Lung Ultrasound as a Predictor of Mechanical Ventilation in Neonates Older than 32 Weeks

Abstract

Background: The prognosis of neonatal respiratory distress may be difficult to estimate at admission. Lung ultrasound is a useful diagnostic tool that is quick, requires little training, and is radiation free. Objective: This study aims to analyze whether early lung ultrasound can predict respiratory failure. Methods: From January to December 2014, lung ultrasound was performed on neonates admitted with breathing difficulties if they were older than 32 weeks and not intubated. A neonatologist, not aware of the patient's clinical condition, analyzed the stored ultrasound images. The findings were classified into the following 2 groups according to the potential risk of a bad respiratory outcome: low risk (normal or transient tachypnea of the newborn) or high risk (respiratory distress syndrome, meconium aspiration syndrome, pneumothorax, or pneumonia). A second investigator made the same classification after reading the chest X-rays. Respiratory failure was defined as a need for mechanical ventilation during the first day of life. Results: In total, 105 neonates were recruited (64.8% in the low-risk sonography group and 35.2% in the high-risk sonography group). Of those, 20% needed intubation, and this was more frequent in the high-risk group (relative risk = 17.5; 95% CI 4.3-70.9, p < 0.01). As predictors of respiratory failure, lung ultrasound and chest X-ray showed a high index of agreement (κ coefficient = 0.91; 95% CI 0.83-1, p < 0.01) and good accuracy (ultrasound: 95% sensitivity, 82.5% specificity, and a negative predictive value of 98.5%). Conclusions: Early lung ultrasound is a useful tool to determine which neonates admitted with respiratory distress will require mechanical ventilation. It may help the clinician to carrying out appropriate transfers.