Electromyographic activity of the sternocleidomastoid muscle in infants with bronchopulmonary dysplasia

Objective: To analyze and compare the activity of the sternocleidomastoid muscle in preterm infants with bronchopulmonary dysplasia, preterm infants without bronchopulmonary dysplasia, and healthy full-term infants. Material and methods: A cross-sectional study was conducted with 21 infants in the first year of life, categorized into three groups: preterm infants with BPD (GBPD); preterm infants without BPD (GPT); and control group (GC) with healthy full-term infants. The band frequency (BAND), coefficient of variation (CV), median frequency of the signal (F50), and root mean square (RMS) of the surface electromyography (EMG) signal were calculated. Results: The comparison of sternocleidomastoid (SM) activity showed lower F50 (p= 0.028) for GBPD when compared to GC; there was no statistical difference between the other features and the respective comparisons between the groups. Regarding the effect size, the results showed that there is a very large effect size between GBPD and GC in feature F50 (ES = 1.2). Additionally, there is a moderate effect size (ES = 0.5) in the features BAND (between GPT and GC), CV (between GBPD and GC), F50 (between GPT and GC), and RMS (between GPT and GC). The other comparisons have a small or very small effect size. Conclusion: Infants with BPD have lower F50 of the SM, in relation to full-term infant group. There was no statistical difference between the other features and the respective comparisons between the groups.