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Time-varying pulmonary arterial compliance.
B J Grant1, J M Fitzpatrick, B B Lieber
1Department of Medicine, State University of New York, Buffalo 14215.
Journal of Applied Physiology (Bethesda, Md. : 1985)
|February 1, 1991
Summary
Pulmonary arterial compliance (Ca) changes during breathing, being higher at the start of expiration than inspiration. These passive mechanical changes are linked to lung volume shifts, not active neurohumoral mechanisms.
Area of Science:
- Cardiovascular Physiology
- Respiratory Physiology
- Pulmonary Circulation
Background:
- Pulmonary arterial compliance (Ca) is crucial for cardiovascular function.
- Understanding dynamic changes in Ca during the ventilatory cycle is important.
Purpose of the Study:
- To test the hypothesis that pulmonary arterial compliance (Ca) varies during the ventilatory cycle.
- To investigate the mechanisms underlying these variations.
Main Methods:
- Measurements of pulmonary artery pressure and flow in open-chest dogs.
- Calculation of input impedance and pulmonary arterial compliance (Ca) using a lumped parameter model.
- Assessment of effects of positive end-expiratory pressure (PEEP), meclofenamate, and vagotomy.
Main Results:
- Pulmonary arterial compliance (Ca) was significantly greater at the start of expiration (SE) than at the start of inspiration (SI).
- Positive end-expiratory pressure (PEEP) increased Ca at SE but not at SI.
- These changes were not affected by meclofenamate or vagotomy, indicating passive mechanical origins.
Conclusions:
- Pulmonary arterial compliance (Ca) is time-varying during the ventilatory cycle due to dynamic lung volume changes.
- The increase in Ca at SE is likely due to blood volume shifts, not active neurohumoral control.
- These findings highlight the passive mechanical influences on pulmonary arterial mechanics during respiration.