Evaluating tidal volume stability in extremely preterm infants on high-frequency oscillatory ventilation with volume guarantee.

Abstract

Background: High Frequency Oscillatory Ventilation (HFOV) combined with volume guarantee (HFOV-VG) represents an innovative ventilation mode designed for managing respiratory failure in neonates. This study aimed to assess the stability of High Frequency tidal volume (VThf) in extremely preterm infants ventilated on HFOV with VG during the first 48 h of life. Additional objectives included examining the correlations between VThf, Diffusion Coefficient of Carbon Dioxide (DCO₂) and key respiratory markers.

Methods: This retrospective, single-center study included 22 extremely preterm infants treated with HFOV-VG as the primary mode of ventilation at King Abdulaziz Medical City. Data were collected directly from the ventilator every minute for the first 48 h of life. Blood gases were analyzed every 4-6 h to maintain normocapnia (PCO₂ 40-55 mmHg). The distribution of continuous variables was assessed using the Shapiro-Wilk test for normality. As most data were found to be non-normally distributed, results are presented as medians with interquartile ranges (IQR). The Kruskal-Wallis test was used to compare non-normally distributed continuous variables across groups. The Spearman's rank correlation coefficient (Spearman's rho) was used to evaluate correlations between key clinical and ventilatory variables. All statistical analyses were conducted using Stata software (version 17; StataCorp LLC, College Station, TX), with statistical significance set at p < 0.05.

Results: Twenty-two infants had a median gestational age of 26.5 weeks (IQR 24-28) and a median birth weight of 830 g (IQR 600-1300). The median set VThf per kilogram was 2.2 mL/kg [IQR 2,2.6], which was consistent with the measured VThf. Significant correlations were observed between weight-corrected DCO₂ and VThf (spearman rho = 0.8089, p < 0.0001), and between measured amplitude and weight corrected DCO₂ (spearman rho = 0.6497p < 0.0001). Raw DCO₂ correlated with measured amplitude (spearman rho = 0.1364, p < 0.0001). PCO₂ showed no significant correlation with raw DCO₂ (p = 0.4813) and weight-corrected DCO₂ (p = 0.4845). Notable variations in FiO₂, frequency, and MAP were identified between different PCO₂ levels (p < 0.01) as well as the weight corrected DCO₂ (p = 0.04).

Conclusions: HFOV-VG effectively stabilized VThf in extremely preterm infants with fluctuations in amplitude, providing consistent ventilation support during the early critical period. The weight-corrected DCO₂ correlated strongly with VThf and measured amplitude, underscoring its potential as a reliable marker for CO₂ clearance. These findings highlight the utility of HFOV-VG in managing respiratory needs in extreme preterm infant.