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Biomedical subjects

T A Krouskop

Publications and source records attributed to T A Krouskop.

At least 19 recordsLinked to original sources
PubMed1992

Toward a practical mobile robotic aid system for people with severe physical disabilities.

A simple, relatively inexpensive robotic system that can aid severely disabled persons by providing pick-and-place manipulative abilities to augment the functions of human or trained animal assistants is under development at Rice University and the Baylor College of Medicine. A stand-alone software application program runs on a Macintosh personal computer and provides the user with a selection of interactive windows for commanding the mobile robot via cursor action. A HERO 2000 robot has been modified such that its workspace extends from the floor to tabletop heights, and the robot is interfaced to a Macintosh SE via a wireless communications link for untethered operation. Integrated into the system are hardware and software which allow the user to control household appliances in addition to the robot. A separate Machine Control Interface device converts breath action and head or other three-dimensional motion inputs into cursor signals. Preliminary in-home and laboratory testing has demonstrated the utility of the system to perform useful navigational and manipulative tasks.

Activities of Daily Living↗
PubMed1990

Kinetics of colonization of a porous vitreous carbon percutaneous implant.

Implants of porous vitreous carbon with pore diameters 200-500 microns were surgically placed in rabbits and pigs. Skin colonization experiments were carried out by topically inoculating concentrations of Staphylococcus aureus and Escherichia coli in a test area adjacent to the implant and to a remote control area. Subsequent swab cultures were taken at 6, 24, 48 and 72 h and one or more weeks. In vitro attachment studies were also performed using bacteria stained with FITC on 1 mm slices of the porous carbon. Proplast was used as a control. Results showed that despite a temporary high rate of colonization and obvious binding of the bacteria to the carbon, the skin-implant interface resists infection by both normal and pathogenic flora.

Animals↗
PubMed1989

Noninvasive measurement of the stiffness of tissue in the above-knee amputation limb.

In order to characterize the mechanical properties of the soft tissue in above-knee amputations, nine subjects were measured with a Doppler ultrasound system. Measurements were made at four locations: anterior, posterior, lateral, and medial. The characterizations included tissues up to 2.5 cm deep. The average posterior moduli are significantly greater than the anterior and lateral parameters. No significant difference was found among moduli from the medial zone compared to other areas. Superficial tissue had a significantly higher modulus than the tissue beneath. A simple method for transducer placement produced repeatable results. The present technique proved to be useful with patients in good health, and with no severe residual limb complications. The information generated with the ultrasonic device may aid in prosthesis fitting and will be used in a Computer-Aided Design (CAD) system as well as in other clinical applications.

Amputation, Surgical↗
PubMed1988

Bacterial challenge study of a porous carbon percutaneous implant.

Numerous percutaneous devices for power transmission and control to electrically powered, intracorporeal blood pumps have been used for periods ranging from 12 months to 4 yrs; however, consistent and reliable performance has not been achieved, due most frequently to the development of infection and sinus tracts at the percutaneous lead exit site. The present study showed that percutaneous devices fabricated from porous vitreous carbon can function satisfactorily in vivo over extended periods. The implant sites successfully resisted infection by normal flora bacteria for as long as 48 months, although superficial surface colonization and infection did occur after deliberate application of pathogens.

Animals↗
PubMed1988

Measuring the shape and volume of an above-knee stump.

A set of design criteria for sensing the shape of an above-knee (AK) stump is presented and used as the basis for evaluating various shape sensing technologies. A mechanical probe type shape sensing system is described and its use in quantifying the external shape of the AK stump is discussed as it relates to generating a grid for finite element analysis in CAD/CAM studies and comparing the segmental volumes of the loaded and unloaded stump. This study also discusses a method that uses circumferential measurements to compute total and incremental volumes of the stump.

Amputation Stumps↗
PubMed1988

Tissue pressure management in the vocational setting.

A significant problem that confronts a spinal cord injured person who returns to work is how to design the work station and tasks so that pressure sores do not develop and compromise the worker's productivity. In this study, reach was investigated as a mechanism to cause weight shift during task execution. It is shown that by using an extended reach motion, it is possible to cause effective weight redistribution. By incorporating this type of motion in task design for mobility impaired workers, it should be possible to reduce their risk of developing pressure sores with a minimal effect on job performance.

Arm↗
PubMed1987

A pulsed Doppler ultrasonic system for making noninvasive measurements of the mechanical properties of soft tissue.

In response to the need for a more precise means of predicting the interaction of a prosthetic socket with an amputee's residual limb, a gated Doppler ultrasonic motion sensing system was devised for making noninvasive measurements of the elastic modulus of soft tissue in vivo. Ultrasound was chosen for its ability to indicate the viscoelastic behavior of biological materials without damaging tissue. The system consists of a holding jig to support the limb being tested, a tissue vibrator, and an ultrasonic transducer to monitor the motion of the tissue. The ultrasonic transducer is controlled by an external computer to control the depth at which the sensor is measuring tissue displacement. This ultrasonic measuring technique provides as much information as more conventional techniques, but with more convenience and fewer restrictions.

Artificial Limbs↗
PubMed1987

Computer-aided design of a prosthetic socket for an above-knee amputee.

A computer-aided design process for fabricating the rectified cast for an above-knee prosthetic socket is described. The methodology for collecting the parameters required for the computer analysis is discussed. The input variables include the unloaded shape of the residual limb, the mechanical properties of the soft tissues that comprise the limb, and the surface loading that deforms the tissue. The technologies that have been developed to ascertain these parameters are presented, and the clinical experience of using the computer-generated shape is presented.

Artificial Limbs↗
PubMed1987

Interface pressures in above-knee sockets.

The interface pressures in above-knee sockets of amputee patients were measured during the stance phase of the gait cycle. The pressures were monitored with a pneumatic sensor array that covered the inside of the socket. A pressure map of the socket surface was developed. This map has been related to the fit of the prosthetic socket. The pressures generated by the quadrilateral socket and the Normal Shape Normal Alignment (NSNA) socket were compared. Significant variations were noted in pressure distribution between the two sockets, but the magnitudes of the pressures in well-fitting sockets of both types were similar. Thus, magnitude of pressure in an above-knee socket may provide a more useful guide than distribution for predicting the fit of an appliance.

Artificial Limbs↗
PubMed1986

Inflation pressure effect on performance of air-filled wheelchair cushions.

Air-filled wheelchair cushions are frequently used in the prevention of pressure sores. Their effectiveness in reducing interface pressures and in redistributing body weight (BW) appears dependent on their internal inflation pressure. This pilot study examines and defines this relationship. Interface pressures were measured with the TIPE (Texas Interface Pressure Evaluator) system for 14 subjects while sitting on each of three commercially available air-filled wheelchair cushions. This relationship between interface pressure and internal pressure was then determined for each of the three body-build categories. In each category the interface pressure displayed a higher degree of sensitivity to underinflation than to overinflation. A high correlation found between BW and internal air pressure (IAP), may be useful in the design of a customized pressure indicator system. The study documents the influence of IAP on seating pressure and supports the need for further research in the development of an indicator system that alerts users to under- or overinflation of the cushion.

Air↗
PubMed1986

Factors affecting the pressure-distributing properties of foam mattress overlays.

A universal concern of those in nursing care is the occurrence of decubitus ulcers. To minimize this problem foam overlays are routinely used on hospital beds throughout the country. This study was undertaken to develop laboratory testing procedures which will reliably predict the support characteristics of mattress overlays in clinical service. Initially, test methods based on constant load and constant deformation boundary conditions were developed. These methods were applied to measure the pressure-distributing properties of 10 polyurethane foams fabricated in a wide range of pliancies and densities. Based on these laboratory data, a single index was developed to express the effectiveness of each overlay in distributing interface pressures. This index was found to be influenced by the stiffness (ILD), density, and thickness of each device. These data were then compared with measurements of interface pressure obtained from volunteer subjects who were supported on mattress overlays fabricated from each of the original foams. Correlation of these data with the laboratory results demonstrated that the effectiveness index was an accurate predictor of mattress overlay performance under end-use conditions.

Beds↗
PubMed1985

Effectiveness of mattress overlays in reducing interface pressures during recumbency.

This study evaluates the pressure-reduction characteristics of seven mattress overlays. Thirty subjects were evaluated on each support surface to determine the interface pressures that are generated under the most common pressure sore sites. The results of this study indicate that there is great variability in the effectiveness of traditional mattress overlays. The most effective overlays are the Roho and Akros DFD mattresses; whereas 2-inch thick convoluted foam provides no significant protection for the trochanter when the subjects were lying on their sides (lateral position).

Beds↗
PubMed1978

Modelling the cell-mediated immunity in homograft refection.

Lymphocytes which become sensitised at the periphery travel to the regional lymph nodes where they initiate an immunological response by increasing the production of immuno-competent lymphocytes. These lymphocytes migrate into the tissues via the blood stream and bring about the destruction of target cells. These notions, in the present analysis, are translated into a simple mathematical model. The model specifically considers the lymphocyte memory and increased secondary response.

Computers↗
PubMed1978

A system for clinically evaluating wheelchair pressure-relief cushions.

Pressure-related decubitus ulcers are a frequent disability and life-threatening complication in the management and rehabilitation of patients with spinal cord injuries. This paper describes a system developed to quantitate and evaluate a patient's response to wheelchair pressure-relief cushions. Maximum pressure and the tissue pressure distribution on six varieties of wheelchair cushions were determined for a sample of 57 patients with a history of decubitus ulcers. Wide variations in (mean) maximum pressure were observed. However, even greater variations were found in the distribution (bony/soft tissue) of the pressure. These data demonstrate that no single cushion was clearly superior in relieving pressure for all patients. Therefore, individualization of wheelchair cushions for each patient may be essential in order to minimize the probability that the person will experience a tissue-pressure problem.

Equipment and Supplies, Hospital↗