Demedts M, Verhamme M, Roelandts J
Eur J Respir Dis. 1983 May;64(4):306-12.
The underlying mechanism of the occurrence of a downward phase V at the end of a bolus washout curve was investigated in three healthy subjects. Phase V appeared not to originate from apical zones with low concentration of tracer gas but from dependent lung zones, which were not pathological. Indeed: 1) a reversed, upward, terminal slope was obtained when the bolus had been directed to the lung base by imposing a transition of the body through 180 degrees between inspiration and expiration or by inhaling a bolus close to TLC; 2) phase V was also present on N2 washout curves and, thus, originated from zones with smaller RV/TLC than the apical ones. Phase V increased with flow rate.
在三名健康受试者中研究了团注洗脱曲线末端出现向下的V期的潜在机制。V期似乎并非源自示踪气体浓度低的肺尖区域，而是源自非病理性的肺下垂部位。实际上：1）当通过在吸气和呼气之间将身体旋转180度或在接近肺总量（TLC）时吸入团注使团注指向肺底部时，可获得反向的、向上的末端斜率；2）V期也出现在氮气洗脱曲线上，因此，它源自残气量/肺总量（RV/TLC）比肺尖区域小的区域。V期随流速增加。
