Accuracy of stroke volume variation in monitoring blood volume during one-lung ventilation in patients undergoing thoracoscopy operation

Objective To evaluate the accuracy of stroke volume variation (SVV) in monitoring blood volume during one-lung ventilation in patients undergoing thoracoscopy operation. Methods Twenty-two ASA Ⅰ or Ⅱ patients ( 12 male, 10 female) aged 18-60 yr undergoing thoracoscopy operation under general anesthesia were studied. Anesthesia was induced with midazolam, sufentanil, propofol and rocuronium and maintained with TCI of propofol and remifentanil and intermittent iv boluses of vecoronium. Robertshow double-lumen endobronchial tube was inserted. Correct position of the tube was verified by fiberoptic bronchoscopy. The patients were mechani40 mm Hg. Radial artery was cannulated and connected to FloTrac pressure transducer and Vigileo monitor. A loading dose of 6% HES 5 ml/kg was infused over 10 min. MAP, HR, CO and SVV were recorded before and at 3 min after loading dose. The change rate of SVV (SVV) and CI (△CI) were calculated. Increase in CI by 11% was considered effective volume expansion. The ROC curve for SVV in determining the volume expansion efficacy was plotted. The area under the curve for SVV and 95% confidence interval were calculated. Results (1) CO were significantly increased while SVV decreased after a loading dose of HES. (2) During two-lung ventilation 12 patients responded to the 6% HES loading dose.SVV correlated with△CI ( - 0.710, P ＜ 0.05). The volume expansion efficacy was determined by SVV 11.5 % (sensitivity = 82 %, specificity = 92 % ). The area under the curve for SVV and 95% confidance interval were 0.880 (0.580-0.987). (3) During one-lung ventilation 11 patients responded to the 6 % HES loading dose. SVV correlated with CI ( - 0.668 , P ＜ 0.05). The volume expansion efficacy was determined by SVV 9.5 % ( sensitivity = 77 %, specificity = 63 % ). The area under the curve for SVV and 95% confidance interval were 0.971 (0.917-1.024). Conclusion One-lung ventilation does not alter the ability of SVV in monitoring blood volume in patients undergoing thoracoscopy operation. Key words: Stroke volume; Vascularcapacitance; Respiration,artifical