The Functional Residual Capacity and Closing Volume in Aged Patients under Supine Position

Abstract

We evaluated the functional residual capacity and closing volume of aged patients under supine position as preoperative examination.
Patients are forced to under supine position during and post operative course. The airway closure is influenced by posture, age, smoking and the rest. We examined the respiratory functions in nonsmokers and smokers, and in young and aged patients under supine position.
Spirometory measurements (%VC, FEV_1.0%, V₂₅/HT), subdivisions of the lung volume (TLC, FRC/TLC), and closing volume (CV, CV/VC, ΔN₂, CC/TLC) were measured. We have got the results as follows.
1. V₂₅/HT was significantly influenced by aging and smoking factors.
2. Closing volume increased obviously with aging, and ΔN₂ was more reliable parameter in the aged than CV.
3. (FRC-CC)/TLC negatively related with aging.
4. It was suggested that V₂₅/HT was a good parameter for the closing volume.