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Updated: Jul 6, 2025
Continuous Telemetric In Utero Tracheal Pressure Measurements in Fetal Lambs
Published on: December 22, 2023
Continuous Telemetric In Utero Tracheal Pressure Measurements in Fetal Lambs
Mar Janna Dahl1, Stefano Robbiani2, Chiara Veneroni2
1School of Human Sciences, The University of Western Australia; marjanna.dahl@hsc.utah.edu.
Insights
This study introduces a new method to measure pressures in fetal lambs with congenital diaphragmatic hernia (CDH). This helps determine optimal tracheal occlusion for treating lung hypoplasia in CDH fetuses.
Area of Science:
- Fetal Surgery
- Developmental Biology
- Medical Engineering
Background:
- Normal fetal lung development requires airspace expansion and lung liquid regulation.
- Congenital diaphragmatic hernia (CDH) causes lung hypoplasia due to abdominal organ displacement into the chest.
- Tracheal occlusion can improve lung hypoplasia in CDH fetuses but risks premature birth.
Purpose of the Study:
- To develop and validate a method for continuous measurement of intratracheal and amniotic pressures in a fetal lamb model of CDH.
- To establish a foundation for optimizing tracheal occlusion parameters for in utero CDH treatment.
- To quantify pressure dynamics during tracheal occlusion in CDH fetuses.
Main Methods:
- A surgical model of CDH was created in fetal lambs via hysterotomy.
- A device was implanted to continuously measure intratracheal and amniotic pressures.
- Data were collected, filtered, and transrespiratory pressure was calculated post-delivery.
Main Results:
- A novel method for continuous pressure monitoring in a fetal CDH model was successfully implemented.
- The study enabled the collection of pressure data essential for understanding tracheal occlusion effects.
- Transrespiratory pressure was calculated from the collected data.
Conclusions:
- Accurate pressure measurement is crucial for optimizing in utero tracheal occlusion therapy for CDH.
- This methodology provides a basis for future studies on improving CDH treatment strategies.
- Further research is needed to correlate pressure measurements with lung development outcomes.
Abstract:
Normal in utero lung development and growth rely upon the expansion of airspaces and the controlled efflux of lung liquid into the amniotic space. Infants with congenital diaphragmatic hernia (CDH) also have lung hypoplasia due to occupation of the chest cavity by the stomach and bowel and, in the most severe cases, the liver. Balloon tracheal occlusion reduces the severity of lung hypoplasia in fetuses with CDH but increases the risk of premature birth. Understanding the optimal occlusion pressure and duration required to improve lung hypoplasia with tracheal occlusion is essential to improving in utero corrective treatments for CDH. The study reports a new method for continuous measurement of the intratracheal and amniotic pressures in an unoccluded and occluded fetal lamb surgical model of CDH. Time-pregnant Merino ewes underwent two recovery hysterotomies: the first at ~80 days of gestation to create the CDH, and the second at ~101 days of gestation to occlude the fetal trachea and implant an intratracheal and amniotic pressure measurement device. Lambs were delivered at ~142 days, and the pressure measurement device was removed and cleaned. The data were downloaded and filtered using a 6 h window. Transrespiratory pressure was calculated.
