Detection of Hypovolemia Using Pleth Variability Index (PVI)

"The purpose with the planned study is to study pleth variability index (PVI) as a non invasive indicator for mild hypovolemia during spontaneous breathing in healthy subjects. Lower body negative pressure (LBNP), a well established technique, is used to create defined levels of hypovolemia.~Baseline data are recorded with the subjects in the supine position breathing with normal tidal volume without PEEP and without LBNP applied. Data are then recorded with LBNP applied in two steps (40 and 15 mmHg). Recordings are continued 5 minutes after releasing the negative pressure. Data are collected in total in four different series; normal tidal volume without PEEP; normal tidal volume with PEEP 5cm H2O; three doubled tidal volume without PEEP; three doubled tidal volume with PEEP 5 cm H20."