Characterization of the Rapid Drop in Pulse Oximetry Reading After Intraoperative Administration of Methylene Blue in Open Thoracoabdominal Aortic Repairs

Abstract

This study evaluates the changes of oxygen saturation (SpO2) after intravenous administration of methylene blue in 103 patients undergoing open repair of thoracoabdominal aortic aneurysms. We found that SpO2 decreased by a median (interquartile range [IQR]) of 49% (37%-81%) <1 minute after methylene blue administration and recovered completely after approximately 6 minutes-median (IQR) of 270 seconds (180-510). A shorter time to nadir SpO2 was associated with a higher nadir (Spearman r [95% confidence interval {CI}], -0.32 [-0.50 to -0.13]; P = .001). Body surface area (BSA) was positively correlated with nadir SpO2 (Spearman r [95% CI], 0.36 [0.15-0.51]; P < .001).