Flow-related techniques for preoperative goal-directed fluid optimization.

Background: Improved postoperative outcome has been demonstrated by perioperative maximization of cardiac stroke volume (SV) with fluid challenges, so-called goal-directed therapy. Oesophageal Doppler (OD) has been the most common technique for goal-directed therapy, but other flow-related techniques and parameters are available and they are potentially easier to apply in clinical practice. The objective of this investigation was therefore to use OD for preoperative SV maximization and compare the findings with a Modelflow determined SV, with an OD estimated corrected flow time (FTc), with central venous oxygenation ( Svo2 ) and with muscle and brain oxygenation assessed with near infrared spectroscopy (NIRS).

Methods: Twelve patients scheduled for radical prostatectomy were anaesthetized before optimization of SV estimated by OD. A fluid challenge of 200 ml colloid was provided and repeated if at least a 10% increment in OD SV was obtained. Values were compared with simultaneously measured values of Modelflow SV, FTc, Svo2 and muscle and cerebral oxygenation estimated by NIRS.

Results: Based upon OD assessment, optimization of SV was achieved after the administration of 400-800 ml (mean 483 ml) of colloid. The hypothetical volumes administered for optimization based upon Modelflow and Svo2 differed from OD in 10 and 11 patients, respectively. Changes in FTc and NIRS were inconsistent with OD guided optimization.

Conclusion: Preoperative SV optimization guided by OD for goal-directed therapy is preferable compared with Modelflow SV, FTc, NIRS and Svo2 until outcome studies for the latter are available.