Work of breathing during HHHFNC and synchronised NIPPV following extubation

Our aim was to compare the work of breathing (WOB) during synchronised nasal intermittent positive pressure ventilation (SNIPPV) and heated humidified high flow nasal cannula (HHHFNC) when used as post-extubation support in preterm infants. A randomised crossover study was undertaken of nine infants with a median gestational age of 27 (range 24–31) weeks and post-natal age of 7 (range 2–50) days. Infants were randomised to either SNIPPV or HHHFNC immediately following extubation. They were studied for 2 h on one mode and then switched to the other modality and studied for a further 2-h period. The work of breathing, assessed by measuring the pressure time product of the diaphragm (PTPdi), and thoracoabdominal asynchrony (TAA) were determined at the end of each 2-h period. The infants’ inspired oxygen requirement, oxygen saturation, heart rate and respiratory rate were also recorded. The median PTPdi was lower on SNIPPV than on HHHFNC (232 (range 130–352) versus 365 (range 136–449) cmH2O s/min, p = 0.0077), and there was less thoracoabdominal asynchrony (13.4 (range 8.5–41.6) versus 36.1 (range 4.3–50.4) degrees, p = 0.038).