Impact of high fraction of inspired oxygen before extubation on incidence of postoperative atelectasis in children: a randomized controlled trial.

BACKGROUND: High fraction of inspired oxygen (FiO2) leads to absorption atelectasis during general anesthesia. This can further lead to decreased compliance, increased intrapulmonary shunt, increased pulmonary vascular resistance, hypoxemia, and lung injury. METHOD: To compare the atelectasis formation in pediatric patients receiving different FiO2 before extubation. We evaluated 64 children, aged 1-14 years, ASA status I/ II, planned for elective non-thoracic, non-abdominal surgery in supine position with anticipated duration of general anesthesia between 1 and 3 h from August 2021 to July 2024. Patients were allocated to receive either low FiO2 (50%) or high FiO2 (100%) before extubation. Lung ultrasound was performed before and after extubation in all patients to assess for the presence of atelectasis. RESULTS: A statistically significant difference in incidence of postoperative atelectasis was found between low and high FiO2 groups (0% versus 56.3%; p < 0.001). There was no case of postoperative desaturation in either group. The incidence of postoperative fever was also similar between the groups (4/32 versus 5/32; p = 1.00) and was not associated with postoperative atelectasis (OR 0.69; 95% CI 0.13;3.72). CONCLUSION: 100% FiO2 in children before extubation favors postoperative atelectasis formation, which can be reduced with administration of lower oxygen fractions. IMPACT: This study is the first randomized controlled trial in children to evaluate the effect of pre-extubation inspired oxygen concentration on post-extubation atelectasis, using lung ultrasound. Even short-term administration of 100% FiO₂ (10-20 min) before extubation significantly increases the incidence and severity of postoperative atelectasis in children. A lower FiO₂ of 50% before extubation can be safely used, challenging the routine practice of 100% oxygen during emergence. The results refine existing knowledge by identifying extubation as a critical, previously under-studied window for oxygen-induced atelectasis, thereby emphasizing on lung-protective extubation strategies in children.