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Published on: June 9, 2023
Relationship between Mean Airways Pressure, Lung Mechanics, and Right Ventricular Output during High-Frequency
Emanuela Zannin1, Daniela Doni2, Maria Luisa Ventura2
1Department of Electronics, Informatics and Bioengineering, Politecnico di Milano University, Milan, Italy.
Insights
Respiratory system reactance (Xrs) and right ventricular output (RVO) changes during continuous distending pressure (CDP) maneuvers may guide open lung ventilation in neonates. These measures are more sensitive to overdistension than oxygenation.
Area of Science:
- Neonatal Medicine
- Pediatric Critical Care
- Respiratory Physiology
Background:
- High-frequency oscillatory ventilation (HFOV) is used for respiratory support in neonates.
- Optimizing ventilation strategies, including continuous distending pressure (CDP), is crucial for improving outcomes.
- Open lung maneuvers aim to maintain lung volume and improve gas exchange.
Purpose of the Study:
- To assess changes in lung mechanics and right ventricular output (RVO) during CDP maneuvers in infants on HFOV.
- To determine the optimal CDP settings for maintaining adequate oxygenation.
- To evaluate the utility of lung mechanics and RVO in guiding open lung maneuvers.
Main Methods:
- Studied 13 infants on HFOV with a median gestational age of 26 weeks.
- Performed incremental/decremental CDP maneuvers, measuring oxygenation, respiratory system reactance (Xrs), and RVO via Doppler echocardiography.
- Identified the lowest CDP maintaining optimal oxygenation as the clinically optimal CDP.
Main Results:
- Maximal CDP improved oxygenation and decreased Xrs and RVO.
- During deflation, oxygenation remained stable, Xrs returned to baseline, and RVO increased but not always to baseline levels.
- Xrs and RVO were more sensitive to overdistension than oxygenation.
Conclusions:
- Xrs and RVO changes may serve as sensitive indicators of lung overdistension during CDP maneuvers.
- These parameters could be valuable in clinical practice to guide the application of open lung maneuvers in neonates.
- Optimizing CDP using Xrs and RVO may improve ventilation strategies in infants requiring HFOV.
Objective:
To characterize changes in lung mechanics and right ventricular output (RVO) during incremental/decremental continuous distending pressure (CDP) maneuvers in newborn infants receiving high-frequency oscillatory ventilation, with the aim of evaluating when open lung maneuvers are needed and whether they are beneficial.
Study Design:
Thirteen infants on high-frequency oscillatory ventilation were studied with a median (IQR) gestational age of 261 (253-291) weeks and median (IQR) body weight of 810 (600-1020) g. CDP was increased stepwise from 8 cmH2O to a maximum pressure and subsequently decreased until oxygenation deteriorated or a CDP of 8 cmH2O was reached. The lowest CDP that maintained good oxygenation was considered the clinically optimal CDP. At each CDP, the following variables were evaluated: oxygenation, respiratory system reactance (Xrs), and RVO by Doppler echocardiography.
Results:
At maximal CDP reached during the trial, 19 [1] cmH2O (mean [SEM]), oxygenation markedly improved, and Xrs and RVO decreased. During deflation, oxygenation remained stable over a wide range of CDP settings, Xrs returned to the baseline values, and RVO increased but the baseline values were not readily restored in all patients.
Conclusion:
These results suggest that Xrs and RVO are more sensitive than oxygenation to overdistension and they may be useful in clinical practice to guide open lung maneuvers.
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