Correlation between stroke volume variation and blood volume during hypovolemia

Objective To investigate the correlation between stroke volume variation (SVV) and blood volume during hypovolemia.Methods Twenty ASA Ⅰ or Ⅱ patients,aged 20-64 yr,with body mass index 20-30 kg/m2,scheduled for elective orthopedic operation,were studied.Anesthesia was induced with dexamethasone,midazolam,propofol,fentanyl and cisatracurium and maintained with sevoflurane,fentanyl and cisatracurium.The patients were tracheal intubated and mechanically ventilated.HR,MAP,CVP,arterial pressure-based cardiac output (APCO),SVV,systemic vascular resistance (SVR) and cardiac index (CI) were recorded 5 min after tracheal intubation.Blood was taken from central vein at a rate of 30-50 ml/min,the volume was 5％ of the whole blood volume and the haemodynamic parameters mentioned above were recorded after the haemodynamics was kept stable for 5 min.Blood was taken again as the method mentioned above and the haemodynamic parameters were recorded.6％ HES 130/0.4 was then infused at 50-70 ml/min via right internal jugular vein,the volume was equal to 5 ％ of the whole blood volume and the haemodynamic parameters were recorded after the haemodynamics was kept stable for 5 min.Fluid replacement was performed again using the method mentioned above and the haemodynamic parameters were recorded.Linear correlation of the change in blood volume (difference between the blood volume at each time point and the baseline value) with dSVV (difference between the value monitored at each time point and the baseline value) was analyzed.Results There was significant change in SVV,APCO and CI after each change in blood volume ( P ＜ 0.05 or 0.01),while there was not always significant change in HR,MAP,CVP and SVR after each change in blood volume.The change in blood volume was negatively correlated with dSVV ( r =- 0.875,P ＜ 0.01 ).Conclusion There is high correlation between SVV and blood volume during hypovolemia and SVV can reflect the change in blood volume accurately and be used for volume therapy during hypovolemia. Key words: Hypovolemia; Stroke volume; Vascular capacitance