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Influence of chest wall distortion on esophageal pressure
Insights
Esophageal pressure swings vary significantly in preterm infants due to chest wall distortion. This makes esophageal pressure an unreliable measure of pleural pressure in these vulnerable infants.
Area of Science:
- Neonatal Physiology
- Respiratory Mechanics
- Pediatric Pulmonology
Background:
- Esophageal pressure is commonly used to estimate pleural pressure in infants.
- Preterm infants have unique chest wall mechanics that may affect pressure measurements.
- Understanding these differences is crucial for accurate respiratory assessment.
Purpose of the Study:
- To investigate the caudocephalad profile of esophageal pressure swings in preterm and full-term infants.
- To analyze the impact of chest wall distortion on esophageal pressure swings in preterm infants.
Main Methods:
- Measurements included esophageal pressure, tidal volume, mouth pressure, and rib cage/abdominal motion.
- Techniques involved fluid-filled catheters, pneumotachographs, face masks, pressure transducers, and magnetometers.
- Comparison of esophageal pressure swings during varying degrees of chest wall distortion.
Main Results:
- Preterm infants exhibited a steep caudocephalad fall in esophageal pressure swings.
- Full-term infants showed flat profiles during quiet sleep and steep during REM sleep.
- Esophageal pressure swings were higher with greater chest wall distortion in preterm infants.
Conclusions:
- The compliant preterm rib cage leads to uneven pleural pressure distribution.
- Chest wall distortion significantly influences esophageal pressure measurements in preterm infants.
- Esophageal pressure is an unreliable estimate of mean pleural pressure in preterm and potentially term infants.
Abstract:
The caudocephalad profile of esophageal pressure swings was studied in 10 preterm and 5 full-term infants, and the effect of chest wall distortion on esophageal pressure swings was analyzed in 12 preterm infants. Esophageal pressure was measured with a fluid-filled catheter, tidal volume with a pneumotachograph, mouth pressure with a face mask and pressure transducer, and rib cage and abdominal motion with magnetometers. In preterm infants the profile of esophageal pressure swings fell very steeply in the caudocephalad direction. In full-term infants it was flat during quiet sleep and steep during rapid-eye-movement sleep. When breaths, standardized for pleural pressure, were compared between a period with maximal and a period with minimal chest wall distortion, esophageal pressure swings for both spontaneous and occluded breaths were higher in the former period. We conclude that the complaint preterm rib cage results in an uneven distribution of pleural pressure and that this distribution varies with changes in chest wall distortion. Esophageal pressure measurements are therefore an unreliable estimate of mean pleural pressure in the preterm infant and can be unreliable in the term infant.