Objective: To determine whether electrical activity of the diaphragm (Edi) changes with weaning nasal high flow (HF) therapy in preterm infants according to a standardised protocol. Design: Prospective observational cohort study. Setting: Neonatal intensive care unit. Patients: Preterm infants born at <32 weeks gestation, receiving nasal HF as part of routine clinical care. Interventions: Infants recruited to the study had their HF weaned according to set clinical criteria. Edi was measured

more »

... g a modified gastric feeding tube serially from baseline (pre-wean) to 24hours post-wean. Main outcome measures: Change in Edi from baseline was measured at four timepoints up to 24hours after weaning. Minimum Edi during expiration, maximum Edi during inspiration and amplitude of the Edi signal (Edidelta) were measured. Clinical parameters (heart rate, respiratory rate, and fraction of inspired oxygen) were also recorded. Results: Forty preterm infants were recruited at a mean corrected gestational age of 31.6 (±2.7) weeks. Data from 156 weaning steps were analysed, 91% of which were successful. Edi did not change significantly from baseline during flow reduction steps, but a significant increase in diaphragm activity was observed when discontinuing HF (median increase in Edidelta immediately post-discontinuation 1.7µV [95%