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Topographical ventilation and perfusion distribution during IPPB in the lateral posture.
The American Review of Respiratory Disease
|November 1, 1978
Summary
Intermittent positive pressure ventilation (IPPB) alters ventilation distribution in the lateral decubitus posture, making it less homogeneous. Diaphragmatic tension appears to be the primary factor influencing this topographical ventilation pattern.
Area of Science:
- Pulmonary physiology
- Respiratory mechanics
Background:
- Gravity significantly influences regional lung ventilation and perfusion.
- Understanding ventilation-perfusion distribution is crucial for diagnosing and managing respiratory conditions.
Purpose of the Study:
- To investigate the effects of intermittent positive pressure ventilation (IPPB) on topographical ventilation and perfusion distribution in the lateral decubitus posture.
- To determine how IPPB affects the homogeneity of ventilation-perfusion ratios.
Main Methods:
- Utilized 133Xenon (133Xe) to measure topographical lung ventilation and perfusion in five healthy subjects.
- Subjects were studied in the lateral decubitus posture during both natural breathing and IPPB.
- Analyzed multiple-breath 133Xe washouts at the mouth.
Main Results:
- IPPB significantly increased the ratio of upper to lower lung ventilation compared to natural breathing.
- Regional perfusion distribution remained unchanged between natural breathing and IPPB.
- The distribution of regional ventilation-perfusion ratios became less homogeneous during IPPB.
Conclusions:
- IPPB alters topographical ventilation distribution in the lateral decubitus posture, leading to less homogeneous ventilation-perfusion ratios.
- Diaphragmatic tension is hypothesized to be the main determinant of ventilation distribution in this posture.
- Mouth-based 133Xe washout analysis did not reflect the observed changes in regional ventilation distribution.