Accuracy of Oxygen Saturation Measurements in Patients with Obesity Undergoing Bariatric Surgery

Background We aimed to determine the magnitude, direction, and influencing factors of the concordance between arterial oxygen saturation (SaO(2)) and peripheral capillary oxygen saturation (SpO(2)) in patients with obesity undergoing bariatric surgery, supporting the measurement of SaO(2) and SpO(2 )in key populations. Methods Patients with obesity undergoing bariatric surgery from 2017 to 2020 were included. Preoperative SpO(2) and SaO(2) were collected. Linear correlation and multiple linear regression analyses were performed to characterize the relationships between body mass index (BMI), age, and sex with pulse oximetry and arterial blood gas (ABG) parameters. Bland-Altman analysis was applied to determine the concordance between SpO(2) and SaO(2) and the limits of this concordance. Results A total of 134 patients with obesity undergoing bariatric surgery were enrolled. SaO(2) was negatively associated with BMI (p < 0.0001) and age (p = 0.006), and SpO(2) was negatively associated with BMI (p = 0.021) but not with age. SpO(2) overestimated SaO(2) in 91% of patients with a bias of 2.05%. This bias increased by 203% in hypoxemic patients compared with nonhypoxemic patients (p < 0.0001). The bias was 1.3-fold higher (p = 0.023) in patients with a high obesity surgery mortality risk score (OS-MRS) than in those with low or intermediate scores. Conclusion Compared with SpO(2), preoperative SaO(2) can more accurately reflect the real oxygen saturation in patients with obesity undergoing bariatric surgery, especially for those with BMI >= 40 kg/m(2), age >= 40 years, and high OS-MRS. ABG analysis can provide a more reliable basis for accurate and timely monitoring, ensuring the perioperative safety of susceptible patients.

Automated summary

This study aimed to determine the concordance between arterial oxygen saturation (SaO(2)) and peripheral capillary oxygen saturation (SpO(2)) in patients with obesity undergoing bariatric surgery. It found that SpO(2) overestimated SaO(2) and preoperative SaO(2) can more accurately reflect the real oxygen saturation, especially for patients with BMI >= 40 kg/m(2), age >= 40 years, and high OS-MRS.