Continuous in vivo measurement of arterial oxygen saturation by oximetry.

A new device for continuous measurement of arterial oxygen saturation (SaO2), the Hewlett-Packard Model 47201A ear oximeter, was evaluated. The oximeter calculates saturation as a function of light transmittance through the patient's arterialized pinna. Oximeter SaO2 was compared with SaO2 calculated from 133 simultaneously obtained measurements of arterial blood pH and arterial oxygen tension in 19 subjects. The coefficient of correlation between these two is 0.9884 over a wide range of SaO2 (47 to 99 per cent) with a mean error of 1.09 per cent saturation. The line of regression with 95 per cent confidence bands is SaO2 (oximeter) = 6.51 + 0.93 (+/-0.02) SaO2 (arterial blood). The device permits continuous accurate measurement of SaO2 in vivo and is invaluable for indicating trends in clinical studies and appropriate times to do arterial blood studies.