A study was conducted to clarify the influence of water immersion at different levels on pulmonary response. The subjects, ten healthy men (mean age, 26.2±7.9 years), subjected to measurement of static lung volumes and maximum expiratory flow-volume curves while sitting immersed in water at the level of both the neck and diaphragm. TLC, VC, ERV and FRC for water immersion at the diaphragm level were significantly decreased in comparison with those measured in air. These lung volumes were further decreased upon water immersion to neck level. However, RV did not change significantly upon immersion at either water level. Significant decreases of FEV_1⋅0, FEV_1⋅0%, V₅₀ and V₂₅ were observed upon water immersion at the diaphragm level as compared with those obtained in air. Water immersion to neck level produced further decreases in pulmonary functional parameters. Although peak flow and V₇₅ did not change significantly upon water immersion at either level, V₅₀ and V₂₅ were decreased markedly in comparison with the values obtained in air. A tendency for a marked decrease in pulmonary function parameters was observed upon water immersion to neck level. The changes observed upon water immersion to diaphragm level may have resulted from compression of small airways induced by both an increase of blood volume in the thorax and hydrostatic pressure against the abdomen. The changes induced by water immersion to neck level may have been exacerbated by the two mechanisms described above, in addition to hydrostatic pressure on the chest wall. The present results suggest that the significant reduction of pulmonary functional parameters caused by water immersion may be due to compression of small airways induced by an increase of blood volume in the thorax and hydrostatic pressure on the chest wall and abdomen.

Background/Aims: Bilateral endoscopic drainage with self-expanding metallic stent (SEMS) can be used to effectively manage hilar malignant biliary obstruction. However, the benefits of using a trisegment drainage method remain unknown. Methods: This study retrospectively reviewed the data of 125 patients with Bismuth type IIIa or IV unresectable malignant strictures who underwent bilateral endoscopic drainage using SEMSs at four tertiary centers. The patients were divided into the bilateral and trisegment drainage groups for comparison. The primary endpoint was stent patency and the secondary endpoints were technical success, technical and clinical success of reintervention, and overall survival. Results: The technical success rates of the bilateral and trisegment drainage groups were 95% (34/36) and 90% (80/89) (p=0.41), respectively, with median stent patency durations of 226 and 170 days (p=0.26), respectively. Although the technical success of reintervention was not significantly different between the two groups (p=0.51), the clinical success rate of reintrvention was significantly higher in the trisegment drainage group (73% [11/15] vs 96% [47/49], p=0.009). The median survival times were 324 and 323 days in the bilateral and trisegment drainage groups, respectively (p=0.72). Multivariate Cox hazards model revealed no stent patency-associated factor; however, chemotherapy was associated with longer survival. Conclusions Although no significant difference was noted with respect to stent patency, significantly higher clinical success rates were achieved with reintervention using the trisegment drainage method than using the bilateral drainage method alone.