TY - JOUR
AU1 - Paul, W
AB - An oximeter consisting of an earpiece and associated electronic apparatus provides continuous estimation of oxygen saturation in human arterial blood. The earpiece, made of Duralumin, contains an incandescent lamp, two selenium barrier-layer photocells fitted with suitable gelatin filters, and a pressure capsule. An oscillator supplies the lamp with direct current interrupted at 91 c/s. The a.c. signals from each of the photocells are amplified. The amplified alternating voltages are rectified and each applied to a valve voltmeter. With the earpiece mounted on the pinna of the ear, air pressure (300 mm of mercury) is applied to the pressure capsule, thus removing blood from the transilluminated area. Sufficient positive bias is then applied to each rectifier to set the meters to a fixed point. On release of pressure, blood returns to the ear; the current in one meter (thickness indicator) rises to a finite value depending on the amount of blood in the illuminated vascular bed; the current in the other meter (saturation indicator) rises to a value depending on both the amount of blood in the vascular bed and its state of oxygen saturation. The "saturation" meter is calibrated to read percentage oxygen saturation directly when a variable shunt has been adjusted according to the reading on the "thickness" meter. Instrument accuracy, expressed as standard deviation measured with three earpieces, was  3.8,  3.3 and  3.2% respectively.
TI - An oximeter for continuous absolute estimation of oxygen saturation
JF - Journal of Scientific Instruments
DO - 10.1088/0950-7671/30/5/306
DA - 1953-05-01
UR - https://www.deepdyve.com/lp/iop-publishing/an-oximeter-for-continuous-absolute-estimation-of-oxygen-saturation-7NbCpnaUhz
SP - 165
VL - 30
IS - 5
DP - DeepDyve
ER -