Electrical activity of the diaphragm during nCPAP and high flow nasal cannula

Objective To determine if the electrical activity of the diaphragm, as measure of neural respiratory drive and breathing effort, changes over time in preterm infants transitioned from nasal continuous positive airway pressure (nCPAP) to high flow nasal cannula (HFNC). Design Prospective observational study. Setting Neonatal intensive care unit. Patients Stable preterm infants transitioned from nCPAP to HFNC using a 1: 1 pressure to flow ratio. Interventions The electrical activity of the diaphragm was measured by transcutaneous electromyography (dEMG) from 30 min before until 3 hours after the transition. Main outcome measures At eight time points after the transition to HFNC, diaphragmatic activity was compared with the baseline on nCPAP. Percentage change in amplitude(dEMG), peak(dEMG) and tonic(dEMG) were calculated. Furthermore, changes in respiratory rate, heart rate and fraction of inspired oxygen (FiO(2)) were analysed. Results Thirty-two preterm infants (mean gestational age: 28.1 +/- 2.2 weeks, mean birth weight: 1118 +/- 368 g) were included. Compared with nCPAP, the electrical activity of the diaphragm did not change during the first 3 hours on HFNC (median (IQR) change in amplitudedEMG at t= 180 min: 2.81% (- 21.51-14.10)). The respiratory rate, heart rate and FiO(2) remained stable during the 3-hour measurement. Conclusions Neural respiratory drive and breathing effort assessed by electrical activity of the diaphragm is similar in the first 3 hours after transitioning stable preterm infants from nCPAP to HFNC with a 1:1 pressure-to-flow ratio.