<原著>第 2 編 Closing volume の臨床的研究(Closing volume に関する実験的ならびに臨床的研究)

Abstract

For the purpose of detecting factors affecting the measured values of closing volume (CV), postural effect on CV, reproducibility of CV measurement and gravity effect which is responsible for closing volume phenomenon through intrapleural pressure gradient were examined on total 92 subjects both spirometrically normal and abnormal. Measurement of CV was performed using O_2 single-breath method according to Anthonisen. Nitrogen concentration gradients on signle breath N_2 curves such as &lrtri;N_2, &lrtri;F_<N_2> (IV) and F_<N_2> (T) were also compared quantitatively between control and study groups. The results were as follows. 1) CV/VC measured on individual subject showed the least value in prone getting larger in sitting and supine positions in order. 2) Standard deviations of regression lines obtained from CV/VC values according to various age were within acceptable range in spite of subject's body position. 3) Time course change in CV with repeated measurements in sitting position was almost negligible. 4) Postural change from one lateral decubitus position during inspiratory maneuver to another during expiration resulted in inversed phase IV in N_2 curve with less steep slope compared with original phase IV. 5) In lateral decubitus position biphasic phase IV (CVa, CVb) was observed. The measured values of CVb were more close to CV in other positions compared with CVa in lateral position. 6) In differential nitrogen curves from nondependent zones of lungs using Carlens catheter, N_2 concentration over phase III took higher values and phase IV inflection was less clear compared with dependent zones. 7) CV and slope of phase III both of which could be a useful parameters for detecting abnormalities of intrapulmonary gas distribution likely reflect independent mechanical abnormalities of lung. 8) A positive correlationship between CV and terminal nitrogen concentration of phase IV was demonstrated. A study on gravity effect on intrapulmonary gas distribution was do