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

Abstract

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 FiO2 generally increases the risk of postoperative atelectasis. Therefore, this study aimed to evaluate the effect of FiO2 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% O2 during preinduction and emergence and 50% O2 during anesthesia. Groups B and D received 40% O2 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 FiO2 had a greater effect on the development of atelectasis in obese patients than did low FiO2; however, in normal-weight individuals, FiO2 did not have a significant effect on postoperative atelectasis.

Stubborn hypoxemia after mild to moderate sedation and analgesia: A case report

“…The occurrence of pulmonary atelectasis is related to many factors, and the known relevant factors are obesity, acute lung inflammation, and advanced age in the preoperative period, and the intraoperative factors are ventilation strategy with high partial pressure of oxygen, ventilation strategy without positive end-expiratory pressure (PEEP) and low tidal volume, and body position, etc. [ 1 ] It has been shown in the literature [ 2 ] that when maintained in volume-controlled mode with inhaled oxygen concentration of 100%, pulmonary atelectasis develops within 5 minutes, but when the inhaled oxygen concentration is 40% pulmonary atelectasis starts to appear after 40 minutes. This case shows that in patients at high risk for lung inflammation, such as those of advanced age, pulmonary atelectasis occurs earlier and faster than expected, and is difficult to correct.…”