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Biomedical subjects

T Faber

Publications and source records attributed to T Faber.

At least 19 recordsLinked to original sources
PubMed2006

Stroke volume variation does not predict fluid responsiveness in patients with septic shock on pressure support ventilation.

BACKGROUND: Stroke volume variation (SVV)--as measured by the pulse contour cardiac output (PiCCO) system--predicts the cardiac output response to a fluid challenge in patients on controlled ventilation. Whether this applies to patients on pressure support ventilation is unknown. METHODS: Thirty consecutive patients with septic shock were included. All were on pressure support ventilation, monitored using the PiCCO system and receiving 500 ml of colloid on clinical indications. Arterial pulse contour SVV and the transpulmonary thermodilution cardiac index were measured before and after fluid challenge. RESULTS: Forty-seven per cent of the patients were defined as fluid responders by an observed increase of > 10% in the cardiac index after fluid. Prior to fluid challenge, the cardiac index was lower in responders compared with non-responders (mean +/- SD, 3.0 +/- 0.6 vs. 4.0 +/- 1.2 l/min/m2, P < 0.01). In contrast, pre-infusion values of SVV were similar between subsequent responders and non-responders (13 +/- 5 vs. 16 +/- 6%, P =0.26). The mean areas under the ROC curves were 0.77 (95% confidence interval, 0.60-0.94) and 0.52 (0.30-0.73) for pre-fluid cardiac index and SVV, respectively, indicating a predictive power of only the cardiac index. CONCLUSIONS: SVV did not predict the response in cardiac output to fluid challenge in patients with septic shock on pressure support ventilation.

Aged↗
PubMed2002

Pre-hospital parenteral antibiotic treatment of meningococcal disease and case fatality: a Danish population-based cohort study.

OBJECTIVES: Studies about the efficiency of pre-hospital antibiotic treatment of meningococcal disease are conflicting. We examined the case fatality rate in patients with meningococcal disease treated with pre-hospital antibiotics. METHODS: A cohort study of 534 patients hospitalized with meningococcal disease from two Danish counties. Clinical data were obtained from referral letters from general practitioners and hospital records. Complete follow-up for all patient until death or discharge. RESULTS: Seventy-seven patients (16% of the patients seen by a general practitioner) received parenteral antibiotics before hospital admission; 9 (12%) of them died. Of 402 patients who did not receive pre-hospital parenteral antibiotics, 26 (7%) died. The overall risk of case fatality among antibiotic-treated patients was increased with adjusted odds ratio (OR) = 2.4 (95% CI, 1.0-5.6). Meningococcus serogroup B was associated with increased case fatality in patients who received pre-hospital parenteral antibiotics (OR = 2.6; 95% CI, 0.8-8.3) in contrast to other serogroups. In Aarhus County there were no deaths in patients who received pre-hospital parenteral antibiotics, but in North Jutland County the case fatality was high (OR = 2.9; 95% CI, 1.2-6.8). CONCLUSIONS: The efficiency of pre-hospital parenteral antibiotic treatment seems to be dependent on hospital care and may vary with the serogroup.

Adolescent↗
PubMed2001

Visualizing mushroom body response to a conditioned odor in honeybees.

Combining differential conditioning with optophysiological recordings of bee brain activity allows the investigation of learning-related changes in complex neural systems. In this study we focused on the mushroom bodies of the bee brain. Presenting different odors to the animal leads to significant activation of the mushroom body lips. After differential conditioning, the rewarded odor leads to stronger activation than it did before training. Activation by the unrewarded odor remains unchanged. These results resemble findings in the bee's antennal lobes, which are the first olfactory relay station in the insect brain. As an integrative neural network, enhanced activation of the mushroom body lip may carry additional information, i.e., for processing odor concentrations.

Agaricales↗
PubMed2000

[Acute myocardial ischemia and ventricular arrhythmias in the pathogenesis of sudden cardiac death in coronary disease].

There is increasing evidence for a fatal interaction of myocardial ischemia, ventricular arrhythmias and sudden cardiac death in some patients with coronary artery disease. Evidence comes from autopsy studies, from the evaluation of patients who survived an episode of sudden cardiac death, from follow-up data of these patients either treated or not by revascularization therapy and/or an implantable cardioverter-defibrillator and indicate that reducing the individual ischemic burden will be beneficial to reduce the incidence of sudden cardiac death. Studies in patients with stable and especially with unstable angina using Holter monitoring could demonstrate that there is a close and causal relationship between myocardial ischemia inducing or aggravating life-threatening ventricular arrhythmias and sudden cardiac death particularly in patients with unstable and postinfarction status. This review summarizes some of our clinical knowledge on this topic and indicates that preventive strategies for myocardial ischemia are the antiarrhythmic treatment of choice in patients with severe coronary artery disease and patients with evidence or at risk for ischemic proarrhythmia.

Animals↗
PubMed2000

Echocardiographic validation of gated SPECT ventricular function measurements.

UNLABELLED: Left ventricular (LV) volumes are valuable prognostic indicators in the management of coronary artery disease and traditionally have been obtained by x-ray contrast angiography or echocardiography. There now are several scintigraphic methods to compute volumes that are based on different LV modeling assumptions. Both the reasons that calculations from different nuclear techniques can disagree with one another and the relationship of these values to the more conventional echocardiographic measurements must be investigated thoroughly for calculations to be interpretable for individual patients. METHODS: Echocardiographic volumes were determined in 33 retrospective subjects with coronary artery disease (mean age, 61 +/- 12 y; 42% men; 70% with abnormal perfusion and 58% with abnormal segmental wall motion) using the modified Simpson's rule technique applied to digitized apical 4-chamber and apical 2-chamber views of 4 averaged heartbeats. These volumes were compared with those from 3 gated SPECT methods based on Simpson's rule LV modeling similar to standard echocardiographic algorithms (SPECT EF from St. Luke's-Roosevelt Hospital) (method 1), Gaussian myocardial count profile curve fitting (QGS from Cedars-Sinai Medical Center) (method 2), and an endocardial model based on perfusion sampling and count-based thickening (Cardiac Toolbox from Emory University) (method 3). RESULTS: By ANOVA, there were no significant differences among ejection fractions (EFs), but there were for volumes. Paired t test analysis showed volumes from methods 2 and 3 to be significantly larger than echocardiographic volumes and larger than those of method 1. Linear regression analysis comparing gated SPECT and echocardiographic volumes showed a nearly identical strong correlation (r = 0.92; P < 0.000001) for all 3 methods. Excellent correlation also was found among gated SPECT volumes from the 3 methods (r = 0.94). Bland-Altman analysis and t tests showed that method 1 volumes (70 +/- 61 mL) were the same as for echocardiography (77 +/- 55 mL), but volumes were overestimated by method 2 (105 +/- 74 mL) and method 3 (127 +/- 92 mL), particularly for larger volumes. Pearson coefficients for EFs compared with echocardiography were r = 0.82, 0.75, and 0.72 for methods 1-3, respectively. EFs correlated strongly among the 3 gated SPECT methods (r = 0.86-0.92). The Fisher z test showed no differences among these methods for any of the volume or EF linear correlation analyses. CONCLUSION: All gated SPECT parameters correlated well with echocardiographic values. However, the gated SPECT method for which underlying assumptions most closely resembled those commonly used in echocardiography produced mean volume values closest in agreement with echocardiographic measurements.

Analysis of Variance↗
PubMed1999

Implementation of percutaneous dilation tracheotomy--value of preincisional ultrasonic examination?

BACKGROUND: In this observational study we have evaluated the implementation of percutaneous dilation tracheotomy (PDT), using the forceps dilation technique (Portex) in a multidisciplinary ICU. METHODS: We included a preincisional ultrasonic evaluation of the neck in order to visualise the isthmus glandula thyroidea and major vessels. The observational period comprised one year. PDT was performed in 28 patients. RESULTS: Implementation of PDT was uneventful. Duration of insertion was 10 min (4-40 min). Total time of tracheostomy was 8 days (1-65 days). In nine cases, the proximal end of the isthmus was overlying the space between the 1st and 2nd tracheal ring, which was considered the optimal insertion site. This resulted in seven cases of insertion between the cricoidea and the 1st tracheal ring and in two cases in a more distal insertion. Nineteen tracheotomies were performed in the interstice between the 1st and 2nd tracheal ring. In nine patients, major vessels were overlying the trachea. In none of the patients did this information result in an altered insertion site. Two cases of minor bleeding were observed; both stopped upon compression. In two patients the primary tube size (8.0) was too big and a smaller tube had to be inserted. In one patient the tube was maladapted to the stoma and had to be interchanged with an ordinary tracheostomial tube on the 5th day of tracheostomy. CONCLUSION: Based on the experience gathered in this study and information from the literature, we have abandoned the routine use of ultrasonic examination of the neck prior to PDT. In order to achieve and maintain routine, we suggest that the procedure is performed by a restricted number of doctors.

Adolescent↗
PubMed1999

Associative learning modifies neural representations of odors in the insect brain.

Recording brain activity in vivo during learning is fundamental to understanding how memories are formed. We used functional calcium imaging to track odor representations in the primary chemosensory center of the honeybee, the antennal lobe, while training animals to discriminate a rewarded odor from an unrewarded one. Our results show that associative learning transforms odor representations and decorrelates activity patterns for the rewarded versus the unrewarded odor, making them less similar. Additionally, activity for the rewarded but not for the unrewarded odor is increased. These results indicate that neural representations of the environment may be modified through associative learning.

Animals↗
PubMed1997

A semi-in-vivo preparation for optical recording of the insect brain.

We describe a method for optically recording neuronal activity from an intact insect brain, upon natural sensory stimulation. In this preparation, the head capsule of the honeybee, Apis mellifera, is isolated from the body while leaving the entire brain undamaged. In short, a hole is first cut into the cuticule to allow optical access to the brain and to allow the removal of tracheae and glands. Then the head is cut free and placed into a dye-loaded and cooled ringer solution in a staining chamber for 1 h. Subsequently, the head is fixed in a recording chamber, covered with a cover-slip, and imaged under the microscope with a cooled CCD camera. The whole preparation leaves the antennae dry, free to move, and functional throughout the experiment, allowing for natural odour stimulation of the olfactory system. Using calcium sensitive or potential sensitive dyes (calcium-green or RH795), we could record the processing of olfactory information at the glomerular level in the antennal lobe of the bee.

Animals↗
PubMed1997

Antiarrhythmic effects of increasing the daily intake of magnesium and potassium in patients with frequent ventricular arrhythmias. Magnesium in Cardiac Arrhythmias (MAGICA) Investigators.

OBJECTIVES: This study sought to assess potential antiarrhythmic effects of an increase in the daily oral intake of magnesium and potassium in patients with frequent ventricular arrhythmias. BACKGROUND: Magnesium and potassium contribute essentially to the electrical stability of the heart. Despite experimental and clinical evidence for the antiarrhythmic properties of the two minerals, controlled data in patients with stable ventricular arrhythmias are lacking. METHODS: In a randomized, double-blind study, 232 patients with frequent ventricular arrhythmias (> 720 ventricular premature beats [VPBs]/24 h) confirmed at baseline and after 1 week of placebo therapy were subsequently treated over 3 weeks with either 6 mmol of magnesium/12 mmol of potassium-DL-hydrogenaspartate daily or placebo. RESULTS: Compared with placebo pretreatment, active therapy resulted in a median reduction of VPBs by -17.4% (p = 0.001); the suppression rate was 2.4 times greater than that in patients randomized to 3 weeks of placebo therapy (-7.4%, p = 0.038). The likelihood of a > or = 60% (predefined criterion) or > or = 70% suppression rate (calculated from the placebo-controlled run-in period) was 1.7 (25% vs. 15%, p = 0.044) and 1.5 times greater in the active than in the placebo group (20% vs. 13%, p = 0.085), respectively. No effect of magnesium and potassium administration was observed on the incidence of repetitive and supraventricular arrhythmias and clinical symptoms of the patients. CONCLUSIONS: To our knowledge, this study is the first to provide controlled data on the antiarrhythmic effect of oral administration of magnesium and potassium salts when directed to patients with frequent and stable ventricular tachyarrhythmias. A 50% increase in the recommended minimum daily dietary intake of the two minerals for 3 weeks results in a moderate but significant antiarrhythmic effect. However, with the given therapeutic regimen, repetitive tachyarrhythmias and patient symptoms remain unchanged.

Adult↗
PubMed1996

Adenosine in treating cardiac arrhythmias.

1. Adenosine is an endogenous nucleoside which causes a brief blockade of the AV nodal conduction pathway following intravenous administration. 2. Such a brief AV block can be used therapeutically for reliable termination of AV nodal re-entry tachycardia and WPW re-entry tachycardia. It can also be used for demasking atrial activity in rapid suspected supraventricular tachycardia with a broad QRS complex or a Delta wave, not present during sinus rhythm with normal AV node conduction, indicating the presence of a hidden WPW syndrome. 3. Side effects after adenosine application are frequent, but very transient rarely serious (1-3% of cases, e.g. status asthmaticus, ventricular fibrillation) and therefore require a certain degree of experience with this drug on the part of the treating physician.

Adenosine↗
PubMed1995

Ventricular tachyarrhythmias, myocardial ischemia, and sudden cardiac death in patients with hypertensive heart disease.

Hypertensive heart disease is increasingly considered to be a strong and independent risk factor for sudden cardiac death. Ventricular tachyarrhythmias in these patients are common and mainly the result of electrophysiologic abnormalities and increased electrical vulnerability of the hypertrophic myocardium. However, proarrhythmia in the hypertrophic heart often is facilitated and aggravated by electrolyte disturbances, the sympathoadrenergic tone, transient blood pressure crisis, and especially by the occurrence of myocardial ischemia. Myocardial ischemia in the setting of hypertensive heart disease may result from stenotic lesions in large and/or small coronary artery vessels and, in the absence of both, will result from the altered cellular oxygen supply and consumption in the hypertrophic myocardium. Recent studies have shown that acute and transient myocardial ischemia are common in many hypertensives, often fail to be symptomatic, and that the dynamic interaction of left ventricular hypertrophy, transient myocardial ischemia, and ventricular tachyarrhythmias may provide a crucial link for the high incidence of sudden cardiac death in patients with hypertensive heart disease.

Antihypertensive Agents↗
PubMed1995

Central venous versus mixed venous oxygen content.

Mixed venous oxygen content (commonly measured as oxygen saturation) is a highly relevant parameter in the monitoring of critically ill patients; unfortunately, its measurement requires catheterization of the pulmonary artery. Though less invasive, the central venous oxygen saturation is an unsatisfactory substitute, due to fluctuations in perfusion distribution and regional oxygen extraction in the course of illness. The present study examined the relation of oxygen contents in simultaneously withdrawn central venous and mixed venous blood samples from critically ill patients, in order to validate a hypothetical algorithm for the estimation of mixed venous oxygen content from a central venous sample: Although the proposed algorithm had a fairly high power of prediction, its merits in comparison to assuming simple proportionality between central venous and mixed venous oxygen content seemed marginal. However, as it is likely that the results so far are mathematically coupled, further prospective studies are necessary.

Algorithms↗
PubMed1995

Clinical evidence for the fatal interaction of ventricular tachyarrhythmias, myocardial ischemia and sudden cardiac death.

During recent years, experimental data have collected convincing evidence for the fatal interaction of myocardial ischemia, ventricular tachyarrhythmias, and sudden cardiac death. In the clinical setting, data reporting on the daily relevance of such a fatal interaction lacked until recently. However, there is now increasing evidence from autoptic studies, from the evaluation of patients who survived one episode of sudden cardiac death, from the follow-up of these patients when treated or not by revascularization therapy and/or an implantable cardioverter-defibrillator and, most recently, from studies in patients with stable and especially unstable angina pectoris suffering from Holter-documented ischemic proarrhythmia, that acute and transient myocardial ischemia play an important role for the initiation as well as the aggravation of ventricular tachyarrhythmias and out-of-hospital sudden cardiac death. The present work is directed to summarize our clinical knowledge on this topic and to indicate that preventive strategies for myocardial ischemia are the "antiarrhythmic" of choice in patients with severe coronary artery disease and evidence for ischemic proarrhythmia.

Coronary Disease↗
PubMed1994

Continuous monitoring of acute myocardial ischemia by the implantable cardioverter defibrillator.

The present generation of implantable cardioverter defibrillators (ICDs) provides a very effective device for monitoring and treating life-threatening ventricular tachyarrhythmia. Patients at risk of sudden cardiac death who are directed to this form of treatment usually have severe coronary artery disease, previous myocardial infarction, and low ejection fraction. Progression of the underlying heart disease predisposes these patients to subsequent ischemic events, including symptomatic and asymptomatic myocardial ischemia and reinfarction, which carry a substantial risk of fatal ventricular proarrhythmia. Multipolar lead configurations presently available in the ICD appear to be effective in assessing acute myocardial ischemia as induced by exercise testing or transient coronary artery occlusion. Continuous monitoring of myocardial ischemia (COMONI) by a sophisticated, multimodal ICD appears to be feasible, may offer the means to closely supervise progression and various complications of the underlying heart disease, and may help to guide automatic or interactive antiischemic treatment.

Algorithms↗
PubMed1993

Chronic catheterization of the epidural space in rabbits: a model for behavioural and histopathological studies. Examination of meptazinol neurotoxicity.

A technique of epidural catheterization in rabbits is described. Twelve albino rabbits received a totally implanted epidural catheter system. The system was implanted surgically, and the functioning of the system tested for a period of 3 months. X-ray examinations following epidural contrast injections showed a distribution up to Th4 following 1.5 ml and Th8-9 following 1.0 and 1.25 ml. Epidural injection of lidocaine throughout the study period proved the system to be functioning for all 3 months. Another 12 rabbits were included for the neurotoxicological examinations following epidural catheterization, without any injections (three rabbits), epidural injections of saline (four rabbits) and meptazinol (five rabbits) once a day for 14 days. Histopathological examinations showed a fibrous cocoon, at the tip of the catheter, in all rabbits. In the group of rabbits which did not receive any injections, the cocoon was slightly infiltrated with leukocytes and local depression of the spinal cord was observed in one rabbit. In the saline-injected group this infiltration was more pronounced and in one rabbit it extended into the meninges. Three rabbits showed local depression of the spinal cord and local myelopathy of the white matter in the area adjacent to the cocoon. In the group of rabbits receiving meptazinol, three out of five had local depression and myelopathy of the white matter. In this group these findings were more pronounced. In two rabbits the myelopathy extended transversely through the white matter into the grey matter of the spinal cord. The number of pathological changes in the group receiving meptazinol was significantly higher compared to the control and placebo groups.(ABSTRACT TRUNCATED AT 250 WORDS)

Animals↗
PubMed1992

[Risk stratification and long-term therapy with amiodarone in patients with idiopathic dilated cardiomyopathy].

Patients with cardiomyopathy are known to suffer from a high prevalence of tachyarrhythmic complications and sudden cardiac death. In a prospective study, 30 patients (25 men, 5 women, mean age: 52 +/- 12 years) with dilated cardiomyopathy underwent 48-h-Holter monitoring and programmed electrical stimulation and, independent from the results of the diagnostic work-up, were then randomized either to amiodarone or to a conventional or no antiarrhythmic therapy. At baseline, frequent ventricular arrhythmias (> 30 ventricular premature beats/h) were observed in 15/30 patients (50%), 13 patients (43%) had repetitive ventricular arrhythmias, additionally. Four patients suffered spontaneous sustained tachyarrhythmias. During programmed electrical stimulation, sustained monomorphic ventricular tachycardia was induced in 3/3 patients with and in 1/25 patients (4%) without a history of sustained tachycardia. Sustained monomorphic ventricular tachycardia was induced with one to two extrastimuli; three extrastimuli only increased the incidence of inducible ventricular fibrillation (8 patients, 28%). During a mean follow-up of 28 +/- 6 months 10/30 patients (33%) died for cardiac reasons (sudden cardiac death: 4/10 patients). Cardiac death was most likely in patients with a left-ventricular ejection fraction < 35% (5/18 patients, 28% versus 1/12 patients with ejection fraction > 35%, 8%) and further increased in the presence of reduced exercise tolerance and frequent and repetitive ventricular arrhythmias (4/7 patients, 57%). In the amiodarone group 4/15 patients died (27%, sudden cardiac death: one patient), while in patients not treated by amiodarone 8/15 patients died (54%; sudden cardiac death: three patients). Amiodarone therapy was well tolerated in all but one patient.

Adult↗