Lung ultrasound for early surfactant treatment: Development and validation of a predictive model.

Aim: To develop and validate a feasible predictive model for early surfactant treatment in very preterm infants (VPI) admitted with respiratory distress syndrome (RDS).

Methods: Preterm infants less than 32 weeks of gestation with RDS and stabilized with noninvasive ventilation in delivery room were recruited (January 2018-April 2020). Clinical data, chest X-ray (CXR) score, respiratory support, oxygen saturation/fraction of inspired oxygen ratio (SF ratio), lung ultrasound (LUS) score, and diaphragmatic thickening fraction (DTF) were recorded at 60-120 min of life. Oxygen threshold for surfactant administration was fraction of inspired oxygen more than 30%; ultrasound findings were blinded. Logistic regression models using a stepwise selection of variables were developed in the derivation cohort. Coefficients from these models were applied to the validation cohort and a diagnostic performance was calculated.

Results: A total of 144 VPI with a mean gestational age of 28.7 ± 2.2 weeks were included (94 into the derivation cohort, 50 into the validation cohort); 37 required surfactant treatment (25.7%). Gestational age, SF ratio, LUS score, CXR score, and Silverman score were related to surfactant administration (R  = .823). Predictors included in the final model for surfactant administration were SF ratio and LUS score (R  = .783) with an area under the receiver operating characteristic (AUC) = 0.97 (95% confidence interval [CI]: 0.93-1.00) in the derivation cohort and an AUC = 0.95 (95% CI: 0.85-0.99) in the validation cohort. By applying our predictive model, 26 patients (70.2%) would have been treated with surfactant earlier than 2 h of life.

Conclusion: The predictive model showed a high diagnostic performance and could be of value to optimize early respiratory management in VPI with RDS.