Goal directed volume therapy means that bolus doses of 150-250 ml colloid fluid is
administered to the patient during contemporary measurement of the patients stroke volume.
The fluid status is considered optimized when stroke volume no longer increases with more
than 10%, indicating that the patient is close to the top of the Frank-Starling curve.
Several studies show that volume optimization reduces hospital stay and reduces the amount of
surgical complications. The overall purpose is to investigate if the much more simple non
invasive technique Pleth Variability Index can replace oesophageal doppler to guide volume
therapy in routine health care, and to analyse if a volume kinetic test can be used to
evaluate hypovolemia before surgery and make specific rehydration possible by analysing the
correlation between this test and fluid optimization using stroke volume measurements.
Primary hypothesis: 1. The volume of colloids that is given to volume optimise an
anesthetized patient using Pleth Variability Index shows a good correlation to the volume
used if volume optimisation is undertaken by the guidance of oesophageal doppler. 2. Data
from the two methods correlate and discriminates similarly volume responders from non
responders. 3. A volume kinetic model that indicates dehydration can predict the need for
rehydration in order to achieve a well hydrated patient at start of surgery.