Accuracy of stroke volume variation in monitoring changes in blood volume during laparoscopic surgery

Objective To evaluate the accuracy of stroke volume variation(SVV)in monitoring the changes in blood volume during laparoscopic surgery. Methods Forty ASA physical status Ⅰ or Ⅱ patients of both sexes, aged 40-64 yr, with body mass index ranged from 20 to 25 kg/m2, scheduled for elective laparoscopic surgery under general anesthesia, were studied.After induction of general anesthesia, baseline registrations of variables were obtained.After establishing pneumoperitoneum, 6% hydroxyethyl starch(HES 130/0.4)500 ml was infused over 30 min.Before pneumoperitoneum(T1), at 5 min after pneumoperitoneum(T2), immediately before volume expansion(T3)and at 3 min after volume expansion(T4), cardiac output(CO), cardiac index(CI), SV, stroke volume index(SVI)and SVV were monitored and recorded.The changing rate of CI(ΔCI)was calculated.The criterion for effective volume expansion was ΔCI ≥15%.The ROC curve for SVV in determining the volume expansion responsiveness was plotted, and the diagnostic threshold was determined.The area under the curve and 95%confidence interval were calculated. Results SVV was significantly lower at T2 than at T1.CO, CI, SV and SVI were significantly higher, and SVV was lower at T4 than at T3.The results of ROC curve analysis showed that a 9.2% SVV threshold discriminated between responders and non-responders with a sensitivity of 61% and a specificity of 50%, and the area under the curve(95% confidence interval)was 0.567(0.378-0.757). Conclusion SVV is not a suitable index in monitoring the changes in blood volume during laparoscopic surgery. Key words: Stroke volume; Hypovolemia; Monitoring, intraoperative; Pneumoperitoneum, artificial