[263] PHYSICAL EXERCISE STRENGTH TRAINING TO IMPROVE THE HEALTH OF DIALYSIS PATIENTS
David Alexander Leaf, MD, MPH
Division of General Internal Medicine, West Los Angeles
VA Medical Center, Wilshire & Sawtelle Blvds., Los Angeles,
CA, 90073; email: leaf@west-la.va.gov
Sponsor: Department of Veterans Affairs, VA
Rehabilitation Research and Development Service, Washington,
DC 20420
(Project #F2048-2RA)
PURPOSE--Current physical exercise training (PET) guidelines for renal dialysis patients advise aerobic-based programs. Studies among other comparatively physically debilitated populations indicate resistive- (strength) based PET is effective for improving physical function. However, resistive-based PET programs have not been studied in dialysis patients. The purpose of this study is to compare aerobic- and resistance-based programs among renal dialysis patients.
METHODOLOGY--A sample of 48 renal dialysis patients will be prospectively randomized to receive an 11-mo program of either aerobic- or resistive-based PET. Two-way ANOVA will be conducted between exercise groups to compare entry, 8-week, and 11-mo follow-up measurements of physical work capacity (VO2peak) by cardiopulmonary exercise stress testing (CPX) using a state of the art Med Graphics cardiorespiratory diagnostics system for respiratory gas analysis and a cycle CPX protocol. We shall also measure lower limb strength using kin com testing, markers of exercise-induced lipid peroxidation measured by breath ethane, pentane, and plasma malonaldehyde (MDA) levels, and administer quality-of-life questionnaires.
PROGRESS--To date, 12 patients have been randomized to exercise interventions. The programs have been very well received with 100 percent compliance rate. We are currently completing 8-week follow-up testing on this initial group of subjects.
PRELIMINARY RESULTS--Entry measurements confirm these patients to be extremely deconditioned physically (mean values): right knee torque=55 Nm, left knee torque=54 Nm, maximal number of heel raises right=23, left=21, number of sit-to-stands 14 in 30 s, VO2peak=17 ml O2/Kg body weight/min, and peak workload=87 W.
FUTURE PLANS/IMPLICATIONS--The preliminary findings confirm that renal dialysis patients are physically debilitated both in terms of physical strength and cardiopulmonary work capacity. The findings from this study have major importance in establishing the most effective PET program for improving the health of these patients.
[264] HEALTH BEHAVIORS IN SCHOOL-AGED CHILDREN WITH PHYSICAL DISABILITIES
Catherine Steele, PhD; Douglas Biggar, MD; Joseph
Bortolussi, MSW; Jeffrey Jutai, PhD, CPsych; Ilze Kalnins,
PhD; Beth Ellen Rossen, MSc
Bloorview MacMillan Centre, Toronto, ON, M4G 1R8 Canada;
email: ortccs@oise.utoronto.ca
Sponsor: Easter Seal Research Institute, 250 Ferrand Drive, Suite 200, Don Mills, ON, M3C 3P2 Canada
PURPOSE--Children with physical disabilities are at risk for acquiring secondary disabilities in adulthood, such as heart disease, stroke, respiratory problems, and social and emotional difficulties. Some of these can be reduced by adopting healthy lifestyles during childhood. The purpose of this research is to identify the lifestyle behaviors of children with physical disabilities and to develop health promotion initiatives for these children.
METHODOLOGY--In partnership with 16 Ontario children rehabilitation centers, we administered the questionnaire "Health Behaviour of School-Aged Children: A WHO Cross-National Study (HBSC)" to 319 children, aged 11-16, with physical disabilities such as amputations, arthritis, cerebral palsy, muscular dystrophy, or spina bifida. We developed the required methodology for interviewing children with a variety of physical disabilities. To gain a greater understanding of the survey results, we conducted 16 focus groups with youth with physical disabilities, their parents, young adults with physical disabilities, health care professionals, and researchers.
RESULTS--Our findings showed that lifestyle behaviors of concern to children with a physical disability are: diets high in sugar and fats, lack of exercise, social isolation, and lack of access to information about relevant sexual issues. Our findings also demonstrated that these young people have some healthy lifestyle behaviors and attitudes. They are considerably less likely to smoke or drink, demonstrate no differences in self-esteem and depression, and have more positive attitudes toward parents, teachers, and school.
Focus group participants offered reasons to explain our survey results. They also suggested health promotion initiatives to maintain health-enhancing behaviours and ameliorate health-inhibiting behaviors.
FUTURE PLANS--During the next year, our goal is to: 1) administer the HBSC survey to adults with physical disabilities, with revisions to the survey reflective of an adult population; 2) compare results of the adult survey to our previous results with children; 3) continue developing health promotion initiatives aimed at reducing the prevalence of secondary disabilities; 4) expand our partnerships to further our research, as well as to develop and implement health-promotion initiatives.
[265] ADAPTIVE BIOLOGICAL SIGNAL PROCESSING
Philip A. Parker, PhD
Institute of Biomedical Engineering University of New
Brunswick, Fredericton, NB CANADA E3B 5A3; email:
pap@unb.ca
Sponsor: University of New Brunswick Research Fund, Fredericton, NB CANADA E3B 5A3
PURPOSE--We are investigating the performance of neural network and finite impulse response (FIR) adaptive noise cancellation filters in evoked potential estimation. Such filters have potential in the reduction of interfering myoelectric signal, stimulus artifact, and cardiac signal.
METHODOLOGY To obtain useful somatosensory evoked potentials (SEP), signal enhancement methods must be applied in order to increase the signal-to-noise ratio (SNR). One approach to increase the SNR is to reduce the large interfering stimulus artifact signals through the use of adaptive noise cancellation filters. This technique requires two data channels--the first, primary, containing SEP and stimulus artifact, and the second (reference) a derivative of the stimulus artifact correlated with the primary artifact. The adaptive filter processes the reference channel to generate from its artifact an output matching the primary artifact. The primary artifact is then removed by subtraction. The LMS adaption algorithm will be used and both a multiple layer perception neural network and nonlinear FIR filter investigated.PROGRESS--To date in this project an adaptive matched filter has been investigated, and a SNR gain of 6 dB has been found while tracking slowly varying parameters of the signal. The performance equations for the nonlinear FIR filter have been derived, and the experimental work is encouraging. Cross talk resistant filters have been investigated, as well as multichannel filters. Application of these filters to stimulus artifact and ECG interference reduction in evoked potential measurements has been studied with good results. Artificial neural network implementations of the adaptive filters have proven very effective, and different configurations and adaption methods are currently being investigated.
[266] THE ELECTROPHYSIOLOGICAL BEHAVIOUR OF POSTURAL MUSCLES DURING PROLONGED SEATED TASKS
Linda McLean, MScEE; Maureen Tingley, PhD; Robert Scott,
MScEE; Jeremy Rickards, PEng
Institute of Biomedical Engineering, University of New
Brunswick, Fredericton, NB CANADA E3B 5A3; email:
lindam@math.unb.ca
Sponsor: The Natural Sciences and Engineering Council of Canada (NSERC), Ottawa, ON, Canada; The Workplace Health, Safety, and Compensation Commission of New Brunswick, Grand Bay, NB, Canada; Vanity Software Inc. Toronto, ON, Canada
PURPOSE--This work investigated the neurophysiological behaviour of postural muscles during sustained seated tasks. As a timely example, computer terminal operators were studied in order to determine not only normal behaviour of the postural muscles involved in computer work, but also the effect of 30-s "microbreaks" on this behaviour. This participant population was of interest due to the increase in the incidence of cumulative trauma disorders among them in recent years.
METHODOLOGY--A means of on-line data reduction was determined in order to provide relevant information about changes in the myoelectric signal (MES) in the muscles of the neck, low back, shoulder, and forearm over the duration of prolonged computer work, while avoiding the problems associated with data storage and memory limitations. Once validated, this data reduction technique was used to pre-process MES data from four channels, permitting continuous recording for periods as long as 3 hrs using portable data loggers of our own development. A sampling rate of 1024 Hz per channel was employed. Channel gains were adjusted in order to accommodate individual differences in signal amplitude.
PROGRESS--This work has involved three separate studies to date. In the first, MES data were collected from 18 subjects, both while they remained seated for the duration of the recording session, and while they took 30-s microbreaks at 20-min intervals during the recording session. No significant trends emerged in terms of traditional muscle fatigue measures such as amplitude and frequency slopes, nor for measures of the signal variance changes over time. Furthermore, little difference was noted between trials where participants took breaks and when they did not in terms of any of the measures used. What was discovered was a cyclic trend in the mean frequency (MNF) of the MES.
The presence of this trend was next verified in a small study of six subjects who remained seated without obvious movement for a period of 2 hrs. This study proved encouraging, indicating that the cyclic trend in MNF was present in the cervical extensors and lumbar erector spinae during unsupported sitting.
The benefits of microbreak strategies were finally studied in terms of MNF cycling, musculoskeletal discomfort, and productivity. In order to accomplish this, in addition to MES data, discomfort scores were recorded at 40-min intervals from each participant, using vertical visual analog scales. In addition, productivity was measured in terms of the number of words typed during the sessions. It was found that 30-s microbreaks regularly scheduled at intervals of 20-40 min effectively induced MNF cycling at the prescribed break interval, slowed the development of discomfort, and did not adversely affect productivity.
FUTURE PLANS--The detection of cyclic activity, particularly in the lumbar erector spinae and cervical extensors, has raised many questions in terms of the nature of sustained postural contractions. Future work will be aimed at determining the mechanisms underlying this behaviour. In particular, the next stage of this work will be aimed at measuring seated postural sway simultaneously with MES in order to determine whether the MNF cycling is correlated with sway. In addition, we shall investigate methods of determining whether the MNF cycling results from a trade-off of activity between motor units within a particular muscle, or from a trade-off of activity between muscles as a whole.
[267] REAL-TIME IMPLEMENTATION OF A NONLINEAR ADAPTIVE FILTER FOR STIMULUS ARTIFACT CANCELLATION IN SOMATOSENSORY EVOKED POTENTIAL MEASUREMENTS
Gianluca De Luca, MScEE; Philip A. Parker, PhD; Dennis
F. Lovely, PhD
Institute of Biomedical Engineering, University of New
Brunswick, Fredericton, NB CANADA E3B 5A3; email:
lovely@unb.ca
Sponsor: University of New Brunswick Research Fund, Fredericton, NB CANADA E3B 5A3
PURPOSE--The purpose of this research is to use surface electrodes to measure the somatosensory evoked potentials (SEPs), as a noninvasive diagnostic tool for monitoring the responses of nerves to stimuli.
METHODOLOGY--The measurement of SEPs using surface electrodes is a noninvasive diagnostic tool for monitoring the responses of nerves to stimuli. These measurement techniques have been found useful during surgeries where blood supply to nervous tissues may be compromised.
The recorded SEP signal is typically buried in biological noise, and often has a signal-to-noise ratio less than one. While synchronous averaging can be used in appropriate circumstances to minimize the effects of the uncorrelated biological noise, the stimulus artifact resulting from the evoking process is completely correlated with the SEP, and remains unaffected through averaging. In some cases, the tail of the artifact may mask the onset of the SEP, thus leading to inconclusive SEP data. Offline, nonlinear adaptive filters have been used in the past to successfully minimize the ill effect of the stimulus artifact. For these filters to be useful in clinical settings, it becomes necessary for them to be executed in real-time. This work deals with the implementation of an artifact canceller using the TMS320C50, a fixed point, dedicated signal processor.
PROGRESS--The performance of a nonlinear transverse filter, using a second-order truncated Volterra series, has been analyzed with simulated and real data (spinal and median nerve SEPs). The effect of round-off error associated with a fixed point implementation for both an LMS update algorithm and an RLS updated algorithm has also been addressed. Finally, the hardware performance has been shown to be comparable with that of a neural network-based canceller operating off-line with floating point arithmetic.
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