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Quantitative Mapping of Specific Ventilation in the Human Lung using Proton Magnetic Resonance Imaging and Oxygen as a Contrast Agent
Published on: June 5, 2019
Spontaneous breathing affects the spatial ventilation and perfusion distribution during mechanical ventilatory
Peter Neumann1, Hermann Wrigge, Jörg Zinserling
1Department of Clinical Physiology, Universities of Göttingen and Bonn, Germany.
Critical Care Medicine
|May 14, 2005
Summary
Spontaneous breathing during airway pressure release ventilation (APRV) improves gas exchange by reopening lung tissue and redistributing ventilation and perfusion. This leads to more efficient oxygenation in patients with acute respiratory failure.
Area of Science:
- Critical Care Medicine
- Respiratory Physiology
- Mechanical Ventilation
Background:
- Spontaneous breathing during mechanical ventilation can improve gas exchange in acute respiratory failure.
- Airway Pressure Release Ventilation (APRV) is a mode of mechanical ventilation that allows spontaneous breathing.
- The mechanisms by which spontaneous breathing improves gas exchange during APRV are not fully understood.
Purpose of the Study:
- To investigate the mechanisms by which spontaneous breathing during APRV improves gas exchange.
- To determine if spontaneous breathing during APRV redistributes ventilation and perfusion to previously nonaerated lung regions.
Main Methods:
- Prospective, randomized, controlled animal study in pigs with induced lung injury.
- Pigs were randomized to APRV with or without spontaneous breathing.
- Measurements included respiratory mechanics, hemodynamics, gas exchange (multiple inert gas elimination technique), and spatial ventilation/perfusion distribution (single photon emission tomography).
Main Results:
- Spontaneous breathing during APRV maintained stable shunt, whereas shunt increased without spontaneous breathing.
- Single photon emission tomography demonstrated increased ventilation and pulmonary blood flow in dorsal, juxtadiaphragmatic lung regions with spontaneous breathing.
- These findings occurred at similar minute ventilation and airway pressures between groups.
Conclusions:
- Spontaneous breathing during APRV enhances oxygenation by increasing ventilation to dependent lung regions and reopening nonaerated lung tissue.
- Perfusion redistribution appears secondary to altered ventilation patterns.
- The overall effect is a more efficient utilization of lung tissue for gas exchange.
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