Anesthésie et recherche clinique
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Relationship between Stroke Volume Variation and Stroke Volume during Major Abdominal Surgery Using Arterial Pulse Contour Analysis

Takashi Sugi, Tsuneo Tatara, Takahiko Kaneko, Hiromi Kaneko and Munetaka Hirose

Objective: Changes in stroke volume after fluid bolus infusion (i.e., fluid responsiveness) during major abdominal surgery is affected by painful stimuli, anesthetics and inconsistent increases in cardiac preload following each round of fluid infusion. This study aimed to assess the relationship between stroke volume variation (SVV) and stroke volume during major abdominal surgery using arterial pulse contour analysis by removing data of stroke volume affected by these factors. Methods: Eighty-three patients who underwent major abdominal surgery received 8 ml/kg boluses of either Ringer’s acetate or 6% hydroxyethyl starch 70/0.5 solution over the course of 30 minutes. Stroke volume index (SVI) and SVV were obtained using the FloTracTM/VigileoTM system (Version 3.02). Patients were classified according to values of absolute changes of SVV (ΔSVV, %) and relative changes of SVI (ΔSVI, %) following fluid bolus infusion. For each patient, ΔSVI was linearly regressed against SVV at different time points during the 60 minute period after initiation of bolus infusion. The relationship between SVV and ΔSVI was examined using the angle (radian) of the slope of ΔSVI against SVV. Results: Following fluid bolus infusion, SVI increased in 43% of patients due to an increase in cardiac preload (i.e., SVV decrease), and 33% of patients showed false SVI responses (ΔSVV<0 and ΔSVI ≤ 0, ΔSVV ≥ 0 and ΔSVI>0). Angle values for SVV-ΔSVI in 50 patients were consistent in the SVV range of 9%-20% (i.e., 1.2); a 4% decrease in SVV resulted in a 10% increase in SVI. Conclusions: One-third of patients undergoing major abdominal surgery showed false responses for SVI following fluid bolus infusion. After excluding false responses for SVI, the relationship between SVV and ΔSVI during major abdominal surgery was almost linear in the SVV range of 9%-20%, suggesting that SVV changes following fluid bolus infusion significantly contribute to fluid responsiveness.