Usefulness of stroke volume variation to assess blood volume during blood removal for autologous blood transfusion in pediatric patients.

Abstract

Dynamic variables based on the heart-lung interaction induced by positive pressure ventilation have not been shown to be useful in assessing cardiac preload in pediatric patients. To evaluate whether stroke volume variation (SVV) obtained from the FloTrac/Vigileo(TM) monitoring system can reflect a change in blood volume during the blood removal and fluid replacement protocol in acute normovolemic hemodilution (ANH). Sixteen pediatric patients scheduled for elective cranioplasty were recruited. In the ANH protocol, 10 ml · kg(-1) blood removal and fluid replacement were performed. SVV, heart rate, mean blood pressure, and femoral venous pressure were recorded. Differences at four time points (T0: baseline, T1: 5 ml · kg(-1) blood loss, T2: 10 ml · kg(-1) blood loss, and T3: after fluid replacement) during ANH were compared. The blood volume (EBV) was estimated as 70 ml · kg(-1) at T0 and decreased to 60 ml · kg(-1) at T2. Of the 16 patients, four were excluded and 12 were analyzed. Significant differences in all of the parameters were observed between each time point. The SVV significantly increased after the blood removal and decreased after the fluid replacement (P < 0.01, Bonferroni adjustment). In addition, the increases in SVV during the blood removal, T0-T1 and T0-T2, were 70% ± 40% and 159% ± 91%, respectively. SVV showed a significant correlation with EBV during the blood removal in ANH (rs = -0.68, 95% confidence interval -0.73 to -0.63, P < 0.001). Stroke volume variation obtained from the FloTrac/Vigileo(TM) monitoring system revealed a strong correlation with EBV during ANH without surgical stimulation. The usefulness of this device as an indicator of cardiac preload under hypovolemic or normovolemic conditions in children during surgery remains to be determined.