Association Between High-Flow Nasal Cannula and End-Expiratory Esophageal Pressures in Premature Infants

Background: High-flow nasal cannula (HFNC) is commonly being used to provide noninvasive respiratory support in newborn infants. Continuous distending pressure generated by these devices in preterm infants has not been elucidated. The aim of this work was to determine the association between HFNC flow in L/min and end-expiratory esophageal pressure in cm H2O in premature infants.

Methods: In a prospective observational study, end-expiratory esophageal pressure measurements were conducted in clinically stable premature infants who required HFNC. The end-expiratory esophageal pressure generated by the HFNC was measured by a regular feeding tube overlying the lower esophagus and connected to a pressure transducer. Each infant had different end-expiratory esophageal pressure measurements at different high flows ranging from 2 to 8 L/min.

Results: Nineteen premature infants were studied. Their birthweight (mean ± SD) was 904 ± 574 g, and gestational age was 26.6 ± 3.1 weeks. Overall, 93 end-expiratory esophageal pressure measurements were conducted. At the time of the end-expiratory esophageal pressure measurements, infants were 1,458 ± 828 g and 7.2 ± 4.8 weeks old. At HFNC flows ranging from 2 to 8 L/min, the corresponding esophageal pressures ranged from 2 to 15 cm H2O. There was a statistically significant association between esophageal pressures and flows. In a linear regression model with the end-expiratory esophageal pressure as the dependent variable and HFNC flow as the independent variable, there was a significant correlation between the 2 variables: end-expiratory esophageal pressure (cm H2O) = 1.18 × HFNC (L/min) (r(2) = 0.95, P < .001).

Conclusions: HFNC-associated end-expiratory esophageal pressure is measurable in premature infants. There is a significant association between flows and generated esophageal pressures. There is also variability in the amount of end-expiratory esophageal pressure generated. These observations should be kept in mind when using high HFNC flows in preterm infants.