Lung ultrasound score-based assessment of postoperative atelectasis in obese patients according to inspired oxygen concentration: A prospective, randomized-controlled study

Background: According to a recent meta-analysis, in patients with a body mass index (BMI) ≥ 30, a high fraction of inhaled oxygen (FiO₂) did not increase postoperative atelectasis. However, a high FiO₂generally increases the risk of postoperative atelectasis. Therefore, this study aimed to evaluate the effect of FiO₂on the development of atelectasis in obese patients using the modified lung ultrasound score (LUSS). Methods: Patients were assigned to 4 groups: BMI ≥ 30: group A (n = 21) and group B (n = 20) and normal BMI: group C (n = 22) and group D (n = 21). Groups A and C were administered 100% O₂during preinduction and emergence and 50% O₂during anesthesia. Groups B and D received 40% O₂for anesthesia. The modified LUSS was assessed before and 20 min after arrival to the postanesthesia care unit (PACU). Results: The difference between the modified LUSS preinduction and PACU was significantly higher in group A with a BMI ≥ 30 (P =.006); however, there was an insignificant difference between groups C and D in the normal BMI group (P =.076). Conclusion: High FiO₂had a greater effect on the development of atelectasis in obese patients than did low FiO₂; however, in normal-weight individuals, FiO₂did not have a significant effect on postoperative atelectasis.