The effect of oxygen concentration on atelectasis formation during induction of general anesthesia in children: A prospective randomized controlled trial

In adults, the use of lower oxygen concentration during induction is associated with less atelectasis formation without an increase in incidence of hypoxia. However, it is unknown whether this remains true in the pediatric patients.Fifty-four pediatric patients who were scheduled to undergo elective lower abdominal surgery were randomized to one of three oxygenation groups: 100%, 80%, or 60% oxygen (in air). During anesthesia induction, patients were ventilated with sevoflurane in 100%, 80%, or 60% oxygen. Endotracheal intubation and mechanical ventilation were performed. Atelectasis was diagnosed using LUS, which was performed after anesthetic induction and at the end of surgery.We assessed atelectasis after anesthetic induction and at the end of surgery. After anesthetic induction, the number of atelectatic lung regions was significantly different among the three groups (median [IQR], 2.0 [1.0-2.5], 2.0 [1.0-2.8], and 3.0 [2.0-3.0] in the 60%, 80%, and 100% oxygen groups, p = .033) and between the 60% and 100% groups (p = .015), but not between 80% and 100% groups (p = .074). However, no differences in the number of atelectatic lung regions were found among the three groups at the end of surgery (2.0 [1.3-3.8], 3.0 [1.8-3.0], and 4.0 [2.0-4.0] in the 60%, 80%, and 100% oxygen groups; p = .169).Lower oxygen concentration during anesthetic induction is associated with less atelectasis formation immediately after anesthetic induction in children. In addition, applying 80% oxygen instead of 100% oxygen is not enough to prevent atelectasis formation, and 60% oxygen should be applied to prevent atelectasis. However, this effect does not last until the end of surgery.