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[Changes in systemic and pulmonary hemodynamics during an increase in lung volume]
Fiziologicheskii Zhurnal SSSR Imeni I. M. Sechenova
|May 1, 1985
Summary
Increasing lung volume in dogs with oxygen-air mixtures initially reduces cardiac output but then triggers right ventricular activity, restoring lung circulation despite high intrathoracic pressure.
Area of Science:
- Physiology
- Cardiovascular System
- Respiratory System
Context:
- Investigating the physiological responses to increased lung volume under anesthesia.
- Understanding the effects of positive pressure ventilation on hemodynamics.
Purpose:
- To determine the impact of lung overinflation on caudal venous pressure, cardiac output, and ventricular pressures.
- To observe the compensatory mechanisms of the right ventricle during severe intrathoracic pressure elevation.
Summary:
- Gradual lung inflation in anesthetized dogs (600 ml) elevated caudal venous pressure and decreased cardiac output and ventricular systolic pressure.
- Further inflation (800 ml) led to a critical intrathoracic pressure (21.5 mm H2O), causing cessation of pulmonary circulation.
- The right ventricle responded with increased activity, tachycardia, and elevated pressure (45.2 mm Hg), ultimately restoring pulmonary circulation.
Impact:
- Reveals the complex interplay between lung volume, intrathoracic pressure, and right ventricular function.
- Provides insights into the limits of lung overinflation and the cardiovascular system's adaptive capacity.
- Informs mechanical ventilation strategies to prevent circulatory compromise.