Interaction of Anti-G Measures and Chest Wall Mechanics in Determining Gas Exchange.
Annual progress rept. 1 Apr 82-31 Mar 83,
VIRGINIA MASON RESEARCH CENTER SEATTLE WA
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Efforts during this reporting period have been directed in three areas 1 Examination of regional intrapleural pressure changes during Gz stress in the pig 2 Development of an inexpensive assistcontrol, volume limited animal ventilator and 3 Determining the influence of chest wall motion on gas exchange during mechanical ventilation in dogs. Studies assessing regional intrapleural pressure changes during Gz stress in the dog were repeated in similar sized pigs to determine the role of chest wall mechanics in determining these changes. When the G-suit abdominal bladder was used, increases in regional intrapleural pressure greater than those seen in analogous dog experiments were observed. These results imply that, as the chest wall becomes less compliant, the degree of lung compression attributable to Gz stress without G-suit application should deminish. In another series of experiments, gas exchange during assisted and controlled ventilation were compared in an attempt to ascertain whether an active effort by chest wall muscles coordinated with inspiration can influence gas exchange. The data obtained indicate that an inspiratory muscular effort enhances gas exchange. Measured gas exchange parameters suggest that this enhancement is the result of a redistribution of perfusion rather than a redistribution of ventilation.
- Stress Physiology