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Biomedical subjects

R L Hart

Publications and source records attributed to R L Hart.

8 recordsLinked to original sources
PubMed1998

A comparison between control methods for implanted FES hand-grasp systems.

Implanted neuroprostheses employing functional electrical stimulation (FES) provide grasp and release to individuals with tetraplegia. This paper describes and compares three methods of controlling the stimulated hand movement: shoulder position, wrist position and myoelectric activity from the wrist extensors. Three experienced neuroprosthesis users were evaluated with each of the control methods by performing a grasp release test (GRT). A significant improvement was found between each functional electrical stimulation (FES) method and tenodesis without FES. No significant difference in overall performance was found between the three FES methods of control. Each method of control demonstrated advantages and disadvantages which depend upon characteristics of the individual patient. Factors which must be considered are injury level, voluntary wrist strength, proximal upper limb strength, the level of cognition of the patient, hand-grasp characteristics, cosmeses, importance of using both arms, and personal preference. Due to the unique characteristics of each controller type, it is advantageous to have each type available for the FES patients to adapt the system to the needs and desires of the individual patient.

Electric Stimulation Therapy↗
PubMed1997

An implanted upper-extremity neuroprosthesis. Follow-up of five patients.

An implanted neuroprosthesis supplying functional neuromuscular stimulation was used to provide grasp and release to tetraplegic individuals. This article describes the results, at a minimum of three years, for the first five patients to have operative implantation of an eight-channel stimulator-receiver. All of the patients had a clinically complete spinal cord injury with motor function remaining at the level of the fifth or sixth cervical nerve root. In addition to implantation of the stimulator system, each patient had augmentative operations on the hand to improve function. The procedures included tendon transfers, side-to-side tendon anastomoses, arthrodesis of the interphalangeal joint of the thumb, and rotational osteotomy of the radius. The neuroprosthesis provides two grasp patterns controlled by voluntary motion of the shoulder or wrist. Functional evaluations included measurement of pinch force, a grasp-release test, evaluation of the level of functional independence, and usage surveys. Pinch force ranged from eight to twenty-five newtons. All five patients demonstrated functional grasp patterns, had increased independence, and were able to use the neuroprosthesis at home on a regular basis. The implanted stimulator has proved to be safe and reliable, with seven years as the longest time in situ at the time of writing.

Activities of Daily Living↗
PubMed1978

Plasma levels, half-life values, and correlation with physiologic assays for growth and immunity.

Plasma prednisolone levels have been measured hourly in children receiving a single dose of oral prednisone. Peak prednisolone levels occurred one to two hours after ingestion; half-life studies gave a mean value of 132 minutes in most children. Some children had marked variability in absorption and metabolism of prednisone. Somatomedin activity and cell-mediated immunity were inhibited by plasma prednisolone values which were achieved by single doses of prednisone of 0.5 mg/kg or higher. Monitoring prednisolone levels may be of value in identifying those children who accumulate excessively high levels on moderate dosage regimens.

Administration, Oral↗