Publications by authors named "Dirk Cysarz"

41 Publications

Comparison of Two Algorithms Analysing the Intracranial Pressure Curve in Terms of the Accuracy of Their Start-Point Detection and Resistance to Artefacts.

Acta Neurochir Suppl 2021 ;131:243-248

Gemeinschaftskrankenhaus Herdecke (Community Hospital Herdecke), Herdecke, Germany.

Objectives: For further insight into the possibly predictive quality of the intracranial pressure (ICP) waveform morphology a definite and reliable identification of its components is a prerequisite but presents the problem of artefacts in physiological signals.

Methods: ICP and electrocardiogram (ECG) data were recorded to depict not only their numerical value but also their respective waveforms and were analysed by two algorithms, which were then compared for their artefact resistance.The algorithms in question identify the start point of every ICP wave, one (AR[SA]) by scale analysis, the other (AR[ECG]) by analysing the ICP wave linked to the ECG.

Results: Start-point identification accuracy in rhythmic patients showed sensitivity of 95.14% for AR[SA] and 99.99% for AR[ECG], with a positive predictive value (ppv) of 98.30% for AR[SA] and 99.76% for AR[ECG].In arrhythmic patients sensitivity was 98.05% for AR[SA] and 99.73% for AR[ECG], with a ppv of 100% for AR[SA] and 99.78% for AR[ECG].

Conclusions: AR[ECG] has proven to be more resistant to artefacts than AR[SA], even in cases such as cardiac arrhythmia. It facilitates reliable, three-dimensional visualisation of long-term changes in ICP-wave morphology and is thus suited for analysis in cases of more complex or irregular vital parameters.
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http://dx.doi.org/10.1007/978-3-030-59436-7_46DOI Listing
June 2021

Binary symbolic dynamics analysis to detect stress-associated changes of nonstationary heart rate variability.

Sci Rep 2020 09 22;10(1):15440. Epub 2020 Sep 22.

Integrated Curriculum for Anthroposophic Medicine, Witten/Herdecke University, Herdecke, Germany.

Psychological stress may have harmful physiological effects and result in deteriorating health. Acute psychological stress acts also on cardiac autonomic regulation and may lead to nonstationarities in the interbeat interval series. We address the requirement of stationary RR interval series to calculate frequency domain parameters of heart rate variability (HRV) and use binary symbolic dynamics derived from RR interval differences to overcome this obstacle. 24 healthy subjects (12 female, 20-35 years) completed the following procedure: waiting period, Trier Social Stress Test to induce acute psychological stress, recovery period. An electrocardiogram was recorded throughout the procedure and HRV parameters were calculated for nine 5-min periods. Nonstationarities in RR interval series were present in all periods. During acute stress the average RR interval and SDNN decreased compared to rest before and after the stress test. Neither low frequency oscillations (LF), high frequency oscillations (HF) nor LF/HF could unambiguously reflect changes during acute stress in comparison to rest. Pattern categories derived from binary symbolic dynamics clearly identified acute stress and accompanying alterations of cardiac autonomic regulation. Methods based on RR interval differences like binary symbolic dynamics should be preferred to overcome issues related to nonstationarities.
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http://dx.doi.org/10.1038/s41598-020-72034-2DOI Listing
http://www.ncbi.nlm.nih.gov/pmc/articles/PMC7509783PMC
September 2020

Heart rate variability categories of fluctuation amplitude and complexity: diagnostic markers of fetal development and its disturbances.

Physiol Meas 2019 07 3;40(6):064002. Epub 2019 Jul 3.

Hans Berger Department of Neurology, Biomagnetic Center, Jena University Hospital, Jena 07747, Germany.

Objective: In fetal diagnosis the myriad and diversity of heart rate variability (HRV) indices prevents a comparable routine evaluation of disturbances in fetal development and well-being. The work aims at the extraction of a small set of HRV key indices that could help to establish a universal, overarching tool to screen for any disturbance.

Approach: HRV indices were organized in categories of short-term (prefix s) and long-term (prefix l) amplitude fluctuations (AMP), complexity (COMP), and patterns (PATTERN) and common representatives for each category were extracted. This procedure was done with respect to the diagnostic value in the evaluation of the maturation age throughout the second and complete third trimester of pregnancy as well as to potential differences associated with maternal life-style factors (physical exercise, smoking), nutrient intervention (docosahexaenoic acid (DHA) supplementation), and complications of pregnancy (gestational diabetes mellitus (GDM), intra-uterine growth restriction (IUGR)).

Main Results: We found a comprehensive minimal set that includes [lAMP: short term variation (STV), initially introduced in cardiotocography, sAMP: heart rate increase across one interbeat interval of phase rectified averaged signal - acceleration capacity (ACst1), lCOMP: scale 4 multi-scale entropy (MSE4), PATTERN: skewness] for the maturation age prediction, and partly overlapping [lAMP: STV, sAMP: ACst1, sCOMP: Lempel Ziv complexity (LZC)] for the discrimination of the deviations.

Significance: The minimal set of category-based HRV representatives allows for a screening of fetal development and well-being. These results are an important step towards a universal and comparable diagnostic tool for the early identification of developmental disturbances. Novelty & Significance Fetal development and its disturbances have been reported to be associated with a multiplicity of HRV indices. Furthermore, these HRV indices change with maturation. We propose the abstraction of HRV categories defined by short- and long-term fluctuation amplitude, complexity, and pattern indices that cover all relevant aspects of maturational age, behavioral influences and a series of pathological disturbances. The study data are provided by multiple centers. Our approach is an important step towards the goal of a standardized diagnostic tool for early identification of fetal developmental disturbances with respect to the reduction of serious complications in the later life.
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http://dx.doi.org/10.1088/1361-6579/ab205fDOI Listing
http://www.ncbi.nlm.nih.gov/pmc/articles/PMC7020698PMC
July 2019

A proof-of-concept trial of HELIOX with different fractions of helium in a human study modeling upper airway obstruction.

Eur J Appl Physiol 2019 May 8;119(5):1253-1260. Epub 2019 Mar 8.

Philipp Klee-Institute for Clinical Pharmacology, HELIOS Clinic Wuppertal, Wuppertal, Germany.

Background: Helium in oxygen (HELIOX) can relieve airway obstruction and lower the work of breathing because it increases the threshold at which turbulent gas flow is induced. Less turbulent and more laminar flow lowers the work of breathing. According to guidelines, the fraction of Helium in HELIOX should be maximized (e.g. to 79%). Here, we investigate whether HELIOX with less than 60% of Helium is able to relieve the sensation of dyspnea in healthy volunteers.

Methods: 44 volunteers underwent resistive loading breathing different gases (medical air and HELIOX with a fraction of 25%, 50% or 75% helium in oxygen) in a double-blinded crossover design. Subjects rated their degree of dyspnea (primary outcome parameter) and the variability of noninvasively measured systolic blood pressure was assessed.

Results: Dyspnea was significantly reduced by HELIOX-containing mixtures with a fraction of helium of 25% or more. Similarly, blood pressure variability was reduced significantly even with helium 25% during respiratory loading with the higher load, whereas with the smaller load an effect could only be obtained with the highest helium fraction of 75%.

Conclusion: In this clinical trial, HELIOX with less than 60% of helium in oxygen decreased the sensation of dyspnea and blood pressure variability, a surrogate parameter for airway obstruction. Therefore, higher oxygen fractions might be applied without losing the helium-related benefits for the treatment of upper airway obstruction.

Trial Registration: Registration with clinical trials (NCT00788788) and EMA (EudraCT number: 2006-005289-37).
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http://dx.doi.org/10.1007/s00421-019-04116-7DOI Listing
May 2019

On the relevance of symbolizing heart rate variability by means of a percentile-based coarse graining approach.

Physiol Meas 2018 10 24;39(10):105010. Epub 2018 Oct 24.

Faculty for Health, Integrated Curriculum for Anthroposophic Medicine and Institute of Integrative Medicine, University of Witten/Herdecke, Herdecke, Germany. Author to whom any correspondence should be addressed. Integrated Curriculum for Anthroposophic Medicine, Institute for Integrative Medicine, University of Witten/Herdecke, Gerhard-Kienle-Weg 4, 58313 Herdecke, Germany.

Objective: Symbolic transformations of the cardiac interbeat interval series yield a coarse-grained description of the dynamical information of the underlying system and complement standard measures of heart rate variability. The most commonly utilized coarse graining procedures are strongly influenced by the presence of a few extreme values wasting precious symbols to code very unlikely values.

Approach: Here, we used a transformation procedure that ensured the appearance of each symbol with equal probability using a short alphabet, A   =  {0, 1, 2, 3}, and a long alphabet, A   =  {0, 1, 2, 3, 4, 5}. The procedure was applied to the cardiac interbeat interval series of 17 healthy subjects, obtained during graded head-up tilt tests at tilt table inclinations of 0°, 15°, 30°, 45°, 60°, 75°, 90°. The dynamics of the symbolic series was assessed by the rate of symbolic pattern categories. Symbolic patterns of length three were grouped according to the variations of the symbols in each pattern: no variation (0V%), one variation (1V%), two like variations (2LV%) and two unlike variations (2UV%) of the symbols.

Main Results: As for the alphabet A , the linear regression analysis on tilt angle showed that 0V% increased with increasing tilt angle whereas 1V%, 2LV% and 2UV% decreased. As for the alphabet A , the categories 0V%, and 1V% increased with increasing tilt angle whereas 2LV% and 2UV% decreased.

Significance: The symbolic transformation ensuring a uniform distribution of the symbols is capable of reflecting changes in the cardiac autonomic nervous system during graded head-up tilt. This approach is more robust against outliers and data with skewed distributions compared to previously used symbolizations.
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http://dx.doi.org/10.1088/1361-6579/aae302DOI Listing
October 2018

Sleep Instabilities Assessed by Cardiopulmonary Coupling Analysis Increase During Childhood and Adolescence.

Front Physiol 2018 8;9:468. Epub 2018 May 8.

Integrated Curriculum for Anthroposophic Medicine, Institute of Integrative Medicine, University of Witten/Herdecke, Witten, Germany.

The electrocardiogram-based cardiopulmonary coupling (CPC) technique may be used to track sleep instabilities. With progressing age, maturational changes during childhood and adolescence affect sleep. The objective was to assess developmental changes in sleep instabilities in a natural setting. ECGs during nighttime sleep on regular school days were recorded from 363 subjects aged 4 to 22 years (204 females). The estimated total sleep time (ETST) decreased from 598 to 445 min during childhood and adolescence. Stable sleep linearly decreased with progressing age (high frequency coupling (HFC): 70-48% ETST). Unstable sleep [low frequency coupling (LFC): 9-19% ETST], sleep fragmentation or disordered breathing (elevated LFC: 4-12% ETST), and wake/REM states [very low frequency coupling (VLFC): 20-32% ETST] linearly increased with age. Hence, with progressing age the sleep of children and adolescents shortens, becomes more unstable and is more often affected by fragmentation or sleep disordered breathing, especially in the age group >13 years. It remains to be clarified whether some of the changes are caused by a social jetlag, i.e., the misalignment of body clock and social time especially in adolescents.
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http://dx.doi.org/10.3389/fphys.2018.00468DOI Listing
http://www.ncbi.nlm.nih.gov/pmc/articles/PMC5951979PMC
May 2018

Stress-associated changes in salivary microRNAs can be detected in response to the Trier Social Stress Test: An exploratory study.

Sci Rep 2018 05 8;8(1):7112. Epub 2018 May 8.

Chair for Biochemistry and Molecular Medicine, Division of Functional Genomics, Witten/Herdecke University, Witten, Germany.

Stress is an important co-factor for the genesis and maintenance of many diseases and is known to have an effect on gene expression via epigenetic regulation. MicroRNAs (miRNAs) appear to function as one of the key factors of this regulation. This is the first study to investigate the response of 11 stress-associated miRNAs in human saliva - as a non-invasive source - in an experimental condition of acute psychological stress, and also their correlation with established psychological (subjective stress perception), physiological (heart rate and heart rate variability) and biochemical stress parameters (salivary cortisol and alpha-amylase). 24 healthy participants between 20 and 35 years of age were investigated, using the Trier Social Stress Test (TSST) to induce acute psychological stress. Stress-associated changes were significant for miR-20b, -21 and 26b, and changes in miR-16 and -134 were close to significance, recommending further research on these miRNAs in the context of stress reactions. Significant correlations with alpha-amylase suggest their integration in sympathetic stress regulation processes. Additionally, our results demonstrate the TSST as a reliable tool for studying salivary miRNAs as non-invasive indicators of epigenetic processes in acute psychological stress reactions.
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http://dx.doi.org/10.1038/s41598-018-25554-xDOI Listing
http://www.ncbi.nlm.nih.gov/pmc/articles/PMC5940676PMC
May 2018

Monitoring fetal maturation-objectives, techniques and indices of autonomic function.

Physiol Meas 2017 May 10;38(5):R61-R88. Epub 2017 Feb 10.

Hans Berger Department of Neurology, Biomagnetic Center, Jena University Hospital, Jena 07747, Germany.

Monitoring the fetal behavior does not only have implications for acute care but also for identifying developmental disturbances that burden the entire later life. The concept, of 'fetal programming', also known as 'developmental origins of adult disease hypothesis', e.g. applies for cardiovascular, metabolic, hyperkinetic, cognitive disorders. Since the autonomic nervous system is involved in all of those systems, cardiac autonomic control may provide relevant functional diagnostic and prognostic information. The fetal heart rate patterns (HRP) are one of the few functional signals in the prenatal period that relate to autonomic control and, therefore, is predestinated for its evaluation. The development of sensitive markers of fetal maturation and its disturbances requires the consideration of physiological fundamentals, recording technology and HRP parameters of autonomic control. Based on the ESGCO2016 special session on monitoring the fetal maturation we herein report the most recent results on: (i) functional fetal autonomic brain age score (fABAS), Recurrence Quantitative Analysis and Binary Symbolic Dynamics of complex HRP resolve specific maturation periods, (ii) magnetocardiography (MCG) based fABAS was validated for cardiotocography (CTG), (iii) 30 min recordings are sufficient for obtaining episodes of high variability, important for intrauterine growth restriction (IUGR) detection in handheld Doppler, (iv) novel parameters from PRSA to identify Intra IUGR fetuses, (v) evaluation of fetal electrocardiographic (ECG) recordings, (vi) correlation between maternal and fetal HRV is disturbed in pre-eclampsia. The reported novel developments significantly extend the possibilities for the established CTG methodology. Novel HRP indices improve the accuracy of assessment due to their more appropriate consideration of complex autonomic processes across the recording technologies (CTG, handheld Doppler, MCG, ECG). The ultimate objective is their dissemination into routine practice and studies of fetal developmental disturbances with implications for programming of adult diseases.
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http://dx.doi.org/10.1088/1361-6579/aa5fcaDOI Listing
http://www.ncbi.nlm.nih.gov/pmc/articles/PMC5628752PMC
May 2017

Colchicum autumnale in Patients with Goitre with Euthyroidism or Mild Hyperthyroidism: Indications for a Therapeutic Regulative Effect-Results of an Observational Study.

Evid Based Complement Alternat Med 2016 3;2016:2541912. Epub 2016 Feb 3.

Research Institute Havelhöhe, Kladower Damm 221, 14089 Berlin, Germany; Department of Internal Medicine, Havelhöhe Hospital, Kladower Damm 221, 14089 Berlin, Germany.

Introduction. Goitre with euthyroid function or with subclinical or mild hyperthyroidism due to thyroid autonomy is common. In anthroposophic medicine various thyroid disorders are treated with Colchicum autumnale (CAU). We examined the effects of CAU in patients with goitre of both functional states. Patients and methods. In an observational study, 24 patients with goitre having suppressed thyroid stimulating hormone (TSH) levels with normal or slightly elevated free thyroxine (fT4) and free triiodothyronine (fT3) (group 1, n = 12) or normal TSH, fT3, and fT4 (group 2, n = 12) were included. After 3 months and after 6 to 12 months of CAU treatment, we investigated clinical pathology using the Hyperthyroid Symptom Scale (HSS), hormone status (TSH, fT4, and fT3), and thyroidal volume (tV). Results. After treatment with CAU, in group 1 the median HSS decreased from 4.5 (2.3-11.8) to 2 (1.3-3) (p < 0.01) and fT3 decreased from 3.85 (3.5-4.78) to 3.45 (3.3-3.78) pg/mL (p < 0.05). In group 2 tV (13.9% (18.5%-6.1%)) and TSH (p < 0.01) were reduced. Linear regression for TSH and fT3 in both groups indicated a regulative therapeutic effect of CAU. Conclusions. CAU positively changed the clinical pathology of subclinical hyperthyroidism and thyroidal volume in patients with euthyroid goitre by normalization of the regulation of thyroidal hormones.
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http://dx.doi.org/10.1155/2016/2541912DOI Listing
http://www.ncbi.nlm.nih.gov/pmc/articles/PMC4756131PMC
March 2016

A percentile-based coarse graining approach is helpful in symbolizing heart rate variability during graded head-up tilt.

Annu Int Conf IEEE Eng Med Biol Soc 2015 ;2015:286-9

Coarse graining of physiological time series such as the cardiac interbeat interval series by means of a symbolic transformation retains information about dynamical properties of the underlying system and complements standard measures of heart rate variability. The transformations of the original time series to the coarse grained symbolic series usually lead to a non-uniform occurrence of the different symbols, i.e. some symbols appear more often than others influencing the results of the subsequent symbolic series analysis. Here, we defined a transformation procedure to assure that each symbol appears with equal probability using a short alphabet {0,1,2,3} and a long alphabet {0,1,2,3,4,5}. The procedure was applied to the cardiac interbeat interval series RRi of 17 healthy subjects obtained during graded head-up tilt testing. The symbolic dynamics is analyzed by means of the occurrence of short sequences (`words') of length 3. The occurrence of words is grouped according to words without variations of the symbols (0V%), one variation (1V%), two like variations (2LV%) and two unlike variations (2UV%). Linear regression analysis with respect to tilt angle showed that for the short alphabet 0V% increased with increasing tilt angle whereas 1V%, 2LV% and 2UV% decreased. For the long alphabet 0V%, and 1V% increased with increasing tilt angle whereas 2LV% and 2UV% decreased. These results were slightly better compared to the results from non-uniform symbolic transformations reflecting the deviation from the mean. In conclusion, the symbolic transformation assuring the appearance of symbols with equal probability is capable of reflecting changes of the cardiac autonomic nervous system during graded head-up tilt. Furthermore, the transformation is independent of the time series' distribution.
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http://dx.doi.org/10.1109/EMBC.2015.7318356DOI Listing
October 2016

Eurythmy therapy increases specific oscillations of heart rate variability.

BMC Complement Altern Med 2015 Jun 6;15:167. Epub 2015 Jun 6.

Integrated Curriculum for Anthroposophic Medicine, University of Witten/Herdecke, Gerhard-Kienle-Weg 4, 58313, Herdecke, Germany.

Background: Mind-body therapies are beneficial for several diseases (e.g. chronic pain, arterial hypertension, mood disorders). Eurythmy therapy (EYT) is a mind-body therapy from Anthroposophic Medicine. In each EYT exercise a short sequence of body movements and simultaneous guided imagery is repeated several times. In this study, the simultaneous effects of two different EYT exercises on cardiac autonomic regulation as assessed by spectral analysis of heart rate variability (HRV) were investigated.

Methods: Twenty healthy subjects (age: 29.1 ± 9.3 years, 13 female) performed two different EYT exercises (EYT-A and EYT-B) for 8 min. Each EYT exercise was compared against two matched control exercises: control exercise 1 (CE1-A and CE1-B) consisted of a repetition of the body movements of the EYT exercise but without guided imagery, control exercise 2 consisted of walking on the spot (CE2-A and CE2-B). Spectral power of HRV during each exercise was quantified on the basis of Holter ECG recordings.

Results: During EYT-A the frequency of the peak oscillation in the very low frequency (VLF) band matched the repetition rate of the sequence of body movements (0.02 Hz). Low frequency (LF) oscillations were augmented when compared to the control exercises (EYT-A: 7.31 ± 0.84, CE1-A: 6.98 ± 0.90, CE2-A: 6.52 ± 0.87 ln ms(2), p < 0.05). They showed a peak frequency at 0.08 Hz indicating that the body postures had an impact in HRV. Performing EYT-B increased VLF oscillations when compared to the control exercises (EYT-B: 9.32 ± 0.82, CE1-B: 6.31 ± 0.75, CE2-B: 6.04 ± 0.80 ln ms(2), p < 0.05). The frequency of the peak oscillation again matched the repetition rate of the sequence of body movements (0.028 Hz).

Conclusions: The repetition of the sequence of body movements of both EYT exercises clearly affected cardiac autonomic regulation in a rhythmic manner according to the stimulus of the specific body movements of each EYT exercise. These results offer a physiological basis to develop a rationale for specific clinical indications of these EYT exercises such as stress reduction or prevention of hypertension.

Trial Registration:

Clinical Trials Registration Number: DRKS00006760 (registered on 10/10/2014, i.e. retrospective registration); view details at http://www.drks.de/DRKS00006760.
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http://dx.doi.org/10.1186/s12906-015-0684-6DOI Listing
http://www.ncbi.nlm.nih.gov/pmc/articles/PMC4457978PMC
June 2015

Complexity analyses show two distinct types of nonlinear dynamics in short heart period variability recordings.

Front Physiol 2015 10;6:71. Epub 2015 Mar 10.

Department of Cardiology, S.L. Mandic Hospital Merate, Italy.

Two diverse complexity metrics quantifying time irreversibility and local prediction, in connection with a surrogate data approach, were utilized to detect nonlinear dynamics in short heart period (HP) variability series recorded in fetuses, as a function of the gestational period, and in healthy humans, as a function of the magnitude of the orthostatic challenge. The metrics indicated the presence of two distinct types of nonlinear HP dynamics characterized by diverse ranges of time scales. These findings stress the need to render more specific the analysis of nonlinear components of HP dynamics by accounting for different temporal scales.
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http://dx.doi.org/10.3389/fphys.2015.00071DOI Listing
http://www.ncbi.nlm.nih.gov/pmc/articles/PMC4354335PMC
March 2015

Symbolic transformations of heart rate variability preserve information about cardiac autonomic control.

Physiol Meas 2015 Apr 23;36(4):643-57. Epub 2015 Mar 23.

Integrated Curriculum for Anthroposophic Medicine, University of Witten/Herdecke, Germany. Institute for Integrative Medicine, University of Witten/Herdecke, Germany.

Traditional measures of heart rate variability (HRV) in the time or frequency domain (e.g. standard deviation of normal-to-normal intervals, SDNN, or the high frequency component of spectral analysis, HF) may be used to track vagal and sympathetic modulation directed to the sinus node. In this study, we assess the ability of symbolic analysis to monitor cardiac autonomic regulation during two autonomic challenges (phenylephrine and nitroprusside; low and high dose of atropine). To assess the effect of the coarse graining procedure, symbolic series obtained from four different transformations over the original series and the series of successive differences of the original values. The analysis focused on patterns of length 3 and exploited a redundancy reduction strategy to group patterns into a small number of families. It turns out that each symbolic series created by the four transformations still contained sufficient dynamical features to quantify differences of cardiovascular changes during the pharmacological challenges. The symbolic series created by transformations of the beat-to-beat interview, i.e RR interval series, showed that patterns without variations (0V) appear more often during a high dose of atropine compared to rest or to a low dose of atropine. Furthermore, patterns with two unlike variations (2UV) appear more often during a low dose of atropine and less often during a high dose of atropine. Differences of nitroprusside and phenylephrine could also be assessed by patterns with these variations. In conclusion, the changes of cardiovascular regulation during pharmacological challenges can be assessed by the analysis of symbolic dynamics derived from the RR interval series independently of the specific symbolic transformation.
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http://dx.doi.org/10.1088/0967-3334/36/4/643DOI Listing
April 2015

Enhancing dynamical signatures of complex systems through symbolic computation.

Philos Trans A Math Phys Eng Sci 2015 Feb;373(2034)

Department of Physics, Humboldt-Universität zu Berlin, Berlin, Germany.

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http://dx.doi.org/10.1098/rsta.2014.0099DOI Listing
http://www.ncbi.nlm.nih.gov/pmc/articles/PMC4281870PMC
February 2015

Strategies of symbolization in cardiovascular time series to test individual gestational development in the fetus.

Philos Trans A Math Phys Eng Sci 2015 Feb;373(2034)

Department of Biomagnetism, Grönemeyer Institute for Microtherapy, University of Witten/Herdecke, Witten, Germany.

The analysis of symbolic dynamics applied to physiological time series retrieves dynamical properties of the underlying regulation which are robust against the symbolic transformation. In this study, three different transformations to produce a symbolic series were applied to fetal RR interval series to test whether they reflect individual changes of fetal heart rate variability in the course of pregnancy. Each transformation was applied to 215 heartbeat datasets obtained from 11 fetuses during the second and the third trimester of pregnancy (at least 10 datasets per fetus, median 17). In the symbolic series, the occurrence of symbolic sequences of length 3 was categorized according to the amount of variations in the sequence: no variation of the symbols, one variation, two variations. Linear regression with respect to gestational age showed that the individual course during pregnancy performed best using a binary transformation reflecting whether the RR interval differences are below or above a threshold. The median goodness of fit of the individual regression lines was 0.73 and also the variability among the individual slopes was low. Other transformations to symbolic dynamics performed worse but were still able to reflect the individual progress of fetal cardiovascular regulation.
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http://dx.doi.org/10.1098/rsta.2014.0087DOI Listing
February 2015

Aerobic exercise during pregnancy and presence of fetal-maternal heart rate synchronization.

PLoS One 2014 27;9(8):e106036. Epub 2014 Aug 27.

Grönemeyer Institute of Microtherapy, University of Witten/Herdecke, Bochum, Germany.

Unlabelled: It has been shown that short-term direct interaction between maternal and fetal heart rates may take place and that this interaction is affected by the rate of maternal respiration. The aim of this study was to determine the effect of maternal aerobic exercise during pregnancy on the occurrence of fetal-maternal heart rate synchronization.

Methods: In 40 pregnant women at the 36th week of gestation, 21 of whom exercised regularly, we acquired 18 min. RR interval time series obtained simultaneously in the mothers and their fetuses from magnetocardiographic recordings. The time series of the two groups were examined with respect to their heart rate variability, the maternal respiratory rate and the presence of synchronization epochs as determined on the basis of synchrograms. Surrogate data were used to assess whether the occurrence of synchronization was due to chance.

Results: In the original data, we found synchronization occurred less often in pregnancies in which the mothers had exercised regularly. These subjects also displayed higher combined fetal-maternal heart rate variability and lower maternal respiratory rates. Analysis of the surrogate data showed shorter epochs of synchronization and a lack of the phase coordination found between maternal and fetal beat timing in the original data.

Conclusion: The results suggest that fetal-maternal heart rate coupling is present but generally weak. Maternal exercise has a damping effect on its occurrence, most likely due to an increase in beat-to-beat differences, higher vagal tone and slower breathing rates.
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http://journals.plos.org/plosone/article?id=10.1371/journal.pone.0106036PLOS
http://www.ncbi.nlm.nih.gov/pmc/articles/PMC4146588PMC
November 2015

Adaption of cardio-respiratory balance during day-rest compared to deep sleep--an indicator for quality of life?

Psychiatry Res 2014 Nov 9;219(3):638-44. Epub 2014 Jun 9.

Department of Endocrinology, Diabetology and Clinical Nutrition, Autonomic Lab, University Hospital Inselspital, University of Berne, Murtenstrasse 21, CH-3010 Bern, Switzerland. Electronic address:

Heart rate and breathing rate fluctuations represent interacting physiological oscillations. These interactions are commonly studied using respiratory sinus arrhythmia (RSA) of heart rate variability (HRV) or analyzing cardiorespiratory synchronization. Earlier work has focused on a third type of relationship, the temporal ratio of respiration rate and heart rate (HRR). Each method seems to reveal a specific aspect of cardiorespiratory interaction and may be suitable for assessing states of arousal and relaxation of the organism. We used HRR in a study with 87 healthy subjects to determine the ability to relax during 5 day-resting periods in comparison to deep sleep relaxation. The degree to which a person during waking state could relax was compared to somatic complaints, health-related quality of life, anxiety and depression. Our results show, that HRR is barely connected to balance (LF/HF) in HRV, but significantly correlates to the perception of general health and mental well-being as well as to depression. If relaxation, as expressed in HRR, during day-resting is near to deep sleep relaxation, the subjects felt healthier, indicated better mental well-being and less depressive moods.
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http://dx.doi.org/10.1016/j.psychres.2014.06.004DOI Listing
November 2014

Heart rate variability reflects the natural history of physiological development in healthy children and is not associated with quality of life.

PLoS One 2014 13;9(3):e91036. Epub 2014 Mar 13.

Integrated Curriculum for Anthroposophic Medicine, Institute of Integrative Medicine, University of Witten/Herdecke, Witten, Germany.

Background: Quality of life (QoL), being the sum expression of diverse influencing factors, is not easy to determine. A clinically relevant option would be to identify and measure quality of life on the basis of physiological parameters which correlate plausibly and statistically with psychometrically measured QoL. Analysis of heart rate variability (HRV) offers readily measurable physiological parameters which could be of use here. A correlation of HRV with both course of disease and QoL has been reported in patients with chronic illness. Various psychometric instruments have been developed for use in paediatric oncology. The aim of this study was to obtain data on HRV and QoL and their correlations, initially in healthy children.

Methods: Holter ECG and quality of life were examined in 160 children and adolescents (72 male) aged between 8 and 18 years. QoL was determined with the established questionnaire PEDQoL. Standard parameters of HRV from the frequency domain were calculated and correlated with QoL domains using Spearman (nonparametric) correlation analysis.

Results: Minor but significant associations were revealed only with regard to the PEDQoL domain "autonomy" on the one hand and heart rate and HRV (e.g. MRR, MRRn, MRRd, HRV_ULF, SDNN) parameters which evidently reflect distinct physiological functions on the other.

Conclusions: In healthy children and adolescents we have a first indication that there is a correlation between parameters of HRV and QoL. However, to a greater extent, HRV reflects associated physiological processes of the autonomic nervous system. A higher correlation is more likely to be found in chronically ill children.
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http://journals.plos.org/plosone/article?id=10.1371/journal.pone.0091036PLOS
http://www.ncbi.nlm.nih.gov/pmc/articles/PMC3953202PMC
January 2016

Impact of colored light on cardiorespiratory coordination.

Evid Based Complement Alternat Med 2013 31;2013:810876. Epub 2013 Dec 31.

Integrated Curriculum for Anthroposophic Medicine, University of Witten/Herdecke, 58313 Herdecke, Germany ; Chair for Theory of Medicine, Integrative and Anthroposophic Medicine, University of Witten/Herdecke, 58313 Herdecke, Germany ; Institute for Integrative Medicine, University of Witten/Herdecke, 58313 Herdecke, Germany.

Background. Light exposure to the eye can influence different physiological functions, for example, the suprachiasmatic nucleus (SCN). By affecting the autonomic nervous system, the SCN may influence the heart rate variability (HRV). Standardized colored light exposure alters HRV but the results are inconsistent. In this study we investigated the effects of nonstandardized red light (approx. 640 nm) and blue (approx. 480 nm) light (approx. 50 lx) on cardiorespiratory coordination and HRV. Methods. 17 healthy subjects (7 males, age: 26.5 ± 6.2 years) were exposed to the following sequence (10 minutes each): daylight-red light-daylight-blue light-daylight. Red and blue lights were created by daylight passing through colored glass panes. Spectral measures of HRV (LF: low frequency, HF: high frequency oscillations, and sympathovagal balance LF/HF) and measures of cardiorespiratory coordination (HRR: heart respiration ratio, PCR: phase coordination ratio) were analyzed. Results. The LF component increased and the HF component decreased after red light. Consequently, LF/HF increased after red light. Furthermore, during red light HRR and PCR confined to 4 : 1, that is, 4 heartbeats during one respiratory cycle. Conclusion. Nonstandardized red and blue lights are able to alter the autonomic control reflected by HRV as well as cardiorespiratory coordination.
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http://dx.doi.org/10.1155/2013/810876DOI Listing
http://www.ncbi.nlm.nih.gov/pmc/articles/PMC3893775PMC
February 2014

Different approaches of symbolic dynamics to quantify heart rate complexity.

Annu Int Conf IEEE Eng Med Biol Soc 2013 ;2013:5041-4

The analysis of symbolic dynamics applied to physiological time series is able to retrieve information about dynamical properties of the underlying system that cannot be gained with standard methods like e.g. spectral analysis. Different approaches for the transformation of the original time series to the symbolic time series have been proposed. Yet the differences between the approaches are unknown. In this study three different transformation methods are investigated: (1) symbolization according to the deviation from the average time series, (2) symbolization according to several equidistant levels between the minimum and maximum of the time series, (3) binary symbolization of the first derivative of the time series. Each method was applied to the cardiac interbeat interval series RR(i) and its difference ΔRR(I) of 17 healthy subjects obtained during head-up tilt testing. The symbolic dynamics of each method is analyzed by means of the occurrence of short sequences ('words') of length 3. The occurrence of words is grouped according to words without variations of the symbols (0V%), words with one variation (1V%), two like variations (2LV%) and two unlike variations (2UV%). Linear regression analysis showed that for method 1 0V%, 1V%, 2LV% and 2UV% changed with increasing tilt angle. For method 2 0V%, 2LV% and 2UV% changed with increasing tilt angle and method 3 showed changes for 0V% and 1V%. In conclusion, all methods are capable of reflecting changes of the cardiac autonomic nervous system during head-up tilt. All methods show that even the analysis of very short symbolic sequences is capable of tracking changes of the cardiac autonomic regulation during head-up tilt testing.
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http://dx.doi.org/10.1109/EMBC.2013.6610681DOI Listing
August 2015

Symbolic patterns of heart rate dynamics reflect cardiac autonomic changes during childhood and adolescence.

Auton Neurosci 2013 Nov 28;178(1-2):37-43. Epub 2013 Feb 28.

Integrated Curriculum for Anthroposophic Medicine, University of Witten/Herdecke, Germany; Chair for Theory of Medicine, Integrative and Anthroposophic Medicine, University of Witten/Herdecke, Germany. Electronic address:

Symbolic dynamics derived from heart rate variability (HRV) is able to reflect changes of cardiac autonomic modulations in healthy subjects. It has been shown that linear measures of HRV in children and adolescents monotonically increase or decrease (depending on the measure) with age whereas non-linear measures show a local extreme value at the age of 7 to 9 years. In this study, the age-related variations of dynamical features of the R-R interval series during childhood and adolescence were addressed. In particular, the binary symbolic dynamics reflecting the sequence of acceleration (='1') and deceleration (='0') of heart rate was examined. The R-R interval series of 409 healthy children and adolescents (age range: 1 to 22 years, 220 females) was analyzed with respect to the regularity of binary patterns of length 8 using Approximate Entropy (ApEn). Binary patterns were grouped to patterns sets according to the level of their regularity as assessed by ApEn. Pattern sets containing regular binary patterns occurred more often with increasing age whereas irregular binary patterns occurred less often. Specific regular binary patterns show an unexpected behavior. They occurred fewest in the group 7 to 9 years. Furthermore, regular binary patterns occur more often during daytime whereas irregular binary patterns occur more often during nighttime. In conclusion, the analysis of binary symbolic dynamics is able to reflect age-related changes during childhood and adolescence in spite of the considerable reduction of information involved. As many binary patterns are linked to sympathetic or parasympathetic modulations of the autonomic nervous system e.g. spectral analysis of HRV may be complemented by this kind of analysis.
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http://dx.doi.org/10.1016/j.autneu.2013.02.003DOI Listing
November 2013

Heart rate variability in the individual fetus.

Auton Neurosci 2013 Nov 29;178(1-2):24-8. Epub 2013 Jan 29.

Grönemeyer Institute of Microtherapy, University of Witten/Herdecke, Bochum, Germany. Electronic address:

The change in fetal heart rate and its variability (HRV) during the course of gestation has been documented by numerous studies. The overall drop in heart rate and increase in fetal HRV is associated with fetal growth in general and with the increase in neural integration in particular. The increased complexity of the demands on the cardiovascular system leads to more variation in the temporal course of the heart rate. Most studies that document and interpret these changes are based on data acquired in groups of fetuses. The aim of this work was to investigate HRV within single fetuses. We acquired 213 5min fetal magnetocardiograms in 11 fetuses during the second and third trimesters (at least 10 data sets per fetus, median 17). From the magnetocardiograms we determined the fetal RR interval time series and calculated the standard deviation (SDNN), root mean square of successive differences (RMSSD), approximate entropy (ApEn) and temporal asymmetry (Irrev). For each subject and HRV measure, we performed regression analysis with respect to gestational age, alone and in combination with RR interval. The coefficient of determination R(2) was used to estimate goodness-of-fit. The coefficient of quartile dispersion (CQD) was used to compare the regression parameters for each HRV measure. Overall, the HRV measures increased with age and RR interval. The consistency of the HRV measures within the individual fetuses was greater than in the data pooled over all fetuses. The individual R(2) for the model including age and RR interval was best for ApEn (.79, .59-.94; median, 90% CI), followed by RMSSD (.71, .25-.88), SDNN (.55, .18-.90) and Irrev (.16, .01-.39). These values, except for Irrev, were higher than those calculated over all 213 data sets (R(2)=.65, .63, .35, .28, respectively). The slopes of the regressions of each individual's data were most consistent over all subjects for ApEn, followed by RMSSD and SDNN and Irrev. Interindividually, the time domain measures showed discrepancies and the within-fetus courses were more consistent than the course over all fetuses. On the other hand, the course of ApEn during gestation was not only very consistent within each fetus but also very similar between most of subjects. Complexity measures such as ApEn may thus more consistently reflect prenatal developmental factors influencing cardiovascular regulation.
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http://dx.doi.org/10.1016/j.autneu.2013.01.005DOI Listing
November 2013

Integrative medical education: educational strategies and preliminary evaluation of the Integrated Curriculum for Anthroposophic Medicine (ICURAM).

Patient Educ Couns 2012 Dec 26;89(3):447-54. Epub 2012 Jun 26.

Integrated Curriculum for Anthroposophic Medicine, Theory of Medicine, Integrative and Anthroposophic Medicine, Faculty of Health, Witten/Herdecke University, Germany.

Objectives: the development and preliminary evaluation of a new medical program aimed at educating students in patient-centered integrative care and developing appropriate educational strategies.

Methods: The Integrated Curriculum for Anthroposophic Medicine (ICURAM) was developed with modules on anthroposophic medicine integrated into the full 6 years of the regular medical curriculum. The educational strategy is the ESPRI(2)T approach, combining Exploratory learning, Supported participation, Patient-based learning, Reflective practice, Integrated learning, an Integrative approach and Team-based learning. The student participation, assessed based on the number of credit points earned per year (ctp/year) through the ICURAM (1 ctp=30 h workload), served as a preliminary indicator of student interest.

Results: Of the 412 55%medical students participated in the program: 16% full participation (≥ 4 ctp/year), 18% partial participation (1-3.99 ctp/year) and 22% occasional participation (0.25-0.99 ctp/year). The amount of additional workload taken on by students was between 7.8h/year for occasional participants, 33 h/year for partial participants and 84 h/year for full participants.

Conclusion: More than half of medical students were willing to invest a significant amount of additional time in the optional program.

Practice Implications: An integrative medical curriculum with a student-centered educational strategy seems to be of interest to most medical students.
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http://dx.doi.org/10.1016/j.pec.2012.04.006DOI Listing
December 2012

Multiscale analysis of acceleration and deceleration of the instantaneous heart rate using symbolic dynamics.

Annu Int Conf IEEE Eng Med Biol Soc 2011 ;2011:1965-8

Integrated Curriculum for AnthroposophicMedicine, University of Witten/Herdecke, Germany. [email protected] rhythmen.de

The multiscale analysis of physiologic time series such as the RR interval time series has revealed that the entropy differs according to the scale. Furthermore, healthy subjects show different characteristics on the different time scales compared to patients. Instead of calculating entropies of the time series, the sequence of acceleration and deceleration of the instantaneous heart rate may also be investigated by means of binary symbolic dynamics. This kind of analysis revealed that the healthy heartbeat series also contains numerous regular binary sequences indicating runs of acceleration or deceleration. Here, we investigate whether this approach yields new information when applied to multiple time scales. We investigate the occurrence of binary patterns of length 8 on different time scales of heart rate series from healthy subjects and patients with congestive heart failure (CHF). Healthy subjects and CHF patients show different occurrences of binary patterns. These occurrences change especially on scales 1 to 5. Healthy subjects show more pronounced changes than CHF patients. At larger scales only gradual changes were observed. In conclusion, the application of binary symbolic dynamics on different scales yields new information, in particular on small scales.
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http://dx.doi.org/10.1109/IEMBS.2011.6090554DOI Listing
June 2012

Unexpected course of nonlinear cardiac interbeat interval dynamics during childhood and adolescence.

PLoS One 2011 20;6(5):e19400. Epub 2011 May 20.

Integrated Curriculum for Anthroposophic Medicine, University of Witten/Herdecke, Witten, Germany.

The fluctuations of the cardiac interbeat series contain rich information because they reflect variations of other functions on different time scales (e.g., respiration or blood pressure control). Nonlinear measures such as complexity and fractal scaling properties derived from 24 h heart rate dynamics of healthy subjects vary from childhood to old age. In this study, the age-related variations during childhood and adolescence were addressed. In particular, the cardiac interbeat interval series was quantified with respect to complexity and fractal scaling properties. The R-R interval series of 409 healthy children and adolescents (age range: 1 to 22 years, 220 females) was analyzed with respect to complexity (Approximate Entropy, ApEn) and fractal scaling properties on three time scales: long-term (slope β of the power spectrum, log power vs. log frequency, in the frequency range 10(-4) to 10(-2) Hz) intermediate-term (DFA, detrended fluctuation analysis, α(2)) and short-term (DFA α(1)). Unexpectedly, during age 7 to 13 years β and ApEn were higher compared to the age <7 years and age >13 years (β: -1.06 vs. -1.21; ApEn: 0.88 vs. 0.74). Hence, the heart rate dynamics were closer to a 1/f power law and most complex between 7 and 13 years. However, DFA α(1) and α(2) increased with progressing age similar to measures reflecting linear properties. In conclusion, the course of long-term fractal scaling properties and complexity of heart rate dynamics during childhood and adolescence indicates that these measures reflect complex changes possibly linked to hormonal changes during pre-puberty and puberty.
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http://journals.plos.org/plosone/article?id=10.1371/journal.pone.0019400PLOS
http://www.ncbi.nlm.nih.gov/pmc/articles/PMC3098842PMC
November 2011

Automatic identification of fetal breathing movements in fetal RR interval time series.

Comput Biol Med 2012 Mar 31;42(3):342-6. Epub 2011 May 31.

Department of Biomagnetism, Grönemeyer Institute for Microtherapy, University of Witten/Herdecke, Germany.

Fetal breathing movements are associated with respiratory sinus arrhythmia (RSA). We present an algorithm which processes RR interval time series in the time and frequency domain, identifying spectral peaks with characteristics consistent with fetal RSA. Tested on 50 data sets from the second and third trimester, the algorithm had a sensitivity of 96.1%, false positive rate 35.7%, false negative rate 3.9%. The characteristics of automatically and visually identified episodes were very similar and corresponded the expected changes over gestation. The method is suited for easy and reliable identification of fetal breathing movements.
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http://dx.doi.org/10.1016/j.compbiomed.2011.05.012DOI Listing
March 2012

Thermometer of warmth in the patient-provider relationship (WARMOMETER)--theory-based development of a patient self-report measure and initial validation using cognitive interview methodology.

Patient Educ Couns 2011 Mar;82(3):361-9

Faculty of Medicine, Department of Health, Private University of Witten/Herdecke, Germany.

Objective: The aims of this study are twofold: (1) the theory-based development of a patient self-report measure of physician warmth and (2) the application of cognitive interview methodology to understand patients' perception and interpretation of this new measure.

Methods: A draft measure was developed based on an in-depth literature review of the concept of human warmth by a multidisciplinary expert group. Sixteen cognitive probing interviews were conducted to examine how patients perceive and interpret this new measure and to identify potential problems. A content analysis of the interviews was used to evaluate findings.

Results: Findings indicate that the WARMOMETER is a short patient self-report assessment of physician warmth, which seems easy and intuitive to understand. In addition, most respondents were found to share a common concept of physician warmth.

Conclusions: Verification of our study hypotheses and confirmation of the theoretical assumptions of human warmth give basic indications that the WARMOMETER seems to be a valid and sensitive patient self-report instrument for assessing the socio-emotional quality of physicians.

Practice Implications: These first promising results of our cognitive interviews suggest that the WARMOMETER may also be used and further validated in future health communication studies, also with other healthcare professionals.
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http://dx.doi.org/10.1016/j.pec.2011.01.003DOI Listing
March 2011

Effects of complementary eurythmy therapy on heart rate variability.

Complement Ther Med 2009 Jun 20;17(3):161-7. Epub 2008 Nov 20.

Department of Pediatric Oncology and Hematology, Charité-Universitätsmedizin Berlin, Germany.

Background: The importance of mind-body oriented therapies in oncology has increased in recent years. Eurythmy therapy (EYT, Greek: eurythmy=harmonious rhythm) is a mind-body oriented therapy used in Anthroposophic Medicine. EYT can lead to long-term alleviation of chronic disease symptoms and improve patient quality of life. Yet, little is known about underlying physiological mechanisms.

Objective: This study aims to compare the effects of EYT and conventional ergometer training (CET) on heart rate variability (HRV).

Design: In a cross-over design, 20 healthy subjects performed two different EYT exercises and two sessions of CET. ECGs were recorded throughout these procedures. HRV was quantified by the extent of very low (VLF), low (LF) and high frequency (HF) oscillations of heart rate.

Results: VLF and LF oscillations increased during one EYT exercises when compared to rest after EYT ('B exercise', VLF: 7.65 vs. 6.57 log ms(2); LF: 8.06 vs. 6.15 log ms(2)) whereas during the other EYT exercise only LF increased ('L exercise', LF: 7.19 vs. 6.25 log ms(2)). HF was not affected. During CET VLF, LF and HF decreased compared to rest (VLF: 5.4 log ms(2), LF: 4.5 log ms(2), HF: 3.2 log ms(2)). During rest after both EYT exercises LF/HF decreased when compared to rest after CET (0.4 and 0.5 vs. 1.4).

Conclusion: At comparable workloads, EYT stimulated HRV whereas CET attenuated HRV. The decrease of LF/HF during rest after EYT indicates an improved relaxation. These results suggest that patients may benefit from EYT in terms of HRV improvement.
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http://dx.doi.org/10.1016/j.ctim.2008.09.005DOI Listing
June 2009

The oil-dispersion bath in anthroposophic medicine--an integrative review.

BMC Complement Altern Med 2008 Dec 4;8:61. Epub 2008 Dec 4.

Medical Theory and Complementary Medicine, University of Witten/Herdecke, Gerhard-Kienle-Weg 4, 58239 Herdecke, Germany.

Background: Anthroposophic medicine offers a variety of treatments, among others the oil-dispersion bath, developed in the 1930s by Werner Junge. Based on the phenomenon that oil and water do not mix and on recommendations of Rudolf Steiner, Junge developed a vortex mechanism which churns water and essential oils into a fine mist. The oil-covered droplets empty into a tub, where the patient immerses for 15-30 minutes. We review the current literature on oil-dispersion baths.

Methods: The following databases were searched: Medline, Pubmed, Embase, AMED and CAMbase. The search terms were 'oil-dispersion bath' and 'oil bath', and their translations in German and French. An Internet search was also performed using Google Scholar, adding the search terms 'study' and 'case report' to the search terms above. Finally, we asked several experts for gray literature not listed in the above-mentioned databases. We included only articles which met the criterion of a clinical study or case report, and excluded theoretical contributions.

Results: Among several articles found in books, journals and other publications, we identified 1 prospective clinical study, 3 experimental studies (enrolling healthy individuals), 5 case reports, and 3 field-reports. In almost all cases, the studies described beneficial effects - although the methodological quality of most studies was weak. Main indications were internal/metabolic diseases and psychiatric/neurological disorders.

Conclusion: Beyond the obvious beneficial effects of warm bathes on the subjective well-being, it remains to be clarified what the unique contribution of the distinct essential oils dispersed in the water can be. There is a lack of clinical studies exploring the efficacy of oil-dispersion baths. Such studies are recommended for the future.
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http://dx.doi.org/10.1186/1472-6882-8-61DOI Listing
http://www.ncbi.nlm.nih.gov/pmc/articles/PMC2612644PMC
December 2008

Comparison of respiratory rates derived from heart rate variability, ECG amplitude, and nasal/oral airflow.

Ann Biomed Eng 2008 Dec 15;36(12):2085-94. Epub 2008 Oct 15.

Chair of Medical Theory and Complementary Medicine, University of Witten/Herdecke, Gerhard-Kienle-Weg 4, D-58313 Herdecke, Germany.

It would often be desirable to obtain the respiratory rate during everyday conditions without obtaining an additional respiratory trace. This study investigates the agreement between respiratory rate assessed from the electrocardiogram (ECG) and the reference respiratory rate derived from a nasal/oral airflow (AF). Nasal/oral airflow and a Holter ECG were recorded in 52 healthy subjects (26 males, age range: 25.4-85.4 years) during everyday conditions for at least 10 h, including night-time sleep. The respiratory rate was assessed for each 5-min epoch (1) using respiratory sinus arrhythmia (RSA), (2) utilizing the respiration induced variations of the R-wave amplitude (ECG derived respiration (EDR)). The agreement with respect to AF was quantified using the average/std and the concordance correlation coefficient rho(c). For RSA and EDR the difference with respect to AF was 0.2 cpm (std: 0.6 cpm) during sleep and -0.2 cpm (std: 1.0 cpm) during wake time. During sleep the RSA-approach performed best for subjects < or =50 years (rho(c) = 0.79) and worst for subjects >50 years (rho(c) = 0.41). The correlation of the EDR-approach was rho(c) = 0.73 for both groups. In conclusion, the respiratory rate may be assessed with reasonable agreement by both methods in younger subjects, but EDR should be preferred in the elderly.
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http://dx.doi.org/10.1007/s10439-008-9580-2DOI Listing
December 2008
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