Responsiveness of stroke volume variation and central venous pressure during acute normovolemic and hypervolemic hemodilution / 中华医学杂志(英文版)

<p><b>BACKGROUND</b>Stroke volume variation (SVV) is a robust indicator of fluid responsiveness during volume change. We compared the sensibility of SVV by Vigileo/Flotrac to central venous pressure (CVP) when volume changes in patients undergoing intraoperative acute normovolemic hemodilution (ANH) and acute hypervolemic hemodilution (AHH).</p><p><b>METHODS</b>Forty patients were randomly divided into an ANH group (n = 20) and an AHH group (n = 20). All patients received general anesthesia and were mechanically ventilated. Data were collected from 7 different time-points in the ANH group: baseline, after withdrawal of 5%, 10%, and 15% of the estimated blood volume (EBV) and after replacement with an equal volume of 6% hydroxyethyl starch 130/0.4 (HES) in 5% EBV increments to baseline. There were four time points in the AHH group: baseline, after 5%, 10%, and 15% expansion of the EBV with 6% HES. At each time-point, CVP, SVV and other hemodynamic parameters measurements were obtained.</p><p><b>RESULTS</b>After removal of 10% and 15% EBV, SVV significantly increased from 10.9 ± 3.0 to 14.1 ± 3.4 and 10.9 ± 3.0 to 16.0 ± 3.3 (P < 0.01), and returned to a final value of 10.6 ± 3.4 after volume replacement. The CVP value was unchanged after removal and replacement of 15% of the EBV. There were no significant changes in SVV after 5%, 10% whereas there was a significant reduction after 15% (8.2 ± 1.7) expansion of the EBV compared with baseline (9.9 ± 1.8) (P = 0.033). However, there was a significant increase in CVP after 10% (10.3 ± 2.4), 15% (11.3 ± 2.2) expansion of the EBV compared with baseline (8.2 ± 2.7) (P < 0.01).</p><p><b>CONCLUSION</b>SVV is a more sensitive parameter for volume than CVP during hypovolemia, on the contrary CVP is more sensitive than SVV during hypervolemia.</p>

Effects of propofol anesthesia and sevoflurane anesthesia on the differentiation of human T-helper cells during surgery / 中华医学杂志(英文版)

<p><b>BACKGROUND</b>Surgical stress causes a helper T-cell type 2 (Th2)-dominant status and disturbs the Th1/Th2 cytokine balance. Anesthesia can suppress the stress response to surgery, therefore it may inhibit the imbalance in the Th1/Th2 ratio. In this study, we assessed if propofol anesthesia and sevoflurane anesthesia influence the Th1/Th2 cytokine balance, and which anesthesia method better attenuates this ratio.</p><p><b>METHODS</b>Twenty-eight patients with an American Society of Anesthesiologists (ASA) physical status of I undergoing laparoscopic cholecystectomy were selected. They were randomly allocated into two groups of 14. Group 1 received propofol anesthesia by a target-controlled-infusion (TCI) pump and group 2 received sevoflurane anesthesia. Non-invasive blood pressure, heart rate, and end-expiration CO2 partial pressure were monitored during anesthesia. The depth of anesthesia was measured using the bispectral index (BIS), and maintained between 50 and 60. During surgery we adjusted the doses of propofol and sevoflurane according to the BIS. Samples of peripheral blood were taken before the induction of anesthesia (T1), after the induction of anesthesia (T2), at the beginning of surgery (T3), at the end of surgery (T4) and on the first day after surgery (D1). Blood samples were analyzed to give the Th1/Th2 ratio and plasma level of cortisol.</p><p><b>RESULTS</b>Non-invasive blood pressure, heart rate and end-expiration CO2 partial pressure were not notably different in the two groups. At T4, the percentage of T1 cells was higher in group 1 and had statistical significance (P < 0.05). The percentage of T2 cells was not significantly different in the two groups. At T4, the difference in the Th1/Th2 ratio was significantly different. At T3, T4, and D1, the plasma level of cortisol was lower in group 1 (P < 0.05).</p><p><b>CONCLUSION</b>Compared with sevoflurane, propofol can preferably promote Th cells to differentiate into Th1 cells and inhibit surgical stress. Propofol may therefore be immunoprotective for such patients.</p>

Effect of midazolam pretreatment on propofol sedation by closed-loop TCI during epidural anesthesia / 中华麻醉学杂志

Objective To compare the effect of midazolam pretreatment on propofol sedation using closed-loop target-controlled infusion (TCI) between two age groups - the adult and the aged. Methods Forty-eight ASA Ⅰ-Ⅱ patients of both sexes weighing 45-81 kg undergoing elective lower abdominal or lower extremity operation under epidural anesthesia were divided into two age groups : (A) the adult group (18-39 yrs) and (B) the aged group (66-79 yrs). The two groups were further divided randomly into 2 subgroups : midazolam subgroup ( n=12) received midazolam 0.04 mg?kg-1 10 min before propofol TCI and placebo subgroup ( n = 12) received normal saline instead of midazolam 10 min before propofol TCI. The patients were unpremedicated. An intravenous line was established before operation, which was connected to a TCI system comprising a Graseby 3500 infusion pump and a closed-loop TCI automatic control system. BP, HR, SpO2 and BIS were continuously monitored during operation. During epidural anesthesia the patients were sedated with propofol administered by TCI. The initial target blood concentration of propofol was set at 1.5?g?ml-1 . The level of sedation was assessed by OAA/S scale (5 = alert,0 = no response to prodding). The target blood propofol concentration was then increased or decreased in 0.5?g?ml-1 increment to maintain OAA/S score at 3. The BIS value at this level of sedation (OAA/S=3) was used as feedback in controlling TCI of propofol. The induction dose and the total dose of propofol, induction time and emergence time (OAA/S=5) were recorded. Results Midazolam premeditation significantly reduced the induction dose and total dose of propofol, shorten the induction time and prolonged the emergence time compared with placebo in both groups, especially in the aged group (P