Medical progress through technology
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Colors in video representations of angioscopic images are up until now described by an human observer. Differences in settings of the monitor and the inherent poor ability of the human eye to classify colors objectively results in a very poor intraobserver as well as interobserver variability. ⋯ Results with this method for standard calibrated colors are given. Possible sources of error are discussed and methods to minimize these errors are presented.
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Comparative Study
Assessment of cardiac output during exercise. Transthoracic impedance vs. heart rate alone.
Previous investigators demonstrated divergent results, when comparing impedance to other established methods for the assessment of cardiac output. Cardiac output is defined as stroke volume multiplied by heart rate. Heart rate is easy to measure and the main determinant of cardiac output during exercise under physiologic conditions. ⋯ Transthoracic impedance cardiography is not a reliable technique to measure absolute values of cardiac output at rest. During exercise large scatter limits this method to the measurement of CO in larger groups. At exercise heart rate alone appears to be a better indicator of increase of cardiac output than impedance cardiography.
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Medical technologies that have high initial and operating costs are commonly labeled 'Big Ticket Technologies'. However, technologies with lower initial and operating costs, but which are utilized extensively in patient care, should be considered Big Ticket as well. Some of these technologies are product innovations, because they represent a new product or service. ⋯ Other examples include extracorporeal shock wave lithotripsy and resuscitation and intensive care technologies. Differences in the availability of these technologies in various countries reflects financial incentives and disincentives at work in the countries, expectation levels for health care in the countries, and the degree to which the diffusion and use of medical technologies are regulated. Evidence of the cost-effectiveness of medical technologies, and the impact of their use on health outcomes, is rapidly being added as an additional criterion for evaluation of the usefulness of medical technologies in health care.
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We examined how lowpass filtering has an influence on nystagmus parameters: durations, amplitudes, and mean velocities of its slow and fast phases. We experimented with two types of common linear digital filters by using both nonrecursive and recursive filters, and with two types of nonlinear digital filters by using so-called standard median and hybrid median filters. We concluded that 70 Hz as strict cutoff frequency is high enough not to cause errors in the nystagmus parameters when information content in nystagmus signals is filtered above that cutoff frequency with linear filters. Using nonlinear filters good window lengths of filtering are equal to or less than about nine samples for a sampling frequency of 400 Hz which we applied.
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Use of a closed rebreathing circuit for anesthesia delivery offers several advantages: conservation of anesthetic agent, natural heating and humidification of inspired gases, less pollution, and improved monitoring. However, the technique requires careful control of the fresh gas and anesthetic delivery. An anesthesia delivery system has been developed which automatically controls fresh gas delivery, anesthetic delivery, and ventilation in order to regulate circuit volume, oxygen concentration, end-tidal anesthetic concentration, and end-tidal PCO2. ⋯ No further tuning was required for any of the other patients or controllers. During abdominal surgery, the end-tidal bellows position measurement and end-tidal anesthetic concentration measurement increased in variability. The cause of the variability and its elimination are discussed in the article.