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Lung and chest wall mechanics during differential ventilation with selective PEEP
Acta Anaesthesiologica Scandinavica
|October 1, 1985
Summary
Selective positive end-expiratory pressure (PEEP) during differential ventilation improved lung mechanics in the dependent lung. This PEEP strategy enhanced ventilation distribution, making hemithoracic compliance and resistance more equal.
Area of Science:
- Anesthesiology
- Respiratory Physiology
- Thoracic Mechanics
Background:
- Lateral positioning during general anesthesia can cause uneven ventilation distribution.
- Conventional ventilation often leads to preferential ventilation of the non-dependent lung.
- Understanding hemithoracic mechanics is crucial for optimizing mechanical ventilation strategies.
Purpose of the Study:
- To investigate the effects of selective positive end-expiratory pressure (PEEP) on hemithoracic mechanics during differential ventilation.
- To compare ventilation distribution and lung mechanics between conventional ventilation and differential ventilation with varying PEEP levels.
- To assess the impact of selective PEEP on dependent and non-dependent lung compliance and resistance.
Main Methods:
- Eight healthy adult patients were studied under general anesthesia in the lateral position.
- Hemithoracic mechanics were measured during four ventilation modes: conventional ventilation (CV), differential ventilation (DV) with no PEEP (DV:0), and DV with selective PEEP (0.8 and 1.6 kPa) to the dependent lung (DV:8, DV:16).
- Measurements included ventilation distribution, hemithoracic compliance, and inspiratory resistance.
Main Results:
- During CV, the non-dependent lung received 60% of ventilation, with higher compliance and lower resistance compared to the dependent lung.
- Differential ventilation (DV:0) showed no significant difference between hemithoraces.
- Selective PEEP application (DV:8, DV:16) increased dependent hemithorax compliance and decreased its resistance, leading to nearly equal compliance and resistance between hemithoraces at DV:16.
- Selective PEEP promoted a greater volume increase in the dependent lung with only a minor reduction in the non-dependent lung volume.
Conclusions:
- Selective PEEP applied to the dependent lung during differential ventilation can improve its mechanical properties.
- This strategy leads to a more even distribution of inspired gas within the lungs.
- Selective PEEP may be a valuable tool for optimizing ventilation in patients positioned laterally under general anesthesia.