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Effect of lung volume reduction surgery for emphysema on diaphragm function
Carl Hugo Hamnegård1, Michael I Polkey, Anders Thylen
1Department of Respiratory Medicine, Sahlgrenska University Hospital, S-413 45 Göteborg, Sweden. chh@lungall.gu.se
Respiratory Physiology & Neurobiology
|July 13, 2005
Summary
Lung volume reduction surgery (LVRS) improves diaphragm strength and function in emphysema patients. Patients with poor preoperative diaphragm function and high residual volume to total lung capacity ratio benefit most from LVRS.
Area of Science:
- Pulmonary Medicine
- Respiratory Physiology
- Surgical Outcomes
Background:
- Preoperative prediction of successful lung volume reduction surgery (LVRS) for emphysema remains challenging.
- The impact of LVRS on respiratory muscle function, particularly the diaphragm, is debated.
- Understanding diaphragm strength changes post-LVRS is crucial for patient selection and outcome prediction.
Purpose of the Study:
- To measure diaphragm strength before and after LVRS in emphysema patients.
- To identify preoperative predictors of improved functional capacity after LVRS.
- To elucidate the mechanism by which LVRS affects respiratory muscle function.
Main Methods:
- Diaphragm strength was assessed using transdiaphragmatic pressure (Pdi) and esophageal pressure (Pes) measurements.
- Measurements included sniff transdiaphragmatic pressure (Sn Pdi) and twitch pressures (Tw Pdi, Tw Pes).
- Functional capacity was evaluated using shuttle walking distance, with preoperative variables analyzed for predictive value.
Main Results:
- LVRS led to a significant increase in mean sniff transdiaphragmatic pressure (14%) and twitch transdiaphragmatic pressure (12%) at 3 months.
- A highly significant increase in twitch esophageal pressure (Tw Pes) was observed post-LVRS (60% at 3 months, 46% at 12 months).
- The ratio of Tw Pes to Tw Pdi increased significantly, suggesting improved diaphragm efficiency. Low Sn Pdi, Sn Pes, Tw Pes, and high RV/TLC ratio predicted better shuttle walking improvement.
Conclusions:
- LVRS enhances diaphragm function, primarily through lung volume alteration.
- Preoperative diaphragm weakness and a high RV/TLC ratio are key indicators for potential benefit from LVRS.
- These findings aid in optimizing patient selection for LVRS to improve outcomes in emphysema.