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

According to a recent meta-analysis, in patients with a body mass index (BMI) ≥ 30, a high fraction of inhaled oxygen (FiO(2)) did not increase postoperative atelectasis. However, a high FiO(2) generally increases the risk of postoperative atelectasis. Therefore, this study aimed to evaluate the effect of FiO(2) on 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% O(2) during preinduction and emergence and 50% O(2) during anesthesia. Groups B and D received 40% O(2) for 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 FiO(2) had a greater effect on the development of atelectasis in obese patients than did low FiO(2); however, in normal-weight individuals, FiO(2) did not have a significant effect on postoperative atelectasis.