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Pulsatile pulmonary microvascular pressure measured with vascular occlusion techniques
1Department of Biomedical Engineering, University of Southern California, Los Angeles 90089-1451.
Journal of Applied Physiology (Bethesda, Md. : 1985)
|March 1, 1991
Summary
Pulsatile perfusion causes significant variations in pulmonary microvascular pressure. Increasing pump frequency reduces pressure fluctuations, while vasoconstriction and elevated venous pressure alter pressure dynamics.
Area of Science:
- Pulmonary Circulation Physiology
- Microvascular Dynamics
- Hemodynamics
Background:
- Pulsatile perfusion is crucial for gas exchange in isolated lung preparations.
- Understanding microvascular pressure variations is key to assessing lung function under dynamic conditions.
Purpose of the Study:
- To investigate the periodic variations of pulmonary microvascular pressure during pulsatile perfusion.
- To analyze the effects of varying perfusion frequencies and vasoactive agents on microvascular pressure dynamics.
Main Methods:
- Isolated canine left lower lung lobes were used.
- Arterial occlusion (AO) and double occlusion (DO) techniques were employed at frequencies of 36, 54, 72, and 90 beats/min.
- Serotonin-induced vasoconstriction and elevated lobar venous pressure were tested.
Main Results:
- Microvascular pressure contours, reconstructed from AO and DO, lagged behind pulmonary arterial pressure.
- Pressure contour amplitude decreased with increasing frequency (25% to 14% of arterial pulse pressure).
- Vasoconstriction increased AO pressure contour magnitude; elevated venous pressure increased AO contour amplitude.
Conclusions:
- Pulmonary microvascular pressures exhibit marked fluctuations during pulsatile perfusion.
- Frequency-dependent damping and altered pressure dynamics were observed.
- These oscillations reflect the pulsatility within the pulmonary microvascular bed.