Journal of medical engineering & technology
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Comparative Study
Continuous measurement of blood gases using a combined electrochemical and spectrophotometric sensor.
The use of a combined electrochemical and fibreoptic continuous intra-arterial blood gas sensor is described. The purpose of the study was to evaluate the performance of the sensor in 10 patients in the intensive therapy unit following insertion through a femoral arterial cannula. To our knowledge this is the first published study on the valuation of an intravascular blood gas sensor through a femoral arterial cannula. ⋯ There was a degree of imprecision of the PCO2 sensor, the reasons for which are discussed. In summary, the intra-arterial sensor functioned well when inserted into the femoral artery in post-cardiopulmonary bypass patients. There were no complications attributable to sensor placement.
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Biomagnetism is essentially the study of the weak magnetic fields generated by biological organisms, in particular the human body. The human thorax is composed of a variety of tissues and organs of slightly different magnetic susceptibility. ⋯ In this study susceptibility 'maps' were obtained by measuring the magnetic field at several hundred points over the thorax. Results indicate that magnetic susceptibility mapping produces low-resolution images of internal body structures from which is should be possible to detect pathologies that cause alterations in tissue susceptibility.
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The assessment of the functional performance of non-invasive blood pressure (NIBP) monitors using a commercially available NIBP analyser (Dynatech CuffLink) was evaluated. The CuffLink includes facilities for performing a static pressure calibration, and safety cut-out pressure, leak rate and rapid deflate time measurements. Cuff pressure oscillations simulating a range of blood pressures at a range of heart rates enable dynamic tests of NIBP monitors to be performed. ⋯ The results demonstrate the variable nature of systolic, diastolic and mean blood pressure readings from NIBP monitors (even under stable laboratory conditions), reinforcing the importance of not relying on individual readings, but rather to consider the average of a few successive readings. Normative data for two models of NIBP monitor are provided. Applications of the CuffLink are discussed with reference to a protocol for NIBP monitor performance checks.
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In this paper we present the modelling, design, and initial experimental testing of a nerve cuff multielectrode system for selective stimulation of fibres in superficial peripheral nerve trunk regions which is capable of making a selective activation of multiple muscles. The developed multielectrode nerve cuff consists of 14 platinum stimulating electrodes embedded within a self-curling sheet of biocompatible insulation, exhibiting a spiral transverse cross-section. The spiral shape of the system is such that the number of stimulating electrodes which can be utilized depends on the diameter of the stimulated nerve. ⋯ For this purpose a calculation of activating function for six positions where the nerve fibres were supposed to lie within the longitudinally dissected sciatic nerve was performed. In two acute experiments on the sciatic nerve of the dog the objective was to characterize the effectiveness of the multielectrode system in monopolar selective stimulation of the superficial regions, innervating the gastrocnemius and tibialis anterior muscle. A selectivity preliminary tested by measuring the myoelectric activity of the gastrocnemius and tibialis anterior muscle after 2 months showed good results in both animals.
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A brief history of the regulation of medical device software within the United States is presented, along with a discussion of the reasoning that the US Food and Drug Administration (FDA) presents for modifying the requirements for software regulation from those previously used for hardware devices. The current regulatory status is discussed for the two categories of medical device software, software used within medical devices and software used to produce or test medical devices. ⋯ The two types of medical device software are related to the two areas of FDA regulation, good manufacturing practices and permission to sell medical devices. The expected direction of future medical device software regulation, and its relationship to the European Economic Community (EEC) and international markets is discussed.