Direct Effect of Caffeine on Diaphragmatic Muscles in Preterm Babies Through Ultrasonographic Examination

Caffeine is frequently used for the treatment of apnea in preterm babies. Its mechanism of action includes not only antagonism of adenosine receptors on central nervous system but also an increase in electrical activity of the diaphragm. Caffeine's direct effect on diaphragm was investigated via electromyography, but ultrasound has not been used to show visible changes in muscles after the treatment before. Therefore, we aimed to assess the effect of caffeine on diaphragmatic function through ultrasonographic examination. It was a prospective observational study. Fifty-six participants receiving nasal continuous positive airway pressure with less than or equal to 32 weeks' gestational age born were enrolled. Diaphragmatic thickness, amplitude of excursion, and velocity of movement were measured before and within 5 minutes after caffeine loading dose and compared to each other. The protocol was registered with ClinicalTrials.gov Identifier NCT04483492. Diaphragmatic thicknesses and diaphragmatic velocity of movement did not differ after the treatment. However, amplitude of excursion of the diaphragm was found significantly higher after caffeine loading dose (8.7 mm, 10mm, respectively, P < .05). Diaphragm excursion increased after caffeine treatment in preterm babies, and this finding was potentially supported the direct effect of the caffeine on diaphragm. Another important finding of this study is that it reinforces the utility of ultrasonography in assessing diaphragmatic function in preterm infants.