Artifactual reduction in oxygen saturation readings affected by indocyanine green in ophthalmic angiography

PURPOSE To investigate time-dependent changes in oxygen saturation (SpO2) readings during fluorescein angiography (FA) or simultaneous fluorescein and indocyanine green angiography (F/I). STUDY DESIGN A prospective observational study. METHODS One hundred twenty-five consecutive patients underwent FA or F/I. After application of the exclusion criteria, 67 patients (28 underwent FA, 39 underwent F/I) were included in the study. During angiography, SpO2 was measured by using a pulse oximeter and recording each second. The arm-to-retina circulation time (ARCT) was measured on the angiography video images. Latency time was defined as the time from intravenous injection of the dye to observation of a 3% decrease in the SpO2 reading, and variation SpO2, as the difference between baseline SpO2 and the lowest SpO2 value. RESULTS The mean variation SpO2 was - 1.0 ± 0.6 during FA, and - 6.1 ± 1.5 during F/I. Variation SpO2 was within 2% during FA and > 3% during F/I. No corresponding changes were observed in the other vital signs or subjective symptoms. The mean latency time was 33.3 ± 6.4 s. Latency time was positively correlated with the ARCT in the F/I group (rs = 0.766, P < .001). CONCLUSION Reductions in SpO2 readings were identified during F/I, but not during FA. Our results suggest that clinicians should be mindful that reductions in SpO2 readings during F/I may be artifactually caused by indocyanine green.