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The interaction between applied PEEP and auto-PEEP during one-lung ventilation
1Department of Anaesthesia, The Toronto Hospital, University of Toronto, ON.
Journal of Cardiothoracic and Vascular Anesthesia
|May 16, 1998
Summary
Applying external positive end-expiratory pressure (PEEP) during one-lung ventilation (OLV) has variable effects. Total PEEP depends on the patient's existing auto-PEEP and expiratory time. Measure total PEEP when applying external PEEP during OLV.
Area of Science:
- Anesthesiology
- Respiratory Physiology
- Critical Care Medicine
Background:
- One-lung ventilation (OLV) is crucial for thoracic surgery.
- Positive end-expiratory pressure (PEEP) management during OLV is complex.
- Auto-PEEP can significantly impact respiratory mechanics.
Purpose of the Study:
- To determine the relationship between applied external PEEP and auto-PEEP during OLV.
- To assess the resultant total PEEP experienced by patients.
- To investigate the influence of inspiratory-expiratory ratio on total PEEP.
Main Methods:
- Prospective clinical study involving 10 adult patients undergoing elective thoracotomies.
- Measurements of plateau pressure using end-expiratory airway occlusion during two-lung ventilation and OLV.
- Application of 5 cm H2O external PEEP and variation of inspiratory-expiratory ratio.
Main Results:
- Auto-PEEP increased from 0.9 cm H2O during two-lung ventilation to 6.0 cm H2O during OLV (1:2 ratio).
- Application of 5 cm H2O external PEEP did not significantly alter total PEEP.
- Total PEEP varied significantly with changes in expiratory time and inversely correlated with pre-existing auto-PEEP (r=-0.84).
Conclusions:
- The effect of external PEEP during OLV is dependent on the patient's baseline auto-PEEP.
- This interaction may explain clinical variability in PEEP application during OLV.
- Measuring total PEEP is recommended when external PEEP is applied during OLV.