Anesthesia and analgesia
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Anesthesia and analgesia · Apr 2004
Randomized Controlled Trial Comparative Study Clinical TrialThe effects of spread of block and adrenaline on cardiac output after epidural anesthesia in young children: a randomized, double-blind, prospective study.
Epidural anesthesia is considered to be without significant hemodynamic consequence in young children. However, conversely to adults, few studies have investigated cardiac output. Using transesophageal Doppler monitoring of cardiac output, we prospectively investigated hemodynamic alterations in 48 children (median age, 22.5 mo) receiving sevoflurane general anesthesia combined with caudal or thoracolumbar epidural anesthesia. They were randomly assigned to receive 0.8 mL/kg of plain local anesthetic mixture (lidocaine 1% + bupivacaine 0.25% (50/50) + 1 microg/mL of fentanyl) or 1 mL/kg of the same mixture with 5 microg/mL of adrenaline. No significant hemodynamic alteration was elicited in caudal and thoracolumbar groups receiving the plain mixture except a moderate decrease in heart rate. Conversely, a mixture with adrenaline added provoked a significant decrease in mean arterial blood pressure by 14% and 17%, in systemic vascular resistance by 24% and 40%, and an increase in cardiac output by 20% and 34% in caudal and thoracolumbar groups, respectively. The adrenaline effect was greater by the thoracolumbar than the caudal approach. In young children, epidural anesthesia induces an increase in cardiac output only when adrenaline is added to local anesthetics, probably through its systemic absorption from the epidural space. ⋯ Epidural anesthesia may induce significant hemodynamic changes, well documented in adults. Using noninvasive hemodynamic monitoring in children, we reported an increase in cardiac output and a decrease in arterial blood pressure only when epinephrine was added to epidurally-injected local anesthetics.
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Anesthesia and analgesia · Apr 2004
Randomized Controlled Trial Clinical TrialEpidural infusions of ropivacaine and bupivacaine for labor analgesia: a randomized, double-blind study of obstetric outcome.
Studies have shown better obstetric outcome when ropivacaine 0.25% was used for labor epidural analgesia compared with bupivacaine 0.25%, but it is controversial whether there is any difference at smaller concentrations. In a prospective, double-blind trial, we randomized 350 ASA physical status I and II parturients with term cephalic singleton pregnancies to receive epidural labor analgesia using ropivacaine or bupivacaine. Analgesia was initiated with a 0.25% solution and maintained with a continuous infusion of a 0.1% solution with fentanyl 0.0002%. Supplementary boluses of 0.25% solution were given when requested. Labor was managed according to institutional standard labor ward protocols. Among patients who delivered vaginally, the duration of the first stage of labor was shorter in the ropivacaine group (median, 520 min; interquartile range, 377-745 min) compared with the bupivacaine group (645 min; interquartile range, 460-820 min; P = 0.009), but there was no difference in any other obstetric or neonatal outcomes. The mode of delivery was similar between groups, with operative (instrumental vaginal and cesarean) delivery rates of 61.8% (95% confidence interval, 54.4%-68.8%) in the ropivacaine group and 58.4% (95% confidence interval, 50.9%-65.5%) in the bupivacaine group (P = 0.72). ⋯ In a randomized-controlled study, we found no major outcome advantage of continuous epidural infusion of ropivacaine 0.1% with fentanyl 0.0002% over bupivacaine 0.1% with fentanyl 0.0002% for labor analgesia. Although ropivacaine was associated with a shorter first stage of labor, the relative difference is probably of limited clinical importance, and there was no difference in the mode of delivery.
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Anesthesia and analgesia · Apr 2004
Randomized Controlled Trial Clinical TrialInotropes improve right heart function in patients undergoing aortic valve replacement for aortic stenosis.
The administration of inotropes after aortic valve replacement (AVR) for aortic stenosis (AS) is controversial. Issues include the risk of left ventricular (LV) systolic outflow obstruction (LVOTO) and the proper treatment of diastolic dysfunction for patients in whom LV systolic function is often preserved and subsequently improved. In this study, we assessed the hemodynamic benefits of inotropes for patients undergoing AVR for AS. Thirty-four patients were prospectively randomized to one of three groups: epinephrine, milrinone, or placebo. Hemodynamic and echocardiographic data were obtained before and immediately after cardiopulmonary bypass (CPB). Data were also obtained before and after increases in ventricular preload to assess the effects of inotropes on diastolic function. The use of inotropes was associated with significantly larger increases in right ventricular (RV) (placebo, 0.5%; epinephrine, +9%; milrinone, +8%; P < 0.01) and LV (placebo, +7%; epinephrine, +18%; milrinone, +20%; P = 0.07) ejection fractions (EF) and cardiac output after CPB. Changes in cardiac output and index were more strongly correlated with changes in RVEF (r = 0.56, P < 0.01; r = 0.47, P < 0.01, respectively) than with LVEF (r = 0.22, r = 0.08). Of all patients receiving epinephrine or milrinone, only one (1 of 22) had a decrease in RVEF, whereas 6 of 12 patients receiving placebo had a reduction in RVEF from pre-CPB to post-CPB. Correspondingly, for LVEF, 1 of 22 patients receiving inotropes had a decrease in LVEF, whereas 3 of 12 placebo patients had a reduction in LVEF from pre-CPB to post-CPB. No patient had evidence of LVOTO. Inotropes improved hemodynamics after AVR for AS. This was attributable more to improved RV function than to changes in LV function. Although there were no changes in diastolic function, it is possible that this study did not allow significant timing to observe benefits of inotropes on diastolic function in this setting. ⋯ Compared with placebo, both epinephrine and milrinone similarly improved biventricular performance after aortic valve replacement, with a greater impact on right ventricular function. Choice of either inotropic drug should be driven by blood pressure and hemodynamic goals in this setting.
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Anesthesia and analgesia · Apr 2004
Randomized Controlled Trial Clinical TrialPostoperative epidural anesthesia preserves lymphocyte, but not monocyte, immune function after major spine surgery.
Extensive spine surgery is associated with postsurgical pain. Epidural pain therapy may reduce postoperative stress responses and thereby influence immune functions. In a randomized, controlled, double-blinded prospective trial, 54 patients received either conventional patient-controlled IV analgesia (PCIA; morphine 3 mg/15 min) or patient-controlled epidural analgesia (PCEA; 0.125% ropivacaine plus sufentanil 1 microg/mL at a base rate of 12 mL/h and bolus application of 5 mL/15 min). Circulating cytokines, C-reactive protein (CRP), cortisol, and cell-surface receptor expression of immune cells (cluster of differentiation [CD]14, human leukocyte antigen-DR, CD86, CD71, CD3, CD4, CD8, CD16, and CD19) were measured perioperatively to characterize immunological functions. PCEA, compared with PCIA, had no influence on altered levels of circulating cytokines (interleukin (IL)-6, IL-8, IL-10, tumor necrosis factor-alpha, monocyte chemoattractant protein-1, and macrophage inhibitory factor) or indicators of the stress response (CRP and cortisol). Also, no significant difference was found in monocyte numbers or their human leukocyte antigen-DR, CD86, or CD71 expression. In contrast, the postoperative decrease in B lymphocytes and T-helper cells was significant in the PCEA group. Natural killer cells decreased significantly in patients receiving PCEA compared with PCIA. Therefore, postoperative epidural pain therapy has no influence on monocyte functions but reduces natural killer cells and preserves B-cell and T-helper cell populations. Epidural analgesia thus influences the specific rather than the innate immune system and potentially blunts the postsurgical lymphocyte depression, which is relevant for infectious resistance. ⋯ Epidural analgesia affects the immune system. Postoperative epidural analgesia, compared with conventional IV opioid therapy, preserves lymphocyte rather than monocyte functions. An improvement of postoperative immune function by epidural analgesia therefore may improve postoperative resistance to infectious complications or to chronic pain states.
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Anesthesia and analgesia · Apr 2004
Randomized Controlled Trial Clinical TrialThe supraclavicular block with a nerve stimulator: to decrease or not to decrease, that is the question.
Portable nerve stimulators for nerve blocks have been available for more than 40 yr. It is generally accepted that seeking a motor response at low outputs increases the chances of success. It is customary to start the procedure at a higher current with the goal of finding the nerve. After an adequate response is elicited, the current is decreased before the local anesthetic is injected. However, how low is low enough and, for that matter, how high is too high have not been adequately determined. Our experience seems to indicate that, in the supraclavicular block, the type of response obtained is as important as the output at which it is elicited, provided that this current is not higher than 1 mA. In this context, it is theoretically possible that our initial seeking current of 0.9 mA could be an adequate injection current if it is combined with an appropriate response. We designed this study to test the hypothesis that a response of the fingers in flexion or extension, elicited at 0.9 mA, could be followed immediately by the local anesthetic injection. We did not intend to compare 0.5 and 0.9 mA as minimum stimulating currents but rather as currents able to elicit an unmistakable motor twitch. Sixty patients were randomly assigned to one of two groups. Group 1 (n = 30) was injected with a motor twitch in the fingers that was still visible at 0.5 mA. Group 2 (n = 30) was injected after a similar response to that in Group 1 was elicited, but at the initial output of 0.9 mA, without any further decrease. The blocks were injected with 40 mL of local anesthetic solution. One patient was excluded from the study for failing to meet protocol criteria. The success rate in the remaining 59 patients was 100%; success was defined as complete sensory blockade at the median, ulnar, and radial nerve territories of the hand that was accomplished in