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Biomedical subjects

U Frey

Publications and source records attributed to U Frey.

At least 19 recordsLinked to original sources
PubMed2004

Effect of sighs on breathing memory and dynamics in healthy infants.

Deep inspirations (sighs) play a significant role in altering lung mechanical and airway wall function; however, their role in respiratory control remains unclear. We examined whether sighs act via a resetting mechanism to improve control of the respiratory regulatory system. Effects of sighs on system variability, short- and long-range memory, and stability were assessed in 25 healthy full-term infants at 1 mo of age [mean 36 (range 28-57) days] during quiet sleep. Variability was examined using moving-window coefficient of variation, short-range memory using autocorrelation function, and long-range memory using detrended fluctuation analysis. Stability was examined by studying the behavior of the attractor with use of phase-space plots. Variability of tidal volume (VT) and minute ventilation (VE) increased during the initial 15 breaths after a sigh. Short-range memory of VT decreased during the 50 breaths preceding a sigh, becoming uncorrelated (random) during the 10-breath presigh window. Short-range memory increased after a sigh for the entire 50 breaths compared with the randomized data set and for 20 breaths compared with the presigh window. Similar, but shorter duration, changes were noted in VE. No change in long-range memory was seen after a sigh. Coefficient of variation and range of points located within a defined attractor segment increased after a sigh. Thus control of breathing in healthy infants shows long-range stability and improvement in short-range memory and variability after a sigh. These results add new evidence that the role of sighs is not purely mechanical.

Carbon Dioxide↗
PubMed2003

Two-year periodicity of respiratory syncytial virus epidemics in Switzerland.

BACKGROUND: The annual respiratory syncytial virus (RSV) epidemics vary in time and severity. The aims of this study were (1) to describe the time-related pattern of RSV epidemics in Switzerland and (2) to deduce the most effective time period for administration of prophylactic measures to high-risk patients. PATIENTS AND METHODS: Descriptive study of (1) RSV hospitalizations between 1997 and 2001 at a pediatric hospital serving a population of 1 million and (2) of national RSV detection rates reported by diagnostic laboratories between 1988 and 1999. RESULTS: 497 RSV hospitalizations and 8,574 reported RSV detections occurring during four and 12 epidemics, respectively, were analyzed. There was fixed alternation of minor and major epidemics differing in the number of RSV infections (two to fourfold), evolution (median interval from onset to peak 13 weeks, range 4-13 weeks vs 8 weeks, range 7-10 weeks; p = 0.065) and median duration (26 weeks, range 24-29 weeks vs 19.5 weeks, range 18-21 weeks; p = 0.005). For minor epidemics it was estimated that a maximum of 85.6% (range, 79.4-86.6%) of annual RSV infections could be covered by a standard five-dose regimen of the monoclonal anti-RSV antibody palivizumab, if initiated in week 50. During major epidemics the most effective time of initiation would be week 43 (88.7%; range 81.9-94.6%). CONCLUSION: RSV epidemiology in Switzerland is characterized by fixed biannual variation. In the absence of active RSV surveillance, such periodicity is useful for scheduling RSV prophylaxis and for hospital resources management.

Disease Outbreaks↗
PubMed2003

[Overview of standardised diagnostic instruments of dementia].

The symptoms of dementia refer to a decline in intellectual abilities and to an impairment of general and instrumental activities of daily living (ADL). Beside cognitive decline and loss of ADL's the diagnosis of dementia requires the documentation of changes in social adaptation, psychopathology and behaviour. There are a large number of scales used in the assessment of the various manifestations of the disease. Some scales focus on a particular aspect of the symptomatology, others prefer a comprehensive approach in the detection of dementia symptoms. We present a list of assessment procedures and scales which seem appropriate to detect different aspects of dementia and which are widely accepted in the scientific community. We describe these scales in detail including their methodology and source of informations, psychometric properties regarding validity and reliability as well as time taken to complete the scales. Our synopsis may serve as an orientation mark in the selection of adequate instruments for the assessment of different symptom domains during the process of diagnosis, the observation of the course of dementia and the efficacy of treatment interventions.

Activities of Daily Living↗
PubMed2002

Reactive macrophage activation syndrome: a simple screening strategy and its potential in early treatment initiation.

QUESTIONS UNDER STUDY: starting treatment of reactive macrophage activation syndromes as early as possible (rMAS, haemophagocytic lymphohistiocytosis), e.g., with intravenous immunoglobulins (IVIG), seems to be essential for optimal outcome. However, there is no diagnostic gold standard which reliably indicates need for early treatment. We used a simple screening strategy consisting of serum ferritin measurements and/or morphological assessment of haemophagocytosis and compared the studied patient population with published series. METHODS: Retrospective analysis of clinical and laboratory data of 57 patients experiencing 60 episodes of rMAS. RESULTS: Screening by serum ferritin measurements and/or morphological assessment of haemophagocytosis of patients presenting with a systemic inflammatory response syndrome (SIRS) indicates that rMAS might be considerably more frequent than stated in the literature. Serum ferritin exceeded >10,000 microg/L in 91% rMAS episodes. Although the patient population studied was otherwise similar in most aspects to the published rMAS series, the fact that 40% of patients fulfilled the criteria for Still's disease (SD) as the disorder underlying rMAS is remarkable and questions the distinct nature of the two diseases. IVIG responders and non-responders did not differ regarding their initial characteristics with exception to the timepoint of IVIG administration, confirming the importance of early treatment initiation. Malignancy-associated rMAS however, has a poor prognosis and seems to be refractory to manipulation with IVIG in most instances, even when responding initially. CONCLUSIONS: rMAS has to be considered in patients with a SIRS- or SD-like clinical presentation. Hyperferritinaemia >or=10,000 microg/l seems to be a good marker for defining patients with or at risk for developing rMAS and should be completed with a morphological assessment of haemophagocytosis. The perception of acute SD and rMAS as two distinct entities has to be questioned at least in a subgroup of patients.

Adolescent↗
PubMed2002

[Influence of treatment with acetyl-cholinesterase inhibitors on psychopathological symptoms in Alzheimer's disease].

The treatment of the cognitive deficits has been the major focus in patients with Alzheimer's disease (DAT) so far. Recently there is increasing interest in Behavioral and Psychological Symptoms of Dementia (BPSD), which can place much burden on DAT patients and their caregivers. With the introduction of Acetylcholinesterase Inhibitors (AChEI) of the second generation the therapeutic armament has been extended. The clinical evaluation of AChEI has found growing evidence that these compounds do not only improve cognitive abilities and activities of daily living (ADL), but also BPSD. The given data regarding the three AChEI available on the market allow the conclusion that there is a general improvement in BPSD. Beside these particularly positive effects on hallucinations, mood symptoms, aggressiveness, and agitation seem possible but need further clarification.

Activities of Daily Living↗
PubMed2002

Role of lung function testing in the management of mechanically ventilated infants.

The mechanical characteristics of the ventilated lung can only be interpreted when the volume of the lung, the elastic properties, and the degree of airway obstruction have been accurately quantified by pulmonary function testing. More gentle ventilation strategies (permissive hypercapnia) are used, and the efficacy of mechanical ventilation can be verified in the intensive care unit. Pulmonary function testing brings new insights, awareness, and applications, but its limitations need to be taken into account when interpreting the acquired data.

Airway Resistance↗
PubMed2002

Elevated nitrite in breath condensates of children with respiratory disease.

The aim of the study was to determine the differences in nitrite, in the exhaled breath condensates of healthy children and those children with asthma, cystic fibrosis (CF) and nonasthmatic, episodic cough. Breath condensates were obtained from 66 children (43 males:23 females, 3.1-16 yrs) and included 29 asthmatics, 12 clinically stable CF patients, 12 children with cough but not asthma and 13 healthy volunteers. The collected condensate was assayed colourimetrically using the Griess reaction to determine nitrite concentrations. Patients with CF (median: 5-95% percentiles; 2.02: 0.43-6.37 microM) or asthma (2.10: 0.63-5.45 microM) had significantly higher levels of nitrite compared to healthy subjects (0.41: 0.13-1.83 microM; p<0.05) or subjects with cough (0.75: 0.03-1.75 microM; p<0.05). Airway inflammation, as assessed by the nitrite in breath condensates, is present in children with asthma and cystic fibrosis, but not those children with nonasthmatic, episodic cough. Nitrite can be conveniently, cheaply and rapidly measured in breath condensates of children as young as 3 yrs of age, and may prove useful for the assessment of airway inflammation in children with respiratory disease.

Adolescent↗
PubMed2002

Measurement of lung volume and ventilation distribution with an ultrasonic flow meter in healthy infants.

Small airway disease in infants is characterised by abnormal lung volume and uneven ventilation distribution. An inert tracer gas washin/washout technique using a pulsed ultrasonic flow meter is presented to measure functional residual capacity (FRC) and ventilation distribution in spontaneously breathing and unsedated infants. With a pulsed ultrasound sent through the main stream of the flow meter, flow, volume and MM of the breathing gas can be calculated. Sulphur hexafluoride was used as a tracer gas. In a mechanical lung model (volume range 53-188 mL) and in 12 healthy infants (aged 38.3+/-9.2 days; mean+/-SD) accuracy and reproducibility of the technique was assessed. Indices of ventilation distribution such as alveolar-based mean dilution number (AMDN) and pulmonary clearance delay (PCD) were calculated. Mean error of volume measurement in the lung model was 0.58% (coefficient of variance (CV) 1.3%). FRC was in the low predicted range for normal infants (18.0+/-2.0 mL x kg(-1)) and highly reproducible (5.5+/-1.7% intra-subject CV). AMDN was 1.63+/-0.15 and PCD was 52.9+/-11.1%. Measurement of functional residual capacity and ventilation distribution using a sulphur hexafluoride washin/washout and an ultrasonic flow meter proved to be highly accurate and reproducible in a lung model and in healthy, spontaneously breathing and unsedated infants.

Female↗
PubMed2002

Age-related differences in perceived asthma control in childhood: guidelines and reality.

Current guidelines specify the goals of asthma treatment in children and propose a stepwise approach to achieve them. The authors sought to determine whether these goals were attained in children of different age groups in the community and to assess treatment in those with unsatisfactory asthma control. A cross-sectional postal questionnaire survey was performed in 1998 in all members of the major Swiss parents organisation for childhood asthma. With a response rate of 85%, data from 572 Swiss-German children aged 4-16 yrs with wheeze were analysed. Asthma control was excellent in 18% of the children, satisfactory (only episodic symptoms) in 33%, and unsatisfactory in 49% with disturbed sleep, restricted activities and school absences. When stratified by age, excellent or satisfactory control was attained by 66% of children aged 13-16 yrs, but only by 56%, 44%, and 38% of those aged 10-12, 7-9 and 4-6 yrs, respectively. Although the majority were followed-up by a doctor (95%) and were receiving beta2-agonists (82%) and inhaled corticosteroids (68%), intensity and duration of treatment were not sufficiently matched to asthma severity. In virtually all children there was scope to improve medical treatment, preventive measures and knowledge of asthma management, with very few if any children with therapy-resistant asthma. Even in children with poor asthma control, 89% of parents were satisfied with the results of treatment. The goals of asthma treatment were attained in one-half of the children, particularly in younger age groups. Although inhaler use was common, detailed assessment showed evidence for undertreatment, especially in the youngest age group, and insufficient adherence to preventive measures. Parental expectations of asthma control, which were lower than those outlined in guidelines, might be an important but underestimated factor in paediatric asthma management.

Administration, Inhalation↗
PubMed2001

Why are infants prone to wheeze? Physiological aspects of wheezing disorders in infants.

Wheezing in infants is common and increasing in prevalence. Infants are particularly prone to wheezing due to developmental differences in airway mechanics compared to adults. These effects are enhanced in the presence of airway inflammation. Wheezing in infants is related to flow limitation which is a function of airway calibre and airway wall compliance. This review discusses the factors contributing to flow limitation and hence, wheezing. It tries to make the link between risk factors influencing airway structure, and thus function, with particular emphasis on the special physiological peculiarities of infants and lung growth. While in adults inflammation and remodelling alone may explain structural and functional changes in wheezing disorders, this reviews proposes a model emphasising that in infants inflammation, remodelling and airway development have to be considered as a continuously interacting system.

Algorithms↗
PubMed2001

Hyperferritinemia as indicator for intravenous immunoglobulin treatment in reactive macrophage activation syndromes.

The underlying mechanisms of reactive macrophage activation syndromes (rMAS) are not understood in detail, and there is no specific treatment. This observational study was prompted by intravenous immunoglobulin (IVIG), dramatically halting two distinct rMAS episodes in the same patient. We evaluated the potential benefits of IVIG administration in treating fulminant rMAS and the usefulness of monitoring serum ferritin levels as an indication for emergency treatment with IVIG. Ten females and 10 males experiencing 22 episodes of rMAS were recruited on the basis of serum ferritin levels >or=10,000 microg/l and/or direct evidence of haemophagocytosis in 11 intensive care units in secondary and tertiary care hospitals in Switzerland between October 1993 and May 2000. In individual patients, serially measured ferritin was closely related to disease activity. Abrupt increases of up to >100,000 microg/l could be observed within hours. Rapid and profound beneficial effects of emergency IVIG treatment were seen in 12 episodes of rMAS accompanied by a prompt decrease of serum ferritin. IVIG produced partial or delayed improvements in 5 patients. No apparent effects were seen in 5 patients. IVIG was only successful if started early during the ferritin run-up to peak values. In conclusion, IVIG is effective in at least a subgroup of adult rMAS when started at the beginning of the macrophage activation process. The monitoring of serum ferritin levels might be helpful in detecting macrophage activation in order to commence IVIG treatment early enough.

Adolescent↗
PubMed2001

Clinical applications of infant lung function testing: does it contribute to clinical decision making?

Infant lung function testing is important in clinical research and recent standardisation efforts have enabled measurements to be made in infants in different laboratories throughout the world. Thus, the theoretical conditions are now fulfilled for use of these techniques in clinical practice. This review discusses the usefulness of various infant lung function techniques in a clinical setting and their potential present or future clinical application. It will focus on the role of infant lung function in the clinical management of infants with respiratory disease.

Age Factors↗
PubMed2001

[Frozen shoulder--MRI-verified continuous block of suprascapular nerve].

Suprascapular nerve block may provide sufficient analgesia in painful immobilisation of the shoulder joint. In the following case report a 41 year old male presenting with adhesive capsulitis (frozen shoulder) has been treated successfully by performing continuous delivery of local anesthetics to the suprascapular nerve via catheter. The location of the catheter has been verified using MRI examination. Pain relief was quantified by using visual analog scale (VAS 1 - 10) and showed decretion from VAS 8 - 10 pre treatment to VAS 1 - 2 after insertion of the catheter and throughout five days of intensive physiotherapy, respectively. The technique of catheterization using a nerve stimulator and alternative peripheral nerve blocks are discussed. In summary, continuous suprascapular nerve block offers an advantageous alternative for pain relief in patients with frozen shoulder. It may provide better pain control and earlier discharge in the ambulatory setting than repetetive single dose blocks.

Adult↗
PubMed2001

[Psychoactive mushrooms - an update].

Psychoactive mushrooms ("magic mushrooms") have been consumed in northern Europe since the late seventies. Recently, the use of hallucinogenic fungi has become popular among young people again. In autumn, psychoactive mushrooms can be collected from their natural habitats throughout Europe. Some species are cultivated in the Netherlands and are sold in "smart-shops" or via Internet. In Germany, dried specimens are sold as "Duftkissen" (aroma pads). The article reviews the common psychoactive species and illustrates medical risks.

Agaricales↗
PubMed2001

Analysis of the harmonic content of the tidal flow waveforms in infants.

The aim of this study was to examine whether the spectral characteristics of tidal flow waveform reflect the interaction between the control of breathing and lung mechanics in 10 healthy infants (H), 10 infants with a history of wheezing disorders (W), and 10 infants with chronic lung disease (CLD). From the flow waveform, we calculated a shape index, the harmonic distortion (k(d)), which quantifies the extent to which a periodic signal deviates from a sine wave. The k(d) of the entire tidal flow waveform did not significantly discriminate between diagnostic groups. However, k(d) was sensitive to maturation: it increased from 0.26 at 1 mo to 0.37 at 6 mo of age (P < 0.002). Furthermore, the frequency (f) spectra of the flow (V) amplitudes between 0.13 and 10 Hz followed a power law: V(f) approximately f(-s), where s (slope) is the exponent in the power law. The exponent of the healthy infants s(H) was 4.24 [95% confidence interval (CI) = 0.2] at 1 mo, 4.39 (CI = 0.16) at 6 mo, and 4.35 (CI = 0.19) at 12 mo and not significantly changing with age. The mean value of s(W) was marginally lower (4.09 +/- 0.28; P < 0.05) than that of s(H). The mean s(CLD) was significantly lower (3.04 +/- 0.31; P < 0.001). Lower values of s and higher values of k(d) indicate an increased complexity of the feedback mechanisms determining tidal flow waveform and may be associated with disease.

Algorithms↗
PubMed2001

An isoflow-volume technique for assessing airway dynamics in children and adults.

BACKGROUND: We propose a new approach to the measurement of small airway function as an alternative to recordings of maximal expiratory flow-volume (MEFV) curves. OBJECTIVES: A newly developed technique to record isoflow-volume (IFV) curves to be tested against maximal respiratory flow curves. METHODS: An isoflow whistle (IFW; Iflopen) measures the length of a constant expiration after full inspiration. The note of the whistle enables a subject to generate an even expiration, and the isoflow maintenance times at 1 l x s(-1) (IFMT1) and 2 l x s(-1) (IFMT2) are recorded. The accuracy and reproducibility of the IFV technique were evaluated in 17 healthy adults (age 17-55 years) and in 14 asthmatic children (age 6-14 years). Comparisons with standard lung function parameters, such as forced expiratory volume in 1 s (FEV1), maximal expiratory flow at 50% (MEF50) and 25% (MEF25) vital capacity and peak expiratory flow (PEF), obtained with a Wright Peakflow Meter were undertaken in 102 healthy (aged 8-14 years) and 101 asthmatic children (aged 6-17 years). A bronchial challenge test was performed in 13 asthmatic children. RESULTS: The expired volume measured by the IFW showed an acceptable agreement with that of a pneumotachograph (mean error of 4.32% for IFMT1 and 5.93% for IFMT2). In healthy and in asthmatic children, the correlations between FEV1 and IFMT1 or IFMT2 (r = 0.92 and 0.94, respectively) were found to be greater than that between FEV1 and PEF (r = 0.68). During bronchial challenge tests in 13 asthmatic children, the FEV1 decreased to 69% of baseline and IFMT1 to 58% of baseline. CONCLUSIONS: The IFV technique accurately measured airway obstruction and closely followed changes in standard parameters of the MEFV curve.

Adolescent↗
PubMed2001

Evaluation of the interrupter technique in healthy, unsedated infants.

The interrupter technique may be used to monitor respiratory resistance and does not require active patient cooperation, but has yet to be applied in unsedated, spontaneously breathing infants. The aim of this study was to determine if the interrupter technique is feasible in spontaneously breathing infants and to investigate the influence of facemask types and analysis techniques on the interrupter resistance (Rint). Rint was measured in 14 healthy, unsedated, sleeping infants (aged 38.4 (31-56) days (mean (range)). Paired measurements were made using large volume, compliant (Mcomp) and small volume, rigid (Mrigid) facemasks. Flow and pressure were measured at the airway opening prior to- and following a brief airway occlusion (500 ms). Rint was calculated using four previously reported analysis techniques. Rint could be measured in all infants. Mcomp, independent of the analysis method significantly underestimated Rint (p<0.001). The variability and magnitude of Rint were significantly influenced by the choice of analysis method. The conclusion is that the interrupter technique is feasible in spontaneously breathing, unsedated infants. Equipment design and analysis method significantly influences interrupter resistance. Studies standardizing equipment and identifying the most appropriate analysis technique in this age group are needed.

Airway Resistance↗