Effect of different oxygen concentrations developing pulmonary atelectasis of neonates during anesthesia: a randomized controlled trial

Objectives: This study sought to evaluate the effect of different oxygen concentrations on the development of pulmonary atelectasis in neonates during anesthesia with mechanical ventilation using ultrasound.

Methods: Sixty-three neonates undergoing laparotomies were randomly divided into three groups. A: FiO2 = 30%, B: FiO2 = 40%, C: FiO2 = 50%. Ultrasound was performed to guide pulmonary resuscitation maneuvers after tracheal intubation and before tracheal extubation and performed at the end of surgery in each group to evaluate lung consolidation. The following parameters were assessed: (1) primary observation index: pulmonary consolidation score; (2) secondary observation index: area of pulmonary atelectasis, changes in oxygenation index, pulmonary atelectasis, and the incidence of hypoxemia; (3) pulmonary complications at 72 hours postoperatively.

Results: There was a significant difference in pulmonary consolidation scores between the 30% and 50% groups (p < 0.001) and the 40% and 50% groups (p < 0.01); the difference between the 30% and 40% groups was not significant (p > 0.05). The incidence of pulmonary atelectasis was 82.54%. Pulmonary atelectasis occurred in the posterior (81%) and in the right posteriolateral positions (51%). There was a significant change in the oxygenation index before and after pulmonary ultrasound-guided re-expansion before recruitment (T1) compared to after preoperative recruitment (T2) (p < 0.001) and before postoperative recruitment (T3) compared to after postoperative recruitment (T4) (p < 0.001). 6 children in the 30% oxygen concentration group developed mild hypoxemia and 2 children developed moderate hypoxemia; while no hypoxemia occurred in the remaining two groups. No pulmonary complications occurred at 72 hours postoperatively.

Conclusions: 40% FiO2 may be the oxygen concentration that neither causes significant pulmonary atelectasis nor hypoxemia during the maintenance of mechanical ventilation during neonatal anesthesia. However, there may also be lower lung consolidation scores and no hypoxemia between 30% oxygen concentration and 40% we have not studied it. Pulmonary atelectasis is present in most anesthetized patients and occurs mainly in gravity-dependent areas, more on the right than on the left side. Pulmonary ultrasound-guided pulmonary recruitment maneuvers can significantly improve neonatal pulmonary gas exchange function.

Lung ultrasound; Pulmonary atelectasis; Neonates; Oxygen; Anesthesia

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