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Pulmonary lobar vascular resistances during constant and pulsatile flows
J M Maarek1, D A Chartrand, T H Ye
1Department of Biomedical Engineering, University of Southern California, Los Angeles 90089-1451.
Respiration Physiology
|November 1, 1990
Summary
Pulmonary vascular pressure distribution can be determined using occlusion measurements in both constant and pulsatile flow. Time-averaged pulmonary arterial pressure accurately reflects upstream pressure during pulsatile perfusion.
Area of Science:
- Cardiovascular Physiology
- Pulmonary Circulation
- Hemodynamics
Background:
- Understanding pulmonary vascular pressure distribution is crucial for diagnosing and managing cardiopulmonary diseases.
- Previous studies have primarily utilized constant flow models, which may not fully represent physiological conditions.
- Pulsatile flow is characteristic of the native cardiovascular system, necessitating investigation into its effects on pressure measurements.
Purpose of the Study:
- To compare arterial and venous occlusion pressure profiles in dog lungs under constant versus pulsatile flow perfusion.
- To determine if pulsatile flow influences the accuracy of occlusion pressure measurements for assessing pulmonary vascular pressures.
- To establish the reliability of using occlusion techniques in pulsatile flow for inferring longitudinal pressure distribution.
Main Methods:
- Measurements of pulmonary arterial pressure, flow rate, and venous pressure were conducted in isolated dog lungs.
- Occlusion pressure profiles were recorded during both constant flow and pulsatile flow perfusion at identical flow rates.
- Inflow and outflow occlusions were performed to assess pressure dynamics under different perfusion modes.
Main Results:
- Arterial occlusion pressures were comparable between constant and pulsatile flow perfusion.
- During pulsatile perfusion, arterial pressure variations post-occlusion depended on the occlusion timing within the pressure cycle.
- Time-averaged pulmonary arterial pressure effectively recovered the arterial pressure drop during pulsatile flow; venous occlusion curves were similar in both modes, with pressure drops of ~4.8 mm Hg (arterial) and ~4.2 mm Hg (venous).
Conclusions:
- Occlusion pressure measurements are reliable for assessing pulmonary vascular pressure distribution, even during pulsatile perfusion.
- Time-averaged pulmonary arterial pressure serves as a valid upstream pressure reference during pulsatile flow.
- These findings support the use of occlusion techniques in pulsatile flow models for studying pulmonary hemodynamics.