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Polysomnographs designed for simultaneous recording of a variety of physiologic parameters during sleep in non-attended locations. These instruments typically consist of a multichannel recorder that typically have a reduced number of channels (i.e., less than 12 channels), but that should assess at least heart rate, oxygen saturation, and respiratory analysis. These polysomnographs include a set of detachable sensors and electrodes fixed to the patient at the distal end that provide the input signals needed for graphic representation of the parameters; the instruments also include transducers (e.g., temperature, pressure), amplifiers, filters, and memory. The devices measure, assess, and display graphics of the variations in time of some or all of the electrocardiographic, electroencephalographic, and electromyographic signals, as well as other parameters such as cardiac and breathing rhythms, oxygen saturation, and eye and legs movements; some instruments may include a synchronized patient video camera. The sensors and leads transmit the signals to an electronic recorder which is capable of reproducing their characteristics in an amplitude versus time graph (i.e., a polysomnogram) and may also provide a spectral analysis of the signals. Portable polysomnographs are mainly used to evaluate sleeping disorders, particularly for screening a primary assessment of sleep apnea; the instruments are not intended for a real-time assessment of the patient\'s conditions.
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