FloTrac/Vigileo Predict Hypotension In Beach Chair Position During Shoulder Arthroscopy

Objective:To evaluate the values of CI, stroke volume index(SVI), stroke volume variation (SVV), and MAP measured with FloTrac/Vigileo system in supine position on predicting hypotension in beach chair position(BCP) during general anesthesia.Methods:One hundred healthy adult patients aged 18-65 years who were undergoing elective arthroscopic shoulder surgery were enrolled. This study included two phase. In the first phase,50 patients were placed in beach chair position 5 minutes after anesthesia induction, CI, SVI, SVV and MAP were measured with FloTrac/Vigileo system and recorded at the following time points-pre-induction,5 min after anesthesia induction,1 min after BCP,5 min after BCP and 10 min after BCP. Patients were classified into two groups as the hypotension group and the non-hypotension group according to the development of hypotension. Hypotension defined as any hypotension between adopting the BCP and the first 10 min in BCP. Receiver operating characteristic(ROC) curves of MAP, CI, SVI and SVV were adopted to predict hypotension, and their predict abilities were also investigated. For each variable, a cut-off value was assessed according to sensitivity and specificity. In the second phase, another 50 patients were enrolled. At 5 min after anesthesia induction, patients were classified into two groups according to the cut-off value of the hemodynamic variables. Then additional volume therapy was performed for high risk group. MAP and HR in BCP were compared in the two groups.Results:In the first step,20 patients developed hypotension after being moved from the supine to the BCP. The areas under the ROC curves for pre-induction values of CI, SVI and post-induction value of CI, SVI, SVV before a positional change were 0.774 (0.644-0.905; P< 0.05),0.761 (0.630-0.892; P< 0.05),0.763 (0.632-0.893; P< 0.05),0.799 (0.677-0.922; P< 0.05),0.844 (0.739-0.949; P<0.05), respectively. In the second step,5 min after anesthesia induction, the H group (SVV>15.5%) patients were infusion. The two groups had no significant difference in the MAP, HR, CI, SVI and SVV in the BCP.Conclusion:The values of CI and SVI before induction as well as the values of CI, SVI and SVV after tracheal intubation, which were obtained by FloTrac/Vigileo system before changing the position of patients, could predict hypotension in the BCP during shoulder arthroscopy under general anesthesia. For the patients whose SVV were higher than 15.5% after tracheal intubation during general anesthesia, infusion therapy can reduce the incidence of hypotension in the BCP.