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Elevated mean systemic filling pressure due to intermittent positive-pressure ventilation
E Chihara1, S Hashimoto, T Kinoshita
1Department of Physiology and Anesthesiology, Kyoto Prefectural University of Medicine, Japan.
The American Journal of Physiology
|April 1, 1992
Summary
Intermittent positive-pressure ventilation (IPPV) significantly increases mean systemic filling pressure (Psf) and central venous pressure (Pcv), decreasing cardiac output. This suggests a blood shift from unstressed to stressed volume during IPPV.
Area of Science:
- Cardiovascular Physiology
- Respiratory Physiology
Background:
- Intermittent positive-pressure ventilation (IPPV) is a common mechanical ventilation strategy.
- Its precise effects on systemic circulation, particularly mean systemic filling pressure (Psf) and venous return dynamics, require further elucidation.
Purpose of the Study:
- To investigate the impact of IPPV on systemic circulation parameters.
- To quantify changes in mean systemic filling pressure (Psf), circulating blood volume, and venous return during IPPV.
Main Methods:
- Hemodynamic parameters, including Psf and circulating blood volume, were measured in anesthetized rats.
- Circulating blood volume was assessed using 51Cr-labeled erythrocytes.
- Vascular compliance (Cvas) was determined by measuring Psf changes after blood bolus injection.
Main Results:
- IPPV reduced cardiac output (CO) by 20.9% compared to spontaneous respiration.
- Mean systemic filling pressure (Psf) and central venous pressure (Pcv) increased significantly.
- The pressure gradient for venous return decreased, while total peripheral resistance increased significantly.
Conclusions:
- Increased Pcv during IPPV attenuates the venous return pressure gradient, leading to decreased CO.
- The compensatory rise in Psf during IPPV is attributed to a shift of blood from unstressed to stressed volume.