The Effect of Minimally Invasive Surfactant Therapy on Diaphragmatic Activity.

Background: Minimally invasive surfactant therapy (MIST) is increasingly used to treat preterm infants with respiratory distress syndrome (RDS). However, the effect of MIST on breathing effort is poorly studied.

Objectives: To describe the effect of MIST on neural breathing effort assessed with transcutaneous electromyography of the diaphragm (dEMG) in preterm infants with RDS.

Methods: Preterm infants with a gestational age < 37 weeks treated with MIST for RDS were included. dEMG measurements were done from 15 min before to 1 h after MIST. The percentage change in dEMG activity after MIST and the clinical response were analyzed.

Results: Twenty preterm infants (mean gestational age 29.3 [SD 2.1] weeks; mean birth weight 1,230 [SD 391] g) were included. Seventeen infants did complete the 1-h measurement. Eleven (65%) infants had a decrease in their peakdEMG activity (median change -11.8% [IQR -26.8 to 5.8, p = 0.08]) 1 h after MIST. TonicdEMG activity decreased in 12 (71%) infants, with a median reduction of 6.3% (IQR -29.2 to 9.0, p = 0.07). FiO2 showed a rapid decrease following MIST (before, 0.47 [IQR 0.38-0.84]; 1 h after, 0.25 [IQR 0.21-0.30], p < 0.001).

Conclusion: In addition to improved oxygenation, MIST results in a decrease in neural breathing effort measured by dEMG activity in the majority of preterm infants with RDS.