PubMed Health⌕ Search

Biomedical subjects

H W Breuer

Publications and source records attributed to H W Breuer.

At least 19 recordsLinked to original sources
PubMed1998

Amiodarone-induced severe hepatitis mediated by immunological mechanisms.

A 64-year-old man developed a fulminant hepatitis 4 days after initiation of amiodarone treatment and a total dose of 7.1 g. The direct Coombs test was positive and became negative again soon after stopping treatment. Immediately after stopping treatment the extremely increased parameters of hepatic failure returned to normal again. A rechallenge with 200 mg of amiodarone was accompanied by a positive Coombs test which again became negative after several days. We conclude that the occurrence of an acute hepatitis soon after initiation of amiodarone treatment is mediated by immunological mechanisms. There should be high vigilance with respect to this rare life-threatening adverse drug reaction.

Amiodarone↗
PubMed1994

[Does the choice of a reference system modify the analysis of ergospirometric values?].

The importance of the reference system (arbitrary abscissa units) for the analysis of the time courses of cardiopulmonary exercise test indices was assessed. Ten untrained students, 10 athletes, and 10 triathletes performed an exhaustion-limited cycling test. The courses of 20 pulmonary and hemodynamic indices were investigated with respect to the reference systems "heart rate," "relative and absolute oxygen consumption," "power," and a newly developed index "power-duration-product." Most of the significant differences were observed by reference to the power-duration-product. When using the power-duration-product as reference, the courses of eight indices differed significantly between students and triathletes, the courses of five indices between students and athletes, and the course of one index between athletes and triathletes. Since the number of the significant differences between the groups, as well as the courses themselves, depended clearly on the underlying reference system, the choice of the reference system must be considered as an important determinant for the analysis of cardiopulmonary exercise tests.

Adult↗
PubMed1993

Transcutaneous pCO2-monitoring for the evaluation of the anaerobic threshold. Comparison to lactate and ventilatory thresholds.

The monitoring of transcutaneous pCO2 (pCO2(tc) is an alternative to the invasive determination of the anaerobic threshold by analysis of arterial lactate concentration or to the uncomfortable determination of the ventilatory threshold. We compared the threshold determination by pCO2(tc)-monitoring to the 4 mmol/l lactate threshold and to the ventilatory threshold (point where the ventilatory equivalent of oxygen started to increase continuously) in 15 athletes during cycle exercise. The first distinct deflection point in the pCO2(tc) time course after the start of exercise was chosen to indicate the anaerobic threshold. The mean threshold determined by pCO2(tc) occurred at the same workload as the ventilatory threshold but at a lower workload than the lactate threshold. In spite of the good correspondence in the respective means there was a wide range of individual differences between the pCO2(tc) derived thresholds and both reference thresholds. Thus, looking at an individual, the continuous monitoring of the pCO2(tc) does not provide reliable data on the occurrence of the transition from aerobic to anaerobic metabolism.

Adolescent↗
PubMed1993

Heart rate variability and circulating catecholamine concentrations during steady state exercise in healthy volunteers.

OBJECTIVES: To assess whether exercise induced suppression of heart rate variability in the low frequency domain (0.06-0.15 Hz) is related to the increase in circulating catecholamine concentrations. DESIGN: Randomised crossover trial of three exercise tests characterised by different workloads. Pharmacological simulation of exercise-induced changes in vagal and sympathetic activity. PARTICIPANTS: Six healthy men with a mean age of 31.2 (SD 3.0) years. INTERVENTIONS: Three different workloads of steady state cycling ergometry: control state without cycling, cycling at a target heart rate of 100 beats/min, and cycling at a target heart rate of 150 beats/min. Intravenous infusion of atropine (target heart rate 100 beats/min) followed by the additional infusion of adrenaline and noradrenaline. MAIN OUTCOME MEASURES: Fast Fourier analysis of heart rate variability; blood pressure; and venous plasma concentrations of lactate, adrenaline, and noradrenaline. RESULTS: During the control exercise period there were no changes in the assessed variables compared with the preceding resting period. During exercise at a heart rate of 100 beats/min systolic blood pressure increased and heart rate variability decreased. During exercise at a heart rate of 150 beats/min systolic blood pressure and lactate, adrenaline, and noradrenaline concentrations increased. In addition, low frequency (LF) was lower than during exercise at 100 beats/min, high frequency (HF 0.15-0.80 Hz) resembled that during exercise at 100 beats/min, and diastolic blood pressure was reduced. Infusion of atropine caused no changes in blood pressure or plasma concentrations of lactate, adrenaline, and noradrenaline and decreased heart rate variability. The additional infusion of adrenaline and noradrenaline completely suppressed heart rate variability and increased blood pressure. CONCLUSIONS: The reduction in LF and HF during exercise at a heart rate of 100 beats/min, which is not characterised by increased plasma catecholamine concentrations, and during atropine infusion suggests that heart rate variability in the supine state is largely influenced by vagal activity. The additional reduction in LF during exercise at 150 beats/min and during catecholamine infusion may reflect a negative feedback of circulating catecholamines on the sympathetic control of heart rate.

Adult↗
PubMed1992

The power-duration product--evaluation of a new reference system for cardiopulmonary exercise testing.

The aim of this study was to assess the discriminatory power of the new reference system, power-duration product (PDP), for the analysis of haemodynamic and metabolic variables derived from cardiopulmonary exercise tests. The PDP was calculated as the cumulative index of the product of power (W) times the duration (minutes) of each individual exercise step. The study comprised 30 healthy male volunteers, who were classified into three groups with respect to their regular physical activity: 10 untrained medical students (students), 10 sprinters and long-jumpers (athletes) and 10 endurance athletes performing triathlon (triathletes). Twenty metabolic and haemodynamic variables were recorded throughout exhaustion-limited cycling ergometry. The data were analysed with respect to five reference systems (heart rate, relative and absolute oxygen consumption/body surface area, power, and PDP). A total of 14 differences between modified time courses of haemodynamic and metabolic variables in the three groups of volunteers were observed by reference to PDP, 12 by reference to relative oxygen consumption/body surface area, 11 by reference to heart rate, 8 by reference to absolute oxygen consumption/body surface area, and 7 by reference to power. When using PDP as the reference, the time courses of 8 parameters differed significantly between students and triathletes, 5 between students and athletes, and 1 between athletes and triathletes. In addition to its discriminatory superiority for the comparison of different groups characterized by different cardiopulmonary training and endurance, it was found that PDP permitted a better characterization of the individually performed exercise than the consideration of power per se.

Adolescent↗
PubMed1992

[Poor reproducibility of parameters of heart rate variations].

The analysis of heart rate variability is supposed to be a marker of autonomic cardiac activity and is used for risk stratification of post-infarction patients. Analysis of heart rate variability in the frequency domain may permit a differentiation of vagal and sympathetic control; for such analyses only short time intervals characterized by a steady-state autonomic balance can be used. Yet, it is unclear whether single determinations of heart rate variability indices derived from short time intervals yield reproducible results. Therefore, the reproducibility of heart rate variability indices was studied with weekly measurements in 10 healthy volunteers under the following defined conditions: 13 min supine rest, 10 min standing, 13 min sitting, and 15 min cycle ergometry followed by a 14 min recovery period. Heart rate variability was determined in the frequency domain (fast Fourier transformation) and in the time domain. The reproducibility was estimated by the coefficient of variation (CV). Additionally, the reproducibility of heart rate, blood pressure, and the expiratory-inspiratory ratio of heart rate was determined. The reproducibility of the frequency domain indices (36.6-74.9% CV) and of the time domain indices (19.6-32.8% CV) was considerably worse than that of heart rate (5.2-8.2% CV), blood pressure (5.1-8.2% CV) and the expiratory-inspiratory ratio of heart rate (4.6% CV). The reproducibility of heart rate variability indices was not improved by orthostatic or ergometric challenge. This poor reproducibility does not permit a reliable interpretation of heart rate variability on the basis of single measurements in healthy volunteers. Given the wide range and scatter of the measured parameters, the diagnostic and prognostic value of heart rate variability indices derived from short recording periods appears questionable.

Arrhythmias, Cardiac↗
PubMed1990

Comparative analysis of arterial oxygen saturations during exercise by pulse oximetry, photometric measurements, and calculation procedures.

Pulse oximetry allows non-invasive monitoring of arterial oxygen saturation (SO2). To study the validity of pulse oximetry, comparative measurements were performed. During exhaustion limited exercise SO2-values measured by pulse oximetry (SO2puls), calculated SO2-values (algorithms of Kelman, Severinghaus, and Siggaard-Andersen--SO2calc), and as "golden standard" photometric measured SO2-values (SO2meas) were compared. Fourteen triathletes performed a stepwise cycling exercise test in the supine position. SO2calc was determined on the basis of capillary actual blood gas values. SO2puls was measured continuously with a finger probe attached to the second finger. The SO2puls- and SO2calc-values differed from the SO2meas-values (p less than 0.05); however, the differences were of no clinical relevance. Performing linear regression analysis, only SO2puls correlated significantly (r = 0.47, p less than 0.001) with SO2meas. Pulse oximetry is able to replace invasive measurements of arterial oxygen saturation in athletes. It is superior to SO2-calculations and permits reliable, valid and non-invasive continuous monitoring of SO2.

Adult↗
PubMed1990

[Long-term therapy with almitrine dimesilate has no effect on pulmonary hemodynamics at rest and during stress].

A 6-month double-blind study was conducted in 26 patients suffering from a severe obstructive disturbance of ventilation and respiratory insufficiency to find out the behaviour of blood gases and pulmonary haemodynamics under Almitrin treatment compared with placebo. The acute administration of 75 mg Almitrin resulted in a significant increase of PaO2 by 11.7 mmHg, as well as of PAPR by 4.4 mmHg. Statistical significance was seen only for the systolic pressure of the a. pulmonalis. After subsequent 6-month treatment with 3 x 25 mg Almitrin, a significantly higher PaO2 is seen at T6 than in the control group. Another additional administration of 75 mg Almitrin results in a further increase of PaO2 by 7.7 mmHg. At T6 the behaviour of pulmonary haemodynamics is identical in both groups A and P.

Almitrine↗
PubMed1990

[Transcutaneous blood gas measurements in ergometry].

Blood gases were determined simultaneously both transcutaneously and arterially in 23 healthy male subjects during spiroergometric, exhaustion-limited stress. The individual correlation coefficient between arterially and transcutaneously measured pO2/pCO2 was 0.66 and 0.80, respectively. The median correlation coefficient between the individual correlation coefficients of the pO2 and pCO2 measurements was 0.85 (p less than 0.01). Hence, the validity of transcutaneous blood gas measurement under stress is significantly dependent on individual factors that influence both the pO2 and pCO2 measurements to an equal degree.

Blood Gas Monitoring, Transcutaneous↗
PubMed1990

[Pneumonia in AIDS: pathogen spectrum and diagnostic value of various fiberoptic bronchoscopy methods for the detection of pathogens].

39 fibre-bronchoscopic examinations were performed prospectively in 29 AIDS-patients with pneumonia. Specimens were obtained from the central bronchial system with a protected brush and by suction, from the infiltrated peripheral area by catheter suction, protected brush, bronchoalveolar lavage (BAL) and transbronchial biopsy in randomized order. In patients with non-bacterial pneumonia, pneumocystis carinii (n = 20) was the most frequent pathogen. In this group BAL had a significantly higher rate of pathogen detection than other techniques. In patients with bacterial pneumonia (n = 10) the pathogens were found in all cases by suction from the central bronchial system. Fibre-bronchoscopy in patients with AIDS and pneumonia should include specimens from the central bronchial system and a bronchoalveolar lavage.

Acquired Immunodeficiency Syndrome↗
PubMed1990

[Validity of calculating oxygen saturation at rest and during exercise].

Oxygen saturation calculated with the formulae proposed by Heck, Kelman, Lutz, Marsoner, Severing-haus and Siggaard-Andersen, was compared with oxygen saturation measured photometrically. An analysis of 1350 peripheral venous, mixed venous and arterial blood samples obtained during bicycle ergometry revealed that only the calculations using the Kelman, Siggaard-Andersen and Severing-haus formulae had adequate validity and reliability over a wide measuring range. If, however, the oxygen saturation figures are to be used for further calculations, direct measurement should be given preference to avoid errors (for example, in shunt calculation).

Exercise Test↗
PubMed1990

[Pneumonia in patients with and without immunosuppression--value of bronchoscopic biopsy technics for the detection of pathogens].

Bronchoscopic diagnosis was performed in 91 patients with 100 episodes of fresh pneumonia. In already existing immunosuppression (n = 51, Group A) pathogens were most frequently identified via bronchoalveolar lavage (70%); in patients without immunosuppression (n = 49, Group B) the identification quota in respect of the central bronchial secretion (53%) and bronchoalveolar lavage (47%) were comparable. In Group A the most frequently occurring pathogens were Pneumocysti carinii (n = 18) and Aspergillus fumigatus (n = 7), in Group B Streptococcus pneumoniae (n = 8) and Staphylococcus aureus (n = 7).

Adult↗