CLINICAL APPLICATIONS OF AN IMPROVED, RAPIDLY RESPONDING FIBEROPTIC CATHETER.

Abstract Recent modifications of a fiberoptic catheter system now permit direct and continuous measurement of intravascular oxygen saturation. The response time of the new instrument is 0.1 sec. By an interchange of optical filters, the device can also be used for the registration of indicator dilution curves using indocyanine green dye. Oxygen saturation has been measured without complications in 30 patients for periods as long as three hours. The system proved particularly useful in facilitating rapid and thorough catheterization studies in patients with left to right shunts, without the necessity of withdrawing blood. In addition, the rapid response time of the catheter-tip oximeter permitted study of phasic changes in the pulmonary arterial oxygen saturation during respiratory maneuvers. Variations of up to 3 per cent saturation were noted with deep respirations, a decrease in saturation resulting from inspiration. Changes in pulmonary arterial oxygen saturation during the Valsalva maneuver were variable in patients without circulatory shunts, although decreases occurred on its release. In patients with atrial septal defect, pulmonary arterial oxygen saturation also decreased with inspiration, while during the Valsalva maneuver, an increase in the saturation was observed. Finally, the catheter-tip oximeter permitted continuous measurement of the pulmonary arterial oxygen saturation before, during and after muscular exercise either in the supine or upright positions. It is concluded that this instrument provides a new and valuable tool both for cardiovascular diagnosis and for clinical investigations.