Digital stethoscope technology to assess effects of surfactant administration in preterm neonates.

Background: Assessing lung aeration in preterm neonates with respiratory distress syndrome (RDS) assists in classifying the severity of the disease and guiding treatment. An increase in lung aeration has been shown to increase the attenuation of high frequency sounds. Hence, digital stethoscopes (DS) may offer a simple, non-invasive method to assess lung aeration in preterm neonates with RDS. Method(s): A commercially available DS and smartphone software was used to record the breath sounds of preterm neonates born at gestational age less than 32 weeks. One-minute DS recordings were performed within an hour prior to and following surfactant replacement therapy (SRT). The recordings were filtered to reduce background noise and spectral analysis performed to assess parameters including total power and the proportion of power in the low (100-200 Hz), medium (200-400 Hz) and high (400-800 Hz) frequency ranges. Result(s): Twenty-one neonates were studied. After exclusions due to background noise, crying or insufficient breath sounds, nine neonates with paired recordings (median (IQR) gestational age 26.3 (5.4) weeks and weight 726 (674) grams) were analysed. There was a significant decrease in the fraction of inspired oxygen following SRT (P = 0.03). There were no significant differences in the acoustic features before and after SRT. Conclusion(s): There were no detectable differences noted in the acoustic characteristics of preterm neonatal breath sounds following SRT. This may be due to the small sample size, sound interference from respiratory support devices or a lack of change in lung aeration.