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Updated: Aug 28, 2025
Monitoring Lung Function with Electrical Impedance Tomography in the Intensive Care Unit
Published on: September 6, 2024
Humidity during high-frequency oscillatory ventilation compared to intermittent positive pressure ventilation in
Claude Danan1,2, Manon Tauzin1, Camille Jung3,4
1Neonatal Intensive Care Unit, Centre Hospitalier Intercommunal de Creteil, Creteil, France.
Background:
Inappropriate humidification of inspired gas during mechanical ventilation can impair lung development in extremely low birthweight (ELBW) infants. Humidification depends on multiple factors, such as the heater-humidifier device used, type of ventilation, and environmental factors. Few studies have examined inspired gas humidification in these infants, especially during high-frequency oscillatory ventilation (HFOV). Our objective was to compare humidity during HFOV and intermittent positive pressure ventilation (IPPV), in vitro and in vivo.
Methods:
In vitro and in vivo studies used the same ventilator during both HFOV and IPPV. The bench study used a neonatal test lung and two heater-humidifiers with their specific circuits; the in vivo study prospectively included preterm infants born before 28 weeks of gestation.
Results:
On bench testing, mean absolute (AH) and relative (RH) humidity values were significantly lower during HFOV than IPPV (RH = 79.4 ± 8.1% vs. 89.0 ± 6.2%, p < 0.001). Regardless of the ventilatory mode, mean RH significantly differed between the two heater-humidifiers (89.6 ± 6.7% vs 78.7 ± 6.8%, p = 0.003). The in vivo study included 10 neonates (mean ± SD gestational age: 25.7 ± 0.9 weeks and birthweight: 624.4 ± 96.1 g). Mean RH during HFOV was significantly lower than during IPPV (74.6 ± 5.7% vs. 83.0 ± 6.7%, p = 0.004).
Conclusion:
RH was significantly lower during HFOV than IPPV, both in vitro and in vivo. The type of heater-humidifier also influenced humidification. More systematic measurements of humidity of inspired gas, especially during HFOV, should be considered to optimize humidification and consequently lung protection in ELBW infants.
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