Biomedical subjects

Martin Frey

Publications and source records attributed to Martin Frey.

14 recordsLinked to original sources

PubMed2006

Interval versus continuous high-intensity exercise in chronic obstructive pulmonary disease: a randomized trial.

BACKGROUND: Guidelines recommend high-intensity continuous exercise to reduce peripheral muscle dysfunction in patients with chronic obstructive pulmonary disease but acknowledge that interval exercise might be an equally effective alternative that is better tolerated by patients. OBJECTIVE: To assess whether interval exercise is no less effective than high-intensity continuous exercise and whether it is tolerated better by patients with severe chronic obstructive pulmonary disease. DESIGN: Randomized, noninferiority trial. SETTING: Publicly funded rehabilitation hospital in Switzerland. PATIENTS: 98 patients with severe chronic obstructive pulmonary disease, with or without recent exacerbations. INTERVENTION: 12 to 15 supervised interval or high-intensity continuous exercise sessions (over 3 weeks) followed by exercise at home. MEASUREMENTS: Health-related quality of life determined by using the Chronic Respiratory Questionnaire (CRQ) (scores from 1 [most severe impairment] to 7 [no impairment]) after 5 weeks and number of unintended breaks during supervised exercise. RESULTS: Both groups experienced large improvements in health-related quality of life (increase of CRQ total scores of 1.00 [SD, 0.98] for the interval exercise group and 1.02 [SD, 1.05] for the continuous exercise group). Adjusted between-group differences between the interval exercise group and the continuous exercise group (-0.05 [95% CI, -0.42 to -0.32] for CRQ and 1.1 meters [CI, -25.4 to 27.6 meters] for 6-minute walking distance) were within the a priori defined boundaries of noninferiority (0.5 for CRQ and 45 meters for 6-minute walking distance). Twenty-one (47.9%) patients using interval exercise and 11 (24.0%) patients using continuous exercise were able to adhere to the protocol (difference, 23.9 percentage points [CI, 5.0 to 42.8 percentage points]; P = 0.014). The median number of unintended breaks lasting 1 minute or more was 2 (interquartile range, 0 to 16) for patients in the interval exercise group and 11 (interquartile range, 2 to 26) for patients in the continuous exercise group (P = 0.023). LIMITATIONS: The study focused on initiation of exercise and not on outpatient or home-based maintenance of exercise. CONCLUSIONS: Clinicians and patients can choose either of the 2 exercise plans to initiate physical exercise. International Standard Randomized Controlled Trial number: SRCTN11611768.

Aged↗

PubMed2006

Respiratory effects of environmental tobacco exposure are enhanced by bronchial hyperreactivity.

RATIONALE: Exposure to environmental tobacco smoke (ETS) is associated with increased reports of respiratory symptoms and reduced lung function, but the long-term effects of ETS are unclear, notably in healthy individuals with bronchial hyperresponsiveness (BHR). OBJECTIVE: To assess the longitudinal effects of ETS exposure on the development of respiratory symptoms and spirometry in subjects with BHR. METHODS: The study population included 1,661 never-smokers from the SAPALDIA (Swiss Study on Air Pollution and Lung Diseases in Adults) cohort, assessed in 1991 (baseline) and 11 yr later, who were symptom-free at baseline. Incident reports of respiratory symptoms and results of spirometry were assessed at the follow-up survey. MAIN RESULTS: Exposure to ETS reported in the two surveys was strongly associated with the development of cough (odds ratio, 2.1; 95% confidence interval, 1.2-3.7; p = 0.01). In subjects with BHR exposed to ETS at both surveys, a trend for strong associations were observed for wheeze, cough, dyspnea, and chronic bronchitis; however, the association reached statistical significance only for the symptom of dyspnea (p < 0.01). Lower FEV1/FVC (mean +/- SD, 72.9 +/- 7.7 vs. 76.8 +/- 6.1%; p < 0.01) and FEF(25-75) (forced expiratory flow, midexpiratory phase)/FVC (mean +/- SD, 56.1 +/- 22.5 vs. 68.1 +/- 21.6%; p < 0.01) were observed in subjects with BHR exposed to ETS compared with nonexposed subjects without BHR. Lower values were found in subjects continuing exposure by the follow-up survey. CONCLUSION: Exposure to ETS was strongly associated with the development of respiratory symptoms in previously asymptomatic subjects with BHR within 11 yr. Furthermore, subjects with underlying BHR had reduced lung function at follow-up, thus suggesting a higher risk for the development of chronic respiratory disease in this subset of the population.

Adult↗

PubMed2006

A novel mechatronic body weight support system.

A novel mechatronic body weight support (BWS) system has been developed to provide precise body weight unloading for patients with neurological or other impairments during treadmill training. The system is composed of a passive elastic spring element to take over the main unloading force and an active closed-loop controlled electric drive to generate the exact desired force. Both force generating units, the passive spring and the active electric drive, act on the patient via a polyester rope connected to a harness worn by the patient. The length of the rope can be adjusted with an electric winch to adapt the system to different patient sizes. The system is fully computer controlled. At unloading loads of up to 60 kg and walking speeds of up to 3.2 km/h, the mean unloading error and the maximum unloading error of the presented BWS system was less than 1 and 3 kg, respectively. The performance was compared with those of two purely passive BWS systems currently being used by most other rehabilitation groups. This comprised counterweight systems and static BWS systems with fixed rope lengths. Counterweight systems reached mean and maximum unloading errors of up to 5.34 and 16.22 kg, respectively. The values for the static BWS were 11.02 kg and 27.67 kg, respectively. The novel mechatronic BWS system presented in this study adjusts desired unloading changes of up to 20 kg within less than 100 ms. Thus, not only constant BWS, but also gait cycle dependent or time variant oscillations of the desired force can be realized with high accuracy. Precise and constant unloading force is believed to be an important prerequisite for BWS gait therapy, where it is important to generate physiologically correct segmental dynamics and ground reaction forces. Thus, the novel BWS system presented in this paper is an important contribution to maximize the therapeutic outcome of human gait rehabilitation.

Biomechanical Phenomena↗

PubMed2005

Elastic properties of an intact and ACL-ruptured knee joint: measurement, mathematical modelling, and haptic rendering.

An analytical, dynamic model of the human knee joint has been developed to simulate the unloaded knee joint behaviour in 6 degrees of freedom. It is based on extensive robot-based measurements of the elastic properties of a human cadaver knee joint. The measured data are compared with data from the literature to ensure that a proper database for modelling is used. The analytical modelling of the passive elastic joint properties is done with Local Linear Model Trees. The deduced knee joint model incorporates passive elastic properties of the internal knee joint structures, passive elastic muscle forces, damping forces, gravitational forces, and external forces. There are two sets of parameters, one simulating the movement of the intact knee joint, and a second simulating the knee joint with ruptured anterior cruciate ligament. The dynamic model can be easily processed in real-time. It is implemented in the haptic display of the Munich Knee Joint Simulator (MKS), which enables a person to move a plastic leg driven by a robot manipulator and feel the simulated knee joint force. Orthopaedic physicians judged the performance of the dynamic knee joint model by executing physical knee joint tests at the MKS.

Anterior Cruciate Ligament↗

PubMed2005

Accelerated decline in lung function in smoking women with airway obstruction: SAPALDIA 2 cohort study.

BACKGROUND: The aim was to determine if effects from smoking on lung function measured over 11 years differ between men and women. METHODS: In a prospective population based cohort study (Swiss Study on Air Pollution and Lung Diseases in Adults) current smokers in 1991 (18-60 yrs) were reassessed in 2002 (n = 1792). Multiple linear regression was used to estimate effects from pack-years of cigarettes smoked to 1991 and mean packs of cigarettes smoked per day between 1991 and 2002 on change in lung volume and flows over the 11 years. RESULTS: In both sexes, packs smoked between assessments were related to lung function decline but pack-years smoked before 1991 were not. Mean annual decline in FEV1 was -10.4 mL(95%CI -15.3, -5.5) per pack per day between assessments in men and -13.8 mL(95%CI-19.5,-8.1) in women. Decline per pack per day between 1991 and 2002 was lower in women who smoked in 1991 but quit before 2002 compared to persistent smokers (-6.4 vs -11.6 mL, p = 0.05) but this was not seen in men (-14.3 vs -8.8 mL p = 0.49). Smoking related decline was accelerated in men and women with airway obstruction, particularly in women where decline in FEV1 was three fold higher in participants with FEV1/FVC<0.70 compared to other women (-39.4 vs -12.2 mL/yr per pack per day, p < 0.002). CONCLUSION: There are differences in effects from smoking on lung function between men and women. Lung function recovers faster in women quitters than in men. Women current smokers with airway obstruction experience a greater smoking related decline in lung function than men.

Adolescent↗

PubMed2004

Value of supplemental interventions to enhance the effectiveness of physical exercise during respiratory rehabilitation in COPD patients. A systematic review.

BACKGROUND: There is a controversy about the additional benefit of various supplemental interventions used in clinical practice to further enhance the effectiveness of respiratory rehabilitation in patients with Chronic obstructive pulmonary disease (COPD). The aim of this research was to assess randomised controlled trials (RCTs) testing the additional benefit of supplemental interventions during respiratory rehabilitation in COPD patients. METHODS: Systematic review with literature searches in six electronic databases, extensive hand-searching and contacting of authors. Two reviewers selected independently eligible RCTs, rated the methodological quality and extracted the data, which were analyzed considering the minimal important difference of patient-important outcomes where possible. FINDINGS: We identified 20 RCTs whereof 18 provided sufficient data for analysis. The methodological quality was low and sample sizes were too small for most trials to produce meaningful results (median total sample size = 28). Data from five trials showed that supplemental oxygen during exercise did not have clinically meaningful effects on health-related quality of life while improvements of exercise capacity may be even larger for patients exercising on room air. RCTs of adding assisted ventilation, nutritional supplements or a number of anabolically acting drugs do not provide sufficient evidence for or against the use any of these supplemental interventions. INTERPRETATION: There is insufficient evidence for most supplemental interventions during respiratory rehabilitation to estimate their additional value, partly due to methodological shortcomings of included RCTs. Current data do not suggest benefit from supplemental oxygen during exercise, although the methodological quality of included trials limits conclusions. To appropriately assess any of the various supplemental interventions used in clinical practice, pragmatic trials on respiratory rehabilitation of COPD patients need to consider methodological aspects as well as appropriate sample sizes.

Anabolic Agents↗

PubMed2004

Interval exercise versus continuous exercise in patients with moderate to severe chronic obstructive pulmonary disease--study protocol for a randomised controlled trial [ISRCTN11611768].

BACKGROUND: Physical exercise has become a cornerstone of management of chronic obstructive pulmonary disease (COPD) because it leads to clinically relevant improvements of exercise capacity and health-related quality of life (HRQL). Despite the scarcity of randomised trials directly comparing exercise protocols, current guidelines recommend high intensity continuous exercise for lower extremities as the probably most effective exercise modality. However, for patients admitted to inpatient respiratory rehabilitation programmes, it is often difficult to initiate such an exercise programme because they are severely limited by dyspnoea and leg fatigue and therefore unable to perform continuous exercise at higher intensities and for periods longer than 30 minutes. Interval exercise may be an attractive alternative for these COPD patients because it allows high intensity exercise with recovery periods. The aim of this study is to assess if interval exercise compared to high intensity continuous exercise is not of inferior effectiveness in terms of HRQL and exercise capacity improvements but associated with better exercise tolerance in patients with moderate to severe COPD at the beginning of a respiratory rehabilitation. METHODS/DESIGN: We will assign patients with moderately severe to severe COPD to either continuous exercise or interval exercise using a stratified randomisation. Patients will follow 12-15 exercise sessions during a comprehensive inpatient respiratory rehabilitation. Primary end point for effectiveness is HRQL as measured by the Chronic Respiratory Questionnaire (CRQ) two weeks after the end of rehabilitation and secondary endpoints include additional clinical outcomes such as functional exercise capacity, other HRQL measures, patients' experience of physical exercise as well as physiological measures of the effects of physical exercise such as cardiopulmonary exercise testing. Including expected drop-outs, we will need 52 patients per group to show differences corresponding to the minimal clinically important difference of the CRQ. Outcome assessors and investigators involved in data analysis will be blinded to group assignment until analyses have been carried out. DISCUSSION: Clinicians and the scientific community need evidence on the benefits and tolerance of exercise protocols available in clinical practice. The proposed trial will provide important and needed data on interval and continuous exercise for decision making in clinical practice.

Journal Article↗

PubMed2004

Self-administration and interviewer-administration of the German Chronic Respiratory Questionnaire: instrument development and assessment of validity and reliability in two randomised studies.

BACKGROUND: Assessment of health-related quality of life (HRQL) is important in patients with chronic obstructive pulmonary disease (COPD). Despite the high prevalence of COPD in Germany, Switzerland and Austria there is no validated disease-specific instrument available. The objective of this study was to translate the Chronic Respiratory Questionnaire (CRQ), one of the most widely used respiratory HRQL questionnaires, into German, develop an interviewer- and self-administered version including both standardised and individualised dyspnoea questions, and validate these versions in two randomised studies. METHODS: We recruited three groups of patients with COPD in Switzerland, Germany and Austria. The 44 patients of the first group completed the CRQ during pilot testing to adapt the CRQ to German-speaking patients. We then recruited 80 patients participating in pulmonary rehabilitation programs to assess internal consistency reliability and cross-sectional validity of the CRQ. The third group consisted of 38 patients with stable COPD without an intervention to assess test-retest reliability. To compare the interviewer- and self-administered versions, we randomised patients in groups 2 and 3 to the interviewer- or self-administered CRQ. Patients completed both the standardised and individualised dyspnoea questions. RESULTS: For both administration formats and all domains, we found good internal consistency reliability (Crohnbach's alpha between 0.73 and 0.89). Cross-sectional validity tended to be better for the standardised compared to the individualised dyspnoea questions and cross-sectional validity was slightly better for the self-administered format. Test-retest reliability was good for both the interviewer-administered CRQ (intraclass correlation coefficients for different domains between 0.81 and 0.95) and the self-administered format (intraclass correlation coefficients between 0.78 and 0.86). Lower within-person variability was responsible for the higher test-retest reliability of the interviewer-administered format while between person variability was similar for both formats. CONCLUSIONS: Investigators in German-speaking countries can choose between valid and reliable self-and interviewer-administered CRQ formats.

Adult↗

PubMed2004

Measurement of agreement on health-related quality of life changes in response to respiratory rehabilitation by patients and physicians--a prospective study.

INTRODUCTION: To provide optimal care for patients with chronic obstructive pulmonary disease physicians need to understand if their patients benefit from an intervention. The objective of this study was to assess agreement between patients and physicians on health-related quality of life (HRQL) changes in response to respiratory rehabilitation and to explore sources for disagreement. METHODS: Sixty-one patients rated their health states on a validated preference-based instrument, the feeling thermometer (FT). In an analogous manner, the eight treating physicians rated the patients' health states on the FT. Patients and physicians were blinded to each other's ratings. We calculated intraclass correlation coefficients (ICC) to assess agreement between patients and physicians and used HRQL instruments and the 6-min walking test to assess the evaluative properties of the FT. RESULTS: We found moderate agreement at baseline (ICC 0.40, P = 0.018) and follow-up (ICC 0.49, P = 0.008) but large disagreement about change scores (ICC 0.02, P = 0.46). Patients' FTchange scores correlated well with change scores of the Chronic Respiratory Questionnaire, SF-36 and the Borg scale for dyspnoea whereas physicians' FT change scores correlated significantly with the change score of the 6- min walking test (r = 0.33). Physicians' ratings showed an inconsistent pattern for correlations with HRQL measures. CONCLUSIONS: There is large disagreement between patients and physicians on HRQL changes in response to respiratory rehabilitation. Investigators should assess whether the introduction of HRQL instruments into clinical practice raises the awareness of physicians towards HRQL and improves agreement with their patients.

Adult↗

PubMed2004

Phantom-based multimodal interactions for medical education and training: the Munich Knee Joint Simulator.

Simulation environments based on virtual reality technologies can support medical education and training. In this paper, the novel approach of an "interactive phantom" is presented that allows a realistic display of haptic contact information typically generated when touching and moving human organs or segments. The key idea of the haptic interface is to attach passive phantom objects to a mechanical actuator. The phantoms look and feel as real anatomical objects. Additional visualization of internal anatomical and physiological information and sound generated during the interaction with the phantom yield a multimodal approach that can increase performance, didactic value, and immersion into the virtual environment. Compared to classical approaches, this multimodal display is convenient to use, provides realistic tactile properties, and can be partly adjusted to different, e.g., pathological properties. The interactive phantom is exemplified by a virtual human knee joint that can support orthopedic education, especially for the training of clinical knee joint evaluation. It is suggested that the technical principle can be transferred to many other fields of medical education and training such as obstetrics and dentistry.

Computer Graphics↗

PubMed2004

A sensorized human torso phantom.

Force-torque measuring input devices can significantly enhance the performance of classical simulation environments that are, for example, based on pure passive phantoms. Such devices allow not only the determination of force/torque amplitude and direction but also the contact point on the phantom. The force/torque information can be displayed visually or acoustically, drive a realistic graphical animation environment or it can be saved and compared with a haptic library comprising the force/torque history of any medical specialist. In this paper the technical principle is exemplified by an interactive human torso. A plastic phantom model of a human torso is instrumented with a 6-degree-of-freedom force/torque sensor, thus, allowing an intuitive and interactive use for education of human anatomy.

Humans↗

PubMed2004

Phantom-based interactive simulation system for dental treatment training.

In this paper, we propose a new interactive simulation system for dental treatment training. The system comprises a virtual reality environment and a force-torque measuring device to enhance the capabilities of a passive phantom of tooth anatomy in dental treatment training processes. The measuring device is connected to the phantom, and provides essential input data for generating the graphic animations of physical behaviors such as drilling and bleeding. The animation methods of those physical behaviors are also presented. This system is not only able to enhance interactivity and accessibility of the training system compared to conventional methods but it also provides possibilities of recording, evaluating, and verifying the training results.

Computer Simulation↗

PubMed2003

Force-torque input enhances medical VR applications.

Force-torque measuring input devices can significantly enhance the performance of classical simulation environments that are, for example, based on pure passive phantoms. Such devices allow not only the determination of force/torque amplitude and direction but also the contact point, where a torque-free force is applied to the phantom. The force/torque information can be displayed visually or acoustically, drive a realistic graphical animation environment or it can be saved and compared with a haptic library comprising the force/torque history of any medical specialist.

Computer Simulation↗

PubMed2003

The JoyntStick: a new force-input-device for a multi-modal desktop simulator.

This paper presents a new force-torque input device that can be used to navigate within any kind of anatomical atlas. As an example, we demonstrate how it can be used to drive a virtual knee joint. The device is comprised by a realistic phantom shank that is attached to a self-made high-sensitive force-torque sensor. It records forces and moments in six degrees-of-freedom and feeds them into a biomechanical model of the knee. Resulting joint movements and sounds are displayed by a visual and acoustic display, respectively. The entire multi-modal simulation environment can provide a better understanding of joint anatomy, e.g. for the education of medical students. Furthermore, it can be a practical tool for resident orthopaedic physicians in order to enhance the consultation, clarification, and treatment planning together with the patient.

Biomechanical Phenomena↗