RESUMEN

Shape memory alloys (SMAs) are gaining popularity in the fields of automotive and aerospace engineering due to their unique thermomechanical properties. This paper proposes a numerical implementation of a comprehensive constitutive model for simulating the thermomechanical behavior of shape memory alloys, with temperature and strain as control variables to adjust the shape memory effect and super elasticity effect of the material. By implementing this model as a user subroutine in the FE code Abaqus/Standard, it becomes possible to account for variations in material properties in complex components made of shape memory alloys. To demonstrate the potential of the proposed model, a skid plate system design is presented. The system uses bistable actuators with shape memory alloy springs to trigger plate movement. The kinematics and dynamics of the system are simulated, and effective loads are generated by the shape memory alloy state change due to the real temperature distribution in the material, which depends on the springs' geometrical parameters. Finally, the performance of the actuator in switching between different configurations and maintaining stability in a specific configuration is assessed. The study highlights the promising potential of shape memory alloys in engineering applications and demonstrates the ability to use them in complex systems with accurate simulations.

Asunto(s)

RESUMEN

The occurrence of several geriatric conditions may influence the efficacy and limit the use of drugs prescribed to treat chronic conditions. Functional and cognitive impairment, geriatric syndromes (i.e. falls or malnutrition) and limited life expectancy are common features of old age, which may limit the efficacy of pharmacological treatments and question the appropriateness of treatment. However, the assessment of these geriatric conditions is rarely incorporated into clinical trials and treatment guidelines. The CRIME (CRIteria to assess appropriate Medication use among Elderly complex patients) project is aimed at producing recommendations to guide pharmacologic prescription in older complex patients with a limited life expectancy, functional and cognitive impairment, and geriatric syndromes, and providing physicians with a tool to improve the quality of prescribing, independent of setting and nationality. To achieve these aims, we performed the following: (i) Existing disease-specific guidelines on pharmacological prescription for the treatment of diabetes, hypertension, congestive heart failure, atrial fibrillation and coronary heart disease were reviewed to assess whether they include specific indications for complex patients; (ii) a literature search was performed to identify relevant articles assessing the pharmacological treatment of complex patients; (iii) A total of 19 new recommendations were developed based on the results of the literature search and expert consensus. In conclusion, the new recommendations evaluate the appropriateness of pharmacological prescription in older complex patients, translating the recommendations of clinical guidelines to patients with a limited life expectancy, functional and cognitive impairment, and geriatric syndromes. These recommendations cannot represent substitutes for careful clinical consideration and deliberation by physicians; the recommendations are not meant to replace existing clinical guidelines, but they may be used to help physicians in the prescribing process.

Asunto(s)

RESUMEN

BACKGROUND: Prescribing pharmacological treatment for hospitalized older patients represents a challenge for physicians. In particular, hospitalized older adults present with acute and chronic diseases, which may require multiple treatments and increase their susceptibility to adverse drug reactions. Patterns of drugs use have rarely been investigated in these patients. OBJECTIVE: To describe patterns of drugs use among hospitalized older adults participating in the CRiteria to assess Appropriate Medication use among Elderly complex patients (CRIME) project. METHODS: We performed a cross-sectional multicentre study based on data from the CRIME project, a study performed in geriatric and internal medicine acute care wards of 7 Italian hospitals. The only two exclusion criteria were: age < 65 years old and unwillingness to participate in the study. Participants were assessed at hospital admission and followed until discharge. RESULTS: Mean (Standard Deviation) age of 1123 participants was 81.5 (7.4) years, with 629 (56%) being women and 572 participants (51%) were admitted from Emergency Room. Mean length of stay was 11.2 (6.7) days. Mean number of drugs used greatly varied before (6.2, SD 3.2), during (10.6, SD 5.6) and after (7.1, SD 3.1) hospitalization. No difference in the number of drugs used during hospital stay was observed across age groups. During hospital stay, drugs for acid related disorders (77.9%) and antithrombotic agents (76.8%) were the most commonly used drugs, followed by drugs acting on the renin-angiotensin system (58.0%) and diuretics (57.1%). Very common was the use of psycholeptics (34.3%) and psychoanaleptics (22.4%). CONCLUSION: Use of multiple drug treatments is common in hospitalized older adults and hospitalization is associated with a substantial increment in the number of drugs used, with no differences across age groups.

Asunto(s)

RESUMEN

Changes in pharmacokinetics and pharmacodynamics, associated with increasing age, are often considered the only culprits of increasing Adverse Drug Reactions (ADR) rate observed in older adults, but other factors may be responsible for a reduction in drug efficacy and increase the risk of iatrogenic illness in this population. The aging process is characterized by a high level of complexity, which makes the care of older adults and the use of medications a challenging task. In particular, comorbidity, geriatric syndromes, cognitive and functional deficits, limited life expectancy are typical conditions observed in older adults which may reduce the efficacy of prescribed drugs and increase the risk of iatrogenic illness. As a consequence, a comprehensive assessment and management of the health care problems, with the goal of recognizing and preventing potential drug-related problems and improve quality of prescribing is necessary to reduce the risk of ADR. Several studies have assessed the effect of a comprehensive geriatric assessment and management on drug prescribing and drug related illness, showing a substantial improvement in quality of prescription and a reduction in rate of ADR. In addition, clinical guidelines providing recommendations regarding the use of drugs in chronic disease rarely assess the level of complexity observed in older adults and therefore they should be applied with caution in this population.

Asunto(s)