course was evaluated by a questionnaire and multiple-choice questions (MCQ) about arrhythmias. RESULTS: We received 222 questionnaires. The content-time ratio was rated almost perfect in both groups, but the students in Group S rated the course better suited to link theory and practice. Students in Group S considered the simulator helpful and a good tool for teaching, and the extra effort to be worthwhile. A significantly higher number of students in Group S preferred electric cardioversion as therapy for ventricular tachycardia. CONCLUSIONS: An ALS manikin can be an effective tool in teaching clinical pharmacology.

Adult↗
PubMed2005

[Teaching methods in anesthesia and intensive care medicine. The new legislation and its possibilities for the specialty].

BACKGROUND: As of October 1, 2003, a new government-initiated legislative basis for undergraduate medical education was initiated in Germany which resulted in substantial changes to the structure of the medical curriculum and in a heightened teaching load. METHODS: The Medical Faculty of the University of Dresden established an interdisciplinary reform curriculum in 1998. Since then a hybrid model of traditional lectures, seminars, practical and problem-based learning courses has been implemented for all courses in undergraduate medical training (Dresdener Integrated Problem-based Learning: DIPOL). RESULTS: Examplarly for all other DIPOL courses, the 2003 evaluation results of the "Emergency medicine-Injuries-Intensive care medicine" are presented and show that the course was very well received by students and tutors, and that 95% of the students passed the exams. CONCLUSIONS: The DIPOL anesthesiology course conforms with the new German federal law. A continuous further evaluation is an essential part of quality control and is necessary for the further development of a new curriculum.

Anesthesiology↗
PubMed2005

[Clinical risk management. Implementation of an anonymous error registration system in the anesthesia department of a university hospital].

BACKGROUND: The main goal of a medical risk management system is reduction of treatment errors and the primary focus is patient safety. MATERIALS AND METHODS: A task force on risk management in anaesthesia was established in the department of Anaesthesiology and Intensive Care at the University Hospital Dresden with the aim to implement a critical incident reporting system (CIRS) followed by a structured analysis. The theoretical basic principles and tools for the incident analysis are presented. RESULTS: The task force developed a machine-readable, structured, anonymous questionnaire, which was implemented in clinical practice after a primary test period. CONCLUSIONS: Prerequisites for the implementation of an effective CIRS are support from the department head, anonymity, independence of the task force from the department head and competence of the task force to initiate changes and improvements. CIRS is a powerful tool to register and analyse critical incidents and may influence the following domains: education and training (human factors), medical equipment (technical factors), quality of working processes and departmental communication (organisational factors).

Anesthesia Department, Hospital↗
PubMed2005

[Dynamic decision making in emergency medicine. Example of paraplegia after a traffic accident].

Dynamic decision making is one of the key skills in crew resource management training in aviation. In emergency medicine it is important to practice this skill as a prerequisite for effective treatment of patients. We report a case of paraplegia after a road traffic accident and cervical spine injury. During the prehospital treatment the patient's state was re-evaluated at different times. Although the patient was initially unconscious the physician at the scene decided not to intubate the trachea as the level of consciousness improved during resuscitation. In the emergency room a C5 fracture and a prolapsed intervertebral disc were diagnosed and immediate decompression and stabilisation of the cervical spine were performed. Dynamic decision-making has been in practise for a long time in aviation, similarities to decisions in medicine and the psychological background are described on the basis of the case report.

Accidents, Traffic↗
PubMed2005

[Impact of thoracic epidural analgesia on revenue for G-DRG M01B, OPS-301 5-604.0 (radical retropubic prostatectomy)].

INTRODUCTION: Using the surgical procedure OPS 5-604.0 (radical retropubic prostatectomy) as an example, our study identifies revenue-relevant patient characteristics and describes the impact of the perioperative application of thoracic epidural analgesia (TEA). METHODS: Factors affecting duration of stay were determined in 460 patients undergoing OPS 5-604.0 in the year 2001 and 2002 using multifactorial regression analysis. Preoperative parameters served as factors for matched-pair analysis of the effects of TEA. RESULTS: Characteristics significantly affecting length of postoperative hospital stay were ASA status, age, preoperative haemoglobin concentration, postoperative tachycardia, number of transfused packed red cells, wound infection and surgical revision. Based on identical matching criteria 27 pairs (with/without TEA) could be formed. While the induction time in the TEA group was 8+/-18 min longer (p=0.04), emergence was briefer by 3+/-9 min (p=0.045). Neither anaesthesia presence time nor anaesthesia costs or total costs of surgery differed significantly between the pairs. However, duration of epidural postoperative pain therapy was longer with TEA but in contrast, the postoperative length of hospital stay after TEA was reduced. Assuming a continuous demand for OPS 5-604.0 procedures, TEA enables 32 more procedures to be carried out per year with an increased yield on turnover of 2.7%. CONCLUSION: At first sight combined anaesthesia procedures require more human resources and material, however, as a result of shortened hospital stay and optimized pain therapy patient satisfaction increases and a substantial potential for increased revenue is gained.

Age Factors↗