Stable microbubble test and click test to predict respiratory distress syndrome in preterm infants not requiring ventilation at birth

Aims: To determine the usefulness of the stable microbubble test (SMT) and of the click test (CT) on gastric aspirates obtained soon after birth to predict respiratory distress syndrome (RDS) in preterm babies not requiring ventilation at birth. Patients and methods: The study was carried out with a cohort between 24 and 34 weeks of gestational age. Gastric secretions were collected before 1 hour of life and frozen for further analysis. Results: 110 neonates were studied. For a cut-off value ≤ 10 microbubbles/mm2 (mb/mm2) the sensitivity and specificity to predict RDS were 73.9% and 92%, respectively, in the SMT. The best SMT cut-off point to predict RDS was ≤ 15 mb/mm2 (sensitivity = 82.6%;specificity = 85.1%) if equal weight was given to false-positive and false-negative results. CT (104 samples) showed a sensitivity of 100% and a specificity of 45.1% to predict RDS. The overall accuracy of the SMT was better than the overall accuracy of the CT (87.5% vs. 64.4%; p < 0.001) to predict RDS. Conclusions: The SMT is more accurate than the CT to predict RDS in infants below 35 weeks of gestational age and may be helpful to select patients to receive surfactant.