Resuscitation
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Comparative Study
Differential contribution of skin impedance and thoracic volume to transthoracic impedance during external defibrillation.
Two mechanisms by which firm external paddle force decreases transthoracic impedance (TTI) have been proposed. Decreased impedance at the paddle-skin interface has been assumed to be the primary mechanism, but expulsion of air from the lungs, reducing lung volume is also likely to contribute. The relative contribution of each mechanism is unknown. ⋯ The decrease in TTI seen with increasing external paddle force is due primarily to improved electrical contact at the paddle-skin interface, with a decrease in thoracic volume accounting for no more than 16% of the overall decrease at forces used clinically.
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To study long-term survival and estimate the costs per year of survival after out-of-hospital cardiac arrest of cardiac origin. ⋯ Cardiac arrest patients do not occupy intensive care beds too long, and few end up in a vegetative state. Methodological differences in different studies makes meaningful comparisons of costs difficult, but the costs per life year saved are not high compared to other publications.
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Ventricular fibrillation (VF) is a leading cause of sudden death. Electrical defibrillation is the primary modality of treatment, but evidence is accumulating that its use in the late stage of VF prior to providing ventilation, chest compressions and the administration of appropriate medication is detrimental. In VF of <5 min duration a 'shock first' strategy is effective. ⋯ By constructing a flat, circular disk-shaped structure in a three-dimensional phase space and measuring the velocity of rotation of the position vector over time, a statistic is developed which rises from 58 rad/s at 1 min to 79 rad/s at 4 min and then decreases in a linear manner to 32 rad/s at 12.5 min. Using ScE and AV probability density estimated, VF of <5 min duration can be identified with 90% sensitivity on the basis of a single 5 s recording of the waveform. The combination of ScE and AV can be used in developing strategies for the treatment of VF during the different clinical phases of VF.
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Practice Guideline Guideline
Research on procedures in cardiopulmonary resuscitation that lie outside current guidelines.
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This prospective study evaluated the acquisition and retention of skills in cardio-pulmonary resuscitation (CPR) and the use of the automated external defibrillator (AED) by lay volunteers involved in the Department of Health, England National Defibrillator Programme. One hundred and twelve trainees were tested immediately before and after and initial 4-h class; 76 were similarly reassessed at refresher training 6 months later. A standardised test scenario that required assessment of the casualty, CPR and the use of on AED was evaluated using recording manikin data and video recordings. ⋯ Initial training improved performance of all CPR skills, although all except compression rate had deteriorated after 6 months. The proportion of subjects able to correctly perform most CPR skill was higher following refresher training that after the initial class. Although this course was judged to be effective in teaching delivery of counter-shocks, the need was identified for more emphasis on positioning of electrodes, pre-shock safety checks, airway opening, ventilation volume, checking for signs of a circulation, hand positioning, and depth and rate of chest compressions.