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Query: UMLS:C0015672 (fatigue)
 51,768 document(s) hit in 31,850,051 MEDLINE articles (0.00 seconds)

Fatigue is probably the most common symptom of illness affecting sufferers of both acute and chronic conditions. However, confusion surrounds the definition and use of the term fatigue. As with many other nursing concepts, it is a word that is commonly used in colloquial language. This concept analysis aims to identify the attributes that are essential to the concept of fatigue, and to distinguish between its colloquial and its nursing usage by following the strategy suggested by Walker and Avant (1995, Strategies for Theory Construction in Nursing, Appleton Lange, London). A review of the literature identifies nursing uses of the term fatigue which reflect and conflict with colloquial uses. Defining attributes, demonstration cases, antecedents, consequences and empirical referents are identified before a definition of fatigue is developed and proposed for nursing. This clarification of the phenomenon has particular relevance for clinical nursing, future research and the development of fatigue theories.
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PMID:Fatigue: a concept analysis. 888 2

This concept analysis attempts to clarify and analyse the concept 'chronic fatigue' and does so by utilizing the framework outlined by Walker and Avant (1995). The aim is to use this work to underpin future research into the care of patients suffering from chronic obstructive pulmonary disease (COPD). The literature revealed no universal definition of fatigue and a confusion exists between fatigue and chronic fatigue. Three concept analyses are considered to assist clarification. Everyday meanings are sought as well as meanings revealed in poetry. A continuum from tired to exhausted is identified and definitions offered. Defining attributes are decided upon which will be used as an operational definition in later research. Constructed cases are created; antecedents and consequences are devised from the literature; scales, tests and descriptions of general appearance which appear within the literature are considered as empirical referents. However, whilst assisting with the understanding of the concept and future research, the complexity of this subject is still evident.
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PMID:Concept analysis: chronic fatigue. 1111 97

Electrophysiological recordings are considered a reliable method of assessing a person's alertness. Sleep medicine is asked to offer objective methods to measure daytime alertness, tiredness and sleepiness. In this study, EEG signals recorded from 30 subjects were processed by PC-computer using classical and model-based methods. The classical method (fast Fourier transform) and three model-based methods (Burg autoregresse, moving average, least-squares modified Yule-Walker autoregressive moving average methods) were selected for processing EEG signals to discriminate the alertness level of subject. Power spectra of EEG signals were obtained by using these spectrum analysis techniques. These EEG spectra were then used to compare the applied methods in terms of their frequency resolution and the effects in determination of vigilance state of subject. It is found that, FFT and MA methods have low spectral resolution, these two methods are not appropriate for the analysis of the a wake-sleep correlation. Burg AR and least-squares modified Yule-Walker ARMA methods' performance characteristics have been found extremely valuable for the determination of vigilance state of a healthy subject, because of their clear spectra.
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PMID:Application of classical and model-based spectral methods to describe the state of alertness in EEG. 1618 Apr 83

Compassion fatigue is a relatively new term in nursing. This term describes mood swings experienced by healthcare providers that are both complex in origin and intensify over time due to cumulative stress. Quality of care can be affected if compassion fatigue goes untreated. This paper presents a concept analysis of compassion fatigue using Walker & Avant's method. Results show the defining attributes of compassion fatigue to include: 1. accumulated patient and family suffering; 2. sufferer unable to release built-up stresses effectively; and 3. negative effects on physical, psychological, and spiritual health. Identified antecedents of compassion fatigue included: (1) working as a healthcare provider; (2) investing sympathy in others over a long period of time; and (3) ignoring stress symptoms and personal emotional needs over time. Identified consequences of compassion fatigue included: (1) decreased coping ability; (2) damage / destruction of patient relationship; and (3) increased medical care costs. This study conducted a concept analysis to offer a better understanding of the concept of compassion fatigue and provide a reference for nursing practice and compassion fatigue-related nursing research.
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PMID:[Compassion fatigue: a concept analysis]. 2145

Walker and Avant's method of concept analysis was used to delve into the initial understanding of compassion fatigue, a relatively new concept being explored with critical care nurses and other health care professionals. The term was originally used in 1992 involving research exploring burnout experienced by critical care nurses when a trend emerged where nurses appeared to have lost their "ability to nurture." The term has since been used synonymously with secondary traumatic stress disorder. Two important goals exist for this article: First, theoretically to conduct a concept analysis of compassion fatigue, thereby providing information for critical care nurses to understand the concept as a universal human experience. Second, from a caring perspective, identifying the effects related to critical care nurses provides an opportunity to address physical and somatic consequences of compassion fatigue that will ultimately become important to nursing practice, education, and research.
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PMID:Concept analysis: compassion fatigue and effects upon critical care nurses. 2294 73

Frost damage to the xylem conduits of trees is a phenomenon of eco-physiological importance. It is often documented in terms of the percentage loss of conductivity (PLC), an indicator of air filling of the conduits. However, trees that refill their conduits in spring could be impacted more by damage to the conduits that reduce cavitation resistance, making them more susceptible to future drought events. We investigated whether ice formation, dynamic flexing of frozen branches or freeze-thaw events could reduce the cavitation resistance (cause "frost fatigue") in first-year shoots of apple (Malus domestica) and clonal hybrid cottonwood (Walker). Frost fatigue was measured in terms of P50 (the negative xylem pressure required to cause a 50 % loss of conductivity). All treatment groups showed significant frost fatigue, with the exception of the pre-flushed, constantly frozen poplar branches. The P50 following freeze treatments was approximately 50 % of the pre-freeze values. The effect tended to be greater in freeze-thawed branches. Dynamic bending of the branches had no effect on either PLC or P50. In three out of four cases, there was a significant correlation between P50 and PLC. Frost fatigue occurred in both apple and poplar, two unrelated species with different drought and frost tolerances, suggesting that it may be a widespread phenomenon that could impact the ecophysiology of temperate forests.
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PMID:Does freezing and dynamic flexing of frozen branches impact the cavitation resistance of Malus domestica and the Populus clone Walker? 2362 4

This paper deals with the effect of several residual stress profiles on the fatigue crack propagation in prestressing steel wires subjected to tension loading or bending moment. To this end, a computer program was developed to evaluate the crack front evolution on the basis of the Walker law. Results demonstrate that the absence of residual stresses makes the crack propagate towards a preferential crack path. When surface residual stresses are tensile and, correspondingly, core residual stresses are compressive, the fatigue crack fronts rapidly converge towards a quasi-straightshape. When surface residual stresses are compressive, with their corresponding tensile stresses in the core area, a preferential crack path also appears.
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PMID:Influence of Residual Stress Field on the Fatigue Crack Propagation in Prestressing Steel Wires. 2879 61

In this study, performance of two existing Walker parameter estimation models has been investigated. Results show that those developed mainly for steel did not provide reasonable fits to experimental Walker parameters for fatigue data for Al-7%Si-Mg alloy castings in the literature. A strong relationship between the Walker parameter and the structural quality, quantified by the quality index, QT, was observed and an empirical equation to estimate the Walker parameter for these alloys was developed. These findings indicate that the Walker parameter is not an intrinsic material property and the structural quality of the specimens must be taken into account for mean stress correction in fatigue testing.
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PMID:Walker Parameter for Mean Stress Correction in Fatigue Testing of Al-7%Si-Mg Alloy Castings. 2929 46

Carbon fiber reinforced plastic (CFRP) laminates are used as main structural members in many applications. Transverse cracks that form in 90° layers of CFRP laminates are mostly initial damage in the case where tensile loading is vertically applied to the 90° layers of CFRP laminates, and they are the origin of more serious damage of delamination and fiber breakage. It is thus important to predict quantitatively the transverse crack initiation of CFRP laminates subjected to cyclic loading to ensure the long-term reliability of the laminates. The initiation and multiplication behaviors of transverse cracks strongly depend on the laminate configuration, thickness, and thermal residual stress. Therefore, a model based on the Walker model was proposed to predict transverse crack initiation in CFRP cross-ply and quasi-isotropic laminates under cyclic loading in the present study. The usefulness of the proposed model was verified with 10 different CFRP laminates formed from four different prepregs with epoxy resin matrices. The analysis results were in good agreement with experimental results. The fatigue life was expressed with three constants, which related to the fatigue strength reduction, the normalized fatigue strength at N = 1 cycle, and the contribution of stress amplitude to the fatigue life, and they are independent of the laminate configuration.
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PMID:Fatigue Life Prediction for Transverse Crack Initiation of CFRP Cross-Ply and Quasi-Isotropic Laminates. 2999 29

Patients' care-seeking behaviors are often based on the symptoms they experience. Prodromal myocardial infarction symptoms are those symptoms that occur prior to a myocardial infarction, and fatigue is common. However, the concept of prodromal myocardial infarction fatigue has not been explored from a multidimensional perspective using a concept analysis approach. The purpose of this concept analysis was to analyze this concept, using Walker and Avant's (2011) concept analysis methodology. A comprehensive literature search revealed 41 records for analysis. The structure and function of this concept was examined, and an operational definition of prodromal myocardial infarction fatigue was developed.
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PMID:Prodromal Myocardial Infarction Fatigue: A Concept Analysis. 3053 51


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