Valoración de un programa para la provisión de sillas de ruedas adecuadas para pacientes con lesión medular tomando como indicadores la calidad de vida y la prevención de úlceras por presión / Evaluation of a program for the provision of appropriate wheelchairs for patients with spinal cord injury using quality of life and pressure ulcer prevention as indicators

Introducción. La lesión medular afecta la calidad de vida y el estado de salud de la persona que la padece. Por su parte, el uso de una silla de ruedas adecuada a las necesidades y características particulares de cada individuo puede aumentar los cuidados en la salud, prevenir complicaciones como las úlceras por presión e incrementar la calidad de vida. Objetivo: Valorar la percepción de la calidad de vida y dar seguimiento a la formación de úlceras por presión como indicadores del impacto que tiene un programa basado en las "Pautas de suministro de sillas de ruedas manuales en entornos de menores recursos" de la OMS. Material y Métodos. A un grupo piloto de lesionados medulares se les otorgó una silla de ruedas adecuada; se les aplicaron los cuestionarios CHART-SF y WHOQOL-BREF para medir su calidad de vida y se les hizo seguimiento del desarrollo de úlceras por presión durante 12 meses. Resultados. Los principales hallazgos fueron una mejor percepción de la movilidad en el CHART-SF, mientras que en el WHOQOL -BREF el grupo no percibió ningún cambio, ni positivo ni negativo, en su calidad de vida. Los pacientes no desarrollaron úlceras por presión durante el estudio. Conclusiones. Los cuestionarios aplicados no son suficientemente sensibles para medir la calidad de vida en pacientes con lesión medular.

Introduction. Spinal cord injury affects the quality of life and health status of the person who suffers it. On the other hand, the use of a wheelchair adapted to the particular needs and characteristics of each individual can increase health care, prevent complications such as pressure ulcers and increase quality of life. Objective: To assess the perception of quality of life and to monitor the development of pressure ulcers as indicators of the impact of a program based on the WHO "Guidelines for the provision of manual wheelchairs in low-income settings". Material and Methods. A pilot group of spinal cord injured persons were provided with a suitable wheelchair; they were administered the CHART-SF and WHOQOL-BREF questionnaires to measure their quality of life and were followed up for the development of pressure ulcers for 12 months. Results. The main findings were a better perception of mobility in the CHART-SF, while in the WHOQOL-BREF the group did not perceive any change, either positive or negative, in their quality of life. Patients did not develop pressure ulcers during the study. Conclusions. The questionnaires applied are not sufficiently sensitive to measure quality of life in patients with spinal cord injury.

Analysis of behavior of forces in a pelvis-soft tissue mechanical model / Análisis del comportamiento de fuerzas en un modelo mecánico de pelvis-tejido blando

Pressure ulcers are tissue damage resulting from the constant pressure on the underlying soft tissue to bony prominences for long periods. Some of the most common ulcers are developed at the ischial tuberosities area (ITs). It has been found that stresses produced in the underlying tissue to the ITs may exceed 5 to 11 times the surface stresses, making it necessary to estimate the forces generated between the soft tissue and the ITs. However, it is not possible to determine these stresses in vivo in a patient, due to ethical reasons. This paper presents a mechanical model of the pelvis-soft tissue in order to study the behavior of contact forces. The model simulates the load on the ITs of a male subject of 70 kg weight and 1.70 m height, which were recorded for 8 min. The registered forces in the model were compared with the surface forces estimated from pressure records measured by the Force Sensing Array system in a patient with spinal cord injury. After 2 min, both forces measured in the model, and the ones estimated in the patient followed the trend described by Crawford during clinical measurements of pressures during sitting. It was also found in the model that measured forces below the ITs are higher than those measured below soft tissue, which suggests that the model may be valid for the study of the forces generated inside the tissue.

Las úlceras por presión son daños en el tejido, derivados de la presión constante por periodos prolongados sobre el tejido blando subyacente a una prominencia ósea, algunas de las úlceras más comunes se desarrollan en la zona de las tuberosidades isquiáticas (TI´s). Se ha detectado que esfuerzos generados en el tejido subyacente a las TI´s pueden exceder entre 5 a 11 veces a los esfuerzos superficiales, lo que hace necesario conocer las fuerzas que se generan entre el tejido blando y las TI´s, sin embargo medir estos esfuerzos in vivo en un sujeto, no es posible por razones éticas. Este trabajo presenta un modelo mecánico del sistema pelvis-tejido blando con la finalidad de estudiar el comportamiento de las fuerzas, el modelo simula la carga en las TI´s de un sujeto masculino de 70 kg y 1,70 m, en el cual se registraron por 8 min. Las fuerzas registradas en modelo fueron comparadas con las fuerzas superficiales estimadas a partir de los registros de presión medidas por el sistema Force Sensing Array, en un paciente con lesión medular. A partir de 2 min, tanto fuerzas medidas en el modelo, como estimadas en el paciente, siguen la tendencia descrita por Crawford para mediciones de presiones clínicas durante la sedestación, también se encontró en el modelo que las fuerzas medidas por debajo de las TI's son mayores a las medidas debajo del tejido blando; lo que sugiere que el modelo puede ser válido, para el estudio de las fuerzas que se generan al interior del tejido.

On the estimation of maximum stress in cushions for wheelchair patients who are prone to develop pressure injuries.

BACKGROUND: Pressure injuries are an important health care issue. This problem is even more evident with patients with neurological conditions. OBJECTIVE: This study aims to develop an analytical tool to predict the magnitude of the maximum stresses developed at the wheelchair cushion-patient contact area. METHOD: Newton's polynomial interpolation method was applied in order to obtain correlations between the maximum stress developed and the weight of the patient and the maximum pressure and body mass index (BMI) of the participants. For this study it was recruited five able-bodies and nine patients with spinal cord injury. RESULTS: The agreement between the computed stress values and those measured with the able-bodied group is excellent, but in the patients within the spinal cord injury group, the concordance is poor. The correlations were applied in data from Crawford's study, and predictions of pressures show lack of agreement. CONCLUSIONS: Correlation between the weight of a person and the maximum stress developed by him or her while sitting for extended periods of time has been demonstrated. The lack of agreement between estimated and measured values in spinal cord injuries and Crawford's data can be mainly attributed to some sort of neurological status.

Análisis del comportamiento mecánico del tejido subyacente a las tuberosidades isquiáticas por medio del método del elemento finito / Analysis of mechanical behavior of the underlying tissue to the ischial tuberosities using finite element method

Las úlceras por presión son las complicaciones secundarias más comunes a una lesión medular, las cuales ponen en riesgo tanto la salud como la vida de quienes las padecen. Las úlceras por presión más comunes en lesionados medulares aparecen en la región pélvica, principalmente en las tuberosidades isquiáticas (TI's). Una estrategia usada en la clínica es medir la presión generada entre el paciente y la superficie donde se encuentra para evaluar el riesgo que representa dicha superficie para el desarrollo de úlceras por presión sin embargo, este tipo de mediciones superficiales no garantizan que la presión en los tejidos internos subyacentes a prominencias óseas sea inocua. Con el fin de estudiar los mecanismos de formación de úlceras por presión, se realizó el análisis de un modelo de pelvis y tejido subyacente por medio del Método de los Elementos Finitos (MEF). De esta manera se puede estudiar el comportamiento de las TI's sobre su tejido circundante, así como analizar los efectos biomecánicos que provocan las úlceras. Se construyó el modelo computacional por medio de un software de CAD (Computing Aided Design) de la pelvis a partir de cortes tomográficos. El modelo fue exportado al software COMSOL y se analizaron seis casos de estudio: un análisis de la pelvis sobre bloques de tejido sano y cinco casos más, los cuales simulan lesiones en el tejido con distintas profundidades, representando úlceras superficiales e internas. Los resultados mostraron que los puntos de máximo esfuerzo, en todas las pruebas, se localizan justo debajo de la TIs además se encontró que las lesiones internas presentan mayores esfuerzos y deformaciones, los cuales pueden ser precursores de daño en el tejido.

Pressure ulcers are the most common secondary complication to a spinal cord injury, which endanger both health and life of the patients who suffer them. The most common pressure ulcers in spinal cord injuries occur in the pelvic region, mainly in the ischial tuberosities (ITs). A strategy used in clinic is to quantify the pressure generated between the patient and the surface, in order to assess the risk posed by that surface for developing pressure ulcers. Despite this, this type of surface measurements does not guarantee that pressure in the internal tissues underlying to bony prominences, to be safe. In order to study the mechanisms of formation of pressure ulcers, an analysis of a model of the pelvis and its underlying tissue was performed using the Finite Element Method (FEM). By this means we can study the behavior of ITs on its surrounding tissue, and at the same time, we analyze the biomechanical effects those cause ulcers. The computational model of the pelvis was built from tomographic slices using CAD software (Computing Aided Design). The model was exported to the finite element software COMSOL and six study cases were analyzed: an analysis of the pelvis on healthy tissue blocks and five more cases, which simulate tissue injury with different depths, representing surface and internal ulcers. The results showed that the maximum stress points in all tests are located just below the ITs it was also found that internal injuries present higher stresses and strains, which can be precursors of tissue damage.

A prospective, longitudinal, descriptive study of the effect of a customized wheelchair cushion on clinical variables, satisfaction, and functionality among patients with spinal cord injury.

The Instituto Nacional de Rehabilitación (Rehabilitation National Institute) (INR) developed a prototype wheelchair cushion (INR cushion) designed to adjust to the anthropometry of the user's ischiogluteal area and prevent pressure ulcer formation while maintaining or promoting functionality. A prospective, longitudinal, descriptive study was conducted from February 2010 to February 2011 to evaluate the effect of using the INR cushion on clinical variables, functionality, and user satisfaction. Sixteen patients were recruited (9 male, 7 female, average age 31.8 [range 22-47] years, average body mass index 25 [range 22-34], average time in a wheelchair 10.1 [range 3-26] years) who met the study protocol inclusion criteria of being pressure ulcer-free for at least 6 months and capable of propulsion and transfer without assistance, chronic spinal cord injury (>2 years), and without chronic-degenerative diseases or cognitive problems. Each participant received the cushion for a 2-month evaluation. Eight clinical variables were assessed: trunk control, posture, spasticity, transfer capacity, comfort, skin reaction, propulsion capacity, and pressure release capacity. The clinical assessment was performed using validated scales and instruments: Modified Ashworth Scale (MAS), Functional Independence Measure™ (FIM), Norton Scale, and assessment of skin reaction. Interface pressures were measured using force sensing array, and participants completed a structured interview to assess user expectation, perceived functionality, perceived quality, and likelihood of recommending the device. Two patients withdrew due to appointment conflicts; of the remaining 14, significant differences between the user's experience with other products and the INR were found with regard to pressure redistribution (P = 0.012); all participants but 1 graded the INR as good in all interview categories. No participants developed a pressure ulcer during the study. The customized cushion was especially functional among patients with incomplete thoracic and cervical injuries, high FIM scores, and moderate levels of activities of daily living. Taller patients (P = 0.01) and patients with higher degrees of spasticity (P = 0.007) were less satisfied with functionality. The results of this study contributed to the redesign process of the cushion. These findings may be useful to establish predictors, both subjective and clinical, for patient utilization of wheelchair cushion use.

[Design and evaluation of preventive seats for pressure ulcers associated with spinal injuries]. / Diseno y evaluación de asientos preventivos de úlceras por presión para lesionados medulares.

INTRODUCTION: Pressure ulcers are a dominant health problem for people who, for various reasons, must spend most of their time in a seated position. The spinal cord injury patients are the most affected for this situation. One strategy to prevent pressure ulcers is throughthe use of special seats. In the Instituto Nacional de Rehabilitación, contoured special seats have been developed according to anatomical measure of spinal cord injured patients. OBJECTIVE: To find one or more combinations of test materials that reduced pressure below 60 mmHg, in the ischial area, in order to help to prevent pressure ulcers. MATERIAL AND METHODS: The special seats were fabricated using thermoplastic materials and polyurethane foams, following prosthetic fitting technique; and were tests in healthy volunteers. RESULTS: The results were compared with a vinyl seat, because most of wheelchairs have it. All different test combinations were superior to vinyl seat, specially the two polyurethane foam- polypropylene combinations. A group of nine patients with spinal cord injury were recruited to test the designed seats, for a three month period. DISCUSSION: The results showed that pressure values are lower in the special seats than in the vinyl seats. No complications or pressure ulcers were found during follow up.