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Effect of position on the mechanical interaction between the rib cage and abdomen in preterm infants
M R Wolfson1, J S Greenspan, K S Deoras
1Department of Physiology, Temple University School of Medicine, Philadelphia, Pennsylvania.
Insights
Prone positioning improves thoracoabdominal synchrony in preterm infants recovering from respiratory disease. This breathing pattern may offer a mechanical advantage for infants with respiratory challenges.
Area of Science:
- Neonatal physiology
- Respiratory mechanics
- Pediatric pulmonology
Background:
- Preterm infants often experience respiratory distress.
- Chest wall and pulmonary function can be affected by body position.
- Understanding breathing mechanics is crucial for managing respiratory failure in neonates.
Purpose of the Study:
- To investigate the impact of supine versus prone positioning on chest wall mechanics and pulmonary function in preterm infants.
- To assess thoracoabdominal motion and ventilatory parameters in different body positions.
Main Methods:
- Studied 20 preterm infants recovering from respiratory disease in both supine and prone positions.
- Assessed thoracoabdominal motion using rib cage and abdominal movement, calculating phase angle for synchrony.
- Measured transpulmonary pressure, airflow, and tidal volume for ventilatory and pulmonary function.
Main Results:
- No significant differences in ventilatory or pulmonary function between supine and prone positions.
- Prone positioning significantly reduced the phase angle (improved synchrony) by 49% and increased rib cage motion by 66%.
- Improved synchrony in the prone position correlated with initial asynchrony in the supine position.
Conclusions:
- Prone positioning enhances thoracoabdominal synchrony in preterm infants.
- Altered chest wall mechanics and diaphragm function likely mediate this improvement.
- Prone positioning may provide a beneficial breathing pattern for preterm infants at risk of respiratory failure.
Abstract:
To determine the influence of body position on chest wall and pulmonary function, we studied the ventilatory, pulmonary mechanics, and thoracoabdominal motion profiles in 20 preterm infants recovering from respiratory disease who were positioned in both the supine and prone position. Thoracoabdominal motion was assessed from measurements of relative rib cage and abdominal movement and the calculated phase angle (an index of thoracoabdominal synchrony) of the rib and abdomen Lissajous figures. The ventilatory and pulmonary function profiles were assessed from simultaneous measurements of transpulmonary pressure, airflow, and tidal volume. The infants were studied in quiet sleep, and the order of positioning was randomized across patients. The results demonstrated no significant difference in ventilatory and pulmonary function measurements as a function of position. In contrast, there was a significant reduction (-49%) in the phase angle of the Lissajous figures and an increase (+66%) in rib cage motion in prone compared with the supine position. In addition, the degree of improvement in phase angle in the prone position was correlated to the severity of asynchrony in the supine position. We speculate that the improvement in thoracoabdominal synchrony in the prone position is related to alterations of chest wall mechanics and respiratory muscle tone mediated by a posturally related shift in the area of apposition of the diaphragm to the anterior inner rib cage wall and increase in passive tension of the muscles of the rib cage. This study suggests that the mechanical advantage associated with prone positioning may confer a useful alternative breathing pattern to the preterm infant in whom elevated respiratory work loads and respiratory musculoskeletal immaturity may predispose to respiratory failure.