Journal of clinical monitoring
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Fiberoptic pulmonary artery catheters provide a practical method for continuously measuring the amount of oxygen in mixed venous blood. To characterize the usefulness of mixed venous oxygen saturation in managing patients with sepsis, we performed serial hemodynamic measurements on 20 patients with documented septic shock. ⋯ Mixed venous oxygen saturation less than 65% was clinically unacceptable in patients with sepsis and was associated with a poor prognosis. In this study, measurement of mixed venous oxygen saturation was a valuable predictor of survival in patients with septic shock and provided a means of continuously monitoring the status of tissue oxygenation.
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We have developed an anesthesia information system (AIS) that supports the anesthesiologist in monitoring and recording during a surgical operation. In development of the system, emphasis was placed on providing an anesthesiologist-computer interface that can be adapted to typical situations during anesthesia and to individual user behavior. One main feature of this interface is the integration of the input and output of information. ⋯ A one-page record of the anesthesia is automatically plotted on a multicolor digital plotter during the operation. An example of the use of the AIS is presented from a field test of the system during which it was evaluated in the operating room without interfering with the ongoing operation. Medical staff who used the AIS imitated the anesthesiologist's recording and information search behavior but did not have responsibility for the conduct of the anesthetic.
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Oximetry, the measurement of hemoglobin oxygen saturation in either blood or tissue, depends on the Lambert-Beer relationship between light transmission and optical density. Shortly after Bunsen and Kirchhoff invented the spectrometer in 1860, the oxygen transport function of hemoglobin was demonstrated by Stokes and Hoppe-Seyler, who showed color changes produced by aeration of hemoglobin solutions. In 1932 in Göttingen, Germany, Nicolai optically recorded the in vivo oxygen consumption of a hand after circulatory occlusion. ⋯ Shaw devised an eight-wavelength ear oximeter. Nakajima and co-workers invented the pulse oximeter, which avoids the need for calibration with only two wavelengths by responding only to the pulsatile changes in transmitted red and infrared light. Lübbers developed catheter tip and cuvette fiberoptic sensors for oxygen tension, carbon dioxide tension, and pH.
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One hundred and five children with congenital heart disease were monitored by pulse oximetry during cardiac catheterization. Excellent correlation (r = 0.95) was found between oxygen saturation values obtained with pulse oximetry and those obtained from arterial blood in 133 data pairs. ⋯ The clinical usefulness of pulse oximetry in the early recognition of decreased pulmonary blood flow or partial airway obstruction was demonstrated. Early diagnosis of changes in oxygenation was especially helpful in children with cyanotic congenital heart disease, in whom small changes in arterial oxygen tension may cause large changes in oxygen saturation.