Respiratory mechanics during NCPAP and HHHFNC at equal distending pressures.
OBJECTIVE
To compare the effect of heated, humidified, high-flow nasal cannula (HHHFNC) and nasal continuous positive airways pressure (NCPAP) on lung function and mechanics in preterm infants with respiratory distress syndrome (RDS) at the same level of retropharyngeal pressure (Prp).


METHODS
Randomised crossover trial.


METHODS
Neonatal intensive care unit, Ospedale Maggiore Policlinico, Milan, Italy.


METHODS
20 preterm infants (gestational age: 31±1 wks) with mild-moderate RDS requiring non-invasive respiratory support within 96 h after birth.


METHODS
Infants were exposed to a randomised sequence of NCPAP and HHHFNC at different settings (2, 4 and 6 cmH₂O for NCPAP and 2, 4, 6 L/min for HHHFNC) to enable comparison at the same level of Prp.


METHODS
Tidal volume by respiratory inductance plethysmography, pleural pressure estimated by oesophageal pressure, and gas exchange were evaluated at each setting and used to compute breathing pattern parameters, lung mechanics and work of breathing (WOB).


RESULTS
A poor linear regression between flow and Prp was found during HHHFNC (Prp=0.3+0.7*flow; r²=0.37). Only in 15 out of 20 infants it was possible to compare HHHFNC and NCPAP at a Prp of 2 and 4 cmH₂O. No statistically significant differences were found in breathing pattern, gas exchange, lung mechanics and total WOB. Resistive WOB in the upper airways was slightly but significantly higher during HHHFNC (0.65 (0.49;1.09) vs 1.57 (0.85;2.09) cmH₂O median (IQR)).


CONCLUSIONS
Despite differing mechanisms for generating positive airway pressure, when compared at the same Prp, NCPAP and HHHFNC provide similar effects on all the outcomes explored.
Anna
A
Lavizzari
Chiara
C
Veneroni
Mariarosa
M
Colnaghi
Francesca
F
Ciuffini
Emanuela
E
Zannin
Monica
M
Fumagalli
Fabio
F
Mosca
Raffaele L
RL
Dellacà
D000399:Air Pressure; D002406:Catheterization, Peripheral / Q000379:methods; D045422:Continuous Positive Airway Pressure / Q000379:methods*; D018592:Cross-Over Studies; D005865:Gestational Age; D006358:Hot Temperature; D006801:Humans; D006813:Humidity; D007231:Infant, Newborn; D007234:Infant, Premature; D007363:Intensive Care Units, Neonatal; D009296:Nasal Cavity; D063087:Noninvasive Ventilation / Q000295:instrumentation / Q000379:methods*; D012127:Respiratory Distress Syndrome, Newborn / Q000503:physiopathology / Q000628:therapy*; D012129:Respiratory Function Tests; D015656:Respiratory Mechanics / Q000502:physiology*