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Biomedical subjects

Valma J Robertson

Publications and source records attributed to Valma J Robertson.

7 recordsLinked to original sources
PubMed2003

Monophasic and biphasic stimulation evoke different responses.

In 31 subjects, psychophysiological sensory perception threshold and the waveform of orthodromic sensory nerve action potentials (SNAPs) produced by constant-current 100-micros monophasic negative pulses were compared to those produced by biphasic (negative-positive) symmetrical pulses (100-micros per phase). In addition, the effects of 200-micros monophasic negative pulses were studied. Graded stimuli were delivered to the index finger, and SNAPs were recorded over the median nerve at the wrist. Perception threshold was significantly different among the three conditions. Furthermore, in 26 subjects, at the lower intensities at which SNAPs first appeared, the evoked potential waveform had two small negative phases with biphasic stimuli, but a single negative phase in response to monophasic pulses. At higher stimulus intensities, all SNAPs had a single large negative phase regardless of the stimulus. These perception and waveform findings suggest that, contrary to historical belief, the trailing positive phase of a biphasic pulse has a stimulating effect at low stimulus intensities.

Action Potentials↗
PubMed2002

Occupational health in physiotherapy: general health and reproductive outcomes.

Physiotherapists are exposed to many risk factors in their work environment. Their general health status is largely unknown, and conflicting studies suggest possible adverse reproductive effects of electromagnetic radiation to which they may be exposed. As part of a larger study, a systematic sample of one in four physiotherapists on a state register (N = 824) was surveyed. Each subject completed an eight page questionnaire, answering questions about musculoskeletal and general health, exposure to risk factors, exposure to electrophysical agents and reproductive outcomes. The response rate was 67.8%. The incidence of congenital malformations and miscarriage among physiotherapists was lower than that in the general community. However, physiotherapists who performed hydrotherapy were more likely to report dermatitis, rashes and fungal skin infections. The prevalence of these conditions increased with the number of hours spent doing hydrotherapy. These findings suggest that physiotherapists are unlikely to have an increased risk of negative reproductive outcomes because of their exposure to electrophysical agents. Physiotherapists who perform hydrotherapy, however, have an increased risk of skin complaints.

Adult↗
PubMed2002

Hospital stay and discharge outcomes after knee arthroplasty: implications for physiotherapy practice.

Patient outcomes at discharge from acute care after knee arthroplasty were investigated in a prospective observational outcome study at three Melbourne public acute care hospitals during a five-month period from November 1999 to March 2000. The participants were 105 consecutive patients (35 at each hospital), with a mean age of 71 years. Outcome measures were length of stay, destination (home or rehabilitation), knee range of movement, and functional mobility at discharge from the acute care facility. During the study period, mean hospital length of stay across the three hospitals was 6.5 days, more than 30% less than the Victorian average for the preceding year. In that time, 56% of patients had achieved functional independence sufficient for discharge directly home, however only 36% were actually discharged home. The reasons identified for discharge to rehabilitation despite the achievement of sufficient functional independence included pressure on clinicians to decrease length of stay and the need to make decisions regarding discharge early in the post-operative recovery when the eventual patient outcome may still be unclear. Unnecessary discharges to rehabilitation increase the overall length of stay in the health care system and costs per patient. This finding suggests a method of risk screening is required to assist clinical decision making with regard to discharge.

Activities of Daily Living↗
PubMed2002

Optimal frequencies for electric stimulation using medium-frequency alternating current.

OBJECTIVE: To determine the effect of single cycles of alternating current of various frequencies on sensory and motor thresholds and on relative thresholds (motor threshold/sensory threshold). DESIGN: Repeated-measures design. SETTING: Laboratory setting. PARTICIPANTS: University student and staff volunteers (N=16; mean age, 34y). INTERVENTIONS: Single cycles of sinewave frequencies between 1 and 35kHz were delivered at 50Hz. The frequencies were applied in a random order. MAIN OUTCOME MEASURES: The motor and sensory thresholds were recorded at each applied frequency. RESULTS: Both sensory and motor thresholds showed a smooth decrease to a minimum at approximately 3kHz. The relative threshold reached a minimum close to 9kHz. Comparison with previous studies showed that although absolute thresholds reach a minimum at a frequency that depends on electrode size, the frequency at which the relative threshold is a minimum was independent of electrode size and independent of whether the stimulus was applied as single pulses or in burst mode. CONCLUSIONS: The optimal frequency for transcutaneous stimulation using medium-frequency alternating current depends on the outcome measure used. It would therefore be desirable for clinical stimulators to provide a selection of carrier frequencies.

Adult↗
PubMed2002

Vastus medialis electrical stimulation to improve lower extremity function following a lateral patellar retinacular release.

STUDY DESIGN: A single-case study design. OBJECTIVES: To examine the effect of electrical stimulation of the vastus medialis muscle on stiffness, pain and function for a patient with delayed functional progress following a lateral patellar retinacular release. BACKGROUND: Five months after an arthroscopic lateral patellar retinacular release, the patient, although highly motivated, had made little progress using routine exercises and taping. METHODS AND MEASURES: An electrical stimulation program producing approximately 300 contractions daily of the vastus medialis muscle was implemented. The electrical stimulation applied for 33 of the 36 days was a rectangular and balanced biphasic pulse of 625-micros duration, 70-Hz frequency, 8-second peak on-time, 3-second off-time, 1-second ramp-up, and 0.5-second ramp-down. Objective measures of stair climbing and hopping, together with the subjective measure of therapist-palpated superomedial patella displacement force, were recorded for each treatment visit. Other subjective measures were the patient's daily recordings of knee pain and stiffness. RESULTS: Patient-reported stiffness reduced rapidly as the actual and cumulative number of daily contractions of the vastus medialis muscle increased. After 8 days of electrical stimulation, the patient was able to ascend stairs unassisted and after another 21 days to hop unsupported. CONCLUSIONS: Stiffness rapidly reduced and function started to improve once the electrical stimulation program was implemented. Recovery during the 36 days of treatment with electrical stimulation was greater than during the previous 5 months using other methods. Compliance was not an issue, nor was muscle soreness.

Arthroscopy↗
PubMed2002

Work-related musculoskeletal disorders and the culture of physical therapy.

BACKGROUND AND PURPOSE: Knowledge, skills, relationships, and attitudes of caring and working hard are all thought to be valued by physical therapists. This article explores how physical therapists see themselves, in light of some of these values, when they experience work-related musculoskeletal disorders (WMSDs). The article also explores the ways in which these values may compete with each other, and it suggests how this may contribute to the onset of WMSDs and to therapists' behavior following a WMSD. SUBJECTS AND METHODS: Eighteen therapists who had made a career change after a WMSD participated in interviews that were designed to gain insight into the attitudes and beliefs of therapists who had had a WMSD. RESULTS: Participants did not anticipate WMSDs, and they typically believed their physical therapy knowledge and skills would have prevented WMSDs from occurring. They saw themselves as knowledgeable and caring and indicated that these characteristics were highly valued by the profession. Their need to demonstrate these attributes sometimes resulted in behaviors that contributed to the development of their WMSDs and made them worse after their onset. DISCUSSION AND CONCLUSION: The cultural values of physical therapists may make it difficult for them to do their jobs in a way that minimizes the risk of WMSDs. The study identified a potential conflict between the therapists' need to (1) demonstrate their ability to work hard and care for their patients and (2) appear knowledgeable and skilled by remaining injury free.

Adult↗