Serial sonographic assessment of diaphragmatic atrophy and lung injury patterns in mechanically ventilated preterm infants to predict extubation failure: a prospective observational study

Diaphragmatic atrophy (DA) and lung injury (LI) have been associated with mechanical ventilation (MV). We aimed to assess the ultrasonographic changes in diaphragmatic thickness and LI during MV and their prediction for extubation failure in preterm infants. In this prospective observational study, mechanically ventilated preterm infants, < 30 weeks gestation, within the first 24 h of life underwent a baseline, within 24 h of MV, and serial diaphragmatic and lung ultrasounds scans until their first extubation attempt. DA was defined as a decline in pre-extubation expiratory diaphragmatic thickness (DT_exp) by ≥ 10% compared to baseline. A total of 251 ultrasound scans were performed on 38 preterm infants with a mean gestational age of 26.6 ± 1.7 weeks. Of these, 18 infants (47%) had DA. Among infants with DA, a pattern of progressive decline in DT_exp was associated with a concomitant pattern of increase in the lung ultrasound score (LUS). Infants in the DA group experienced a significantly higher percentage of extubation failure [13 (72%) versus 5 (25%), p = 0.004] compared to the no-DA group. Pre-extubation LUS was significantly higher in the DA compared to the no-DA group (14.2 ± 6.0 versus 10.3 ± 5.2, p = 0.04). Logistic regression analysis controlling for gestational age, pre-extubation weight, and mean airway pressure at extubation showed that LUS [OR 1.27, 95% CI (1.04-1.56), p = 0.02] was an independent predictor of for extubation failure.

Conclusion: In this cohort of preterm infants, lung ultrasound score has proved to be a stronger predictor of successful extubation compared to diaphragmatic thickness.

What is known: • Ultrasonographic assessment of the diaphragm and lungs is a sensitive tool in diagnosis of ventilator induced diaphragmatic atrophy and lung injury in preterm infants. Accuracy of lung and diaphragmatic ultrasound in predicting extubation outcome in preterm infants is questionable.

What is new: • A pattern of progressive decline in diaphragmatic thickness was associated with a concomitant pattern of increase in the lung ultrasound score in mechanically ventilated preterm infants. Lung ultrasound score has proved to be a stronger predictor of successful extubation compared to diaphragmatic thickness.