Volume Guarantee High-Frequency Oscillatory Ventilation in Preterm Infants With RDS: Tidal Volume and DCO2 Levels for Optimal Ventilation Using Open-Lung Strategies

High frequency oscillatory ventilation with volume-guarantee (HFOV-VG) is a promising lung protective ventilator mode for the treatment of respiratory failure in newborns. However, indicators of optimal ventilation during HFOV-VG mode are not identified yet. In this study, we aimed to evaluate optimal high-frequency tidal volume (VThf) and the dissociation coefficient of CO₂ (DCO₂) levels to achieve normocapnia during HFOV-VG after lung recruitment in very low birthweight infants with respiratory distress syndrome (RDS). Preterm babies under the 32nd postmenstrual week with severe RDS that received HFOV-VG using open-lung strategy between January 2014 and January 2019 were retrospectively evaluated. All included patients were treated with the Dräger Babylog VN500 ventilator in the HFOV-VG mode. In total, 53 infants with a mean gestational age of 26.8 ± 2.3 weeks were evaluated. HFOV mean optimal airway pressure (MAPhf) level after lung recruitment was found to be 10.2 ± 1.7 mbar. Overall, the mean applied VThf per kg was 1.64 ± 0.25 mL/kg in the study sample. To provide normocapnia, the mean VThf was 1.61 ± 0.25 mL/kg and the mean DCO₂corr was 29.84 ± 7.88 [mL/kg]²/s. No significant correlation was found between pCO₂ levels with VThf (per kg) or DCO₂corr levels. VThf levels to maintain normocarbia were significantly lower with 12 Hz frequency compared to 10 Hz frequency (1.50 ± 0.24 vs. 1.65 ± 0.25 mL/ kg, p < 0.001, respectively). A weak but significant positive correlation was found between mean airway pressure (MAPhf) and VThf levels. To our knowledge, this is the largest study to evaluate the optimal HFOV-VG settings in premature infants with RDS, using the open-lung strategy. According to the results, a specific set of numbers could not be recommended to achieve normocarbia. Following the trend of each patient and small adjustments according to the closely monitored pCO₂ levels seems logical.

Intranasal surfactant protein D as neuroprotective rescue in a neonatal rat model of periventricular leukomalacia

BACKGROUND

Periventricular leukomalacia (PVL) is the leading cause of neurocognitive deficits in children with prematurity. We previously hypothesized that surfactant protein D (SPD) with its ability to bind toll-like receptors may have a possible ameliorating effect in PVL.

METHODS

Three groups were defined as: LPS-administered and postnatal intranasal saline administered group, LPS-administered and postnatal intranasal SPD-treated group, and control group. Twenty-eight offspring rats were reared with their dams until their sacrifice for histological evaluation on day 7.

RESULTS

A significant loss of brain weight occurred in the LPS group compared with controls. The postnatal intranasal SPD treatment significantly reduced the number of TUNEL-positive cells in the periventricular white matter as compared with the LPS-treated group. Compared with the control group, LPS injection in the rat brain significantly reduced the MBP-positive staining. Postnatal SPD treatment greatly prevented LPS-stimulated loss of MBP staining.

CONCLUSIONS

Present study demonstrated a neuroprotective effect of SPD in a rat model of PVL. Our results offer future implications towards increasing our understanding about multifactorial mechanisms underlying periventricular leukomalacia and developing plausible therapeutic strategies in order to prevent neurocognitive deficits in preterm infants.

Impact of Volume Guarantee on High-Frequency Oscillatory Ventilation in Preterm Infants: A Randomized Crossover Clinical Trial

BACKGROUND

High-frequency oscillatory ventilation (HFOV) with volume guarantee (VG) is a new ventilation mode that allows the clinician to set a mean tidal volume to be delivered.

OBJECTIVE

This study aimed to investigate whether HFOV with a VG option may result in constant tidal volume delivery and less fluctuant CO2 levels compared to HFOV alone in premature infants with respiratory distress syndrome (RDS).

METHODS

Inborn infants at less than 32 weeks of gestation with RDS requiring invasive mechanical ventilation were eligible. Patients were randomized to receive HFOV + VG or HFOV alone as the initial ventilator mode and then crossed over to the other mode. HFOV was performed with 'optimal lung volume strategy' during both of the periods.

RESULTS

Twenty infants were evaluated. The mean high-frequency tidal volume (VThf) and CO2 diffusion coefficient (DCO2) were significantly higher in the HFOV + VG mode than HFOV alone. HFOV + VG maintains VThf within the target range more consistently than HFOV. The incidences of hypocarbia and hypercarbia were lower in HFOV with VG than HFOV alone.

CONCLUSION

This is the first prospective, randomized, short-term crossover clinical study that compared HFOV with and without VG in infants with acute RDS. Because of the lower VThf fluctuation and lower incidences of out-of-target PCO2 levels, HFOV combined with VG seems to be feasible for preterm infants. However, the results should be interpreted with caution due to the small sample size and short-term crossover design of the study.