Transmission of Oscillatory Volumes into the Preterm Lung during Noninvasive High-Frequency Ventilation

Abstract

Rationale: There is increasing evidence for a clinical benefit of noninvasive high-frequency oscillatory ventilation (nHFOV) in preterm infants. However, it is still unknown whether the generated oscillations are effectively transmitted to the alveoli. Objectives: To assess magnitude and regional distribution of oscillatory volumes (VOsc) at the lung level. Methods: In 30 prone preterm infants enrolled in a randomized crossover trial comparing nHFOV with nasal continuous positive airway pressure (nC-PAP), electrical impedance tomography (EIT) recordings were performed. During nHFOV, the smallest amplitude to achieve visible chest wall vibration was used, and the frequency was set at 8 hertz (Hz). Measurements and main results: Thirty consecutive breaths during artefact-free tidal ventilation were extracted for each of the 228 EIT recordings. After application of corresponding frequency filters, tidal volumes (VT) and VOsc were calculated. There was a signal at 8 and 16 Hz during nHFOV which was not detectable during nCPAP, corresponding to the set oscillatory frequency and its second harmonic. During nHFOV, the mean (SD) VOsc/VT ratio was 0.20 (0.13). Oscillations were more likely to be transmitted to the non-gravity-dependent [mean difference (95% CI): 0.041 (0.025 to 0.058); p<0.001] and right-sided lung [mean difference (95% CI): 0.040 (0.019 to 0.061); p<0.001] when compared with spontaneous VT. Conclusions: In preterm infants, VOsc during nHFOV are transmitted to the lung. Compared with the regional distribution of tidal breaths, oscillations preferentially reach the right and non-gravity-dependent lung. These data increase our understanding of the physiological processes underpinning nHFOV and may lead to further refinement of this novel technique.

Non-invasive High-Frequency Oscillatory Ventilation as Initial Respiratory Support for Preterm Infants With Respiratory Distress Syndrome

“…Therefore, these differences may be due to the airway pressure itself rather than the pressure waveform generated from the two NIV modes. The nHFOV group had a lower rate of air leak syndrome than the BiPAP group, and we suspected that this may be due to the small tidal volumes used, which results in less pressure-andvolume trauma from nHFOV (21). High-frequency oscillation ventilation is a type of oscillation with a high frequency of air flow.…”

Lung volume distribution in preterm infants on non-invasive high-frequency ventilation

“…The setup of the original study has been described previously 7 8. Infants were eligible if they were (1) born <30 weeks’ gestation, (2) older than 7 days, (3) between 26 and 34 weeks’ postmenstrual age, (4) extubated for more than 24 hours and (5) clinically stable while receiving nCPAP support.…”

“…Recently, our group provided evidence of substantial transmission of oscillatory volumes into the lung of preterm infants on nHFOV. We demonstrated that compared with the regional distribution of tidal breaths, oscillations preferentially reached the right and non-gravity-dependent (NGD) lung regions 8. However, the effects of these differences on overall ventilation and lung aeration remain unclear.…”

The Intertemporal Role of Respiratory Support in Improving Neonatal Outcomes: A Narrative Review

“…The meta-analysis by Li et al showed that compared to nCPAP and BiPAP, nHFOV may significantly increase the removal of carbon dioxide and, thus, reduce the need for intubation and IMV in premature infants with RDS [45]. Interestingly, although the actual transmission of oscillations to the alveoli was considered to be minimal with nHFV [108], a recently published study in preterm infants on nHFOV was able to prove a substantial transmission of oscillatory volumes into the lung, preferentially into the right, non-gravitydependent areas [112]. Questions remain, though, regarding the most appropriate settings, ventilator type, and diseases best treated using nHFV [113].…”