ABSTRACT
BACKGROUND: Existing research demonstrates that youth with chronic illness often experience challenges including poor academic performance, attendance, and social success. However, past research demonstrates a lack of support for teachers to best educate students with chronic illness. In this study, we aim to describe the needs of local educators when working with students with chronic illness. METHODS: A questionnaire was completed by 383 middle or high school professionals. Responses were analyzed using descriptive statistics. ANOVA was used to examine differences between school professional groups and chronic illness types. RESULTS: Participants tended to disagree that students with chronic illness faced challenges in school and agreed that they had enough support to meet students' needs. They tended to agree that more collaboration between the health care team, schools, and families was needed. Participants reported feeling least prepared in working with students who had cystic fibrosis, epilepsy, or sickle cell disease. School nurses were more likely to recognize the challenges, supports, and collaboration needed. CONCLUSIONS: More training and support is needed for school professionals in their work with students with chronic illness. Assessments may be useful at a local level to help schools develop better policies and plans for educating youth with chronic illness.
Subject(s)
Chronic Disease/psychology , Health Knowledge, Attitudes, Practice , School Teachers/psychology , Academic Success , Adolescent , Analysis of Variance , Attitude to Health , Chronic Disease/epidemiology , Humans , School Health Services/organization & administration , School Teachers/statistics & numerical dataABSTRACT
Traditionally, it was believed that cardiac rhythm stability was governed by the slope of the restitution curve (RC), which relates the duration of an action potential to the preceding diastolic interval. However, a single RC does not exist; rate-dependence leads to multiple distinct RCs. We measure spatial differences in the steady-state action potential duration (APD), as well as in three different RCs: the S1-S2 (SRC), constant-basic-cycle-length (BRC), and dynamic (DRC), and correlate these differences with the tissue's propensity to develop alternans. The results show that spatial differences in APD, SRC slope, and DRC slope are correlated with the tissue's propensity to exhibit alternans. These results may lead to a new diagnostic approach to identifying patients with vulnerability to arrhythmias, which will involve pacing at slow rates and analyzing spatial differences in restitution properties.
Subject(s)
Ventricular Fibrillation/diagnosis , Ventricular Fibrillation/physiopathology , Action Potentials/physiology , Animals , Arrhythmias, Cardiac , Cardiac Pacing, Artificial , Electrodes , Equipment Design , Heart Conduction System/physiology , Humans , Microelectrodes , Models, Cardiovascular , Neural Conduction , Rana catesbeiana , Signal Processing, Computer-AssistedABSTRACT
Experimental studies have linked alternans, an abnormal beat-to-beat alternation of cardiac action potential duration, to the genesis of lethal arrhythmias such as ventricular fibrillation. Prior studies have considered various closed-loop feedback control algorithms for perturbing interstimulus intervals in such a way that alternans is suppressed. However, some experimental cases are restricted in that the controller's stimuli must preempt those of the existing waves that are propagating in the tissue, and therefore only shortening perturbations to the underlying pacing are allowed. We present results demonstrating that a technique known as extended time-delay autosynchronization (ETDAS) can effectively control alternans locally while operating within the above constraints. We show that ETDAS, which has already been used to control chaos in physical systems, has numerous advantages over previously proposed alternans control schemes.
Subject(s)
Biophysics/methods , Electrophysiology/methods , Animals , Arrhythmias, Cardiac/diagnosis , Arrhythmias, Cardiac/pathology , Heart/physiology , Humans , Membrane Potentials , Models, Cardiovascular , Models, Chemical , Models, Statistical , Myocardium/pathology , Sensitivity and Specificity , Time Factors , Ventricular Fibrillation/diagnosis , Ventricular Fibrillation/pathologyABSTRACT
We investigate, both experimentally and theoretically, the period-doubling bifurcation to alternans in heart tissue. Previously, this phenomenon has been modeled with either smooth or border-collision dynamics. Using a modification of existing experimental techniques, we find a hybrid behavior: Very close to the bifurcation point, the dynamics is smooth, whereas further away it is border-collision-like. The essence of this behavior is captured by a model that exhibits what we call an unfolded border-collision bifurcation. This new model elucidates that, in an experiment, where only a limited number of data points can be measured, the smooth behavior of the bifurcation can easily be missed.
Subject(s)
Action Potentials , Models, Cardiovascular , Heart , HumansABSTRACT
Various authors have shown that, near the onset of a period-doubling bifurcation, small perturbations in the control parameter may result in much larger disturbances in the response of the dynamical system. Such amplification of small signals can be measured by a gain defined as the magnitude of the disturbance in the response divided by the perturbation amplitude. In this paper, the perturbed response is studied using normal forms based on the most general assumptions of iterated maps. Such an analysis provides a theoretical footing for previous experimental and numerical observations, such as the failure of linear analysis and the saturation of the gain. Qualitative as well as quantitative features of the gain are exhibited using selected models of cardiac dynamics.
