In many catheterization laboratories and intensive care units, oxygen saturation of single blood specimens is measured from the superior vena cava (SVC), right atrium (RA) and pulmonary artery (PA) during right-sided catheterization, but variability of such single measurements in adults with and without intracardiac left-to-right shunting has not been assessed. Oxygen saturation of SVC, RA and PA single blood samples were measured in 1,031 adults (524 men, 507 women, aged 50 ± 13 years [mean ± standard deviation SD]). In the 980 patients without shunting, differences in saturation between SVC and RA, RA and PA and SVC and PA were 3.9 ± 2.4%, 2.3 ± 1.7%, and 4.0 ± 2.5%, respectively, so that the normal limits of variability (mean ± 2 standard deviations) for these saturation differences were 8.7%, 5.7% and 9.0%, respectively. Of the 51 patients with left-to-right shunting, these limits of variability of oxygen saturation correctly identified 46 (90%), and the 5 with shunting whose saturation differences were below these limits had small shunts ( Qp Qs ratios of 1.9 or less). Thus, assessment of oxygen saturation from single blood specimens obtained from the SVC, RA and PA offers excellent sensitivity (more than 90%), specificity (94 to 95%) and predictive accuracy (94% or more) in identifying patients with and without intracardiac left-to-right shunting. The sensitivity of these limits is especially high in patients with large shunts ( Qp Qs of 2 or more).
ASJC Scopus subject areas
- Cardiology and Cardiovascular Medicine